Product category:
Horizontal machining centres (HMC)
News Release from: NCMT | Subject: Okuma twin-pallet horizontal machining centre
Edited by the Manufacturingtalk Editorial
Team on 24 December 2007
HMCs replace VMCs and raise productivity
25%
Two of the latest 4-axis horizontal machining centres are machining aircraft steel engine mounts and have raised productivity by 25% compared with vertical machining centre work.
At the Freshwater works of RD Precision, a third Okuma twin-pallet horizontal machining centre (HMC) of approximately 750mm-cube capacity was installed in November 2007 It has joined a similar MA-50HB model delivered in January 2007 and an older machine of equivalent size dating back to 2004
This article was originally published on Manufacturingtalk on 22 May 2001 at 8.00am (UK)
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The GBP 750,000 investment in two machines plus tooling and training in 2007 was partly a result of an upturn in demand for steel engine mounts for the Hawker jet aircraft.
The components are supplied direct to the assembly line at Airbus, Broughton, where the fuselage and wings for the jet are produced under contract.
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Whereas six 3-axis vertical machining centres (VMCs) are currently used to manufacture the four engine mount variants, the work will be transferred to the two additional HMCs, which will provide sufficient production capacity to meet future production requirements.
They will also reduce the current scrap and rework created by the VMC process.
Prior to 2004, all of RD Precision's aerospace parts were machined on 3-axis VMCs using multiple vice set-ups.
Gradually, many parts have been re-engineered and programs translated through 90 deg to produce them in fewer operations on HMCs.
Advantage is taken of the extra power, higher spindle speed and 60m/min cutting feed rate of the Okuma horizontal-spindle machines.
An example of a component that has already been re-engineered for the 4-axis HMCs is a titanium 'aft machining' engine component for the Dash 8-400 regional jet.
It used to be rough- and finish-machined in six set-ups on a VMC.
Now it is skimmed in one operation on an Okuma HMC and then completed in a second clamping, including probing jig-bored holes in-cycle using a machine-mounted probe.
The latter has proved useful for tracking dimensional drift and adjusting tool offsets automatically.
Significant production savings have also resulted from 4-axis horizontal machining of a titanium load spreader supplied to Stork Fokker for the fuselage of the Airbus A380.
Seven variants in left- and right-hand configurations are currently machined.
The way in which critical features are tied up demands a machining accuracy of +/-12 micron.
The overall improvement in manufacturing efficiency on HMCs compared with VMCs, helped further by multiple set-ups on cube fixtures and by the automatic pallet changers which maximise spindle up-time, has allowed the contract machinist to meet cost-down targets imposed by its customers and still make a profit.
Speed of production is on average 25% quicker on the horizontals than on the verticals, according to RD Precision's site manager, Alan Thompson.
He added that the company chose Okuma machines as they have the robustness necessary for roughing as well as finishing tough materials.
Fewer set-ups have resulted in better component accuracy and lower scrap levels as a result of reduced accumulative error.
Faster delivery to customers and less money and space consumed by work-in-progress are further advantages.
Programs are prepared off-line using EdgeCam software and run on any of the Okuma HMCs.
The control system on the latest machines has uprated features including automatic scheduling of up to eight queued programs listed in an on-screen Excel table, and connectivity for any USB2 compatible measuring equipment. Request a free brochure from NCMT ...
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