Sliders Machine 'Difficult' Steels to Tight Tolerances

During a recent job requiring unattended machining of 316 stainless steel, for example, 10 microns was the total variation allowed on a 1.6 mm diameter hole, while flats needed to be milled to within 20 microns.

Established in 1987 by managing director, Lance Cade, Turncircuit carries out a lot of machining for the analytical equipment sector. After 25 years, the company still works for its first ever customer, PS Analytical in Orpington, indicating the high level of service provided.

It was not until 2007 that the subcontractor installed its first sliding-head lathe, a Star SR-20RIII, to fulfill a contract for 4,000-off shaft-type components per month. The work would not have been cost-effective on the company's fixed-head lathes. However, technical director Kevin de Rosario had experience of multi-axis sliding-head turning centres at a previous firm and helped to source the best make of equipment for Turncircuit's intended range of applications.

In view of the types of materials machined and the extreme accuracies required, Star equipment was first choice due to the high power, rigidity and robustness of build.

Mr Cade said, Cutting trials performed on a number of leading makes of slider were broadly similar in terms of accuracy and cycle time.

However, it was long-term precision we were looking for and that is what we got with the first Star lathe.

It has also proved to be very reliable and has not been down for a single day since we bought it.

Despite working around the clock during the week and at weekends as well, the first SR-20RIII and a second we bought in 2011 produce less than half a percent scrap – and that is down to human error, not the machines.

High pressure coolant delivery at 140 psi has been fitted to both of the Stars to help break up the stringy swarf and assist its removal from the working area, again with accuracy of machining in mind. Productivity has been enhanced by adoption of Eppinger's modular Deco-Flex compact toolholding system that allows preset tools to be exchanged in a matter of seconds, while maintaining the tolerances required.

The level of success enjoyed by Turncircuit with its two Star sliding-head CNC lathes has boosted this type of work to account for 40 per cent of company turnover, from a standing start in 2007. The technology is used across many of the 40 or so customers that the subcontractor services in the analytical equipment, electronics, aerospace, petrochemical and marine sectors.

Mr Cade concluded, We have been impressed not only with the Star machines but also their after sales back-up, particularly the technical support.

If no-one is available when we telephone, someone always calls us back promptly and sorts things out, even over a weekend.

It appears to us that all of the supplier's engineering staff has a high level of technical and product knowledge and we are honoured to be in the Star club!