Originating in Switzerland in the late 1800's to manufacture high-volume, precision parts for the Swiss watch industry, Swiss screw machining has evolved into a precision machining technology that produces critical parts and components for many industries and applications across the globe. Capable of producing parts with very tight tolerances and fine surface finishes, and essentially the only process capable of producing parts in volume with very high length-to-diameter ratios, while maintaining very tight tolerances, Swiss screw machining has become a critical aspect of any industry that requires parts and components of that nature.

Swiss screw machines are defined by their unique machining process utilizing both a "sliding" head-stock feed and guide bushing. The sliding headstock allows both the tooling and the headstock to move simultaneously, and in conjunction with the guide bushing, allows the actual machining to take place very close to the guide bushing where this support and minimized deflection provides the capability to hold tight tolerances on long, cylindrical parts, and to also create fine surface finishes.

Over the years, these cam-driven machines were enhanced with various attachments that were integrated into the Swiss screw machine and allowed drilling, milling, boring, tapping, thread-whirling, knurling and other operations to be performed in conjunction with the primary turning operations, thereby allowing parts to be produced complete, or with a minimum of secondary operations.

Technological advancements and the continued "miniaturization" of products has led to increased demand for the small, thin, tight-tolerance components that Swiss screw machines excel at producing. That progression has made Swiss screw machining a key aspect of many technologically advanced industries.

CNC Swiss Screw Machining

Using a battery of Swiss Screw Machines including Tornos, Bechlers, and Escomatics, and CNC equipment with a large secondary department and fully staffed toolroom, microminiature shapes, compound curves/right angles, miniature components and numerous shapes and sizes are manufactured. Large centerless grinders, automatic lathes that accommodate up to 1.125" diameters with automatic bar feeders and spindle-stopping devices are applied to mill and cross-drill. Lengths up to 26" can be handled.

The Escomatic coil-fed machines have up to 0.157" diameter capacity. Tolerances within 0.0005" diameter and lengths within 0.001" are achieved. The secondary equipment should include double-drill, cross-hole semiautomatics, single semiautomatic slotting machines, Brown and Sharpe lathes, Swiss-type CNC lathes and rotary tables. Heat treating is available in-house or offered through outside services along with plating and related functions.

The products manufactured under Statistical Process Control (SPC) are used in electronics, automobiles, aircraft, cameras, appliances, ordnance, instrumentation, valves and personal communications. Materials used are copper alloys, stainless steels, aluminum, carbon steels, tool steels, brass, beryllium and some plastics.

Important are a fully equipped toolroom and the ability to perform engineering, CAD designing and fabrication of special jigs, tools and fixtures including CNC-controlled cam cutting. It is also important that the tooling be maintained through an organized program.

If implemented, a savings in parts can be realized through a program of blanket orders for a year's supply that can be released from stock as needed.

Criteria to be considered when selecting a source of screw machine products include the following:

• Degree of compliance with all industry and governmental regulations.
• Experience history of company.
• Quality methods in place.
• Reasonable pricing.
• Timely delivery.