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Shops Continue to Rethink Brass and HSM

Adam Estelle
By Adam Estelle Director, Rod & Bar Council, Copper Development Association

At the Copper Development Association (CDA), we are eager to help shops discover and tap into the high-speed machining advantages of brass. The substantial benefits of doing so have an increasing number of shops rethinking their part materials and, when possible, converting those parts to brass.

Brass offers important advantages for many projects and for many reasons. Unlike other metals, brass serves as an ideal medium for drilling deep, accurate holes at high speed and extending tool life at the same time. In turning operations, brass withstands aggressive metal removal rates for long production runs while maintaining tight tolerances and discrete chip formation.

Machine wear drops at high speeds with brass because it produces less tool deflection and requires less power to remove the same amount of material. The benefits continue even after the workflow is completed, because brass scrap can hold up to 90 percent of its value. Scrap buy-back programs yield a favorable net material cost for shops and reduce the industry’s carbon footprint.

Successful Application Testing

For example, in application testing at SPR Machine, a job shop in Hamilton, Ohio, the fast and easy machinability of brass contributed to process optimization and, more importantly, to a reduction in cycle time from six minutes, 17 seconds down to two minutes, 20 seconds per part. That efficiency increased throughput from 76 to 191 pieces per shift.

Through SPR’s collaboration with the Cincinnati-based machinability experts at TechSolve, which provides manufacturing process solution services, SPR gained a unique opportunity to optimize this application, which involved a part for off-road, radio-controlled (RC) hobby cars. After rethinking the part in brass, Scott Pater, co-founder and vice president at SPR Machine, went all in on the technology necessary to produce it, adding a Swiss-style multi-spindle machine with dual 6,000-rpm spindles, 27 tools, linear ways and a 12′ (3.66 m) hydrostatic bar feeder.

Initially, the part required ball milling, drilling and boring. Together, SPR Machine, TechSolve and CDA uncovered several ways to boost productivity. First, we realized that by substituting broaching for ball milling—a move that wouldn’t work well if the part were made from either stainless steel or steel—SPR could gang up five parts simultaneously. Pecking with a carbide drill using fewer retracts and more-aggressive feeds and depths saved even more time, and balancing the workload between the machine’s dual spindles also helped increase throughput.

A Vast Improvement

The new brass RC car part was a vast improvement over the existing version made from 12L14 steel. In the latter material, corrosion and swelling made it difficult to remove the installed part once the car ran through mud and water. In aluminum, the part lacked enough heft and strength to work properly in a fast-moving miniature vehicle. In brass, however, it could take the pounding of RC racing, provided weight to stabilize the vehicle’s low center of gravity, and offered aesthetically pleasing benefits to attract customers.

We thank SPR Machine for partnering with us on this project, which produced the kinds of results that showcase the versatility of brass. On today’s fast machine tools, the high-speed machining capabilities of brass play a key role in helping shops take full advantage of their high-performance equipment, and produce compelling advantages that can increase productivity and profitability.

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