Producing medical components from tough materials

Adam Thornton (left) with one of Kirkstall’s setter-operators in front of the Brother Speedio M200Xd1-5AX, showing the rotary torque table that allows in-cycle turning operations to be completed

Leeds-based Kirkstall Precision, a sub-contract machining company, has enhanced its capability to serve the medical sector with the installation of a new Brother Speedio M200Xd1-5AX, a Japanese-built, simultaneous five-axis CNC machining centre supplied by Kenilworth-based Whitehouse Machine Tools Ltd, the sole UK and Ireland sales and service agent.

For the past seven years, the sub-contractor has focused almost exclusively on producing components for the medical industry, while also producing surgical instruments and implants for the veterinarian sector. The company is seeing a 15 to 20% year-on-year growth rate due to high demand.

The Brother Speedio M200Xd1-5AX on the shopfloor at Kirkstall’s Leeds facility. The high-speed, BBT30, 16,000rev/min spindle machine, normally associated with cutting aluminium and other light materials, here machines mainly stainless steels, titanium and other tough alloys

The Brother was chosen for its accuracy, repeatability, versatility and compact footprint. Adam Thornton, Kirkstall’s managing director said: “Accuracy in the medical sector is a given. Everything has to be completely correct, so we inspect and report all dimensional tolerances. Opting for a top quality machine tool like the Brother was a fairly obvious decision for us.”

Approved to ISO 13485, a globally recognised quality management system standard for medical devices, Kirkstall produces mainly low-volume orthopaedic components from challenging materials, including stainless steel, hardened stainless, titanium and other tough alloys. The 30-taper Speedio is ideal for machining these materials continually. Additionally, it is able to combine on a single platform five-axis prismatic machining using the 16,000rev/min spindle with turning using the rotary torque table, which was a further key attraction.

20% cycle time reduction
Mr Thornton added: “We have used 40-taper five-axis technology for some time, but the Brother is faster and takes up less space. It is ideal for the smaller, high-accuracy parts we produce and has delivered typically a 20% cycle time reduction compared with our larger production centres.”

One such component, a keel punch for total knee replacement surgery, previously required four separate operations on three machines. The Brother now completes 90% of the features in a single setup, so only a short second operation is needed, reducing cycle time by 30% and improving accuracy. Setup times are faster, the amount of handling has reduced, and most importantly there has been a big improvement in the accuracy of the product, which is machined to within 15 to 20µm over the entire form.

This stainless steel keel punch used in total knee replacement surgery is 90% machined on the Brother much faster than previously

Another attribute of the Speedio is its exceptional energy efficiency, a key highlight of its design. Compared to traditional 40-taper machining centres, it draws up to 80% less power, which translates into cost savings of several thousands of pounds a year.

Energy saving measures that have been incorporated include power regeneration during deceleration, high efficiency motors driving the spindle and axis motions, an optimised pump for coolant recirculation, LED lighting, low air consumption, and automatic power off when the machine is not being used.

Low power consumption is not just through energy-saving features, but is also inherent in the machine’s design. Fast cutting speeds and rapids, plus an ability to combine milling and turning operations in one setup, lead to reduced cycle times which in turn lowers power consumption.

Mr Thornton said: “Whitehouse Machine Tools has been a collaborative partner, very similar to us in terms of values and ambition. We plan to add robotic component handling with optical part recognition to the Brother in 12 to 24 months’ time and we feel confident that this supplier will support us with the retrofit.”

He concluded: “We are forming a medical group in the contract manufacturing sector and are aiming to be world class. Investing in top quality brands like the Brother really adds to this strategy.”