LMT helps Verdict make significant cost savings

LMT has revealed how its tooling improvements have helped Verdict Aerospace Components get the balance right between roughing and finishing, enabling significant cost savings to be made.

Ray Gibbs, engineering manager at Verdict Aerospace Components, said: 'If you get the balance right between roughing and finishing, it not only makes finish milling more cost-effective and customer specifications easier to achieve due to a more consistent process, but also as we have found, enables massive savings to be made.' Putting this into practice on a defence component machined from a solid forging of high chrome stainless steel, roughing cycle times were reduced to meet customer cost-down targets.

This was achieved through the combination of Gibbs putting together the toolpath strategies as they were developed on the Catia V5 design and manufacturing software in conjunction with Mark Sheppard, the machine setter, and with LMT's milling specialist, Juergen Meyer.

It was the installation of a Matsuura H Plus-405, 500mm pallet, BT40, 20,000 rev/min spindle horizontal machining centre that drew LMT (UK) into Verdict Aerospace Components through its partner, tooling supplier Valentine Tools.

Verdict requested Valentine to help to try and reduce production costs leading to an introduction for several companies to provide a solution.

The Matsuura had replaced an aging Hitachi-Seiki HS630 BT50 spindle horizontal machine that had been producing the forged steel defence part.

Once installed, Verdict's engineers initially used the already well-proven tooling and methods but very quickly Gibbs was keen to take maximum advantage of the new machine's capability.

Also with its more up-to-date control system with the latest processing technology and look ahead features, new methods could be explored.

Meyer changed an existing 52mm diameter cutter with round inserts that was running at 900 rev/min with a 1mm depth of cut and maximum feed rate of 2m/min to an LMT-Fette Multi-Edge cutter of 42mm diameter with the same depth of cut and increased the speed to 1,500 rev/min.

However, although stepover was reduced to 25mm, the feed rate of the four edge insert cutter was tripled to 6m/min.

When checked, both the new and original tool were pulling similar power which illustrates how the machine had struggled with the larger tool.

Gibbs described how he, Meyer and Sheppard sat down and started to work out a complete new cutting strategy which led to the replacement of the next tool, a 16mm diameter ballnose cutter.

In its place was installed an LMT-Fette 20mm diameter 4feed cutter that immediately produced similar savings and also reduced the demanding task of the final roughing cutter.

On semi-finishing cycles, ballnose and endmills were changed to two different diameters of LMT-Fette Multi-Edge 2feed HSC endmills with two flutes.

These tools of 10mm and 6mm diameter are solid carbide and centre cutting, and were used to finally prepare the component and radii for finishing.

This change produced a reduction in time due to increases in feed rate and extended the in-cut life of the finishing tool.

Not only was this time saving significant, especially when 20 components are produced each month, the cutting cycle is now stable with a predictable tool life giving improved quality levels.

But the re-engineering process team still has further savings to recoup with the possibility of including later turning operations on the machine by applying special stepped LMT boring bars in preference to existing operations now performed on the company's lathes.

Having ordered the tools, Gibbs is confident this improvement could take a further 2.5 hours out of the overall machining time of the part while adding only around 30 minutes to the cycle of the Matsuura.

This move will also mean the two individual operations would be combined into one saving critical lead time.

Inserts are now turned as each part is completed to give edge security and even with a 300 per cent increase in feed rate, insert usage has not really changed.

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