In the medical technology sector, there are few names more established and globally recognised than Smith & Nephew. With over 14,000 employees in 90 countries and annual sales in 2014 of US$4.6billion, Smith & Nephew truly is a world leader in Orthopaedic Reconstruction, Advanced Wound Management, Sports Medicine and Trauma.
A company doesn't establish such a dominant market position without having world class production facilities that churn out parts of the most impeccable standards. To this end, the Leamington Spa site of Smith & Nephew that is dedicated to the production of hip joints has employed workholding equipment from Hainbuch to maintain its commitment to quality.
Predominantly producing hip-joints and additional medical components from a range of materials including titanium alloys, cobalt-chrome alloys and stainless steels, Smith & Nephew approached Hainbuch because of its reputation for delivering project solutions as well as off-the-shelf products. With 10 Doosan MX2000ST mill/turn centres with twin spindle function, the Warwickshire facility is intent upon achieving the highest possible production rates, precision and flexibility.
Prior to the introduction to Hainbuch, Smith & Nephew used an alternate vendor for its workholding products. With the facility conducting both R&D, prototype and full production operations, the issue for the medical device manufacturer was a poor lead-time on standard and bespoke workholding systems. This prolonged the production of development and prototype work and would result in the delivery of new products to full production being delayed by 6-8 weeks.
Furthermore, the nature of the high production volumes of complex components that require front and back-end machining resulted in significant difficulty for Smith & Nephew to retain its high precision, concentricity and surface finishes with its previous workholding vendor. From discussions with Hainbuch; strategies and processes were developed for the clamping, positioning and transferring of components from the front spindle to the rear working spindle.
The turning department primarily turns a wide variation of bar diameters, castings and forgings up to 65mm whereby the machines are bar-fed, continually alternating part quantities and dimensions. By nature, the hip joints undergo significant multi-axis machining. The joints are turned and milled in one-hit with the B-axis milling head on the top and lower 12 station tool turrets removing high stock levels. Removing high stock levels with simultaneous complex machining is performed whilst the parts are securely held in the Hainbuch collet systems. In total, there are approximately 50 castings and forgings that make up the product range at Smith and Nephew, all of which can be machined in varying quantities.
The Hainbuch solution was to provide both dead-length and pull-back quick change collet chucks that could accommodate parts up to 65mm diameter. Part of the Hainbuch program was the supply of machineable collets that would enable Smith & Nephew to machine each collet set to suit the demands of each new prototype. Whereas Hainbuch can supply soft collets or hard collets beyond 60HRc, the collets supplied to Smith & Nephew are through hardened to 40HRc. This enables the medical customer to machine each collet to its specific project demands and still retain the collet hardness and clamping force desired.
The introduction of the Hainbuch Spanntop collet chucks offer clamping force, positional repeatability and very quick change-over times that now enable Smith & Nephew to meet its production demands. Now, all machines in the Smith & Nephew turning department have a Hainbuch Spanntop combi pull-back chuck on the main spindle and dead-length chucks on the sub spindles to obtain a 2 microns roundness precision when transferring from main to sub spindle.
Commenting upon the new workholding strategy, Smith & Nephew's Mr Sean Carroll said: 'Hainbuch have provided more than a top quality workholding product, they have provided a solution that has helped us streamline our manufacturing process and make sure that parts are reliably transferred, accurate and machined with great surface finishes. We have over recent times now replaced all our existing suppliers’ workholding with Hainbuch.'
By replacing the previous workholding systems with the Hainbuch collet chucks, Smith & Nephew has reduced its lead-times for development work with off-the-shelf collets that are immediately available from Hainbuch.
Additionally, Hainbuch collets can be internally adapted and machined by Smith & Nephew to rapidly create new prototypes. Capable of clamping on just 2mm of stock with the exact clamping force required for each part, the Hainbuch collets have reduced set-up and changeover times to less than 30 seconds in most instances. With improved collet availability, a more diverse range available off-the-shelf, reduced set-up times and significantly improved precision, repeatability and concentricity, Smith & Nephew has clearly benefitted from the acquisition of Hainbuch workholding products.