Product category:
Metals foundry, materials and equipment
News Release from: Hoerbiger-Origa | Subject: OSP linear drive range
Edited by the Manufacturingtalk Editorial
Team on 17 August 2004
Even foundry die dressing requires
smooth motion
Electric linear drive replaces pneumatic actuator on a spray head to ensure an even coating of ceramic die dressing in the production of cast iron diesel engine cylinder liners.
An even coating of a ceramic die dressing is the key to the consistent production of perfect cast iron cylinder liners for engine blocks at GKN Sheepbridge Stokes in Chesterfield Automation is essential, and GKN has recently improved its system by swapping from a rodless pneumatic actuator to drive the spray head to a Hoerbiger-Origa electric linear drive
This article was originally published on Manufacturingtalk on 19 Apr 2004 at 8.00am (UK)
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The liners are shipped to manufacturers of diesel generators, marine engines, agricultural machinery and construction plant, and also to many of Europe's automotive majors, including Ford, Toyota, Land Rover and Volvo.
The latter particularly set very high standards in terms of both product quality and just in time supply, requiring GKN to run its production processes with military precision.
"We run a horizontal axis centrifugal foundry on a 24x7 continuous basis, producing 300mm to 2m long castings which are then cut to length," says Alan Drew one of the Foundry Development Engineers.
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"It's a challenging operation in an arduous environment.
And when you are supplying some of the world's most demanding customers, every gain you can make is not only precious in itself but also multiplied by the 150,000 liners we make every week." The site makes liners in 0.2m and 0.5m length, but the process for both is the same.
Molten iron is poured into the die, which is rotating at up to 2000 rev/min to form precision castings.
After casting, the liners are machined to micron levels of tolerances; some are fully machined on both the bore and outside diameter, others are cast O/D finished machined bore, depending on the final use of the liner.
The finish of the inner surface is critical because it forms the running surface with which the piston interacts, while the outer surface has to be able to form a perfect joint when it is fitted into the engine block in a later operation.
For the cast O/D liners the quality of the surface finish is defined by both the surface quality of the die and the way in which its removal is handled once the die is opened.
It is to the production of this type of liner that the special ceramic dressing is applied as it aids careful yet speedy break out.
"With our automation system the Hoerbiger-Origa actuator drives a spray lance along the length of the empty die prior to casting.
This simple sounding task actually incorporates two tricks to ensure a perfect coating of die dressing.
Firstly we have a programmed dwell time between lance extraction and pouring in the molten metal, during which the dressing dries in a controlled time and the rotational speed helps the dressing to form.
"Secondly we have quite a carefully programmed speed profile when the lance switched from insertion (forward motion) to extraction (reverse).
We have a PLC controlling this and originally I thought we may have to use a high performance but expensive servo motor to achieve the accuracy but in fact we are well within tolerances using a standard induction geared motor and inverter." The change from rodless pneumatic to electric linear drive was undertaken to improve the control.
"We used pneumatic for 10 years or more and were very happy with the performance, but as automotive suppliers we are always after improvements in our production processes - however small.
Hoerbiger-Origa suggested the change, but I was a little weary at first because I thought there would be huge amounts of re-engineering to make the electric units fit.
However the Hoerbiger-Origa OSP range is designed specifically to allow a straight swap - it could not have been easier." Drew also questions the electric drives' ability to stand up to the foundry environment, thinking that pressurised actuators had a built in defence against flying dust, dirt and grit.
However he has found that the electric cylinders are just as reliable even using their standard seals.
"Downtime and failure has just not been an issue. Request a free brochure from Hoerbiger-Origa ...
In fact we have about 30 actuators driving lances on different lines and we have not had any untoward problems with any of them," says Drew, "which is just as well because if my lines go down the purchasing directors of several car plants are on the phone to my boss very quickly!".
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