Product category:
Milling cutters
News Release from: Iscar Tools | Subject: Titanium machining at gardner Aerospace, Wales
Edited by the Manufacturingtalk Editorial
Team on 17 July 2008
Iscar tooling cuts titanium scrap to
below 1%,
Using Iscar tools in a Mazak horizontal machining centre to take larger depths of cut at higher feed rates, a contractor reduced scrap to below 1% and eliminated 85% of hand finishing.
Contract machinist, Gardner Aerospace, Wales, won a major contract in 2005 to machine titanium nacelle frames for the Bombardier Dash 8-400 turboprop Gardner's existing machining centres, and the cutting tools, were struggling to achieve the required accuracy in the complex components produced in larger volumes
This article was originally published on Manufacturingtalk on 2 May 2008 at 8.00am (UK)
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Gardner said that some four-fifths of its production involved prismatic machining of Ti64 (6% aluminium/4% vanadium) titanium alloy, while the remainder is aluminium.
Yet three years ago the reverse was true: 80% of throughput was machining aluminium.
* Turnkey machining centre installation - Gardner overcame the growing problem by installing a turnkey system to produce the mid and forward nacelle frames.
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For grooving and recessing applications, precision ground inserts are available in a width range of 0.50 to 3.18mm and a width tolerance of +/-0.02mm and come with a variety of standard corner radii.
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The chosen machine tool supplier was Mazak, which delivered one of its FH8800 4-axis, twin-pallet, horizontal-spindle machining centres (HMC) complete with programs and tooling.
Mazak selected Iscar tooling, consisting predominantly of solid carbide cutters and a variety of indexable insert milling cutters and drills.
Mazak's regional manager, Paul Hughes, said: "In a highly demanding production environment like Gardner, we rely heavily on the tooling supplier to ensure the customer gets the best from our machines".
He continued: "Iscar has excellent engineers including ex Mazak employees that are conversant with our product range.
We always receive a high level of technical support from them, which is why we have entered into a partnership arrangement with them on a number of projects over the years".
General Manager of the Gardner factory in Wales, David Walters, confirmed that he got good service from Iscar.
He added that the performance of the cutters was markedly superior to that of the solid carbide and high-speed steel end mills Gardner had originally been using to machine the nacelles on older machining centres.
Then, cycle times were at least twice as long and it was difficult to maintain the required level of accuracy, leading to an unacceptably large number of components being scrapped.
* Productivity doubled - Iscar tools have doubled productivity as they can take larger depths of cut at higher feed rates.
The modern Mazak machines support this, owing to their greater rigidity and high-torque spindles.
Walters said that tool breakage is rare.
Also, when combined with the ability to hold tolerance easily, the Iscar tooling has produced a four-fold reduction in scrap rate to below 1% of the 200 frames produced annually.
This is important to maintain profitability, as components can cost as much as GBP 10,000 each.
* Finishing - originally, Moreover, some 4-5h of hand fettling was needed to finish each nacelle to the required standard.
Now, the combination of mazak HMC and Iscar tooling has reduced finishing time to around 45 min/component.
So successful was the first new Mazak HMC installation that Gardner won enough new business to justify buying a second, an identical FH8800 at the end of 2006 to cope with the increased workload.
Such is the current level of titanium machining at Gardner Wales that the two newest machining centres cannot complete all of it.
So older HMCs on site continue to be used to machine titanium, as do a number of vertical machining centres (VMC).
To increase their capability for machining the tough material and to raise productivity, they have been retooled by Iscar following its appointment as preferred cutting tool supplier to Gardner Aerospace with effect from May 2008.
* Improvements on older HMCs/VMCs - improvements have been made to Boeing 777 titanium wing rib production by using Iscar Mill2000 cutters.
These cutters have reduced cycles by 40% when compared with the previous solid carbide and HSS tooling.
The latter in particular suffered from cutter 'push-off', which has been eliminated using the Iscar tools.
The productivity benefit has arisen partly from Iscar re-engineering the jobs and partly from the rigidity of the new, indexable-insert milling cutter.
This cutter has strong, dovetail-shaped, AXKT-style inserts that clamp securely in the seats on the cutter body.
Walters said larger depths of cut at higher feed rates can be taken with these tools and in addition, accuracy and surface finish have been improved.
* Coolant management - to realise these benefits, Iscar engineers advised careful control over the coolant.
As through-spindle delivery is not available on the older machinery, sufficient external flow rate and accurate direction are essential.
So too is coolant cleanliness and regular skimming to remove tramp oil was instigated, resulting in a marked increase in the life of the inserts.
Having looked at then existing tooling used on a Mazak AJV50/120 VMC, Iscar suggested using Helido Upfeed six-edge milling cutters with the latest SumoMill coated carbide grades.
These have a low stress, CVD (chemical vapour deposition) coating on top of the PVD (physical vapour deposition) layer to minimise thermal cracking and ensure smooth chip flow.
With very similar tooling types, titanium machining rates have been increased by up to 30% on this machine, said Iscar.
Iscar told manufacturingtalk that it had also investigated aluminium machining at Gardner.
Two Makino HMCs have been equipped with HeliMill 90 deg pocketing cutters using SumoMill S845 inserts with helical cutting edges and positive rake angles.
Significant productivity benefits have since been recorded when roughing, reported Iscar.
Other machines to benefit from an Iscar tooling 'makeover' at gardner for the machining of aluminium wing components are a Mazak VTC300C-II VMC and two Cincinnati 5-axis machines.
The Cincinnatis have been equipped with the unusual Iscar FiniShred solid carbide end mills.
They have two serrated flutes and two continuous flutes to enable simultaneous roughing and semi-finishing of components.
Iscar said that these cutters drastically reduced cycle times as well as freeing up a 'pot' (pocket) in the tool magazine.
This particular tool is also effective at machining titanium, stainless steels and high temperature alloys, claimed Iscar.
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