The wrong precision cutting method could cost you

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The wrong precision cutting method could cost you But choosing the right one can be complicated
In a perfect world, determining the right 2-axis precision cutting method for your close tolerance metal components would be a snap — a relatively easy choice among the many decisions you need to make before production begins. But across the spectrum of metal cutting methods for 2-axis cut-off of metal parts, no one method is suited to all needs. And, the wrong decision can result in production delays, material waste, or other quality issues that can cost you time and money. So, how do you make the right choice for your requirements?

This guide is designed to help you determine which precision cutting method is best for your requirements. It includes:
•A comprehensive overview of key parameters for decision making
•A cost/benefit analysis of the 5 most common precision metal cutting methods
•A handy chart to help you quickly compare all 5 methods at a glance.

Free Guide: Comparing 2-Axis Metal Cutting Methods

Wire Cut EDM Advantages and Disadvantages
Pros and Cons of EDM for 2-Axis Cutoff
For most people,he 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.

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 other2-axis cutting methods that we either perform or are in competition against.

Wire Cut EDM Advantages
Finely Ground Tungsten Neurology ProbesLooking 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” (0.50mm) 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 0.3mm?) 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 notcost-effective for simple 2-axis cutoff of tubing.

While wire EDM can repeatedly cut parts to lengthsfrom0.5” (12mm) to 18.0” (450 mm) — and do so with high dimensional accuracy— the method cannot do very short cutoffs,under 0.125” (3.175mm)Additionally,a negative among the wire cut EDM advantages and disadvantages s that EDM does not producequality 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 products end use.

Resources
At Metal Cutting Corporation, we are precious metal cutting specialists, manufacturing burr-free tight tolerance parts from all metals. We provide the precision required by medical device, electronic, automotive, biotechnology, semiconductor, aerospace, fiber-optic, electrical and many other diverse industries that demand perfection:

 

Metal Cutting Corporation manufactures burr-free tight tolerance parts from all metals. We provide the precision required by medical device, automotive, electronic, biotechnology, semiconductor, aerospace, fiber-optic, electrical and many other diverse industries.

We are specialists with over 45 years cutting, grinding, lapping, polishing and machining metal parts. Our experience, inventory and capabilities provide the skills and capacity to meet the needs of technology device manufacturers. Specialty metals, micron tolerances, low or high volumes, complex metrology--all these and more are the requirements we achieve every day for products shipped worldwide.