Medical parts gain from single set-up efficiency

A trio of Bumotec multi-axis, multi-tasking machining centres are helping Shanghai Medical Instruments (Group) to maintain its 50% market share in China for medical instruments. Moreover, the ability to finish-machine up to six faces at high accuracy and in a single set-up, have enabled the company to expand profitably into the manufacture of minimally-invasive instruments and devices.

Indeed, while the effectiveness of the machines at single set-up multi-operations has brought great rewards in both prototyping and manufacture, the company highlights its latest Bumotec – the five-axis s181 model with ‘front live tools’ on a sub-spindle – as being able to boost productivity by 20% on some parts.

Capable of producing complex, multi-faceted components from bar up to 65 mm diameter, and with up to seven-axis simultaneous machining in a single set-up, Bumotec machining centres are capable of drilling, thread forming, grinding, gear cutting and broaching, in addition to turning and milling. According to Starrag, the machines are renowned globally for producing small, intricate workpieces that come off ready for assembly with no deburring – as Shanghai Medical Instruments has found.

A member of the Yuwell Group, the company has four production plants in the Shanghai area; three manufacturing/assembly facilities and one site dedicated to forging, surface finishing and heat treatment. Established in 1928, Shanghai Medical Instruments annually manufactures over 10 million parts for use by hospitals throughout China and in other countries. Components are produced in limited batches of 200-300-off, with the company’s in-house manufacturing routines complemented by a group of subcontractors. In addition, there is an in-house team of 20 quality control engineers.

Shanghai Medical Instruments has a product catalogue of more than 8000 items, which includes its flagship, award-winning JZ brand. Key products include knives, scissors and surgical clamps, as well as 400 different types of micro instruments for anastomosis, the treatment of lymphatic vessels and limb reconstruction.

Its portfolio also embraces instruments for ENT surgery, orthopaedic implants and 300 types of minimally invasive instruments such as laparoscopic clamps (used in endoscopy procedures) plus 400 instruments for dental surgery. Surgical staplers and electrical tools used in surgery also form part of the portfolio.

The development of so many different products is based on close work with hospitals and universities, and the company’s R&D team collaborates with these ‘partners’ throughout the entire new product development process, from design, studies and validation, up to production. Shanghai Medical Instruments’ well-equipped workshops allow the process to be flexible and responsive, and the prototyping and production of certain parts is a key area for the Starrag-supplied Bumotec machining centres (models s192, s181, s191), the first of which was installed in 2005.

A range of 500 different types of minimally-invasive and ENT instruments are machined in a single set-up from bar on the Bumotec machining centres. Over the years, the company has found that ‘conventional’ separate processes/machines are not able to produce these components effectively, especially in terms of quality and the issue of ‘matching’ parts and features. Also, the multiple complex clamping procedures required for the various stages of machining make traditional production slow and inefficient.

Bumotec machines, on the other hand, can produce complete components in a single clamping from bar stock, finish-machining up to six faces in record time – in one case, up to 20% quicker.

In fact, even the production of separate parts (on the same machine) for an orthopaedic instrument assembly meets the company’s stringent quality standards. The two-part assembly is now produced with high accuracy, ready for assembly and more cost-effectively by a Bumotec s191, rather than the former route of using a lathe, a mill then an electrical discharge machine to finish the parts to the required standard.

Starrag’s Bumotec s191H can achieve highly accurate (±2.5 µm) machining solutions within its X-, Y- and Z-axis range of 410, 200 and 400 mm, respectively, courtesy of linear drives and high-level thermal stability. In addition, a sub-spindle can turn in both horizontal and vertical planes for multi-process/tasking routines. Tool magazine options extend to up to 90 pockets on a machine that offers rapid traverse rates of 50 m/min and a 30,000 or 40,000 rpm spindle, which also contributes to fast cycle times.

Another example concerns the production of an instrument for ENT surgery. This part is produced on a Bumotec s181 in eight minutes, instead of 10 minutes by former methods, thanks to the simultaneous use of the machine’s sub-spindle.

The company continues to invest in Bumotec because, it says, “the machines’ stability in production is extraordinary, and their ease-of-use makes them accessible even to the newest members of our production team”. Also, when installed, “the training supplied means we can get the machines into production very quickly”. Shanghai Medical Instruments adds: “Production changeovers are quick and easy, and maintenance routines are effective and efficient thanks to Starrag’s excellent customer support.”

Commenting on how the success of Bumotec machines can be mirrored by UK medical manufacturers, Lee Scott, Starrag UK’s director for sales and applications, says: “The UK medical manufacturing market is an important sector for Starrag and, underpinned by our engineering applications knowledge, we know that Bumotec users can ‘hit the ground running’ in terms of gaining production efficiencies.”

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