Product category:
CNC lathes
News Release from: Colchester-Harrison | Subject: Tornado A90 chucking lathe
Edited by the Manufacturingtalk Editorial
Team on 13 December 2002
Chucking lathe cranks up production by
50%
The installation of a chucking lathe at a crankshaft manufacturing specialist has enabled its overall productivity to be increased by around 50 per cent.
At Wolverhampton-based crankshaft specialist Britalco Engineering, the installation of a Colchester Tornado A90 chucking lathe has enabled its overall productivity to be increased by around 50 per cent As well as superseding a number of manually set and operated machines, the A90 has also been charged with a proportion of the turning work previously carried out on a high value five-axis mill/turning centre and as a result, has saved up to 10 minutes on the overall cycle time of a shaft
This article was originally published on Manufacturingtalk on 5 Jul 2001 at 8.00am (UK)
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Britalco is owned by managing director Mark Scutt, and was set up in 1994 growing out of the crankshaft manufacturing department of the former Villiers Engine Company.
It specialises in single, two, three and four cylinder crankshafts from 150mm to 500mm in length and with up to 50mm throw for customers drawn from the automotive, aerospace, diesel engine, pump and compressor sectors.
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Batches of shafts generally vary between 10 and 200.
The company tends to tailor its service to customer requirements, as Mark Scutt relates: "Although we concentrate on machining in-house we are able to provide a complete service as we have good working relationships with local pattern makers, foundries and heat-treatment shops for production of both cast and forged shafts.
Our aim is to make life as easy as possible under a 'one-stop' service banner by supplying a good quality, ready-for-assembly product at a highly competitive price." To that end, Britalco has concentrated its recent investments to rationalise the number of operations and produce a more cost-effective product.
As Mark Scutt explains: "There is considerable expertise attached to crankshaft production.
While pin and journal diameters have to be very precise to within =/-0.006 mm, we also have to maintain tight tolerances on axial dimensions and feature positions such as thrust faces and angular relationships between the pins and keyway slots." He maintains: "To ensure we have a productive yet cost-effective method, we have always tried to produce the majority of these critical features in a single set-up as a mill/turning operation.
This leaves the finished journal diameters, thrust faces and crank pins to be finish ground on our specialised crank grinding machines." Originally, the company was set up with a variety of manually operated lathes and milling machines.
However, a few years ago the decision was made to invest in a five-axis mill/turning centre which was its first CNC machine.
This allowed up to 20 operations to be combined into one or two set ups and therefore reduced lengthy set-up procedures and lead times.
Previously up to a day-and-a-half, was needed for setting which is now replaced by a 'push-button' setting process as most of the tooling needed for all of the jobs is now permanently resident on the machine.
However, Mark Scutt realised that there was an additional potential to optimise the earning capability of the machine by feeding it with accurate partially machined components.
So the decision was made to machine the journal diameters, end features and counterbalance diameters using a two-axis CNC lathe.
As a result this has led to an overall saving of up to 10 minutes from the overall machining time of a crankshaft.
"There are a lot of two-axis lathes on the market but when we looked at the machines available the Colchester Tornado A90 offered the ideal solution for the type of work we had," he said.
"It's the right size, rigid enough to handle a lot of interrupted cutting, has plenty of spindle power and torque from the 11 kW drive and is available with a tailstock.
Although it is also very well priced, the major secondary consideration for us was that it was built in the UK and supported locally by Colchester engineers, so the long-term cost of ownership and service was seen as being very reasonable." The quality achieved by the Tornado from its positioning accuracy of +/-0.005mm and repeatability of +/-0.002mm has meant it is well able to maintain tolerance on the components.
Also set-up time, at around half an hour, is a fraction of the previous method.
So far, 30 crankshaft programs have been written.
Following facing and centring of the shaft on a manual machine, and the turning of a process location diameter, the crankshaft is located in the three-jaw 170 mm diameter chuck on the Tornado, and supported using the tailstock.
The end features, journal diameters, thrust faces and web counterweight diameters are then turned and the shaft turned around and relocated so the remainder of the journals, counterweights and crank end diameters can be machined to a process tolerance of 0.05mm ready for finish grinding.
As Mark Scutt describes: "Most of the crankshafts are produced using the same set of four tools in the 12 station turret so changeover between different shafts is very straightforward.
This, together with the power, speed and accuracy of the A90, makes the two-step machining of cranks very practicable.
Moreover, subject to some changes in the layout of the shop, it will soon be possible for one operator to cover both the Tornado and the mill/turn lathe which will further improve our cost-effectiveness.".
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