The NFTC is part of the University’s Elite Centre for Manufacturing Skills (ECMS) and the new UK Centre of Excellence for Additive Manufacturing (AM) based at the £120M construction super campus at Springfield in Wolverhampton.
The collaboration with Ifor Williams Trailers, based in Wales, the United Kingdom’s largest manufacturer of trailers under 3,500 kilograms, investigated the differentiation between hub castings which were bought from a foundry and machined on site to test tolerance before being supplied to the market. The company encountered some variation between batches of material resulting in an unpredictable tool wear and tool life in the machining process.
Colin Whorton, Foundry Manager at the ECMS, said: “We were approached by the company to conduct research into the differences they were having between batches of castings they were buying in. Some castings machined well, others not so well. The investigation was successful and completed as a ‘business assist’ which is a free 12-hour support function that we offer designed to help small to medium businesses.”
The NFTC were sent examples of castings with both good and poor machinability and investigated the root cause. Both castings were sectioned into small test pieces which were processed using the ECMS’s efficient machines in the Metallurgy Lab at Springfield and chemical analysis data. These samples were tested in several areas for hardness, then polished to one micron to allow perfect micro analysis. All test data was recorded. After etching both samples in a Nitric acid solution the results showed a drastic difference between the two castings.
Colin said: “The results revealed a difference in the microstructures between the two castings. The casting with a good machinability had a homogenous microstructure with graphite growth of sufficient inoculation, while the casting with poor machinability was under-inoculated, undercooled and a non-homogenous microstructure. It was suggested to the manufacturer that the inoculation process of the tier two supplier was the root cause of the machining issue.”
Andrew Cooper, Group Manufacturing Engineering Manager at Ifor Williams Trailers, said: “Sometimes we would machine 200 parts from one tool tip, other times it was maybe only one casting, yet with the other hub, the tool life is constant at 80 castings per tool tip.
“The NFTC was invaluable in helping us identify the technical root cause of the variation between batches of material, and variation between different parts from within the same material batch. This information then helped us agree corrective actions with the foundry. The experience was also excellent knowledge building which will benefit us in the future.”
The ECMS Project is an employer led training facility designed to support the development of productivity and growth in SMEs. The Project is focussed upon those organisations operating in the high value manufacturing (HVM) sector, but this has now been extended and the ECMS is now able to work with any SME operating in UK.
