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LMT has helped Brinksway Tool, a precision aerospace, marine, defence and specialist automotive tooling contractor, to cut processing times from about five days down to five or six hours.

As a result of LMT’s milling advice, Brinksway Tool reviewed its pocket milling strategies in the production of formers for composite panels.

As a result of the milling trials, the company can now produce three former plates in the time taken previously for one, with the added bonus of a tool-life increase for milling inserts approaching 25 per cent and the use of one less insert per cutter.

‘Although it was a relatively simple task of removing material to reduce weight by creating six pockets up to 170mm wide by 180mm long and 75mm deep in the underside of composite forming tools some 1.5m by 500mm, the time taken was totally unacceptable, especially as it only involved roughing cycles,’ said Carl Nickerson, works director of the Manchester-based company.

He added that the roll-on effect of producing the formers on the company’s Correa three-axis Prisma 20 CNC machining centre created a ‘log jam’ due to the drawn-out nature of the process.

Nickerson suggested to CNC manager Simon Cornell that the company’s principal tooling distributor, E W Equipment of Cheadle, might offer help.

E W Equipment recommended a joint survey of the process by LMT UK of Meriden using the latest Fette Multiedge cutters and new PVD-coated inserts.

Cornell said: ‘Before we even looked at the methods being adopted, LMT’s engineer was checking out the power and torque curves of the machine and he immediately suggested we reduce the size of the milling cutter from a five-tooth to a four-tooth, uneven, pitch-style cutter, which has a positive rake angle.

‘He also suggested that we change the method from plunging the spindle to depth to one that profiled the programmed forms,’ he added.

Cornell said LMT’s engineer explained that the existing tooling and process had the effect of pushing the inserts into the job and consequently loading the spindle.

This was not helped by the large radii on the circumference of the insert, which ideally demanded higher torque from the spindle drive than was available.

Brinksway Tool has two seats of Delcam Powermill with Powershape modelling and Powerinspect, from which it produces offline programs that are DNC driven to each of six Heidenhain-controlled three-, four- and five-axis machining centres.

Cornell worked with the LMT engineer to formulate the new cutter paths using the LMT Fette Multiedge 4Feed cutter measuring 32mm in diameter.

This cutter was developed specifically for roughing in mould and die applications, requiring 25 per cent less power to drive the tool.

It also has a positive rake angle that helps to lower vibration under cut with deep-chip groove topography at the face.

When combined with the latest generation of the Fette MultiC, PVD AlCrN-coated thick ECP V07 insert – which has the advantage of high heat resistance due to a TiN layer on its circumference supported by a toughened carbide substrate – it gives high stability at both high and low cutting speeds.

The insert can also be used without coolant and, in the Brinksway application, an air blast was introduced to clear the rapidly growing volume of chips from the cutting zone.

Speeds and feeds were reprogrammed to run the cutter at 240m/min with a 10m/min rate of feed but just a 1mm depth of cut.

As a result, the process can be run for at least an hour before the inserts need to be changed, resulting in a 25 per cent improvement over the incumbent tool supplier, with the time taken to remove the stock material reduced to between five and six hours.

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