Surgical precision

Founded more than 50 years ago as a family-owned industrial engraving business, Schnipke Engraving Co. in Ottoville, Ohio, has evolved into a dual-facility organization that specializes in ultra-precision injection molding as well as automated and manual assembly. Electrical discharge machining (EDM) with automatic wire changing capability allows the company’s tooling division to engineer complex molds for critical applications in precision-demanding industries such as medical, defense, and aerospace.

According to John Hoskins, director of sales and marketing at Schnipke Engraving, the company continues to be inspired by its founder, Leonard Schnipke’s mantra, “The impossible we do immediately. The miracles take a little longer.” In following these words, and serving its diversified customer base, the staff at Schnipke Engraving has pioneered a wide range of productive and proprietary processes.

Schnipke Engraving machinists exact precise control over production processes – from the fabrication of molds, to the injection molding, through to the assembly of tight-tolerance components. And, Ron Schnipke, Leonard’s son and vice president of tooling, says the machinists consistently design, fabricate molds, and produce components that exceed customer requirements. In fact, the mold manufacturing methods at Schnipke Engraving have continuously evolved in parallel with business growth and customer demand for increasingly complex molded products.

As part of its high-precision mold making, the EDM equipment at Schnipke Engraving is a key manufacturing technology.
 

Quick-change artist

“When we started designing and fabricating mold cavities, EDM came right along with it,” Ron states.

The tool room’s first EDM machine was a manual diesinker. Today, employees at Schnipke Engraving use a sinker as well as several wire-type EDMs. The most recently acquired system is an AgieCharmilles CUT 3000 wire EDM from GF Machining Solutions that features dual-wire spools and automatic wire changing.

With twin-wire spool capacity, the CUT 3000 permits immediate and fully automatic wire changing capability from one wire diameter to another.

“We needed something that we could change over quickly.” Ron says. With other wire EDM machines, changing wire diameters is time consuming. The new machine takes less than a minute to switch, without operator intervention. The CUT 3000’s wire guide system supports wire diameters from 0.002" (0.05mm or slightly less than the diameter of a human hair) up to 0.012" (0.30mm).

The AgieCharmilles CUT 3000 uses GF Machining Solutions’ universal wire guide technology. Stationary three-point V-guides – an upper and lower – are all that are required to accommodate the wide scope of diameters.

Operators simply enter the desired wire size into the machine’s control, and the guides compensate for the difference between one diameter and the next. Most importantly, the machine is always aware of wire center to maintain exact part location and size once a wire change has occurred and cutting resumes.

All of the EDMs at Schnipke Engraving can run lights out for continuous production and maximized utilization. However, Ron adds that the newer CUT 3000 takes the tool room to the next level when it comes to speed, accuracy, and very fine, intricate high precision cuts. With automatic wire changing, parts can be roughed using more cost-effective large-diameter wire, then finish cut with high-end, high-performance, smaller-diameter wire to get the desired radii in the corners.
 

Using a variety of tactics

While the mold builders occasionally use copper, they generally work with stratified wire. The machinists normally use copper electrodes on the sinker EDM, along with a wide range of tool steels for their molds.

Where appropriate, they produce micro-scale mold features via high-speed milling. The shop considers a 0.250"-diameter cutter to be large, and the application of 0.080"-diameter and 0.040"-diameter tools is commonplace.

Tom DePotter, director of new product development, says, “Schnipke Engraving combines a variety of tactics to ensure that its processes are robust and consistent. The company’s advanced CAD system, for instance, enables us to create 3D models of molds and rotate them to see every aspect. Sigma Soft analysis software helps predict how the component material will move through the mold. It’s this application of technology that allows us to get it right the first time.”

Verifying fabrication results are as important as controlling the molding processes itself.

“Completed parts of the molds get measured in the QA lab or machine side,” Ron adds. “On-machine probing can generate problems if you have any wear on the ball screws. If you don’t measure your tooled pieces off line, you are measuring any possible error right into the mold measurement itself, versus utilizing an independent measuring system.”

Ron’s staff has developed its own automation technologies to maximize productivity and part accuracy, which have revolutionized the production and assembly of many surgical device components.

The combination of advanced fabrication processes, EDM, high precision machining, intelligent automation, and lean principles continue to enhance the machinists’ ability to respond quickly to customer demands.

Hoskins notes that, “Faster fabrication helps us condense our lead times. Our customers are constantly asking us to go faster. We are part of their product development process. They have market windows when they introduce new product; we have to hit their target objectives, because if they miss their window they lose their competitive edge.”

Schnipke Engraving Co.
www.schnipkeengraving.com

GF Machining Solutions
www.gfms.com

IMTS 2014 booth #S-8754