The University of Wolverhampton’s National Foundry Training Centre (NFTC) has joined forces with Ifor Williams Trailers, a prominent UK trailer manufacturer, to explore discrepancies in the machining of hub castings as part of its ‘business assist’ program.
Situated within the University’s Elite Centre for Manufacturing Skills (ECMS), the NFTC is part of the newly established UK Centre of Excellence for Additive Manufacturing (AM) located at the university’s £120 million super campus in Springfield, Wolverhampton.
This collaboration focused on identifying variations in hub castings sourced from a foundry, which were machined on-site to test tolerances prior to market distribution. The manufacturer faced challenges with inconsistent material batches, leading to unpredictable tool wear and reduced tool life during the machining process.
Colin Whorton, Foundry Manager at ECMS, stated, “The company approached us to investigate the discrepancies they were experiencing with the castings they were procuring. While some castings machined effectively, others did not perform as expected. This successful investigation was carried out as a ‘business assist’ initiative, which is a complimentary 12-hour support service we provide to aid small to medium-sized enterprises.”
The NFTC received samples of both well-machined and poorly machined castings for analysis. The team examined the root causes by sectioning the castings into smaller test pieces and utilizing the ECMS’s advanced machinery in the Metallurgy Lab at Springfield. The samples underwent chemical analysis and were tested for hardness, followed by a polishing process to one micron for precise microanalysis. All data collected from these tests was meticulously documented. After applying a nitric acid solution to etch both samples, significant differences emerged between the two castings.
Colin added, “Our findings indicated notable differences in the microstructures of the castings. The casting exhibiting good machinability had a homogeneous microstructure with adequate graphite growth due to proper inoculation. Conversely, the casting with poor machinability was under-inoculated, undercooled, and displayed a non-homogeneous microstructure. We proposed to the manufacturer that the inoculation process employed by their tier two supplier was likely the source of the machining problems.”
Andrew Cooper, Group Manufacturing Engineering Manager at Ifor Williams Trailers, commented, “There were instances when we could machine 200 parts from a single tool tip, while at other times, only one casting would be produced. In contrast, the tool life for the other hub consistently yielded 80 castings per tool tip.”
“The NFTC played a crucial role in helping us identify the technical root causes behind the variations in material batches and the inconsistencies in parts produced from the same batch. This analysis enabled us to implement corrective actions with the foundry. Furthermore, this experience provided us with invaluable knowledge that will benefit our operations moving forward.”
The ECMS project is an employer-led training initiative aimed at enhancing productivity and growth within small and medium-sized enterprises (SMEs). Originally targeted at organizations within the high-value manufacturing (HVM) sector, the ECMS has expanded its scope to support any SME operating within the UK.
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