Cutting Edge Technology
Imagine a configuration made from almost any type of material. Now think of a computer-controlled band saw that can cut through this material and transform it into the configuration you've imagined. Sound interesting? There's more.
Replace the blade with a wire and an electrical charge that can cut any material that conducts electricity and can independently control the top and bottom of a contour to achieve a 3-dimensional cut. What you've now envisioned puts you well on the way to exciting insights into the fast- evolving technology of Wire Electrical Discharge Machining (EDM) - the sole specialty of Chuck Porter and his firm MicroCut, Inc., York, PA.
Founded in 1981, the firm is a pioneer in the field of wire EDM. High-speed wire EDM has rapidly changed the wire EDM industry by cutting parts that no one thought feasible, and cutting them quickly. Today's wire cutting technology is challenging conventional machining in many areas, including production time, precision and price. And more advancements in the wire EDM field are on the way.
According to Chuck Porter, "MicroCut really took a step forward in the industry when we installed automatic wire threading systems on all of our machines. With autothreading, unattended machining has become an exciting reality."
At MicroCut, a company whose motto is "Give us a challenge", you can find machines programmed to automatically change cutter offsets, power settings, flushing parameters, taper changes, and wire tension. The autothreading system on all MicroCut's machines enables the wire cut professional to instruct the machine to cut and retract the wire, move to the next start hole or opening in the job, and then automatically rethread the wire to continue machining.
Today at the company you will find fixtures containing 100 piece lots with 200 openings each that are that are machined to a non-accumulative tolerance of 0.0002" running in fully automatic 48-hour cycles with the option to run to 200 hours with operator intervention only at fixture changes.
While the capabilities of the EDM machines are limitless, the ability to fully utilize wire EDM technology really begins with the design engineer. A great many applications are offered for wire cut only after they have been designed by conventional manufacturing-minded engineers.
Chuck Porter encourages customers to talk to wire cut professionals during the concept and design stage. "Many times getting away from conventional thought into imaginative engineering results in product benefit." said Porter. "Our motto came about as a result of the technological advances in the wire cutting industry in the past few years that beg for challenging applications."
Modern contract EDM shops, like MicroCut, are also equipped with small hole drilling machines. These machines can drill a 0.040" diameter hardened tool steel in less than one minute, with part thicknesses up to 8.75". While these machines can drill holes through any electrically conductive material efficiently and burr-free, the most common use of small EDM drilling is to put start holes in hardened hole through 1" thick haplates or blocks of stainless or tool steel, or carbide stock.
Once the plates are drilled they can be transformed into finished tools or parts within hours, greatly reducing lead time and inventory of finished goods. This efficient schedule enables MicroCut to furnish close tolerance carbide and steel parts on a J.I.T. delivery schedule for many stampers and plastic molders.
Recent new technology has enabled MicroCut to offer superfine finishes on carbide and steel, down to 6 RMS. This new capability was developed for intricate plastic molds and small precision Stampings. Also, fine wire technology using tungsten wire as small as 0.001" diameter is now an economical process, making a practical achievement of inside radii of 0.0008", even in automatic wire threading applications.
Wire EDM is proving that it can turn a wide range of wire cutting applications into realities. MicroCut has been challenged numerous times to produce unique wire EDM-formed parts.
A part is made from 50 stacked pieces of 0.062" thick sheets of steel welded together. A computer program is written to nest the parts in a repeating progression that maximizes stock utilization. The stack is then clamped into the small-hole burning machine and all holes are put on location through the stack.
The 0.95" diameter holes that end up in the finished parts are burned in undersize by 0.015". After the stack is fixtured into the wire EDM machine the computer program is loaded, along with the technology files, into the machine's CNC. The wire machine program now skims all of the holes to size using automatic wire threading and the appropriate technology settings. The program then automatically moves the machine to the start holes for the outside cuts, again calls up the appropriate technology to finish the outside cuts, and stops just a few thousandths of an inch short of break-off before cutting the wire and moving to the next start hole.
When the stack is removed from the machine, a light tap on each stack frees the parts. From start to finish, 2000 parts are processed with no operator intervention.
Another example of the same process is an aerospace washer produced in order quantities of over 3000 parts. Extremely hard materials such as Crucible's CPM-IOV tool steel can be processed as easily as common tool steels with no increase in cutting time.
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