MACHINING


Experience is everything


The milling and drilling of modern composite products may still be seen as a ‘black art’ by many, but with the aid of machinery developed specifically for the task, suppliers and OEMs have been honing their skills and experience to produce repeatable, reliable products. One such user is Lola, which has been producing highly complex components for its motorsport programmes as well as the safety-critical defence and aerospace industries for some time. Simon Lott reports


metallic components, the wide differences in the nature of the material types and the improved quality requirements of newer products meant that specialist equipment soon entered into the


W


hile in the early days of the composite industry, it was common to see the milling of carbon and glass fibre products taking place on machines designed for


equation. CMS Industries has been supplying the market since 1969 and as one might expect, has refined its products to a high standard. By their very nature, machines designed specifically for the


milling of composites need to be more versatile than their metallic counterparts, accommodating not only a broader range of materials, but wider variation in their inherent properties. Lola, for example, has invested in two CMS Ares mills – a 36-26 PX5 and a 48-18 – to aid not only its core motorsport offering, but a whole range of other applications. For example, parts currently produced onsite include large naval radar structures, vertical wind turbine blades and fuselage sections for the Watchkeeper and Mantis UAV programmes, all hand laid in its three aerospace standard clean rooms and cured in one of five autoclaves or two curing ovens. As many different components covering many different


application requirements pass through the facility, the mills employed at Lola are regularly employed for the processing of carbon fibre parts with all kinds of fibre thicknesses, tow thicknesses, resins and layer orientations and which have undergone a variety of curing processes, leading to considerable differences in strength and stiffness between what are often low batch components. Similarly, the mills are utilised regularly for the trimming of one-off epoxy blocks for patterns and moulds where there is little room for error and can also be used in the milling of aluminium, although Lola rarely does so.


No compromise


A CMS Ares machine, similar to the ones used at Lola


22 | Composites in Manufacturing | Autumn 2010


Due to the complex and specific nature of many of the components produced at by the manufacturer, most of the patterns produced and milled on the CMS machines are one-offs, so the need to achieve ‘right first time’ quality is of primary importance and extensive work goes into model preparation. There may be as much as £3,000-£4,000 worth of carbon fibre in one raw blank, so, aside from whatever tooling requirements there may be, machines need to behave predictably.


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