Wire Changing EDM Proves Big in Micro Tooling Production

Advanced EDMs allow shops to micro machine complex tooling with the utmost speed, accuracy and surface finish quality. Plus, with automatic wire-changing capability (AWC), parts can be roughed using more cost-effective large-diameter wire types, then finish cut with high-end high-performance smaller-diameter wire to help reduce wire consumables costs.

One shop finding microstamping tool machining success with today’s advanced wire EDM technology and AWC capability is Scenic Tool and Stamping, Inc. (Campobello, SC). This full service tool and die shop, established in 1995, handles a wide range of job sizes.

However, its real niche is providing intricate micro stampings of electric contact connectors to the automotive and electronics industries. In 2011, the company produced slightly fewer than 1 billion electric contact connector stampings for its various customers, with individual order volumes ranging from 50 to millions of pieces.

Much of the connector stampings Scenic Tool and Stamping produces are tiny, complex and stamped out of very thin rolls of raw material. For example, some stampings measure in the area of 0.030 in wide and 0.150 in long with features as small as 0.012 in and overall dimensional tolerances that often must be held to within ± 0.0005 in. And while producing connector stampings to such exacting tolerances is challenging, the shop’s customers continually request that they be made even smaller.

“Wire EDM is at the heart of our shop. We design tooling according to the capabilities of that technology,” said Mike Blackwell, the president of Scenic Tool and Stamping. “With the ability to cut parts using wire diameters down to 0.002 in, we are able to easily meet customer requirements for smaller more precise micro stampings, and do so while also reducing overall processing times for the tooling. But most importantly, wire EDM allows us to generate the extremely high-quality surface finishes critical for micro stamping tooling. ”

Scenic Tool and Stamping relies on a CUT 2000 wire EDM from GF AgieCharmilles (Lincolnshire, IL), with a new third-generation twin-head Automatic Wire Changer, to easily achieve surface finishes of .2 Ra. According to Eric Blackwell, the CNC and EDM manager at Scenic Tool and Stamping, the necessary settings and parameters for doing so are built into the machine’s control, so the shop rarely goes through any trial and error processes.

The CUT 2000 features a cast iron, C-frame construction to maintain high stability and dynamic rigidity. Additionally, the machine is equipped with the GF AgieCharmilles highly efficient Intelligent Power Generator (IPG) that provides reliable machining of even the most complex parts requiring superior surface finishes.

Much of the tooling components at Scenic Tool and Stamping are produced for production tooling or 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 carbide, begin as saw-cut blocks of raw material, and machining operations can start either with manual or CNC milling, then involve jig-boring or threading holes before parts go to heat treating. Once hardened, parts are rough ground and either finished ground or wire cut on the CUT 2000 EDM.

The shop sometimes runs multiple parts in one setup on the CUT 2000, but most often workpieces are run one at a time because they can require as many as 20 different cavities each. With the machine programmed to move from cavity to cavity, typical burn times vary from 30 minutes to five or more hours.

With the AWC, the CUT 2000 lets the company easily switch between wires of different sizes and materials, allowing optimization of both roughing and finishing operations while also conserving the use of high-end small-diameter coated wire. For one of many applications at Scenic Tool and Stamping, the wire-changing capability played a key role in reducing processing time for carbide punches.