Forming in cycle cuts medical component cost
The Star SV-32 generally machines the larger tubular medical component in one hit, including in-cycle forming in addition to turning, milling and deburring
Royston subcontractor First Instruments is using in-cycle forming on a CNC sliding head lathe to produce thousands of stainless steel medical instruments in one operation instead of five.
The two lathes chosen for the job are from Star GB's SV-range, a 32 mm capacity slider and a 20 mm model. Applications engineers from the Melbourne, Derbyshire machine supplier were instrumental in making the production process a reality at the outset, since which time First Instruments has refined the cycle to minimise production time.
The medical instrument is an assembly comprising two 304 stainless steel tubes, one inside the other, plus six internal pins. It is the tubes that are made on the Star lathes and both the inner and outer can be machined on either machine.
The inner starts as a solid, 5 mm diameter bar which is deep-hole-drilled to ten times diameter from both ends in three pecks using a 3.5 mm Mikron CrazyDrill. The high-pressure coolant facility on the Stars is crucial for this operation.
The outer stainless steel component is produced from tube stock of 7 mm diameter, 1 mm wall thickness. After mill-turning operations are complete, the end of the component is formed in a highly unusual operation, the exact nature of which First Instruments prefers to keep confidential.
Phil Grove is a director of First Instruments and also of sister company, PBH Engineering, which developed the process and produced early prototypes. He said, "Star was the only sliding-head lathe supplier prepared to put the work into helping us develop a viable process for producing this component.
"They provided a turnkey, two-machine package complete with tooling, programs and training, which was essential for us as we were a first-time user of sliding-head technology."
A huge reduction in production time results from one-hit machining of the outer component, compared with the five operations that were previously needed. They comprised CNC turning, milling on a machining centre, manual forming and then back onto the machining centre for the form to the profiled. Subsequent deburring, formerly carried out by hand, is now performed automatically in the same cycle on the Star lathe using a 3D milling routine generated by the company's OneCNC CAD/CAM system.
With 40,000 sets of parts required per year, the cost savings in terms of labour and work-in-progress are considerable.
First Instruments Tel: 01763 269988.
PBHengineering@aol.com
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