Any and all materials that conduct electricity are a candidate for EDM, such as:
Tungsten & Titanium Carbide
Polycrystalline Diamond (PCD)
Cubic Boron Nitride (CBN)
What Are The Different Types Of EDM Machines? Back to Top
This process utilizes an electrically conductive wire primarily made of brass to cut holes or contours that extend completely through a workpiece
Best Uses: Holes, Tapered Surfaces, Die Openings, Gears, Plastic Mold Components and High Precision Machined Parts
Tolerance: 60 millionth contour accuracy can be attained under optimum conditions with our equipment
Surface Finishes Achieved can be as low as a measurable .1 Ra (3-4 RMS).
However, surface finish varies based upon material type, wire diameter and material thickness. Our best finish attainable is what we’ve described and it can be reached on a fairly substantial number of material and thickness combinations.
CNC Ram EDM
Utilizes an electrically conductive electrode to erode a cavity to depth and size
Tolerance: .0002″ can be attained on a part to part basis under optimum conditions with our equipment
Surface Finish: as low as .2 Ra (8 RMS) but please see the notes above
Hole Popper EDM
Utilizes an electrically conductive tube type electrode to erode a hole to a particular depth or through a work piece
What About Burrs Created in the EDM Process? Back to Top
Generally, wire EDM is a burr-free process within reasonable limits. As the process capability approaches the finest contour accuracies that the process is capable of, the surface finish of the workpiece needs to be processed accordingly, resulting in an exceptionally fine cutting edge. For Ram EDM, burr formation is more common as there is typically more material removed and the work piece is generally processed to a coarser finish. Keep in mind that these burrs that we are referring to are always significantly smaller than those produced by more traditionally machined/ground processes.
What Is The Smallest Radius That Can Be Wire EDM’d? Back to Top
We can accurately maintain an internal radius of 0.0008″ to 0.0010″ cost-effectively using fine wire. This is under optimal conditions to be sure, but it is done at NEDCO on a regular basis. For optimum cost efficiency, as well as tool longevity, try to maintain a .006″ minimum internal corner radius, if possible. We’ve even produced .0013″ wide slots in Tungsten Carbide utilizing .0008″ wire.
What Are The Smallest Features That Can Be Wire Cut? Back to Top
There are several variables that determine minimum feature size. First, is the ability to produce a start hole small enough! We regularly produce features in the .005″ (0.13mm) x .005″ (0.13mm) range with .002″ (0.05mm) minimum internal corner radii as a standard.
The smallest wire we utilize is .0008″ (0.020mm) diameter and the largest is .0130″ diameter.
Can You Cut Blind Holes In A Wire EDM Machine? Back to Top
No. Wire must pass thru the material to be cut. Conventional (RAM) EDM is required to burn blind holes and we have substantial capacity in RAM EDM, as well as being Connecticut’s oldest active EDM shop (since 1957).
We can read many of the standard files which include DXF, DWG, IGES, PDF, SLDPRT, SLDDRW, and CADL. Examples of compatible CAD systems are Autocad, CADKEY, SolidWorks, Pro-E, Kubotek, Inventor, and others. Send us a file through our online Quote form.
Why Do We Have to Grind It, Can’t It Be Hard Turned? Back to Top
This is a common question that has been asked, discussed and even argued about for years with as many different answers as there are applications. Yes, No and Maybe. Certainly tungsten carbide tooling and precision parts cannot be adequately turned to any reliable degree. In some rough machining applications with some of the more “ductile” grades of carbide, some work can be done but for all practical purposes, finished components made from tungsten carbide need to be ground and/or lapped and/or polished. While there is a tremendous amount of hard turning of tool steels being done, it is still not the most precise method that can be used to produce the most accurate results. Hard turning excels in difficult contour situations though with some more generous tolerance bands however. Even with that level of success, the very difficult to machine tool steels still offer some resistance to the cutting forces of hard machining which are generally greater than those generated with a grinding wheel.
We can pretty much grind any material that can be machined although some of the plastic and ceramic materials need very special handling and processing due to their unique material properties.
What Can It Do or Better Yet, What Can’t Grinding Accomplish? Back to Top
Grinding, both surface and OD/ID, is a very old process that’s been around for ages. Due to the nature of the process, i.e. requiring the most precise and diligent craftsmen to accomplish, it can impart a level of precision to machined parts or tooling that is otherwise difficult if not impossible to achieve. What it can’t do is magic! You can’t efficiently grind a part that hasn’t been prepped properly for that operation. In that regard, feel free to call us for proper blank prep allowances so that we are able to process your parts in the most efficient manner. Grinding also cannot remove deformation in a part (bow or bend) that is greater than the stock allowance left. It is also difficult to impart very fine surface finishes on material that may be too porous to support that requirement.
Numerically, the Studer S33 maxes out at about 13″ in diameter and 40″ long. There are limits within that though that relate to workhead load, center bearing load, stability of the workpiece, etc. Call for details.
What Special Features Does Our Studer S33 Have? Back to Top
Our machine has both OD and ID spindles on a motorized axis so that parts can be processed on multiple surfaces utilizing multiple grinding wheels in one setup for maximum precision. We also have the ability to Contour Grind using the corner of a formed wheel in steel as well as tungsten carbide materials. Finally, we have the ability to grind parts that are non-round while mounted on centers or held in a chuck. These are features that allow us to process parts that other grinding shops struggle with or have to process as a separate operation.
How Does the Addition of the Studer S33 Affect the Quality of My Tooling or Precision Machined Parts? Back to Top
Good question. For any of our long time customers, we hope you never notice the difference between parts previously ground and finished manually to those processed utilizing our new Studer S33. Why? We pride ourselves in consistency. One inch is one inch and it’s never changed, a mirror polish is just that, it’s not defined by a piece of equipment. Our attention to detail will be what it always has been, unmatched in the industry. Our Studer simply allows us to be more efficient and repeatable in how we process your parts. Yes, craftsmen are still involved but the addition of CNC controls to such a precise process allows our toolmakers to focus more on the small details that matter most.
Now For One of My Favorites… It’s the Physics! Back to Top
It’s one of my favorite questions because it comes into play so often! You can’t beat the physics of the process or the materials involved. For example… “Can we grind a Ø .0200″ bore .2500″ deep into tungsten carbide?” No, sorry, that’s beyond common grinding principles of good depth to diameter ratio for a grinding wheel. “Can I grind a Ø .2500 rod on centers 25″ long?” Well, no. That sort of part would be better suited to centerless grinding, a completely different process. “Can I grind a Ø 4.000 bore in a carbide ring up to a shoulder and maintain a .0015″ internal corner radius?” Not regularly no, the time, wheel grit and repeatability of the grinding process would be tough to maintain. “Can you grind these 10 parts for me right away, I left a little extra grind stock (.125″ on the diameter) and, oh, by the way, I forgot to machine the centers!” This would mean those parts would probably need to be hard machined to prepare them properly for the grinding process. There are many more examples that we have had over the years but that’s just a good sample. When in doubt, contact us for advice.