Page 80 - MetalForming October 2012

Microstamping
nents inside them shrink as well. This means that the tooling needed to pro- duce those stamped components has to, in turn, be smaller than ever, as well as more precise and have superior sur- face finishes. These are manufactur- ing demands that Scenic Tool over- comes using precision wire-EDM technology.
“Wire EDM is at the heart of our shop,” says Scenic Tool president Mike Blackwell. “We design tooling accord- ing to the capabilities of that technol- ogy. With the ability to cut parts using wire diameters down to 0.002 in., we easily can meet customer requirements for smaller, more precise microstamp- ings, while also reducing overall pro- cessing times for the tooling. And most importantly, our wire-EDM machine (a GF AgieCharmilles CUT 2000 model) allows us to generate the extremely high-quality surface finishes critical for microstamping tooling.”
With its wire EDM, the shop easily achieves surface finishes of 0.2 Ra. And, according to the company’s CNC and EDM manager Eric Blackwell, the nec- essary settings and parameters for doing so are built into the machine’s control, so the shop rarely goes through any trial and error processes. Addi- tionally, the machine provides twin- head automatic wire changing, a fea- ture that allows the shop to optimize cutting speed and economize its use of high-end small-diameter coated wire.
From Milling to Jig Boring, Hardening and Wire Cutting
Much of the tooling components at Scenic Tool are produced for produc- tion tooling or for replacement parts for customers. The shop also designs and manufactures assembly equipment, as well as provides spare tooling. Parts, made mostly from tool steels and car- bide, begin as saw-cut blocks of raw material. Machining operations can start either with manual or CNC milling, then include jig-boring or threading of holes before parts go to heattreating. Once hardened, parts are rough-ground and either finish-ground or wire-cut.
The shop
sometimes wire-
cuts multiple
parts in one
setup, but most
often work-
pieces are run
one at a time
because each
part can require
as many as 20
different cavi-
ties. With the
machine pro-
grammed to
move from cavi-
ty to cavity, typi-
cal burn times
range from 30 min. to 5 hr. or more.
With automatic wire-changing tech- nology, the CUT 2000 lets Scenic Tool easily switch between wires of different sizes and materials, allowing it to opti- mize roughing and finishing opera- tions while also conserving the use of high-end small-diameter coated wire. Eric Blackwell describes one of many applications at Scenic Tool where auto- matic wire changing plays a key role in reducing processing time for carbide punches. Previously the punches were cut using only 0.004-in.-dia. wire for roughing and finishing the 1.750-in.- thick parts. Eric now runs the rough pass much faster, using 0.008-in.-dia. wire. Then the machine automatically changes to the smaller-diameter wire for the finish pass.
According to Eric, the CUT 2000 automatically makes wire changes in less than 2 min., and is designed to determine the exact center location of its V-guides. The operator only has to enter the desired wire diameter into the machine’s control, and the guides compensate for the difference between one wire diameter and the next.
Most importantly, adds Eric:
“The machine is always aware of wire center to maintain exact part loca- tion and size once a wire-diameter change has occurred and cutting resumes. When we first looked at the CUT 2000, we were a bit skeptical as to how well the twin-head wire changing
Scenic Tool’s GF AgieCharmilles CUT 2000 wire-EDM machine achieves sur- face finishes of 0.2 Ra. With automatic wire-changing technology, the machine allows the firm to easily switch between wires of different sizes and materials, allowing it to optimize roughing and fin- ishing operations while also conserving the use of high-end small-diameter coat- ed wire.
would work. We run small-diameter zinc-coated steel wire with high tensile strength, and the machine’s wire changer quickly and smoothly goes from that to standard larger-diameter brass wire.”
78 MetalForming/October 2012
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