Ten out of ten for Smith & Nephew Orthopaedics Ltd

Date: 08 April 2010

Leading orthopaedic manufacturing specialist invests in tenth mill-turn centre from Mills CNC.

Smith & Nephew Orthopaedics Ltd has recently invested in its tenth Doosan multi-axis mill-turn centre from Mills CNC.

The machine, a MX 2000ST, was installed at the Company's Advanced Bearing Systems' facility in Leamington Spa in Autumn 2009 and is being used to manufacture complex, high-precision orthopaedic ball (femoral) and socket (acetabular) components used in BHR (Birmingham Hip Resurfacing) surgical procedures.

BHR

BHR hip resurfacing, pioneered by UK Orthopaedic Surgeons Dr. McMinn and Dr. Treacy in 1997, uses low wear, metal-on-metal bearing resurfacing technology and is a procedure where the articular surfaces of the femur and acetabulum are replaced, leaving the femoral head substantially preserved.

BHR is a less radical and invasive bone sparing solution, unlike THR (Total Hip Replacement), to treating arthritis, disease and hip injuries in younger or more active patients - and well over 100,000 operations in over 42 countries have been successfully performed using the BHR approach.

To understand the reasons leading to Smith & Nephew's latest MX 2000ST investment, we need to go back several years when the first 2 x MX machines were purchased by the Company.

MX - the right tool for the job

Smith & Nephew had acquired (in 2004) MMT (Midland Medical Technology Ltd), the Company that pioneered the BHR technique some 7 years earlier.

To ensure the consistent high quality and high precision of its BHR components (femoral heads and acetabular cups), and to improve productivity, eliminate waste, reduce manufacturing cycle times and lead times, and ramp up production etc - Smith & Nephew introduced and implemented comprehensive and integrated Lean Manufacturing and Continuous Improvement Strategies at its Advanced Bearing Systems facility.
Says Paul Footman, Manufacturing & Production Manager:

'When we set up our manufacturing operation here in Leamington, building on our earlier experiences, and began cellularising all elements of production - we needed access to advanced CNC machine tool technologies.

'Essentially we were looking for machine tools that could achieve and maintain consistently high levels of precision.'

BHR components are made from cobalt chrome castings (an extremely hard and durable material), and part accuracy repeatability, and surface finish requirements are extremely demanding (roundness tolerances are generally less than 2 microns; surface finish requirements are in the region of Ra 0.015µm).

Continues Paul Footman:

'We also wanted to significantly reduce cycle times (to meet demand, reduce lead times and increase productivity), and to standardise our method of production.

'To acquire the machine tool(s) to help us do this we invited 3 machine tool manufacturers to enter into a trial to produce sample batches. Mills CNC with its Doosan MX 2000ST machine was one of the companies invited.'

Smith & Nephew's trial was not just limited to identifying the optimum machine tool - instead the Company was also looking for a full turnkey manufacturing solution, involving tooling, fixturing, coolant etc, to be replicated in its manufacturing cells at its Leamington facility.

The MX machine, with its high-torque main and sub-spindles; +/- 80mm Y-axis for performing mill/drill operations across the centre line; B-axis rotation capability on its milling spindle (240 degrees/0.001 increments) for machining complex angled features; large servo-driven bottom 12-station turret (5.5kW 4,000rpm), and large capacity ATC - provided Smith & Nephew with the power, flexibility, process reliability and 'one-hit' machining potential required.

The performance of the MX machine combined with Mills CNC's technical and applications expertise and support, resulted in Smith & Nephew continuing it's investment in MX 2000ST machines in 2005.

Now, some 5 years on, a further 8 x MX machines have been purchased and all are performing well. Machine cycle times are constantly being reduced and the Lean Manufacturing Strategies introduced by the Company, have helped improve quality and productivity still further.

Concludes Paul Footman:

'Our decision to invest in Doosan mill-turn machine tool technology has proved to be a good one. We value Mills CNC's contribution to our business and in addition to their applications and technical support - we also rely on their service and maintenance too - and that's why all of our Doosan machines are covered by Mills '360' Service Contracts.'