Subcontractor, Staffordshire Precision Engineering finds that a 30-taper machining centre is the clear choice for volume production of commercial aerospace components.
30-taper machining centres these days are much more robust than formerly and are not only fast but can also cut tough materials. One company that has discovered the merits of this type of prismatic machining equipment is Staffordshire Precision Engineering (SPE).
The subcontractor recently purchased a Brother R650X2 30-taper 4-axis machining centre with a table-mounted indexing trunnion from the Japanese manufacturer's sole sales agent in the UK and Ireland, Whitehouse Machine Tools. Programming support and unlimited training were included in the deal.
Installed at the end of March 2023, the machine is the subcontractor's first 30-taper machine and is being put to work producing aluminium parts for the aerospace industry, among others. The material currently accounts for about 60% of prismatic component production in the factory. However, it so happened that the first job put on the Brother involved the production of a batch of 304 stainless steel pivot blocks for an aerospace customer.
It was at this point that Phil Smith, joint managing director of SPE with his brother Gary, realised that he had been harbouring an incorrect view that 30-taper machines are unable to cut tough metals productively. He is now convinced that modern Brother machines with their high-torque spindles are much more robust than he thought, capable of cutting stainless steels, titanium and other difficult alloys - just not heavy cuts in those materials all day long; that type of work would be put on a 40-taper machine. Being able to tackle a wide variety of materials ideally suits a machine to production in a subcontracting environment, where the mix of work coming in is unpredictable.
Smith says there are twelve 40-taper 5-axis machines in operation on SPE's shopfloor, some with automatic twin pallet change (2APC) and others with multi-pallet magazines. These reflect the company's decision in 2016, when it moved into a £1.2 million, 26,000ft2 factory, to target more complex prismatic machining work.
There are also eight 40-taper 3-axis VMCs on site, some with a fourth CNC axis, which are between 10 and 15 years old and these will gradually be replaced by more capable and productive plant. Smith predicts that the 4-axis Brother will do the work of two of these older models. It produced the aerospace pivot block, for example, in two operations in a total cycle time of 15 minutes, whereas one of the older machines took 38 minutes to produce the part in four operations. Moreover there is now far less workpiece handling and work-in-progress, as well as minimal risk of accumulating dimensional errors through repeated set-ups.
Apart from speed and versatility, another facet of the Brother machine, especially with energy prices presently so high, is that the 30-taper machine draws typically 80% less power than a 40-taper VMC. SPE's electricity bill more than trebled from £9,000 to £28,000 per month between December 2022 and May 2023. It’s clear that low energy consumption is no longer merely an added bonus, but just as critical to manufacturing parts cost-effectively as fast cycle times.
It was the high speed of the Brother machining centre that was central to Smith's decision to make the investment. He says the machine is faster than a 40-taper model, thanks to its dynamics. This is due to 2.2g linear axis acceleration, 0.2 second spindle acceleration to 16,000rpm, simultaneous tool changing (0.7 second) and repositioning of the spindle for the next cut, reduced machine downtime for tool replenishment thanks to the 40-station tool magazine (14 or 22 tools are optional), and the fact that the 2APC arrangement means that there is only a short delay before the first cut is taken on the next part.
The high productivity enables him to keep customer prices at a constant level, despite the surge in material and energy costs, and is also helping him to win new business. Smith is now actively selling the capacity, with its benefits of economy and short lead-times, to customers and prospects that require components machined within the machine's 650 x 400 x 435mm working envelope.
