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Wayne Ross and Jacob Hebbeler of Silfex, based in Eaton, Ohio, have both used ballbar analysis to maintain and enhance the accuracy of the plant’s 50 machines for more than a decade. But experienced ballbar users can learn a few new tricks. After upgrading to a QC20-W wireless ballbar and taking the Renishaw Advanced Ballbar course, TPM manager Ross and machine operator Hebbeler now use captured ballbar data to evaluate machines, to ‘super-tune’ them to better-than-factory accuracy and to get longer life out of machine components.

Silfex’s machining application is like a military proving ground for machine tools, so machine diagnostics are a way of life. Its lathes and vertical machining centres — primarily Haas and Mazak — use diamond tooling to grind and polish silicon and quartz for the semiconductor industry, resulting in glass-like debris and diamond particles forming an abrasive compound that wears out components in months.

Processing the silicon involves wire sawing, waterjet cutting, milling, drilling, grinding and lap polishing before inspection in metrology rooms with CMM and VCMM equipment. Parts then go to an on-site cleanroom for packaging. Production runs range from five to 100 pieces per setup and the required tolerances are typically ±0.001in, with some requiring ±0.0005in.

Grinding silicon creates a harsh machining environment. Ross said: ‘We’re using conventional machines to do unconventional processing, and using ballbar diagnostics to stay on top of our machine capability in a high-wear application. We use the ballbar to diagnose ballscrew wear every six months, but usually get called to test machines before that.’ 

Key benefits of product application

  • Following the training, Ross and Hebbeler have changed the way the company proves out machines, schedules maintenance and evaluates the need for new machines. Ross said: ‘We’ve done ballbar testing for years, but until we took the advanced ballbar course we weren’t making full use of the results. Now we’re using the ballbar to qualify metrology, time our maintenance decisions, implement TPM and SPC and even forecast machine life. It’s helping us make operational and capital equipment decisions in ways we never thought possible.’
  • According to Ross, the advanced ballbar training showed them how to determine if they could make machine adjustments or if it is time to replace the ballscrews. This allows them to control downtime scheduling and maintain accuracy as machine components wear out, rather than judging machine capability from the quality of finished parts.
  • Ross and Hebbeler came away from Renishaw advanced training with a much better understanding of their ballbar data and how to use it. Hebbeler said: ‘I’ve been working with ballbars for 13 years and thought I knew my stuff. But after 10 minutes, I was learning new tricks. Among other things, we learned how to troubleshoot scale mismatch, which has helped us super-tune our circular interpolation and extend the useful life of the mechanical parts of our machines. We also look at lateral play to gauge the condition of our linear guides.’
  • Silfex is now using ballbar data to establish thresholds in relation to its various processes and determine process capability. Ross said: ‘We now have diagnostics to back up what we think is happening with our machines. This data is being used for our TPM programme, implementation of SPC and our future OEE monitoring. Full SPC will allow us to move away from 100 per cent inspection. We are also working to determine what will be the useful life of a machine based on capability, maintenance costs and consistent quality.’

Renishaw

A world leader in engineering technologies, Renishaw’s core skills in measurement and precision machining serve sectors as diverse as dimensional metrology, spectroscopy, machine calibration, motion control, dentistry and surgical robotics.

A world leader in engineering technologies, Renishaw’s core skills in measurement and precision machining serve sectors as diverse as dimensional metrology, spectroscopy, machine calibration, motion control, dentistry and surgical robotics.

Sensors for co-ordinate measuring machines (CMMs) are an industry standard, from basic touch-trigger probes through to automated stylus and probe changers, motorised indexing probe heads, and revolutionary five-axis measurement systems.

Machine probes for CNC machine tools allow automated tool setting, workpiece set-up, in-cycle gauging and part inspection. Products include laser tool setters, contact tool setters, tool breakage detectors, touch probes and high accuracy inspection probes.

For motion control, Renishaw supplies laser encoders, optical linear encoders, optical angle encoders, optical rotary encoders, magnetic rotary encoders, magnetic chip encoders and magnetic linear encoders.

To analyse the static and dynamic performance of position-critical motion systems, Renishaw’s laser interferometer and environmental compensation system offers a linear measurement accuracy of 0.5 ppm, readings of up to 50 kHz and a linear measurement speed of up to 4 m/s, with a linear resolution of 1nm.

Renishaw’s Raman spectroscopy products exploit the Raman effect to identify and characterise the chemistry and structure of materials. A diverse range of analytical applications include pharmaceutical, forensic science, nanotechnology, biomedical and semiconductors.

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