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They’re Either Simple and Obvious — or They’re Not

We’ve talked before about many of the geometric parameters that appear on drawing specifications, as well as some of the methods used to measure and inspect parts such as the precision metal components we make here at Metal Cutting Corporation. What we’ve only lightly touched on, however, are some of the challenges (dare we say, headaches?) involved in the calibration standards for various tools used in our business as well as by our customers.

Getting the Terminology Straight

Calibration standards can be simple and obvious — or they can be not simple and obvious at all. That’s because while, in theory, calibrating is absolute, there are many reasons why it is not exactly absolute. Even the shared assumptions about calibration standards are not without challenges. For instance:

  • While there are accepted temporal intervals, technically a device could be out of calibration minutes after it has been calibrated.
  • The traceability of the documents used for calibration is normally tracked back to a standard established by the National Institute of Standards and Technology (NIST); however, there are some circumstances where there simply are no NIST standards for calibration.

Measuring equipment is almost always calibrated, but there are certainly functional aspects of manufacturing equipment that need to be within specifications and therefore need to be calibrated. However, even the term calibration is subject to some interpretation: When someone says they are doing a calibration, are they actually performing some action to bring a device back into specification? Or by “calibrating,” do they simply mean they are checking devices to see if they are still functioning within the specified tolerance according to the calibration standards?

For example, here at Metal Cutting, when we calibrate our ovens, we are checking to make sure they are reading temperatures properly. If an oven is not working correctly, it is deemed out of calibration, and we will repair it and then perform the temperature calibration procedure again. While ovens cannot be sent out to be calibrated, other specialized tools we use are regularly sent out for calibration, with the purpose of bringing them back into specification. This might involve a measurement equipment vendor cleaning a device or programming it to measure in a certain way. For this category of equipment, calibration is more akin to rebuilding than adjusting.

Not All Calibration Standards Are Straightforward

For some things, it is simple to imagine the objects or concepts that serve as the basis for the established calibration standards. For example, it’s easy to get traceable NIST calibration standards for parts that are 1.0” (25.4 mm) long or 0.04” (1 mm) in diameter. However, it can be difficult to get a traceable standard for a part that is very long or a diameter that is very large or very small. For instance, a standard that is 2 meters long or 10 microns in diameter is simply too difficult to handle, for opposite reasons. And what about calibrating for electrical resistance, such as the ohm resistance of deionized water? There are techniques and methods for calibrating all of these; however, they are not as simple as calibrating for easy-to-handle lengths and diameters.

In the work we do with specialty metals here at Metal Cutting Corporation, we are often asked to ensure there are no cracks or voids in the metal we are either sent to process or we ourselves purchase and supply on behalf of our customers. Eddy current testing (ECT) is a familiar and interesting method we use that involves subtle techniques to inspect metal parts for surface flaws such as cracks. However, one truism about this method that can be hard for customers to appreciate is there is no NIST traceable calibration standard for ECT; there is no crack standard object or even a concept that can be used to set the ECT parameters such as frequency, amplitude, and sensitivity.

Are there other parameters for which there are no obvious calibration standards? Please leave a comment below to tell us about your experience.

Other Dimensional Challenges

Manufacturers all want calibration to be an independent reference of an immutable standard. However, all calibration involves some dependency between the NIST standard that exists in a vault and everything that is measured thereafter down the supply chain. So, whether it is an A2LA lab relying on their reference back to the object in the vault or a manufacturer that relies on objects that are referenced back to the independent lab’s object, there is always a series of contingencies in the execution of any calibration system, as well as tolerances in the system.

For example, the impact of stacked tolerances must be considered. If you send a piece of equipment out for calibration, you must remember to account for the stacking of the tolerance of the device being calibrated plus the tolerance of the pin used to calibrate the device and the tolerance of the lab that performs the task.

An issue that frequently comes up with calibration standards is, how many decimals out (how many zeros) should the calibration be? Here at Metal Cutting we use a Class XXX pin gage with a tolerance of 0.000020″ (0.000508 mm) to calibrate something with a much looser tolerance, such as a hand micrometer that goes out to 0.00005″ (0.00127 mm). Another interesting dimensional issue is that if an A2LA lab measures an object with a nominal of 1.000000″ to be 1.000003″ using their NIST-traceable equipment, then 1.000003” becomes the new normal — that is, it becomes the new size for calibrating measuring equipment that reads out to six decimal points.

Additionally, two different people might measure a part, each using a calibrated device that is in perfect working order and within the confines of the specified tolerance, and yet there can still be a difference in their measurements. Perhaps one is using a device calibrated to the higher end of the tolerance range, while the other is using a device a calibrated to the lower end. Especially with precision parts having very small measurements, this is another potential calibration issue, requiring corroboration that both are not just measuring with same devices, but also that they are calibrated using the same method and to the same tolerance. (You can read more about whether calibrated measuring is consistent measuring in our blog 7 Steps to Ensuring Your Measured Results Are in Spec.)

Three Distinctions in Calibration Standards

In the end, you might say there are really three distinctions in calibration standards:

  • The obvious standards, such as NIST traceable calibrated pins for pass-fail inspection of lengths or diameters
  • The not-so-obvious, such as those for temperature and other characteristics for which there are no objects that define the standards
  • Those things for which there simply are no calibration standards at all, such as ECT

Here at Metal Cutting Corporation, where every day we produce thousands of small metal parts, these considerations are vital to maintaining our Quality Management System (QMS) standards so that we can meet our goal of delivering high-quality precision parts that meet your specifications.

Picking the right manufacturing partner will not only help you achieve the quality you want, but also help to ensure that your production costs stay within budget. For tips on finding the best partner for your metal fabrication needs, download our free guide, 7 Secrets to Choosing a New Contract Partner.

This week’s blogger, Josh Jablons, is the President of Metal Cutting Corporation.

The post The Quandaries of Calibration Standards appeared first on Metal Cutting Corporation.

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Controlling Feature Variation in Two vs. Three Dimensions

You might recall that in our last blog, we talked about circular runout versus total runout, the first of which controls variation of circular features in a particular cross section of a part, while the second controls variation in the entire part surface. Similarly, we get asked about two more GD&T features that are sometimes called out on engineering drawings — the profile of a line versus profile of a surface, our topic for this week’s blog.

What Is Profile of a Line vs. Profile of a Surface?

Generally applied to parts that have varying cross sections or to specific cross sections that are critical to functionality, GD&T profile of a line controls individual lines of a feature, usually having a curved shape. An example of where profile of a line might be applied is a part feature that curves in multiple axes at once, which is, of course, common for Swiss-style automatic lathe machining but also possible with in-feed centerless grinding. When called out on a feature such as a radius on a part, profile of a line indicates how much a particular cross section of that feature can vary from a true curved radius.

Like circular runout, profile of a line looks at a cross section — in this case, at any point along the linear surface, setting a tolerance zone on either side of the profile. The profile of a line tolerance zone falls within two parallel curves that follow the contour of that profile. Since measurements might need to be taken at multiple cross sections of a part, the number of cross sections to be measured is usually included on the drawing along with the called out tolerance.

GD&T profile of a surface is a three-dimensional version of the profile of a line — so, like total runout, it does not pertain to just a cross section, but instead controls the entire feature surface (again, usually having a curved shape) with the goal of making sure every point falls in the tolerance zone. In other words, with profile of a line vs. profile of a surface, the latter looks only at a specific cross section while profile of a surface looks at how measurements vary from one cross section to the next.

The profile of a surface tolerance zone is the range that falls within two parallel curves following along the contour of the surface profile across the entire length of the surface. Typically, it might be called out where you have a surface that curves in multiple axes at once and where you want to ensure every point falls within a specific tolerance. When profile of a surface is called out on a curved surface such as a fillet on a welded part, the entire surface where the radius is has to fall within the tolerance. Surface profile is also commonly called out for cast parts with curved surfaces where the amount of variation needs to be controlled, as well as for complex designs where two parallel surfaces of the same shape must fit together.

Sometimes both profile of a line and profile of a surface are called out; in these cases, the line profile tolerance will be tighter than the surface profile tolerance. This ensures the part will be tightly controlled along any particular cross section while also meeting the looser surface requirement.

Profile of a Line vs. Profile of a Surface in Precision Parts

Although profile of a line and profile of a surface can apply to Metal Cutting’s world of lathes and grinding work, these GD&T features are more commonly applied when we do milling work. However, our in-feed grinding, profile grinding, and CNC grinding techniques can be used to create trapezoidal features or curves on circular parts such as pins or rods.

With in-feed centerless grinding and Swiss-style automatic lathe turning, it is very unusual to have non-uniform surfaces around a single point on a circumference. Along a linear length, we can have all different types of shapes, such as tapers, shoulders, screw threads, and so on. Complex features such as flats, ovals, and ellipses are possible with the use of special techniques, but oblong and circular features are more appropriate for milling and 3D additive manufacturing.

With lathes and grinding, if your machines are out of true or the spindles are bad, it can result in chatter or distortions in the cross section representing the profile of a line. With the profile of a surface and features such as tapers, shoulders, straight lines, and so on, customers want the surface to be smooth. However, if your machines are in bad condition and variations are being ground into the parts, that is when shapes become complex in a way that is not intentional or what customers want.

Therefore, it is our goal to make the profile of a surface as consistent as the profile of a line. The more perfectly a machine is running, the less complex that shape actually will be because it all points around a 360 circumference, so it will be equivalent to the 2D tolerance.

Profile in the Polishing Process

When we receive a drawing, it is generally a two-dimensional representation, but we know that our customer wants (and that we need to make) a three-dimensional part. Remarkably, our in-feed grinding is capable of grinding flat, single-plane sections into complex, round parts with a diameter. So, the complexity that is implicit in the profile of a surface called out on a drawing is fully understood by us, in terms of not only the tolerance that needs to be kept, but also the parameters that need to be maintained while making the ground finish or turned surface.

For complex shapes — whether we are talking about the final product or the construction of a mold — profile of a line vs. profile of a surface also comes up in an unusual circumstance: when we do mechanical polishing. In this process, we are not only creating ultra-smooth surfaces, but also removing material such as sharp edges, corners, and intersections. It may not be a lot of material, but for our customers and their precision metal parts, even the smallest dimensions matter. Therefore, the profile of a line tolerance and profile of a surface tolerance become very important to the control we exert in our production process.

When we polish a 3D part, we must also take into consideration the amount of material removed during the final polishing process when a 3D or molded part is being made by an upstream or downstream supplier, in order that the supplier accounts for that final material removal in the design process.

Here at Metal Cutting Corporation, our goal is to deliver high-quality precision parts that meet your specifications for profile of a line, profile of a surface, and other features while also keeping your production costs within budget. For tips on how to improve the accuracy of your specs and project quotes, to help you manage costs and get the results you need, download our free guide, How to Fine-Tune Your Quote Request to Your Maximum Advantage: Frequently Asked Questions in Small Parts Sourcing.

This week’s blogger, Josh Jablons, is the President of Metal Cutting Corporation.

The post Profile of a Line vs. Profile of a Surface appeared first on Metal Cutting Corporation.

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What ECT Can Find Vs.‭ ‬What It Cannot

In our previous blog,‭ ‬we touched on some‭ ‬interesting‭ ‬facts about‭ ‬the eddy current testing procedure.‭ ‬This time,‭ ‬we’ll‭ ‬take a closer look at some of the variables that‭ ‬have an effect on‭ ‬eddy current testing,‭ ‬what it can find,‭ ‬and‭ ‬what it cannot find.

Not All Defects Are Detected Equally

The types of defects in a material determine the effectiveness of the eddy current testing procedure.‭ ‬For instance,‭ ‬discontinuities and defects that are parallel to the flow of the eddy current‭ ‬— such as radial or point cracks‭ ‬— will not be detected by most eddy current testing equipment, which works best for defects that occur along the length of a part. To find a single point crack using a radial coil requires a specialized setup,‭ ‬with multiple probes that rotate around circumference of the part.‭ ‬In addition,‭ the morphology of ‬‬a crack is both a surface defect and an internal defect; this means the eddy current testing procedure‭ ‬needs to filter multiple readings.

Internal defects that exist solely in the interior of metal parts are more difficult or even impossible to detect,‭ ‬especially with thicker materials,‭ ‬due to the skin effect‭ ‬— the tendency for internal defects to produce an exponentially weaker eddy current signal than external defects.‭ ‬The technical term for the‭ ‬intensity of the signal on the depth of a thicker part is‭ ‬depth of penetration.‭ ‬At Metal Cutting Corporation,‭ ‬our ECT system has a depth of penetration of about‭ ‬0.050‭”‬ (1.27‭ ‬mm‭)‬ for molybdenum and tungsten.

‬Eddy Current Testing Procedure For Non-Radial Defects

At Metal Cutting,‭ ‬our focus is‭ ‬on draw lines and elongated grain structures.‭ ‬Draw lines are‭ ‬more‭ ‬common and‭ ‬can‭ ‬occur in many different‭ ‬types of‭ ‬metal materials.‭ ‬Draw lines can be‭ ‬either‭ ‬occlusions in the metal that got pulled through the die or defects of the die that score and damage the metal as it is being drawn.‭ ‬In our world of refractory metals,‭ ‬such as molybdenum and tungsten,‭ ‬the materials are formed through‭ ‬powder metallurgy and are sintered and then‭ ‬swaged and drawn‭; ‬therefore,‭ ‬these metals are‭ ‬never in a molten state,‭ ‬and their elongated grain structures are entwined.‭ ‬However,‭ ‬there is potential at the grain boundaries for gaps that are in the longitudinal direction.

Conveniently,‭ ‬the eddy current testing procedure,‭ ‬which involves passing a long part through a‭ ‬round, hollow coil,‭ ‬is ideal‭ ‬for detecting these types of defects.‭ ‬What ECT‭ ‬struggles with is radial cracks,‭ ‬which are highly transient‭ ‬— appearing and disappearing quickly.‭ ‬The cross section where the crack is might be so small that the eddy current cannot detect it.‭ ‬For example,‭ even ‬if you have a wire with as much as a‭ ‬90%‭ ‬radial crack,‭ ‬it would be tricky to detect the crack unless you have eddy current testing equipment with specialized rotating multi-coils.

Depth‭ ‬Perception But Not‭ ‬Depth Measurement

Even when an internal crack can be detected,‭ ‬the‭ ‬actual‭ ‬depth of‭ ‬the crack cannot be measured accurately using the eddy current testing procedure.‭ ‬The oscilloscope of the eddy current tester will show a graphic representation of a crack feature,‭ ‬analogous to a polar chart‭; ‬as with a polar chart,‭ ‬you can zoom in or zoom out on the graphic representation.‭ ‬However,‭ ‬the graphic or numerical representation does not correlate to the dimensions of the crack.

Although the depth of an internal crack cannot be measured with the eddy current testing procedure,‭ ‬at Metal Cutting we often receive drawings specifying,‭ ‬for example,‭ ‬that a crack cannot be greater than‭ ‬10%‭ ‬of the diameter or that the customer will not accept a defect greater than‭ ‬0.001‭”‬ (0.0254‭ ‬mm‭)‬.‭ ‬The challenge is,‭ ‬how do you operationalize those requirements‭? ‬Both are difficult without having any parameters described.‭ ‬The percentage of diameter generally refers to depth,‭ ‬but‭ “‬a defect no greater than‭”‬ is often not defined as depth,‭ ‬width,‭ ‬or even length.‭ ‬While after further inquiry we almost always discover that it does not refer‭ ‬to length,‭ ‬width and depth are very important variables in the eddy current testing procedure,‭ ‬and‭ ‬finding defects as small as 0.001″ in any dimension is very challenging.

The good news is,‭ ‬the‭ ‬depth‭ ‬of an internal crack‭ ‬can be estimated by using the phase of the‭ ‬ECT‭ ‬signal and other little tricks we‭ ‬at Metal Cutting‭ ‬have learned through years of experience‭ ‬working with the eddy current testing procedure.‭ ‬Our system uses stationary probes‭ ‬— something we keep in mind when using reference samples to find the optimal settings for‭ ‬frequency,‭ ‬amplitude,‭ ‬phase,‭ ‬sensitivity,‭ ‬filtering,‭ ‬and other variables that are part of the recipe for the eddy current testing procedure‭ — ‬and we‭ ‬also have a two-coil setup so that we can use absolute and differential probes at the same time.

Other‭ ‬Factors‭ ‬That Influence The Eddy Current Testing Procedure

There are a number of other‭ ‬variables that have an impact on the eddy current testing procedure and the results it produces.

Properties of the‭ ‬Test Material

The properties of the material being tested can affect‭ ‬the‭ ‬flow of eddy‭ ‬currents.‭ ‬For instance,‭ ‬the eddy current testing procedure can struggle with non-pure materials that are combinations of metals with dissimilar electrical properties.‭ ‬The metals in an alloy generally are not a perfectly homogeneous distribution throughout the entire length of material,‭ ‬so it can be difficult to set a baseline for eddy currents.‭ ‬Additionally,‭ ‬even pure element metals will contain trace elements,‭ ‬such as non-volatile residues‭ (‬NVRs‭)‬ of well less than‭ ‬1%,‭ ‬which will show‭ ‬up as defects.‭ ‬These types of material variations create noise that forces us to reduce the actual sensitivity we can utilize, regardless of the theoretical sensitivity of the eddy current testing procedure.

Material Surface Finish

Even though people like to think of eddy current testing as being like an x-ray,‭ ‬the reality is‭ ‬that‭ ‬it is not.‭ ‬Unlike x-rays,‭ ‬the entirety of the material being tested has an effect on the electrical properties of‭ ‬the eddy current testing procedure,‭ ‬and the surface finish‭ ‬can throw off the‭ ‬ECT results.

Because a rougher surface finish produces noise,‭ ‬it‭ ‬creates a need to adjust the eddy current testing equipment settings to compensate,‭ ‬so that surface finish noise is not mistaken for a material defect.‭ ‬So,‭ ‬for example,‭ ‬if we are being asked to identify defects greater than‭ ‬0.001‭”‬ (0.0254‭ ‬mm‭)‬,‭ ‬it becomes a major threshold problem. For example, a defect that is 10 times greater than the area surrounding it will literally stand out. But what if a defect of‭ ‬0.001‭”‬ is surrounded by a rough surface finish consisting of grooves that are ‬0.0009‭”‬ (0.0229‭ ‬mm‭)‬ deep? Distinguishing that‭ ‬0.0001‭”‬ (0.00254‭ ‬mm‭) ‬variation will be really challenging for ECT.

‬Coil Fill Factor

To the naked eye,‭ ‬coil fill factor seems like a ratio between the OD of the material and the ID of the coil.‭ ‬However,‭ ‬more accurately,‭ ‬the‭ ‬fill factor is the ratio between the area of the coil and the area of the material.‭ ‬Determining‭ ‬the correct ratio between the coil and‭ ‬the material‭ ‬helps to ensure that the test‭ ‬sample will be able to move freely‭ ‬during scanning‭ ‬and‭ ‬the coil‭ ‬will generate‭ ‬the necessary‭ ‬eddy currents.

Position of‭ ‬the‭ ‬Material in‭ ‬the‭ ‬Coil

Ideally,‭ ‬the‭ ‬part to be tested‭ ‬will sit‭ ‬at the true center of the coil,‭ ‬but‭ ‬realistically it rarely can do so.‭ ‬Simple variations in material diameter,‭ ‬even within tolerance,‭ ‬affect the ability to place the part in the true center.‭ ‬Also,‭ ‬fixturing‭ ‬— both as originally designed and after wear from operation‭ ‬— can cause the true center to be more theoretical than actual.

Vibration

The vibration of the eddy current testing machine itself,‭ ‬as well as‭ ‬vibration of the feeding device that places the part inside the coil,‭ ‬causes noise that can interfere with the flow of eddy currents or create false signals that will be mistaken for defects in the test material.

‬Bottom Line on ECT‭?

None of these variables defeat the eddy current testing procedure,‭ ‬but they do mean it cannot be used for dimensional measuring.‭ ‬While‭ ‬the procedure can be used to estimate dimensions,‭ ‬obviously‭ ‬that does not produce the‭ ‬kind of‭ ‬accuracy‭ ‬you would get doing a true metallurgical sample and studying the specimen.‭ ‬Still,‭ ‬eddy current testing is‭ ‬a valuable tool that is utilized effectively by Metal Cutting Corporation to‭ ‬inspect‭ ‬materials for flaws‭ ‬and is‭ ‬an‭ ‬important‭ ‬part of our QMS standards‭ ‬— enabling‭ ‬us‭ ‬to‭ ‬deliver‭ ‬high-quality‭ ‬precision‭ ‬metal‭ ‬parts that meet‭ ‬customer‭’‬s tight specifications.‭

Return to this space‭ ‬in future weeks‭ ‬for more on‭ ‬eddy current testing and similar topics‭ ‬still to come.

This week‭’‬s blogger,‭ ‬Josh Jablons,‭ ‬is the President of Metal Cutting Corporation.

The post Variables That Affect the Eddy Current Testing Procedure appeared first on Metal Cutting Corporation.

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‬Is Precision Parts Manufacturing ‬3D‭ ‬Print-Ready?

The topic of 3D additive laser printing ‬of metal is ‬frequently in the news.‭ ‬So you might wonder:‭ ‬When is Metal Cutting Corporation going to talk about laser printing? ‬After all,‭ ‬we often talk‭ ‬about‭ ‬various other methods for making‭ ‬metal parts.‭

At Metal Cutting ‬we make parts that are very small,‭ ‬for our example here often with dimensions that are 1‭ ‬mm (0.039″) by‭ ‬2‭ ‬mm (0.079″),‭ ‬and we make a‭ ‬LOT of them.‭ ‬These parts don’t usually have a lot of complex features or inner voids.‭ ‬They might be a tube or they might be solid.‭

So, our question for the 3D laser printing experts is, ‬can you‭ ‬use 3D laser printing of metal for‭ ‬such large quantities of such small parts?

‭‬Basic‭ ‬Methods‭ ‬Of 3D Laser Printing Of Metal

To begin,‭ ‬let’s take a quick look‭ ‬at the‭ ‬three‭ ‬primary methods for‭ ‬3D additive laser printing of metal.

Direct Metal Laser Sintering (DMLS)

This most popular method basically ‬melts a‭ ‬2D design onto a flattened bed of powder,‭ ‬fusing the powder and‭ ‬then adding layer upon layer to build the‭ ‬object.‭ ‬DMLS allows heretofore impossible designs.‭ ‬However,‭ ‬the process is very slow and produces metallurgy that approaches but does not in every instance equal traditional fabrication. DMLS is also known as selective laser sintering‭ (‬SLS‭)‬ or selective laser melting‭ (‬SLM‭)‬.

Directed Energy Deposition (DED)

In this powder-fed method, a highly concentrated metal powder stream‭ ‬is‭ ‬slowly released‭ ‬through an extruder and‭ ‬is fused as it‭ ‬meets up with‭ ‬a laser,‭ ‬forming layers at the surface of the part.‭ ‬DED is highly accurate‭ ‬for‭ ‬3D‭ ‬laser‭ ‬printing‭ ‬of metal and is also used for‭ ‬repairing broken parts.‭ ‬This method is known as‭ ‬laser metal deposition‭ (‬LMD‭)‬.

Metal Binder Jetting

This method ‬involves‭ ‬applying‭ ‬a liquid binding resin onto a powdered metal material.‭ ‬The layers are,‭ ‬in effect,‭ “‬glued‭” ‬together and then sintered in a high-temperature kiln.‭ ‬This‭ ‬process‭ ‬is faster and less expensive than the other two methods‭; ‬however,‭ ‬the results are not nearly as strong or dense as the results you get with DMLS or DED.‭

‭Some Applications For Laser Printing Metal

Laser printing of metal has become popular for a number of applications.‭ ‬These include everything from prototyping‭ ‬to functional component parts‭ ‬in‭ ‬various‭ ‬industries,‭ ‬to mass customized production of‭ ‬everyday items such as‭ ‬‬jewelry‭ ‬and kitchenware.‭

Laser printing‭ ‬of metal‭ ‬is highly popular in dental and orthopedic implant applications.‭ ‬It allows these products to be customized to meet individual patient needs.‭ ‬(You can read more in our blog Polishing Metal Parts for‭ ‬3D Printed Medical Devices.‭) ‬Laser printing of metal is‭ ‬also‭ ‬a widely used for the aerospace industry.‭ ‬For instance,‭ ‬the next-generation‭ ‬LEAP jet engine has‭ ‬3D-printed fuel nozzles.‭

‭Some Common Mistakes

People make some incorrect assumptions when it comes to‭ ‬3D laser printing of metal.‭ ‬‬It sounds silly but bears noting that just because a product is designed using 3D CAD modeling does not make it‭ “3D print-ready‭”; ‬3D laser printing processes require unique post-processing.

‬As with any manufacturing method,‭ ‬the properties of the specific material to be used must also be considered. For example, one assumption is that laser printing of metal is a substitute for metal casting.‭ ‬On the contrary,‭ ‬laser is great for unique,‭ ‬complex parts that‭ ‬cannot be cast.‭ ‬The properties of a‭ ‬3D laser printed‭ ‬metal object are different from the properties of the‭ “‬same‭” ‬object when it is cast in metal.‭

‬Also,‭ ‬laser printing‭ ‬of metal‭ ‬parts designed for a process such as CNC milling would be very expensive. That is because subtractively produced parts have more mass and volume, and their designs are not optimized for the inherent advantages of 3D manufacturing — essentially, voids and lightweight, high-strength structures.

‭‬Advantages Of Laser Printing‭ Of Metal

From an engineer’s perspective, probably the most significant advantages of 3D laser printing of metal are:

  • The ability to produce fully enclosed voids and other features that are impossible to subtractively machine
  • Structures that produce extraordinary part strength and a lightweight design that was previously impossible to achieve

For an‭ ‬industry such as aviation,‭ ‬where reduced weight of an aircraft means lower fuel consumption,‭ ‬lightweight is an important‭ ‬goal.

From an application perspective, the most significant advantage of laser printing of metal would be the “mass customization” that 3D additive laser printing ushered into industries ranging from aviation’s replacement parts to dentistry’s crowns and bridges, to orthopedic and prosthetic innovations, and of course, the entire prototyping business. Some of these unique shapes could never be produced subtractively. Even for those that could be machined or cast at a lower per-piece cost, neither method could conceivably approach the almost instantaneous delivery times that 3D laser printing of metal has made possible.

Laser printing of metal‭ ‬also can reduce the amount of‭ ‬waste‭ ‬material in the production process.‭ ‬Where traditional subtractive cutting methods involve the removal of material to create a shape,‭ ‬3D laser printing of metal achieves a shape through the addition‭ ‬of just the needed material.‭

As long as the metal powder is available, ‬3D‭ ‬laser‭ ‬printing is flexible in terms of the metals it can use.‭ ‬They include‭ ‬titanium,‭ ‬stainless steel,‭ ‬Inconel,‭ ‬and cobalt chrome,‭ ‬as well as brass,‭ ‬copper,‭ ‬bronze,‭ ‬and precious metals such as gold,‭ ‬silver, and platinum. However, while the challenges of 3D laser printing in an inert atmosphere have been surmounted, it remains impossible to properly anneal certain metals. For example, while tungsten can be “constructed” via 3D printing, the resulting block of tungsten metal is too brittle to be usable.

‭Disadvantages Of Laser Printing For Metal Parts

Additive 3D laser printing is certainly famous for making the impossible possible, but what about precision? Is‭ ‬3D printing a good method for making small precision metal parts‭?

Let’s looks at DMLS,‭ ‬the most mature and well-developed method, where the important variables driving dimensional precision are:

  • The size of the powder particles‭
  • The height intervals of the elevator steps‭
  • The size of the laser beam‭

Each of these factors determines dimensional tolerances. Large metal powder particle size makes for larger steps. The height of each powder layer similarly determines that tolerances that can be achieved.
And probably the most important variable is the size of the laser.‭ ‬This is where a tiny beam gives you greater precision,‭ ‬and a larger beam produces more imprecise dimensions.‭ ‬The problem is,‭ ‬a smaller laser beam generates less heat‭ — ‬and that means it will take longer to do its job.‭ ‬So,‭ ‬you can have a part that is very precise and/or very small,‭ ‬but it is going to take much longer to produce.‭ ‬That,‭ ‬in turn,‭ ‬raises the cost.

There are other ways in which laser printing of metal is time-consuming.‭ ‬Again look at the very popular DMLS,‭ ‬where every part has a tiny point of attachment,‭ ‬like the tiny thread that keeps a wasp’s nest suspended from a porch.‭ ‬If you have‭ ‬10,000‭ ‬laser printed parts,‭ ‬that means you have‭ ‬10,000‭ ‬attachment points that must be separated.‭ ‬This task of separating from the base is usually accomplished using EDM‭; ‬but whatever method is used,‭ ‬doing it 10,000 times defeats most if not all of the additive advantages.

The reality is that‭ ‬true‭ ‬mass production‭ ‬is‭ ‬still‭ ‬not possible with 3D laser printing of metal.‭ ‬This makes it impractical‭ ‬and costly‭ ‬for‭ ‬producing tens of thousands of very small parts.‭ ‬In addition,‭ ‬there is the high upfront cost of the‭ ‬3D‭ ‭printer‭: at least‭ ‬$100,000 for some of the newest tabletops, which aim to disrupt the previous disruptors, up to over $1 million for the controlled atmosphere printers used with metals such as titanium or the giant enclosures required for machines designed to make aviation parts. ‬That high cost means‭ ‬whatever application laser printer is proposed for needs to “add” something really unique to “subtract” from the value of traditional metal fabricating methods.

‭What Does The Future Hold‭?

We don‭’‬t want you to think we are being stubborn or resistant to change.‭ ‬In fact,‭ ‬we‭’‬d like to give a shout-out to our friend Scott Cohen and his partner,‭ ‬David Bell,‭ ‬at New Lab.‭ ‬They know the future as well as anyone, and we don’t doubt that someone at New Labs will one day solve some of the problems we are seeing now.

While the development of desktop-sized‭ ‬3D laser printers‭ ‬— rather than huge,‭ ‬industrial-sized machines‭ — ‬will make the technology more accessible,‭ ‬we still don’t see laser printing of metal to be suitable for high volumes of small precision parts.‭ ‬In this case, small machines do not make for small parts. But of course, one day we may be proven wrong!

For some helpful tips on how to choose the best precision metal cutting method for‭ ‬your metal fabrication project,‭ ‬download our white paper‭ ‬‬*Choose with Confidence: Comparing 2-Axis Precision Cutting Methods*‭.

The post Facts About Laser Printing of Metal appeared first on Metal Cutting Corporation.

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Things ‬To ‬Consider When Evaluating The Method

Over time,‭ ‬we’ve reviewed many different ways of cutting metal‭ — ‬for instance,‭ ‬just last month we talked about some of the pros and cons of wire EDM‭ — ‬but there are more cutting methods than the ones we usually address.‭ ‬Case in point:‭ ‬We recently realized we have never talked about the Grand Canyon of cutting methods, waterjet abrasive cutting.‭

Modern waterjet abrasive machining has been‭ ‬evolving over the past‭ ‬30-plus years or so and includes some interesting techniques.‭ ‬You can certainly read more online from experts in the field‭ — ‬but for the moment,‭ ‬here are some of our observations about‭ ‬the‭ ‬waterjet‭ ‬method.

‬What Is Waterjet Abrasive Cutting?

Waterjet cutting has its roots in using water (‬although at comparatively low pressure) ‬to cut soft materials such as paper and even food,‭ ‬going back to the ‬1930’s.‭ ‬Over the years,‭ ‬high-pressure technology and equipment were developed and ‬fine-tuned, and today ‬waterjet abrasive machining is ‬another of the techniques used ‬for precision metal cutting.‭ ‬The classic applications for waterjet cutting are complex shapes cut ‬out of large-scale metal or composite material sheets, including very thick ones.

Basically,‭ ‬an abrasive waterjet cutting machine uses a high-pressure stream of water in combination with an abrasive,‭ ‬directing the stream onto a narrow line on the workpiece and removing material by eroding it.‭ ‬The‭ ‬addition of a‭ ‬granular abrasive‭ — ‬primarily,‭ ‬garnet‭ ‬powder‭ ‬is used‭ — ‬boosts the cutting ability of the high-PSI water stream.‭ ‬By adding the abrasive to the water at the nozzle,‭ ‬the waterjet can be switched between water-only and water with abrasive as needed‭; ‬this allows the machine to be used with water-only for positioning (also known in machining parlance as the “rapid”) and then with an abrasive for the workpiece.

The waterjet abrasive method is commonly grouped together with plasma cutting,‭ ‬oxy-fuel cutting,‭ ‬and laser cutting‭ because of their ability to make complex shapes cut in the C/Y axes of a large, flat sheet of material.‭ ‬Plasma cutting has the lowest operating costs but is the most brutal and makes the largest kerf; however, it is indispensable for certain cutting settings.‭ ‬Oxy-fuel‭ ‬cutting is a chemical reaction often described as rapid controlled rusting, but despite that pejorative description, it produces a smaller kerf and smoother ends and edges. Abrasive waterjet cutting has the advantages of not generating heat and the ability the cut through non-metallics with an even smaller kerf, albeit with some complications as described below. Laser cutting,‭ ‬the main challenger to waterjet in appropriate applications,‭ ‬produces the smallest kerf among these four methods and, of course, cannot be summarized in one sentence!

Are There Problems With Waterjet Abrasive Cutting?

As with ‬all precision ‬metal ‬cutting methods,‭ ‬waterjet abrasive machining has its trade-offs — ‬benefits and sacrifices that should be taken into consideration ‬when you are deciding whether to choose it as your cutting method.‭ ‬The following,‭ ‬in no particular order,‭ ‬are some of the potential ‬issues.

Voids,‭ ‬Tubes,‭ ‬Bundles, and ‬Honeycombs ‬Are ‬Problems

As with laser beams, the waterjet stream is most effective when it is most concentrated. Voids, as when cutting through tubing, will cause the stream to diffuse, rapidly losing its accuracy and cutting ability. Similarly, stranded or fibrous materials will act like honeycombs and can also “squirm” in the stream, refusing to be cut or resulting in a very poor cut.

‭‬Standoff Matters

The abrasive waterjet cutting nozzle exit needs to be just the right distance from the work piece that is being cut. The right standoff height to ensure optimal cutting is 1‭ ‬mm ‬(0.0394‭”‬) to ‬1.5‭ ‬mm ‬(0.0591‭”‬), but this creates two dilemmas. The first is a matter of practicality with 3D parts that simply don’t allow such proximity. The second, more universal consequence is that for precision dimensions, the waterjet kerf always has a taper shape. Remarkably, the taper varies, but it is always there.

Tolerance and ‬Bend

That taper mentioned above can wreak havoc on precision tolerances, with conical and barrel effects that modern machines will compensate for by “tilting” the nozzle, which sacrifices one side of the cut in favor of the other. The grain structure of the material being cut combined with the nozzle direction of travel “leaving behind” the stream of water causes the cut surface to show a bending pattern similar to waving a garden hose back and forth. This bending causes a slope in the cut.

‭‬Oh,‭ ‬Your ‬Nibs!

There is another situation analogous to why waterjet struggles to cut fibrous material, with some of the stream sliding around the material to be cut instead of going through the material: When the waterjet stream gets to the end of the cut path, part of the stream is now shooting through air, and like most things, the concentrated energy favors the path of least resistance. The can cause a defective end cut that is not a clean cut and is often called the nib.

‭‬Hazing of the Surface Finish

With waterjet‭ ‬abrasive ‬garnet blasting away at a ‬rate of ‬60,000‭ ‬PSI or more,‭ ‬the garnet powder can rough up or matte the finish of any surrounding,‭ ‬exposed material.‭ ‬This ‬hazing ‬might be strictly cosmetic ‬— or it may be functional if it affects the surface finish and the material‭’‬s‭ ‬Ra value.‭ (You can read more about surface finish and how different processes affect it in our blog Why Use a Surface Finish Chart?)

‭‬So Much‭ ‬Abrasive Debris In So Little Time

Here‭’‬s an amazing fact about ‬waterjet‭ ‬abrasive garnet:‭ ‬The average waterjet setting can produce ‬2‭ ‬pounds of wasted garnet power for every minute of cutting.‭ ‬Of course,‭ ‬the ‬amount of waste depends on the thickness of the cut,‭ ‬the material,‭ ‬and other factors.‭ ‬But as a rule of thumb,‭ ‬that means something that takes ‬15‭ ‬minutes to cut would produce ‬30‭ ‬pounds of abrasive garnet debris,‭ ‬mixed in with a whole lot of water.‭ ‬Thus,‭ ‬it becomes a major disposal issue.

Here‭’‬s another fact:‭ ‬During the waterjet abrasive cutting process,‭ ‬only about‭ ‬5%‭ ‬of the garnet powder is actually performing cutting action‭; ‬the balance is just part of the waterjet‭ ‬stream path.‭ ‬But interestingly,‭ ‬studies done in about‭ ‬2000‭ ‬found that after ejection,‭ ‬even though the garnet is not dulled from cutting,‭ ‬some of it is fractured.‭ ‬That makes it problematic to recycle those many pounds of garnet powder for reuse‭; ‬though not dull,‭ ‬the fractured media would not deliver the proper cutting action.

 ‬Not Tougher Than Tungsten

The ability of waterjet abrasive machining to cut is driven‭ ‬by many variables,‭ ‬but principal among them are the PSI and the hardness of the abrasive particles.‭ ‬For example,‭ ‬items such as paper or food are cut by waterjet alone, not by abrasive waterjet.‭ (‬After all,‭ ‬no one wants abrasive garnet powder in their cheese.‭) ‬But when you are using abrasive powders to cut materials such as metals,‭ ‬waterjet cutting requires the metal being cut to be softer than the abrasive‭ ‬that is‭ ‬being fed into the nozzle as part of the abrasive stream.

For us at Metal Cutting‭ ‬Corporation,‭ ‬where we cut a lot of tungsten,‭ ‬one of the intriguing coincidences is that on the Mohs scale,‭ ‬tungsten and garnet are remarkably similar.‭ ‬While it is possible to‭ ‬cut tungsten using‭ ‬waterjet abrasive‭ ‬machining,‭ ‬it is‭ ‬challenging because of the fact that tungsten and garnet are so close in hardness.

‬To Waterjet Or Not To Waterjet‭?

For cutting complex shapes‭ ‬from a large sheet of material,‭ ‬there is a logic to why one might choose waterjet abrasive cutting‭ — ‬or perhaps even plasmas,‭ ‬oxy-fuel,‭ ‬or laser cutting.‭ ‬However,‭ ‬we leave that discussion to the experts in these methods.‭ ‬For applications such as‭ ‬2-axis cut-off of small precision tubes, rods, and wires,‭ ‬other methods are‭ ‬often‭ ‬a better choice.

For tips on how to choose the best‭ ‬precision metal‭ ‬cutting method for‭ ‬your‭ ‬metal‭ ‬fabrication project,‭ ‬download our white paper‭ ‬download our white paper‭ ‬*Choose with Confidence: Comparing 2-Axis Precision Cutting Methods*‭.

This week‭’‬s blogger,‭ ‬Josh Jablons,‭ ‬is the President of Metal Cutting Corporation.

The post Facts About ‬Waterjet Abrasive Cutting appeared first on Metal Cutting Corporation.

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‬Pros‭ ‬And Cons Of EDM For‭ ‬2-Axis Cutoff

For most people,‭ ‬the topic of wire cut EDM advantages and disadvantages is about how the method stacks up against laser cutting,‭ ‬3D manufacturing,‭ ‬or traditional machining for multi-axis shaping of metal.‭ ‬These days,‭ ‬lasers in particular seem to be the primary culprit in any decline of wire cut EDM applications.‭ ‬

So,‭ ‬we assume that some of our readers today are looking for wire cut EDM‭ ‬advantages and disadvantages as they compare with the‭ ‬pros and cons‭ ‬of laser cutting. Unfortunately,‭ ‬you’ve come to the wrong blog‭!

‬Here at Metal Cutting Corporation,‭ ‬where we‭ ‬produce thousands and thousands of small,‭ ‬precision‭ ‬metal parts every day,‭ ‬the topic of wire cut EDM advantages and disadvantages is all about‭ ‬2-axis cutting.‭ ‬(You can read more about EDM at Metal Cutting here.‭)‬ While laser cutting‭ ‬can be versatile and precise,‭ ‬it is‭ ‬also‭ ‬a very slow and‭ ‬expensive‭ ‬method‭; ‬for‭ ‬2-axis cutting,‭ ‬the cost of laser in time and money is often more than can be justified,‭ ‬especially where other methods can produce excellent results at a better price.

For our purposes,‭ ‬at Metal Cutting our focus on wire cut EDM advantages and disadvantages is entirely about the end formation or the surface finish of the cut‭ — ‬especially,‭ ‬how it compares with the other‭ ‬2-axis cutting methods that we either perform or‭ ‬are in competition against.

Wire Cut EDM Advantages

Looking at wire cut EDM advantages and disadvantages,‭ ‬there are some clear positives‭ ‬that make a good case‭ ‬for using EDM.‭ ‬It is a very precise method for the right applications,‭ ‬such as for cutting small parts with tight‭ ‬tolerances at high volumes.‭ ‬Therefore,‭ ‬for pins,‭ ‬probes,‭ ‬and other solid,‭ ‬small diameter metal parts that are‭ ‬under‭ ‬0.020‭” (‬0.50‭ ‬mm‭) ‬and‭ ‬needed in high volumes,‭ ‬wire EDM can deliver highly repeatable lengths without end-deformation,‭ ‬distortion,‭ ‬or delamination‭ ‬— and it can do so more‭ ‬economically than a‭ ‬method such as laser,‭ ‬which as we said above‭ ‬is not ideal‭ ‬or cost-effective‭ ‬for‭ ‬2-axis cutting.

For‭ ‬small diameter‭ ‬solids,‭ ‬wire cut EDM advantages and disadvantages‭ ‬start with the‭ ‬significantly positive aspect of extremely high measures of central tendency to achieve‭ remarkably ‬high Ppk/Cpk values.‭ For example, EDM can be used to cut a simple metal wire that is ‬0.004‭” (‬0.1‭ ‬mm‭) in ‬diameter to‭ ‬a length of‭ ‬1‭” (25 mm) at a Cpk value of over 5, which is well beyond the process consistency of other cutting methods, even if the overall tolerance is still a remarkable +/-‭ ‬0.001‭” for competing methods with a lower Cpk value. Certain applications require more than the usual 1.33 Cpk minimum, and for these ultra-tight population range applications, the EDM cut is unique in its length consistency.

In addition to cutting small diameters in the thousandths of an inch,‭ ‬wire EDM can cut larger diameters‭ ‬of several inches.‭ ‬Because‭ ‬EDM does not involve a wheel or saw teeth,‭ ‬wire cut EDM advantages and disadvantages‭ ‬also include‭ ‬that the method generally does not leave any burrs,‭ ‬and the‭ ‬kerf is usually from‭ ‬0.004‭” ‬to‭ ‬0.012‭”‬ (0.1‭ ‬to‭ ‬0.3‭ ‬mm‭)‬ wide.

Wire EDM‭ ‬is versatile in the hardness of the conductive metals that it can cut with relative ease,‭ ‬ranging from copper to the hardest materials including molybdenum and tungsten. EDM‭ ‬also‭ ‬gives a natural radius to the end cut,‭ ‬which may or may not be considered‭ ‬a‭ ‬wire cut EDM advantage,‭ ‬depending on the application.‭

‭Wire Cut EDM Disadvantages

Of course,‭ ‬wire cut EDM advantages and disadvantages‭ ‬also include negatives.‭ ‬Due to the very nature of how the method achieves a cut‭ — ‬using‭ ‬rapidly repeating,‭ ‬controlled‭ ‬electrical charges‭ ‬along a strand‭ ‬of metal wire to remove material‭ ‬by eroding‭ ‬it along a cut line in the workpiece‭ — ‬EDM is limited to cutting‭ ‬electrically conductive materials.‭ ‬Therefore, any material that is a composite or coated with‭ ‬a dielectric is not‭ ‬a‭ ‬feasible‭ ‬application‭ ‬for EDM.‭

‬Depending on the metal being cut,‭ ‬another disadvantage of EDM cutting is that an oxide layer can form on the cut surface, which may require secondary cleaning. Although there are techniques to remove this oxide layer, it is a negative feature of EDM.

The most widely known negative among wire cut EDM advantages and disadvantages is that ‬EDM is‭ ‬still‭ ‬a‭ ‬slow method.‭ ‬So,‭ ‬for very high volumes of parts with diameters larger than 0.020″ (0.5 mm) and a tight deadline,‭ ‬a method such as our thin-wheel abrasive cutting might be preferred. On the other hand, modern EDM machines with AWT (automatic wire threading, to automatically re-thread a broken cutting wire) and, of course, CNC capability can be programmed to work “lights out.” This unattended operation can mitigate the inherent slow cutting speed.

Challenges ‬With ‬Cut ‬Tubing And Surface Finishes

Looking at wire cut EDM advantages and disadvantages,‭ ‬the‭ ‬process is also‭ ‬best for materials that are‭ ‬solid‭ ‬as well as conductive,‭ ‬making EDM a method that is not recommended for cutting tubing.‭ ‬The conductivity that must be maintained in order to cut parts using wire EDM requires the parts to be held firmly in place without moving. In addition to creating significant risk of deformation to the tubing, this can cause the cutting wire to contact the workpiece, which shorts out the cut and causes the cutting wire to break and the workpiece to possibly have a “step.” Although you can fixture a tube can‭ ‬so that it‭ ‬will rotate in the EDM machine,‭ ‬the‭ ‬method is optimized for more complex shapes and is not‭ ‬cost-effective for simple‭ ‬2-axis cutoff of tubing.

While wire EDM can repeatedly cut parts to lengths‭ ‬from‭ ‬0.5‭” (‬12‭ ‬mm‭)‬ to‭ ‬18.0‭” (‬450‭ ‬mm‭) ‬— and do so with high dimensional accuracy‭ — ‬the method cannot do very short cutoffs,‭ ‬under‭ ‬0.125‭” (‬3.175‭ ‬mm‭)‬.‭ ‬Additionally,‭ ‬a negative among the‭ ‬wire cut EDM advantages and disadvantages‭ ‬is that EDM does not produce‭ ‬quality cut end surface finishes‭; ‬in fact,‭ ‬it can result in surface roughness that is often characterized as‭ “‬craters of the moon”!

Considering the‭ ‬wire cut EDM advantages and disadvantages,‭ ‬for applications such as medical device metal tubing that must be cut to very short lengths and have a very smooth end finish,‭ ‬an alternative method such as thin-wheel abrasive cutting will deliver the necessary tight tolerance,‭ ‬burr-free results and a clean end cut without tube wall deformation.

‭A Myriad Of Options

Clearly,‭ ‬there are many‭ ‬wire cut EDM advantages and disadvantages‭ ‬as well as the pros and cons of other methods to be considered when it is time to specify a cutting method for precision metal parts.‭ ‬The‭ ‬efficiency of any cutting method can vary‭ ‬greatly depending on the‭ ‬material you use and how well any one method will achieve the desired end results.‭ ‬Making the right choice‭ ‬requires‭ ‬an in-depth understanding of your‭ ‬application,‭ ‬its parameters,‭ ‬and the product‭’‬s end use.‭

For tips on how to select the best cutting method for your small parts requirements,‭ ‬download our white paper‭ ‬Choose with Confidence: Comparing 2-Axis Precision Cutting Methods‭.

This week‭’‬s blogger,‭ ‬Josh Jablons,‭ ‬is the President of Metal Cutting Corporation.

The post ‬Wire‭ ‬Cut‭ ‬EDM Advantages and Disadvantages appeared first on Metal Cutting Corporation.

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What ECT Can Find Vs.‭ ‬What It Cannot

In our previous blog,‭ ‬we touched on some‭ ‬interesting‭ ‬facts about‭ ‬the eddy current testing procedure.‭ ‬This time,‭ ‬we’ll‭ ‬take a closer look at some of the variables that‭ ‬have an effect on‭ ‬eddy current testing,‭ ‬what it can find,‭ ‬and‭ ‬what it cannot find.

Not All Defects Are Detected Equally

The types of defects in a material determine the effectiveness of the eddy current testing procedure.‭ ‬For instance,‭ ‬discontinuities and defects that are parallel to the flow of the eddy current‭ ‬— such as radial or point cracks‭ ‬— will not be detected by most eddy current testing equipment, which works best for defects that occur along the length of a part. To find a single point crack using a radial coil requires a specialized setup,‭ ‬with multiple probes that rotate around circumference of the part.‭ ‬In addition,‭ the morphology of ‬‬a crack is both a surface defect and an internal defect; this means the eddy current testing procedure‭ ‬needs to filter multiple readings.

Internal defects that exist solely in the interior of metal parts are more difficult or even impossible to detect,‭ ‬especially with thicker materials,‭ ‬due to the skin effect‭ ‬— the tendency for internal defects to produce an exponentially weaker eddy current signal than external defects.‭ ‬The technical term for the‭ ‬intensity of the signal on the depth of a thicker part is‭ ‬depth of penetration.‭ ‬At Metal Cutting Corporation,‭ ‬our ECT system has a depth of penetration of about‭ ‬0.050‭”‬ (1.27‭ ‬mm‭)‬ for molybdenum and tungsten.

‬Eddy Current Testing Procedure For Non-Radial Defects

At Metal Cutting,‭ ‬our focus is‭ ‬on draw lines and elongated grain structures.‭ ‬Draw lines are‭ ‬more‭ ‬common and‭ ‬can‭ ‬occur in many different‭ ‬types of‭ ‬metal materials.‭ ‬Draw lines can be‭ ‬either‭ ‬occlusions in the metal that got pulled through the die or defects of the die that score and damage the metal as it is being drawn.‭ ‬In our world of refractory metals,‭ ‬such as molybdenum and tungsten,‭ ‬the materials are formed through‭ ‬powder metallurgy and are sintered and then‭ ‬swaged and drawn‭; ‬therefore,‭ ‬these metals are‭ ‬never in a molten state,‭ ‬and their elongated grain structures are entwined.‭ ‬However,‭ ‬there is potential at the grain boundaries for gaps that are in the longitudinal direction.

Conveniently,‭ ‬the eddy current testing procedure,‭ ‬which involves passing a long part through a‭ ‬round, hollow coil,‭ ‬is ideal‭ ‬for detecting these types of defects.‭ ‬What ECT‭ ‬struggles with is radial cracks,‭ ‬which are highly transient‭ ‬— appearing and disappearing quickly.‭ ‬The cross section where the crack is might be so small that the eddy current cannot detect it.‭ ‬For example,‭ even ‬if you have a wire with as much as a‭ ‬90%‭ ‬radial crack,‭ ‬it would be tricky to detect the crack unless you have eddy current testing equipment with specialized rotating multi-coils.

Depth‭ ‬Perception But Not‭ ‬Depth Measurement

Even when an internal crack can be detected,‭ ‬the‭ ‬actual‭ ‬depth of‭ ‬the crack cannot be measured accurately using the eddy current testing procedure.‭ ‬The oscilloscope of the eddy current tester will show a graphic representation of a crack feature,‭ ‬analogous to a polar chart‭; ‬as with a polar chart,‭ ‬you can zoom in or zoom out on the graphic representation.‭ ‬However,‭ ‬the graphic or numerical representation does not correlate to the dimensions of the crack.

Although the depth of an internal crack cannot be measured with the eddy current testing procedure,‭ ‬at Metal Cutting we often receive drawings specifying,‭ ‬for example,‭ ‬that a crack cannot be greater than‭ ‬10%‭ ‬of the diameter or that the customer will not accept a defect greater than‭ ‬0.001‭”‬ (0.0254‭ ‬mm‭)‬.‭ ‬The challenge is,‭ ‬how do you operationalize those requirements‭? ‬Both are difficult without having any parameters described.‭ ‬The percentage of diameter generally refers to depth,‭ ‬but‭ “‬a defect no greater than‭”‬ is often not defined as depth,‭ ‬width,‭ ‬or even length.‭ ‬While after further inquiry we almost always discover that it does not refer‭ ‬to length,‭ ‬width and depth are very important variables in the eddy current testing procedure,‭ ‬and‭ ‬finding defects as small as 0.001″ in any dimension is very challenging.

The good news is,‭ ‬the‭ ‬depth‭ ‬of an internal crack‭ ‬can be estimated by using the phase of the‭ ‬ECT‭ ‬signal and other little tricks we‭ ‬at Metal Cutting‭ ‬have learned through years of experience‭ ‬working with the eddy current testing procedure.‭ ‬Our system uses stationary probes‭ ‬— something we keep in mind when using reference samples to find the optimal settings for‭ ‬frequency,‭ ‬amplitude,‭ ‬phase,‭ ‬sensitivity,‭ ‬filtering,‭ ‬and other variables that are part of the recipe for the eddy current testing procedure‭ — ‬and we‭ ‬also have a two-coil setup so that we can use absolute and differential probes at the same time.

Other‭ ‬Factors‭ ‬That Influence The Eddy Current Testing Procedure

There are a number of other‭ ‬variables that have an impact on the eddy current testing procedure and the results it produces.

Properties of the‭ ‬Test Material

The properties of the material being tested can affect‭ ‬the‭ ‬flow of eddy‭ ‬currents.‭ ‬For instance,‭ ‬the eddy current testing procedure can struggle with non-pure materials that are combinations of metals with dissimilar electrical properties.‭ ‬The metals in an alloy generally are not a perfectly homogeneous distribution throughout the entire length of material,‭ ‬so it can be difficult to set a baseline for eddy currents.‭ ‬Additionally,‭ ‬even pure element metals will contain trace elements,‭ ‬such as non-volatile residues‭ (‬NVRs‭)‬ of well less than‭ ‬1%,‭ ‬which will show‭ ‬up as defects.‭ ‬These types of material variations create noise that forces us to reduce the actual sensitivity we can utilize, regardless of the theoretical sensitivity of the eddy current testing procedure.

Material Surface Finish

Even though people like to think of eddy current testing as being like an x-ray,‭ ‬the reality is‭ ‬that‭ ‬it is not.‭ ‬Unlike x-rays,‭ ‬the entirety of the material being tested has an effect on the electrical properties of‭ ‬the eddy current testing procedure,‭ ‬and the surface finish‭ ‬can throw off the‭ ‬ECT results.

Because a rougher surface finish produces noise,‭ ‬it‭ ‬creates a need to adjust the eddy current testing equipment settings to compensate,‭ ‬so that surface finish noise is not mistaken for a material defect.‭ ‬So,‭ ‬for example,‭ ‬if we are being asked to identify defects greater than‭ ‬0.001‭”‬ (0.0254‭ ‬mm‭)‬,‭ ‬it becomes a major threshold problem. For example, a defect that is 10 times greater than the area surrounding it will literally stand out. But what if a defect of‭ ‬0.001‭”‬ is surrounded by a rough surface finish consisting of grooves that are ‬0.0009‭”‬ (0.0229‭ ‬mm‭)‬ deep? Distinguishing that‭ ‬0.0001‭”‬ (0.00254‭ ‬mm‭) ‬variation will be really challenging for ECT.

‬Coil Fill Factor

To the naked eye,‭ ‬coil fill factor seems like a ratio between the OD of the material and the ID of the coil.‭ ‬However,‭ ‬more accurately,‭ ‬the‭ ‬fill factor is the ratio between the area of the coil and the area of the material.‭ ‬Determining‭ ‬the correct ratio between the coil and‭ ‬the material‭ ‬helps to ensure that the test‭ ‬sample will be able to move freely‭ ‬during scanning‭ ‬and‭ ‬the coil‭ ‬will generate‭ ‬the necessary‭ ‬eddy currents.

Position of‭ ‬the‭ ‬Material in‭ ‬the‭ ‬Coil

Ideally,‭ ‬the‭ ‬part to be tested‭ ‬will sit‭ ‬at the true center of the coil,‭ ‬but‭ ‬realistically it rarely can do so.‭ ‬Simple variations in material diameter,‭ ‬even within tolerance,‭ ‬affect the ability to place the part in the true center.‭ ‬Also,‭ ‬fixturing‭ ‬— both as originally designed and after wear from operation‭ ‬— can cause the true center to be more theoretical than actual.

Vibration

The vibration of the eddy current testing machine itself,‭ ‬as well as‭ ‬vibration of the feeding device that places the part inside the coil,‭ ‬causes noise that can interfere with the flow of eddy currents or create false signals that will be mistaken for defects in the test material.

‬Bottom Line on ECT‭?

None of these variables defeat the eddy current testing procedure,‭ ‬but they do mean it cannot be used for dimensional measuring.‭ ‬While‭ ‬the procedure can be used to estimate dimensions,‭ ‬obviously‭ ‬that does not produce the‭ ‬kind of‭ ‬accuracy‭ ‬you would get doing a true metallurgical sample and studying the specimen.‭ ‬Still,‭ ‬eddy current testing is‭ ‬a valuable tool that is utilized effectively by Metal Cutting Corporation to‭ ‬inspect‭ ‬materials for flaws‭ ‬and is‭ ‬an‭ ‬important‭ ‬part of our QMS standards‭ ‬— enabling‭ ‬us‭ ‬to‭ ‬deliver‭ ‬high-quality‭ ‬precision‭ ‬metal‭ ‬parts that meet‭ ‬customer‭’‬s tight specifications.‭

Return to this space‭ ‬in future weeks‭ ‬for more on‭ ‬eddy current testing and similar topics‭ ‬still to come.

This week‭’‬s blogger,‭ ‬Josh Jablons,‭ ‬is the President of Metal Cutting Corporation.

The post Variables ‬That ‬Affect ‬the ‬Eddy Current Testing Procedure appeared first on Metal Cutting Corporation.

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Things To Know And Factors To Consider

As a company that does a significant amount of work with specialty metals, Metal Cutting Corporation often employs eddy current testing (ECT) to inspect materials for defects such as cracks or voids. This method utilizes electromagnetic induction to detect and characterize flaws in the surface or sub-surface of conductive materials, including metals. In addition to detecting flaws, the eddy current testing procedure can be used to measure thickness and conductivity.

Below are 5 interesting things to know about eddy current testing.

Eddy Current Testing Is Nondestructive Testing

Eddy current testing is an important method of nondestructive testing (NDT) — one of the techniques used in science and industry for performing inspections and taking measurements to ensure that:

  • Structural components and systems perform reliably, safely, and cost-effectively
  • The testing itself is done in a way that does not damage parts or materials, and does not affect their future use and function

There are, in fact, a variety of NDT techniques, with new ones being developed all the time. The most basic method is a visual examination, which may mean simply looking at a part for visible surface imperfections or using computer-controlled optical systems to detect and measure the features of a component.

Some of the technologies used in NDT are familiar because they are also used in medicine, such as radiography (RT), which uses gamma-radiation or X-rays to look for defects or see internal features. Another example is ultrasonic testing (UT), using high-frequency sound waves to detect imperfections or changes in material properties.

Magnetic particle testing (MT) uses a magnetic field in a ferromagnetic material and a dusting of iron particles to produce a visible indicator of surface defects. Leak testing (LT) finds leaks in pressurized parts by using various methods ranging from electronic listening devices to pressure gages, to simple soap-bubble tests.

Another method is acoustic emission testing (AE), which finds imperfections by detecting bursts of acoustic energy. We often encounter helium leak testing, which uses the second lightest element to find a leak path, with or without the use of penetrant testing (PT), which uses visible or fluorescent dye.

In eddy current testing — the NDT technique we focus on here at Metal Cutting — electrical currents (eddy currents) are generated in a conductive material by exposing it to an expanding and collapsing magnetic field. The strength of these eddy currents can be measured; defects or changes in the material cause interruptions in the flow of the currents, alerting us to problems in the material or part being tested.

It Is Critically Important In Daily Life

While not everyone has heard of eddy current testing and NDT, these methods touch all of our lives, perhaps even on a daily basis. That’s because these techniques are used in a wide range of industries — not least of all, in those where component failure could cause devastating damage and loss.

For example, eddy current testing is used to inspect tubing and other structures for applications such as oil and gas pipelines, nuclear reactors, chemical manufacturing, and municipal water systems. Portable eddy current testing equipment is used for on-site inspections in the field, such as looking for cracks in bridges and in airplane components from wings to landing gear. That makes ECT, as well as other methods of nondestructive testing, vitally important to public safety — playing a role in helping to prevent catastrophic events like pipeline breaks, bridge collapses, and plane crashes.

Even in a world of small parts, such as the metal components we produce here at Metal Cutting, eddy current testing has an impact on safety, in less visible but still critically important ways. For instance, we use this method to inspect glass to metal seals in parts for night vision goggles that are ultimately used by military personnel, who may need them long after manufacture and far from home.

There Are Different Probes For Different Modes

Eddy current testing equipment includes test probes, which are available in a variety of shapes, sizes, and configurations. These probes also have different modes of operation, depending on how the test coils are wired and how they interface with the test sample.

For example, an absolute measurement probe uses a single coil to generate eddy currents, detect changes in the current field, and provide a reading from a single point on the test sample. A differential probe uses two coils to provide a basic of comparison for detecting flaws, even in materials that may have inconsistencies; when one coil is over a defect and the other is over good material, a differential signal is produced. There are also reflection and hybrid probe modes.

An alternating current (AC) is passed through the coil or coils to create an expanding and collapsing magnetic field in and around the coil(s). When the probe is positioned next to a conductive material — the test sample — this changing magnetic field is what generates the eddy currents within the sample. Through the interaction of the coil’s magnetic field and the eddy currents, we can observe and measure changes in frequency, amplitude, sensitivity, impedance, and other characteristics that indicate the presence of a crack, void, or other defects in the test sample.

Many Factors Affect The Eddy Current Testing

In addition to settings such as frequency, amplitude, sensitivity, and so on, which make up the “recipe” for eddy current testing, there are other factors to consider — things that can affect the flow of eddy currents, including the properties of the material or part being tested. Some are beneficial while others may require making adjustments to the settings or using other techniques to compensate for the effects.

Obviously, the electrical conductivity of the material being tested — or what we can think of as the ease with which electron flows in the material — has an effect on the flow of eddy currents it produces, as does magnetic permeability. While the measurement of permeability can be useful in sorting materials, this property can pose problems. For instance, the so-called “noise” created by changes in permeability when testing ferrous materials makes it difficult to use eddy current testing on carbon steel welds. However, issues may be overcome by using magnetic saturation, multi-frequency inspection, or differential coil arrangements.

Speaking of noise — actual room noise is a physical, ambient factor that can have an impact on eddy current testing. However, noise can often be filtered out, to produce a clearer signal. When a test sample is a part with edge or sharp changes in geometry, there can be what is called an “edge effect” on the eddy currents; placing and balancing the probe near the edge and scanning at that distance can avoid this effect. Similarly, a sample with a complex geometry could create false signals, caused by changes in geometry rather than a defect in the material itself.

Another important consideration is the coil fill factor, which is used to establish how much space an inspected tube or rod should take up inside the inspection coil. By determining the correct allowance between the coil and the test sample, you can make sure the sample will be able to move freely during scanning while also making sure the coil is close enough to the sample to generate eddy currents and perform the inspection correctly.

The frequency of AC passing through an eddy current testing coil affects the depth of penetration of the eddy current field in a test material; with increasing depth into the material, there is decreasing intensity of the eddy current flow. The depth of a crack cannot be measured accurately by using eddy current testing, and the method also will not detect flaws such as laminations, which run parallel to the flow of eddy currents. However, cracks, lack of weld fusions, and other planar discontinuities that are perpendicular to the flow of eddy currents will be detected.

Metal Cutting Is Skilled In ECT

Here at Metal Cutting, we frequently use the eddy current testing procedure to inspect tungsten and molybdenum rods and other metal parts for potential issues such as cracking, pitting, and fractures. We also utilize ECT to look for surface flaws in the round rod, flat ribbon, and capillary tubing used in glass to metal seals. (You can read more about that in our blog Problems with the Glass to Metal Seal in Electronics.)

Whether we have purchased a material on behalf of a customer or the customer has provided the material for us to process, we speak with the vendor or customer to find out what settings they use on their own eddy current testing equipment. This enables us to create our mutual, shared recipe for successful ECT, adjusting the settings as needed, using either absolute or differential measurements, and choosing from an array of coil sizes and tooling options. For passing rods through an ECT coil, we also pay close attention to the fill factor and use a bushing to position the rod so it is centered within but never touching the coil.

Additionally, we often seek out a reference sample as a basis for comparison — especially when we are inspecting for internal defects, which cannot be seen. A reference sample allows us to check whether we are likely to find the defects we will be looking for by using our established ECT settings. Using a sample with a known defect, we can adjust our equipment settings as needed to find that specific, verified defect.

It can be difficult to find a good reference sample. After all, you don’t want to cut open a sample to verify an internal defect and thus destroy the sample for any future ECT use. However, we can use a sample our vendor or customer believes has a sub-surface defect based on their testing and corroborated by previous failed ECT inspection. For external flaws, we can work with a vendor or customer to attempt to create a specific surface defect on a part, and then both of us can use that as our reference sample.

Do you want to know more about eddy current testing? Tell us your questions or concerns in the comments — then come back to this space for more on ECT in the coming weeks!

This week’s blogger, Josh Jablons, is the President of Metal Cutting Corporation.

The post 5 Fascinating Facts About Eddy Current Testing appeared first on Metal Cutting Corporation.

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More Than A Century Of Innovation At Work

Recently, we talked a little about the National Institute of Standards and Technology (NIST) and how NIST traceable standards are an important part of our QMS standards. But NIST traceability is not just a cornerstone of our industry, setting the standards for inches, grams, and other measurements. NIST traceable standards come into play in many wonderfully weird, wacky, and interesting ways.

A Lot Of Bread For NIST Traceable Peanut Butter

A case in point: Just a few years ago, there was a big stir when a photo of a $761 jar of peanut butter started making the rounds on the Internet. What made this jar of golden goo so special and it’s price so remarkable? Designed to aid in the calibration of machines in food science labs, this product is one of more than 1,300 standard reference materials (SRMs) created by NIST. SRMs are used by scientists and researchers, regulatory agencies, and manufacturers the world over, serving as the basis for NIST traceable calibration and as reference points for quality control.

The NIST traceable SRM menu isn’t limited to peanut butter. There are similarly pricey standards for everything from baking chocolate to slurried spinach to “meat homogenate” — a familiar and somewhat mysterious product designed to last on the shelf for a very long time. And of course, NIST traceable standards extend beyond food chemistry, with SRMs for materials such as the organics in whale blubber, lake sediment powder, and nicotine metabolites in frozen human urine. In fact, NIST has had an impact on a wide range of products and applications throughout the organization’s remarkable history and continuing to the present day.

A Brief History Of NIST

NIST was founded in 1901 as the National Bureau of Standards, thanks to the efforts of Dr. Samuel Wesley Stratton, who served as its first director (until 1923) and convinced the U.S. Congress how important it was to establish a national standards laboratory. The utter lack of standards at that time meant, for example, there were at least eight different versions of gallons and four different feet in use; product inspectors were often poorly trained, and inaccurate or outright fraudulent measuring devices made products inconsistent or left consumers open to deceptive practices.

In 1905, NIST convened the first National Conference on Weights and Measures (NCWM) to write laws, distribute uniform standards, and provide training for inspectors. The first official NIST traceable standardized material (SRM 1) was argillaceous limestone, launched in 1910 for use by the limestone industry to measure the composition of trace chemicals. The collection of NIST traceable standards grew from there, eventually encompassing food manufacturing standards, bodily health markers, and tools for measuring environmental pollutants.

These days, a NIST traceable certificate indicates that a product has been tested against a NIST SRM and meets strict requirements for that product. Each year, NIST ships about 14,500 SRM units and develops 5 to 10 new SRMs, often for regulatory agencies such as the CDC or EPA.

Some Other NIST Milestones

In addition to maintaining and developing NIST traceable standards for the SRM program, NIST has been responsible for some fascinating developments. For instance, at the storied 1904 World’s Fair in St. Louis, NIST physicist Perley G. Nutting demonstrated what were arguably the first signs illuminated by electrified gasses. Developed from the gas spectrometry work Nutting was doing at NIST, the signs were nothing more than a novelty at the time, but two decades later the technology would have a huge commercial impact with the advent of neon signs. Times Square would never be the same again.

In 1916, NIST’s improvements to radio direction finder (RDF) technology resulted in a new design that served as a prototype for the U.S. Navy and was used to pinpoint the position of enemy forces during World War I. Speaking of radio: Six months before the first commercial radio station was launched in 1920, NIST was experimenting with broadcasting music and speech in order to study the technical problems being experienced in early radio. By 1923, NIST was broadcasting standard frequencies from its own station, helping commercial radio stations avoid interfering with each other’s signals.

Happily for a lot of industries, in 1926 NIST staffers invented the proving ring, a spring scale-like device used to measure applied forces. While the design has evolved some over time, proving rings are still in wide use today — and they are still manufactured according to NIST traceable standards.

In 1928, NIST intentionally burned down two condemned buildings in Washington, D.C., in what was probably the first full-scale fire test. Monitoring actual conditions as they occurred and comparing them the theoretical time-temperature curves of the time, the team gathered data that eventually became part of NIST traceable standards for fire resistance in buildings.

In the summer of 1936, NIST partnered with the National Geographic Society to send an expedition to Kazakhstan to observe a solar eclipse. Using a special 14-foot camera and 9-inch lens designed and built by NIST, the team took the first natural color photographs of a solar eclipse.

NIST even built the world’s first atomic clock, in 1949. While the clock was not accurate enough to be used as a time standard, it did prove the concept and led to the eventual development of the first atomic clock accurate enough to be a time standard, built at the National Physical Laboratory in the U.K. in 1955. (Note that today, NIST maintains the world’s official atomic clock.)

By 1953, NIST had teamed up with the American Dental Association to invent the panoramic X-ray machine — making it possible to create an image of the entire mouth with only one exposure, helping to minimize radiation exposure. Earlier, NIST and the ADA had contributed to the invention of the high-speed dental drill.

Looking ahead to the 1960 U.S. Census, in 1954 NIST and the Census Bureau developed the Film Optical Sensing Device for Input to Computers. “FOSDIC,” as it was known, allowed hand-marked forms to be scanned to microfilm and then converted into computer code. The device, which was capable of reading 10 million answers per hour, was updated and used to process census data until 1990.

In other digital news, in 1957 a first-generation computer designed and built at NIST was used to produced the first digital image. NIST engineer Russell Kirsch and his colleagues created a scanned image of Kirsch’s three-month-old son, Walden, while working on a method for the Standards Eastern Automatic Computer (SEAC) to recognize numbers and letters. Kirsch’s legacy lives on: Little Walden grew up to work at Intel, and in 2003 Life magazine named the image one of the “100 Photographs That Changed the World” due to its impact on the development of digital photography.

In 1967, the first SRM for clinical applications was a lifesaver: a NIST traceable standard for testing human cholesterol. Prior to that, cholesterol tests were notoriously unreliable; off by as much as 23%, they had often resulted in either unnecessary treatment or undetected risks that put patients in danger.

With the oil crisis of the early 1970s leading to the development of oil reserves and environmental risks to the Alaskan coast, the National Oceanographic and Atmospheric Administration asked NIST to gather baseline data on the marine environment. Much later — in 1989 — the 700 samples of sediment, water, and marine life that NIST collected would prove critical to assessing the impact of the Exxon Valdez oil spill.

In partnership with NASA, a NIST traceable standard was also the first product made in space. In 1983, during the first flight of the Space Shuttle Challenger, NIST SRM 1960 was created in the shuttle’s microgravity environment. Consisting of perfectly spherical, stable polystyrene beads, the product is designed to aid in consistent measurement of small particles such as those found in medicines, cosmetics, food products, paints, cements, and pollutants.

At the request of the research arm of the U.S. Department of Justice, NIST produced the world’s first DNA profiling standard, in 1992. Developed over the course of two years, SRM 2390 is designed to test every step of the complex analysis method for identifying people using DNA.

Over time, NIST has continued to development new and more accurate ways to tell time. The year 1993 saw the introduction of NIST Internet Time Service, which allows people to set their computer clock to match Universal Coordinated Time (UTC), which is to this day accepted as the time standard around the globe. And in 2010, NIST’s experimental quantum logic clock was thought to be the world’s most precise clock; it is projected it will not gain or lose a second in 4 billion years.

What Does The NIST Traceable Future Hold?

Clearly, what NIST has done is not only important but also far reaching — and there is still more work to be done. For example, here at Metal Cutting Corporation, our use of NIST traceable calibration along with our other QMS standards helps us deliver high-quality parts that meet customer specifications. However, we are still waiting for a NIST traceable standard for the eddy current testing method we often use to inspect refractory metals for surface flaws such as cracks. (People from NIST, are you reading this?) You can read more about the lack of an ECT standard and other issues related to calibration in our recent blog “The Quandaries of Calibration Standards.”

Adherence to NIST traceable standards, ISO 9001:2015 certification, and a proven QMS are only some of the qualities to look for in a metal cutting partner. Learn more by downloading our free guide, 7 Secrets to Choosing a New Contract Partner: Technical Guide to Outsourcing Your Precision Metal Fabrication.

This week’s blogger, Joshua Jablons, is the President of Metal Cutting Corporation.

The post NIST Traceable Standards in Action appeared first on Metal Cutting Corporation.

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Metal Cutting Will Be at Booth 2442 — Will You?

Metal Cutting Corporation will be heading to California next month to attend the trade show and conference that bills itself as North America’s largest annual medtech event — Medical Design & Manufacturing (MD&M) West, being held February 6-8, 2018, at the Anaheim Convention Center in California. You can get more information and connect to MD&M West 2018 via our website.

In addition to hosting thousands of industry professionals, a wide range of educational tracks, and a huge expo of suppliers, MD&M West 2018 will offer ample opportunities to catch up with familiar faces and network with colleagues. But in today’s changing business scene, are events such as this becoming a thing of the past? Will YOU be attending MD&M West 2018?

Drastic Changes in Trade Publishing

Of course, with the advent of the Internet and social media, the ways in which people get and share information is changing across virtually every industry. Print as a medium is certainly shrinking, with trade magazines getting thinner and thinner, and many of them getting shut down entirely. When they get turned into online publications, they are clamoring for readers’ attention as always — but in addition they are also clamoring to be found via the search function and to be actually read by an audience with both limited time and ever more competition for their attention.

Some print resources have thrived and been able to transform into go-to websites that are happily bookmarked and referred to repeatedly. But others have simply slipped into the background, a shadow of their former selves. The advantages of reading on a screen are clear: embedded videos, easy links to other resources, the ability to forward and search content. But for readers, another huge advantage is the ability to click “delete” when a newsletter is pushed to them or simply never again pull up a bookmarked link.

Reports of Death Have Been (Maybe) Greatly Exaggerated

As for industry events such as MD&M West and other trade shows, the theory is that people will always want to physically go somewhere and gather together. However, often the biggest promoters of trade shows are trade show promoters. Some shows seem to be must-attend events with an obvious buzz, while others happen in half-empty aisles so devoid of attendees that a bowling ball rolled down the middle wouldn’t hit anyone. On Wednesday!

Change can come in a cycle, with an initial shock and premature predictions of doom that for a while prove unfounded, but then subsequent events confirm the downward trend, sometimes with remarkable pace. For example, online content and digital downloading was going to depopulate movie theaters, which for a time seemed resilient, perhaps (it was theorized) because people want to congregate regardless. However, with relentless increases in bandwidth and advances by content providers such as Amazon and Netflix, streaming by a new generation does seem to portend an accelerating downward trend for theaters (and physical retail locations generally). Is the trend for going to the movies the same for going to a trade show?

Our Theory About People

We do have a theory about people — and it is that they like annual events. Who doesn’t enjoy celebrating someone’s birthday? But imagine trying to convince your friends and family to celebrate your presence on the earth more than once a year! Religions have many different holidays, but most only occur annually. On the U.S. calendar, we have a few national holidays but none that repeat more than once a year.

We conclude from all this that people are comfortable with an annual schedule. Yes, people do look forward to catching up with industry peers — but maybe not more than annually. We can call, email, and even meet as needed during the year, but convening en masse, annual events seems to be the typical cycle. If you serve different industries (as Metal Cutting does), you might find yourself at a few different shows every year, but those address different topics, with different colleagues. To us, a penchant for annual events explains why some annual trade shows are a good thing and others are simply too much of a good thing.

We at Metal Cutting Corporation hope to see you at the annual MD&M West 2018 in Anaheim, as we think it is one of the most important yearly events for the medical device manufacturing community — a great opportunity to see customers, colleagues, and friends in the medical device business. We look forward to the warmer weather in Southern California, in what is the height of winter for us in our Minnesota and New Jersey locations. But we are also a little bit grateful that this gathering is not more than once a year!

What do you think? How relevant are trade shows to your business? How many times a year do you attend conferences? Please comment below — and while you’re at it, let us know if you will be at MD&M West 2018!

This week’s blogger, Joshua Jablons, is the President of Metal Cutting Corporation.

The post Who Is Attending MD&M West 2018? appeared first on Metal Cutting Corporation.

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