Product category:
Vertical machining centres (VMC)
News Release from: Whitehouse Machine Tools | Subject: High-speed, vertical-spindle machining centre
Edited by the Manufacturingtalk Editorial
Team on 22 February 2006
High-speed VMC cuts machining time by
third
Twin-pallet, high-speed, vertical-spindle machining centre achieved a cycle time over one-third faster than the next best machine when producing an aluminium chassis for a telecoms customer.
Three years ago, Plymouth-based subcontractor Morris Engineering had to make some serious decisions on the direction of its business, having lost 75% of its turnover within the space of a few months owing to a downturn in the microwave communications sector Restructuring of the business followed by a few years of consolidation have seen the company not only survive, but emerge as the pre-eminent supplier of machined parts in the West Country
This article was originally published on Manufacturingtalk on 28 Jun 2002 at 8.00am (UK)
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Turnover has risen to GBP 2.5 million, 10% higher than the company's previous best, 45 people are now employed and a late shift has been added within the last 12 months.
In 2003, with a majority of its income lost, Morris Engineering was not in a position to invest in new plant, so set about using its existing machines to expand business within its remaining customer base, adding NC tables to a number of machining centres so it could offer 4- and 5-axis capability.
As soon as possible, however, the firm invested in the most highly productive machining centre it could find to sharpen its competitiveness, as the prices it was quoting were often 15 to 20% higher than the competition's.
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So in October 2005, the company purchased from Whitehouse Machine Tools a Brother TC-32B QT twin-pallet, high-speed, vertical-spindle machining centre (VMC), which has set the seal on the company's transformation.
(A similar machining centre will be demonstrated in May this year on the Whitehouse stand, number 5550, at MACH 2006).
It is difficult to overstate the positive impact that the machine has made to Morris Engineering.
Encouraged by the productivity advantages, after just four months it committed an additional GBP 200,000 by ordering another identical Brother, plus a further machining centre and a CNC lathe from different suppliers.
During pre-purchase trials alongside other shortlisted machines, the Brother achieved a cycle time over one-third faster than the next best machine when producing an aluminium chassis for a telecoms customer.
Operations included extensive pocket milling as well as drilling and tapping.
Cycle time on the Brother was 13 minutes, versus 21 minutes on the next fastest machine and 35 minutes on the third model trialled.
The VMC originally employed to produce the part took 46 minutes - over three and a half times longer than the Brother.
"The difference between the TC-32B QT and its nearest rival was extraordinary, considering that one is often trying to cut seconds out of a cycle, not eight minutes," enthused Antony Dyer, production director at Morris Engineering.
He went on to list the combination of factors that contribute to cycle time savings on the Brother.
First is the very fast, ballscrew-actuated rapid-traverse of 70m/min in all axes, which is half as fast again as the nearest rival.
Idle time is therefore considerably shorter, assisted by 3.4s pallet change and automatic tool change (ATC) in 2.1s, including deceleration from top spindle speed and acceleration to the same speed.
The in-cut element of cycles is also shorter due to the (optional) 16,000 rev/min spindle fitted to the Brother, which is fast for this class of machine and one third higher than that offered by the closest competitor.
Cutting feed is up to 20m/min; and 70 bar through-tool coolant (versus 20 bar on the other machines) greatly increases drilling and tapping productivity, especially on deeper holes, and dramatically extends tool life.
Maximum advantage is taken at the Plymouth factory of the high feeds and speeds on the Brother machine, as instead of having a standard BT30 spindle fitted, Dyer opted for a Nikken NC5-46 spindle with face-and-taper contact.
Drawing tolerances of typically +/-5 microns, down to 5 microns total in some instances, are easily held.
At the same time, the rigidity with which the toolholder is clamped results in between 15 and 20% longer insert life, according to Dyer.
On the subject of tooling, he also commented on Brother's new system within the chain-type magazine for monitoring cutter breakage.
When the next tool is called up into the ATC position, a mechanical arm checks if the length of the tool matches the parameter in the control; if not, the cycle stops automatically, preventing the production of scrap.
As monitoring of the tool is carried out while the previous cut is in progress, there is no loss of production.
On a machine as fast as the Brother, the only tool checking alternatives are a quick visual inspection of the cutter in the spindle after it has been exchanged, or detecting the fault after an out-of-tolerance part has been machined.
Again with speed in mind, Renishaw laser-based tool length setting has been fitted within the machining area, and the same supplier's touch probing is used for datum setting and occasional on-machine inspection.
Machining of aluminium accounts for 40% of parts produced, as Morris Engineering transferred its microwave component machining experience across to other telecoms and aerospace work.
However, the company also machines a lot of stainless steel to fulfil contracts placed by valve and manifold manufacturers.
A wide range of materials is put onto the TC-32B QT, which Dyer says has much higher power, rigidity and capacity than the tapping centres for which Brother has perhaps historically been known.
The turnkey package supplied by Whitehouse, in addition to the Renishaw probing and Nikken spindle, included an uprated pump and pipework to increase the volume of coolant washing the large amount of aluminium swarf from the table; and WDS MicroLoc quick-change fixtures to provide flexibility when scheduling jobs onto the machine.
Programming is carried out off-line from customers' solid models by importing them into Morris Engineering's SolidWorks CAD via IGES, DXF or Solid, and generating cutter paths in EdgeCam.
Programs are downloaded to the Brother machine via Ethernet link.
Dyer said, "With the TC-32B, Brother has managed to transfer the high speed and acceleration of its tapping machines onto a robust, moving-column machining centre platform.
It is completely different from many people's preconception, including mine originally, that machines from this Japanese manufacturer are light-duty." He concluded: "We had nearly decided on another supplier's machine when the Whitehouse sales engineer visited us.
On reading the TC-32B specification, it was impossible not to shortlist it at the eleventh hour, and subsequent cutting trials showed it to be the best machining centre by far for our type of work." * Whitehouse Machine Tools at MACH 2006, NEC, Birmingham, UK, May 15-19, Hall 5, Stand 5550.
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