Blackpool-based Aerolux, a world leader in the manufacture of aircraft galley insert equipment such as ovens, refrigerators, wine chillers and coffee makers, has stolen a march on its two main competitors in Germany and the USA by CNC machining many components that were previously fabricated. Half of all prismatic parts are now machined from solid aluminium on two Hurco vertical machining centres installed in the Spring of 2004 and 2005 respectively. While safety-critical parts in aircraft are always produced this way to prevent the risk of crack generation, food-related equipment in the galley has traditionally been fabricated.
The benefits to Aerolux and its customers are considerable, as parts are quicker and less expensive to make by milling than by welding. Managing director, Ken Metcalfe, says that a fridge door and frame, for example, would require 10 to 12 hours in the fabrication shop whereas they are machined on a Hurco VMX42 in less than half the time. A further advantage is that components are more repeatable than when welded, which introduces distortion, so parts assemble more accurately from batch to batch. Moreover there are no welds to fettle, so a lot of finishing has been eliminated.
Second-operation work such as drilling and tapping, which was previously carried out by hand on the fabrications, is now completed in-cycle on the machining centre, saving further time. The cosmetic appearance of products has been improved as well, as it is possible, for example, to radius corners when CNC machining - a refinement that is not feasible when fabricating products.
The move towards CNC machining has far-reaching implications on the design of Aerolux products. It is possible, for instance, to mill sections down to 2 mm, much thinner than can be fabricated, resulting in reduced weight. Another positive change has been to machine on the Hurcos, the groove that accepts the oven door seal instead of having to use two frames, one inside the other, to achieve a similar, heavier result. Lightness is of key importance to aircraft operators, which are always looking to maximise fuel efficiency.
Mr. Metcalfe has plans for redesigning many other parts and predicts that most of the components that go into the company's products will be CNC machined rather than fabricated within a year or so. He has also adopted a similar policy for turned parts, many of which now go onto CNC lathes.
Until the late 90s, practically everything was fabricated at the Blackpool factory, mainly from aluminium for lightness, stainless steel for hygiene, and expensive, heat-resisting plastics approved for aerospace applications. The plastics were designed out of the ovens, partly due to the high price of the material and of the vacuum forming tools needed to make the oven doors, and also because the plastic was prone to crack when machined.
At the same time, Mr. Metcalfe went to local subcontractors to have frames and doors CNC machined, convinced of the advantages, but found that this was more expensive than fabrication, partly because batches tended to be small. For the same reason, he found that that he was constantly having to chase work, as subcontractors tend to favour customers that place large volume business. The quality of the work was also a problem at times and required constant monitoring. Suddenly, a large order for 100 aluminium and stainless steel oven doors was placed by Kelox, Madrid, for the Spanish Railways (rail industry work accounts for 30 per cent of Aerolux turnover). This extra business justified the purchase of the first Hurco, which was delivered directly from the MACH 2004 exhibition in Birmingham and paid for itself within a year of installation.
Once the VMC was installed, other parts such as mounting rails for expresso machines were soon produced from the solid as well, eliminating buying-in castings and machining them by hand on a turret mill. So successful was this exercise that Aerolux now supplies these components to its competitors. Fridge frames were next onto the Hurco, followed by rear mounting brackets, and the migration of parts from the fabrication shop to the CNC machining section has continued ever since.
By the beginning of 2005, the machine was working flat out during the factory’s 10-hour daily shift. It had become so important in the Aerolux operation that a breakdown would have disrupted customer deliveries; and there was not even time to train more operators. The obvious answer was a second Hurco VMX42, which was installed in May together with an off-line programming station running WinMax software that mimics the capabilities of the machines’ Ultimax control. The latter’s intuitive touch-screen, with drop-down menus and second, adjacent screen for displaying a graphic of the component and simulating the cutting cycle, is used very successfully on the shop-floor for programming. The off-line facility will be used, in the short term at least, for new product development.
A typical order from one of the major airlines might result in batch sizes of 25-off doors or frames and 50-off mounting rails, but it can be as low as one-off if the appliance is to be used in a custom executive jet. Ease of programming at the machine has therefore been of considerable help to Aerolux.