Product category:
Subcontract machining and assembly services
News Release from: H C Holifield (Oxford) | Subject: Subcontract machining
Edited by the Manufacturingtalk Editorial
Team on 10 January 2003
Colleges begin to subcontract out
machining
Educational establishments and research facilities are a significant source of subcontract machining work, particularly as many are winding down their internal facilities, as this example shows.
Educational establishments and research facilities are a significant source of subcontract machining work, particularly as many are winding down their internal facilities Imperial College in London, for example, is adopting this policy and putting more work out, such as the three-part cast aluminium compressor casing and set of five impeller discs recently machined by Holifields, Abingdon
This article was originally published on Manufacturingtalk on 31 Oct 2002 at 8.00am (UK)
Related stories
Pick-up spindle VTLs installed to reduce costs
Another example of the increasing popularity of self-loading vertical turning lathes are the two installed by a contract machinist to keep production costs down.
Jig drastically reduces TIG welding job time
A bespoke TIG welding jig has reduced time taken to position and manually weld eight bosses around a 1.7m diameter cylinder to just 30min, removing a bottleneck within the customer's factory.
The contract was placed by Keith Buffard in the Energy Systems Group at Imperial, which among other projects is building a prototype, high efficiency microturbine capable of delivering power below 100kW at an efficiency approaching 40 per cent, compared with the current average of 30 per cent.
The design harnesses research into the application of an advanced, two-stage, intercooled compression cycle.
The goal is to penetrate the market for small, portable generator sets for providing standby power, and local CHP (combined heat and power) installations.
Further reading
Contract machinist provides stocking service
One feature of a contract machining service that sets it apart from other subcontractors is the extensive 'consignment stocking' service it provides to customers.
Deciding the best way of making a motor cover
To find a way of manufacturing an electric motor cover economically a subcontractor produces both parts of the end assembly in multiple operations using different machining techniques.
Extra cool parts machined and stocked too
Some subcontractors are extending the service they offer to manufacturers by not only producing components but also stocking them free of charge for subsequent delivery when needed, just-in-time.
Said Buffard, "The education and research sectors throughout the UK must place a lot of subcontract machining contracts every year, but budgets are always tight and quotes have to be realistic.
The first one we received for machining our centrifugal compressor components was far too high.
Then someone in the college recommended Holifields, an acceptable price was agreed and the work went forward." Roy Marshall, sales manager at the contract machinists, commented, "You can see why some in our industry might be tempted to load the price on this type of work.
Such business is usually one-off or small batch and very often complex, like the Imperial job.
However if you are set up for this, profit can be made at competitive prices." Two of the three 800mm diameter, cast aluminium elements that make up the compressor casing are shown in the accompanying picture.
Operations on both included two set-ups on a Colchester centre lathe to turn a face and an O-ring groove plus a location step on the reverse.
As the castings were thin-walled, they needed a certain amount of engineer's 'feel' during machining to achieve a satisfactory result.
The parts were transferred to a Hitachi Seiki VS40 vertical machining centre where the bores were interpolated and single arrays of 20 holes were drilled around them.
One set of 48 equispaced holes was also drilled around the periphery of the upper part at a 780mm PCD, the lower part receiving two similar sets of holes.
The impeller discs were machined from 300mm diameter by 20mm thick AL6062-T6 aluminium blanks.
On the same VMC, the face was skimmed, the OD and ID were interpolated to within 32 and 25 microns total tolerance respectively, and a pattern of 6.1mm diameter holes was drilled around the periphery on a 250mm PCD.
Following this, using DXF files supplied by Buffard, Holifields milled 20 angled vanes around the disc, every one of different profile.
While this work was in progress at Abingdon, a further contact was received from another department within Imperial College for very high precision reaming of two bores in rotor components.
Typically, these were also one-off jobs.
• H C Holifield (Oxford): contact details and other news
• Email this article to a colleague
• Register for the free Manufacturingtalk email newsletter
• Manufacturingtalk Home Page
Search the Pro-Talk network of sites
