Angstrom Limited is a successful, small precision engineering subcontractor based in Stoke on Trent. The company has achieved higher productivity and reduced component costs since purchasing a CoroMill 490 milling cutter with four-edge inserts from Sandvik Coromant.

David Lymer, Director of Angstrom Limited, Stoke on Trent, said: 'What benefitted us particularly was its soft cutting action. We could use it in a low power machine tool. We tried other indexable tools but they all wreaked havoc with the machine. The CoroMill 490 was the first to run smoothly, despite the low rigidity of our Cincinnati Arrow machines.'

Angstrom uses a Cincinnati Arrow 500 machine tool with ISO 40 spindle to manufacture dies for mixing elements and extruders in D2 tool steel for a long-term subcontract. When Jason Leese of Mettex and Stephen McCabe of Sandvik Coromant approached David with the suggestion that he might gain savings with the soon to be released CoroMill 490 milling cutter, David was interested and agreed to try it.

Angstrom Limited is a successful, small precision engineering subcontractor based in Stoke on Trent, UK. It operates primarily as a jobbing shop and as such cannot afford to acquire specific tools or tooling for its varied short-run subcontract jobs. Most of the machine tools installed are small and fitted with 40mm spindles; the machines, tools and tooling need to be multi-purpose and cost-effective. Angstrom has four machining centres, three CNC lathes, two wire cutters and manual machines; Fanuc is the preferred controller and Cincinnati the preferred machine tool maker.

Lymer explains: 'We do not keep specific grades for specific jobs. We need universal tooling and multi-function grades and inserts that can cover all our jobs. We are always looking for tooling, tools and techniques to reduce our costs per component.'

Lymer was not specifically looking to alter the processing of the dies. 'It is important that we offer our customers keen component prices.  If we don’t, we risk losing their production contracts to other suppliers or overseas competitors. So I was pleased to try the CoroMill 490 to see if we could benefit from higher productivity or savings. What we achieve in reduced costs, we pass on to our customers.'

Profiling the tool steel dies on the Cincinnati Arrow had proved to be unworkable using other indexable milling cutters because the material is hard and the machine insufficiently rigid. Angstrom had therefore been machining the dies with a high-speed steel ripper. This operation had defied previous indexable milling tools because most small-diameter milling cutters only have two insert pockets causing intermittent cutting (as the cutting edges repeatedly lose contact with and re-enter the material). CoroMill 490 carries three inserts in its 25mm diameter cutter - maybe three cutting edges would make a difference.

Angstrom began a trial of the 25mm CoroMill 490 using the Cincinnati Arrow 500 to profile dies with a 23mm engagement and multi-passes. The results were good, better than good in fact, not only because of the soft cutting action but because the cutting edges remained in continuous contact with the material, thus preventing the problem caused by other 25mm cutters.

Tool life also greatly improved, lasting 40, instead of 25 components without the need to regrind, unlike the ripper. Equally significant was the cycle time CoroMill 490 saved. Despite its higher purchase price, the CoroMill 490 paid for itself in a single batch of 50 components through increased productivity and time saved.

Lymer continues: 'The overlap is good too. In a 4.5mm cut, made by four passes, there is very little mismatch between the cuts and no sharp steps.'

Jason Leese of Mettex comments: 'That’s the feedback we’ve had everywhere, everyone who has tried the CoroMill 490 has bought one.  We’ve sold more CM490s than any other Coromant Distributor in the North West; it’s a fantastic milling cutter.'

The four-edged square inserts give further cost benefits; each insert costs a little more than usual but each cutting edge costs less.

Stephen McCabe, Sandvik Coromant Distributor Support Engineer, adds: 'The CM490 is ideal for 40 taper machine tools, which is great for small machine shops and subcontractors – they also gain cost savings from its four edged inserts and adaptability, one tool can do so much.' As a result of the success of the trial, Angstrom also tried Sandvik Coromant inserts for the first time and was impressed with the new coatings of the new insert generation grades. David has bought TNMG and WMNG for machining a broad range of components in stainless and tool steels.

David concludes: 'I asked an operator who was testing the new grades how he was getting on. He replied that he was amazed he was still on the first edge and had already completed the job!'

Angstrom has since bought a second CoroMill 490 and its association with Sandvik Coromant and partner distributor Mettex looks likely to continue as its seeks advantages and improvements to improve its competitiveness.

www.coromant.sandvik.com