Carbide milling cutter for aluminium machining

The use of a Walter standard carbide milling cutter has transformed aluminium machining operations at SJC Engineering of Chelmsford by reducing cycle times by at least 60 per cent.

The use of a Walter standard carbide milling cutter has not only transformed aluminium machining operations at SJC Engineering of Chelmsford by reducing cycle times by at least 60 per cent, but the resulting savings have also prompted the Essex-based precision sub-contractor to expand its use of Walter tooling to hoist efficiency levels with other machining applications.

Specialising in the provision of small batch, often one-off, high precision machined components to major first and second tier suppliers in the aerospace, Ministry of Defence, electronics and motors sport sectors, for example, BS EN 9001-2000-accredited SJC's continued success throughout its 20-year existence has been characterised by a policy of continual improvement, as engineering manager Tim Baker explains.

"Coupled with a programme of investment in high-tech machine tools, our shopfloor teamwork ethic is underpinned by a quest to improve everything we do," he says.

"It's the only way we can be assured we will consistently exceed customers' demands for cost-down, quick turnaround deliveries.

Importantly, of course, whatever actions we take must not jeopardise component quality levels.

Providing a prototype to production service, the 10-employee company processes most materials - particularly specialist alloys for the electronics sector - and workpieces generally fall within machining envelopes of up to 350 mm diameter (two-/three-axis turning) and circa 1,000 mm by 700 mm by 700 mm (up to four-axis prismatic).

The never-ending quest to reduce cycle times has, says Tim Baker, naturally led to a strong working relationship with technical solutions specialist, SD Tooling UK, the local distributor for Walter GB's comprehensive range of tooling.

Having over the years supplied SJC with a variety of Walter drills, fly cutters and face mills, as well as carbide inserts for various tasks, it wasn't long before the companies were discussing ways to reduce lengthy machining times being encountered during the removal of 90 per cent of an aluminium billet, to create an electronics enclosure measuring approximately 170 mm by 110 mm by 110 mm to satisfy a contract for the MoD.

The suggestion of switching from the existing ripping cutter to a Walter 25 mm F4030 router cutter with two ZDGT 150408 R K85 WK10 inserts immediately made the required impact - slashing the cycle time while at the same time extending insert life significantly.

Feed rate on the 10,000 revs/min vertical machining centre was almost doubled, from 4 m/min with the alternative cutter to 7-8/m/min, and depth of cut was increased from two mm to six mm.

"Producing the enclosure is now like shelling peas," exclaims Tim Baker, "and without the Walter cutter we would find it impossible to turn the component around in the required timeframe - we would have to turn the job away! The development has certainly raised our game.

The success of the project has since led to additional work of a similar nature, and encouraged the team to extend the use of the Walter cutter from what was a straightforward hogging-out application and towards more intricate machining tasks involving blends, for example.

In one instance - the machining of a similar but larger five-sided aluminium enclosure - the Walter cutter is used in conjunction with special fixturing on a fourth axis rotary table for twin component loading to achieve single set-up simultaneous first and second operation machining.

The result is two finished machined components during each cycle.

The arrangement replaces three separate set-ups and the company confidently leaves the job to run unmanned and at night, if necessary.

Following these successes, SJC has since harnessed the power of Walter's innovative Tiger.tec inserts for turning steel.

With first-generation Tiger.tec inserts having high process reliability due to high resistance to flank wear, cratering and thermal cracking, they have regularly achieved up to 75 per cent more components per edge than competitor products - in some cases output has been doubled - and already for SJC, a steel job that traditionally took nine minutes has been reduced to three minutes with the new Tiger.tec for Steel inserts With a targeted 50 per cent improvement in performance, Tiger.tec for Steel turning inserts are already having a positive effect on users' bottom lines.

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