Peter Pryce with the XYZ 500 LR vertical machining centre on which the National Centre for Eye Proton Therapy are machining the precision collimators for the treatment of eye cancers

The National Centre for Eye Proton Therapy, part of The Clatterbridge Cancer Centre NHS Foundation Trust’s Wirral campus, is a world leader for the treatment of rare eye cancers and is unique within the UK.

The advantage of proton treatment is that the penetration depth of the 60 MeV proton beam can be controlled and only has a maximum range of 31mm in water, making it ideally suitable for treating any position within the eye and, in many cases preventing the complete removal of a patient’s eye.

Patients require four treatments over four consecutive days that each take just 20min. Key to the success of that treatment is a small brass component called a Collimator, tailor-made to shape the beam to cover a specific tumour, while protecting the surrounding area. These Collimators are now being machined using the centre’s new XYZ 500 LR vertical machining centre (VMC), in a cycle time that is 95% shorter than previously achieved.

Prior to treatment commencing a patient has the affected eye scanned to precisely identify the size and position of the tumour. That scan is converted using some bespoke software to create a DXF file, which is then processed by the Siemens CAD reader to generate the tool paths for the XYZ 500 LR.

The only input required from Peter Pryce, the centre’s lead engineering technologist, is to input a variable scribed line, patient name and number to be engraved and, on some parts, a tapped hole is also required.

From receiving the scanned data to finished part now takes between 15 and 20min, with less than 7min of that required for actual machining time. Prior to the arrival of the XYZ 500 LR, the machining alone would have taken over 2hr to complete.

This significant time saving has two major benefits. First, it frees up time in the workshop to carry out other tasks, and second, on those occasions where a quick turnround is required, the Collimator can be completed in the time it takes the radiographer to set up the Proton machine and prepare the patient for treatment.

Mr Pryce said: “We were constrained by the design of our previous machine, which lacked a toolchanger and we were not able to run it at the level we can achieve on the new XYZ machine.”

The XYZ 500 LR is the smallest of the four machine linear rail machining centres available from Devon-based XYZ Machine Tools and while relatively compact, with a footprint of 1,660 x 1,860 x 2,300mm, it doesn’t lack in capability.

An 18hp (13kW), 8,000 rev/min, BT40 spindle is supported by a 12-position tool carousel, with a maximum tool weight of 6kg. Table size is 580 x 400mm with a maximum load of 250kg, with axis travels of 510 x 400 x 450mm in the X, Y and Z axes. A fourth axis rotary table is an option, along with Renishaw or Heidenhain tool setting probe and a Siemens 828D CNC control.

The ease-of-use of the Siemens control was a boon to Mr Pryce, who by his own admission hadn’t done any serious CNC programming since his apprenticeship back in the late 1970s.

“The two day on-site training provided by XYZ’s Mark Higson was fantastic and was enhanced by Mark doing preliminary work on part programs before he arrived. He was also impressed by the fact we had all the tooling and workholding from Ceratizit in place, so we were ready to go as soon as he arrived.”

Training wasn’t the only element of the machine purchase that impressed Mr Pryce — from the initial sales discussion through to machine installation “everything went like clockwork”.

He concluded: “Our location isn’t designed as a workshop, so we have no large doors to gain access. The machine had to be stripped to get it in position and the delivery team did an amazing job.”