Precision CNC Machine Shop Improves Production Rate of Aluminium Investment Castings By More Than 80%
Some years ago, ebbing oilfield business conditions spurred Ogden, Utah’s LeanWerks to pursue work in other industries (including aerospace and high-speed automation) to establish a more balanced customer base and steadier work flow. The contract shop, now registered to the AS9100C aerospace standard, also began adapting some of its existing machining capacity to better suit the machining jobs it would encounter within those new industries.
Reid Leland, company president and co-founder, points to one example: an aluminium investment casting for a jet engine fuel filter housing. By the time LeanWerks was introduced to this job, its aerospace foundry customer was nearly one year behind on the delivery schedule because its in-house machining process, thus production rate, was slow. As a result, its customer — the OEM of the jet engine onto which this housing is installed — was losing patience, and the backlog caused by the delays with this job was disappointing other customers. Therefore, in an effort to alleviate some load on its internal machining resources, the foundry contacted LeanWerks to consider taking on the machining of those castings.
Although many engineers specify investment castings for their part designs because they offer form intricacy with good dimensional precision relative to other casting processes, those components still require machining to achieve accurate fit and function in high-performance assemblies.
However, the variability of these types of as-cast parts and their associated tricky work-holding requirements cause some shops to avoid taking on this type of machining work.
For example, the fuel filter housing requires multiple machining operations, including deep-hole milling, boring, facing, drilling, tapping, inner-diameter grooving and 3D contouring. Originally, LeanWerks thought it might complete the job using several set-ups on a three-axis mill and one setup on a turning centre. It ultimately decided that this wasn’t the best strategy, because the part’s tight position tolerances with complicated datum scheme would not be attainable due to the multiple set-ups.
Instead, LeanWerks considered how it might take advantage of the milling capability of its Mazak Integrex i200S turn-mill to minimize the number of times the part is touched during machining. The shop primarily used this machine to produce tapered plug valve inserts for high-pressure pumping operations in the oil and gas industry, such as those required for hydraulic fracturing and coiled-tubing applications. The Integrex was well-suited for the valve insert part because it could both turn the part’s tapered outer diameter and mill its internal cross-axis flow bores. The machine could also mill the bores associated O-ring, which required a five-axis contouring operation because of the bores conical surface.