22 June 2012
Walter GB supports machined-to-size forging effort at Independent Forgings and Alloys
Walter tooling has delivered improved cutting performance at Independent Forgings and Alloys (IFA), Sheffield, where challenging materials such as nickel alloys, Inconel and titaniums are machined.
The company has a host of blue-chip customers throughout Europe and the USA, as well as Japan – and in industry sectors such as aerospace, petro-chemical, gas and oil, and energy. Mark Crossley, machine shop production manager, says the workpieces processed at the Ecclesfield machine shop in Sheffield "are very unforgiving".
As a company, IFA specialises in the single–source supply of proof-machined components; starting with the creation of the original forgings at its headquarters site at Hillsborough, a few miles from the machine shop and where the company history stretches back to 1898. A large range of rings, blanks, boss/double boss blanks, shafts and GFM round, square and rectangular bars is forged.
Mr Crossley and his 17-man team take the forgings and cut through the black forged skin before hogging metal, using a plant list of heavyweight mills, VTLs and lathes. The Ecclesfield site also machines certain tooling for the forge, from EN24 and waspalloy, for example.
Mr Crossley adopts a pragmatic approach to the application of all potential new tooling: "If it can show us any improvement in machining performance, however small, not only in terms of reduced cycle times but also, importantly, in cost per part, then we'll use it."
A broad spread of carbide inserts from Walter GB is used exclusively across all milling operations, which says much about how the potency of the Tiger.tec Silver and Tiger.tec inserts is enabling IFA to remain a supplier of choice of a wide range of high integrity, machined-to-size condition forgings, some weighing 10 tonnes.
Because of the difficult-to-machine nature of these materials, solid tooling "is out of the question", Mr Crossley says. "Regrinding of tools is simply not an economically viable option because of the extreme rates of edge wear.
"We're all about efficient and effective material removal," he continues. "We undertake all the rough machining on workpieces, supplying these guaranteed to size, so we welcome any new tooling that can help improve our competitive edge against not only overseas suppliers, but also some competitors that are literally on our doorstep.
"All our tooling for the past four years or so has been supplied via local distributor Unimerco Walmsley; a variety of Walter Tiger.tec Silver and Tiger.tec carbide inserts, which between them promise anywhere between 50 to 100% improvements in tool performance/tool life, due to improved process reliability. This is courtesy of their high resistance to flank wear, cratering and thermal cracking."
Mr Crossley acknowledges the importance of continued development in tooling materials: "It is important to recognise that tooling manufacturers are constantly developing their products, thankfully. But every new tool's reduction in cutting/cycle times does not necessarily equate to reduced overall tool cost – so, we have to obviously balance the (possibly increased) cost of each insert against the time savings being made.
"Aside from needing milling inserts that can withstand heavy metal removal on hard-to-machine workpieces, another aspect that impacts our choice of tooling is the fact that we have frequent changeovers – we process mainly one-offs and 50 is large batch for us. Ease of insert changeover is important, and I particularly like Walter's button inserts which we can quickly and simply index a few degrees to reveal another new cutting edge."
Tiger tec. inserts combine a mixture of aluminium oxide (Al²O³), titanium carbon nitride (TiCN) and titanium nitride (TiN) coatings on a tungsten carbide substrate, and they feature a grey (TiCN) rake face and a golden TiN finish (flank face) that aids wear identification. The inserts' aluminium oxide coating is particularly effective against tribochemical wear and it permits higher cutting speeds and feeds to be employed while also providing longer service life. The TiN coating simplifies wear detection and thus avoids the unnecessary waste of unused cutting edges. The grey TiCN rake face minimises negative tensile stress and improves adhesion and toughness.
Tiger.tec Silver is Walter's latest generation CVD-coated indexable insert. Its unprecedented machining capability is due to a totally new surface treatment that significantly reduces the in-cycle machining stresses of both wet and dry applications, due to its balanced combination of a high level of toughness and maximised hardness.
In addition, its CVD-Al2O3 grade coating counters any influence from thermal shock that can lead to thermal cracking at the cutting edge and it minimises tribochemical wear on the flank face. These are key areas that can lead to premature insert failure.
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