Invar alternative: Ceramic fiber/ceramic matrix material holds promise

U.K.'s Horizon Composites has developed a lightweight, high-heat, thermally stable material that it says could provide a tooling alternative to Invar. Trelleborg has purchased rights to make the material and tooling from it.

Horizon Composites Ltd. (Rotherham, U.K.) announced at IMTS ’08 in Chicago on Sept. 10 that it has developed a new tooling material that CEO Ron Jones says could be the long-sought, light-weight, high-temperature alternative to Invar tool steel that the composites industry has been seeking.

The material, as yet unnamed, is a woven ceramic fabric with a ceramic matrix that has a coefficient of thermal expansion (CTE) comparable to carbon fiber, remains stable at temperatures up to 1,000°C/1,832°F and can be produced in thicknesses as thin as 3 mm/0.12 inch. The material features an integrated thin-film heating element, can be used with most processes (including vacuum infusion and autoclave) and could provide an out-of-autoclave solution thanks to its high-temperature threshold.

Trelleborg CRP Ltd. has purchased exclusive global rights to manufacture the material and subsequent tools. Chris Mellings, manager – AEM Sales Group at Trelleborg, says his firm will spend the balance of 2008 and early 2009 preparing facilities to produce the ceramic fibre/ceramic resin material and hopes for full commercialization sometime in Q1 2009.

The material has been under development for the past decade, and more earnestly in the last two years. Initial efforts with the material focused on producing tooling from blocks of the ceramic/ceramic, but these proved too heavy. Eventually a thinner laminate version was developed that radically reduced weight while retaining the material’s high-temperature tolerance. Jones estimates that the working surface of a tool about the size of a conference table, 3 by 6 ft (1.1 by 3.3m), would typically weigh 15 to 20 kg (33 to 44 lb) plus 100 kg/220 lb of support structure, whereas a comparable Invar tool would weigh between 250 and 2,500 kg depending on the tool design and geometry of the component to be formed.

Heating “tracks,” thin-film elements sintered into the back of the tool, provide rapid heating that can elevate mold temperature to 500°C/932°F within a few minutes, with similarly fast cooling. The tooling material is said to resist scratches from titanium and other metals. CTE of the ceramic/ceramic is 0.5 x 10.6 , similar to carbon fiber, and HCL is working on a next-generation silica-based material that will have a CTE of zero. Cost of the ceramic tooling material, according to Trelleborg, will be “closer to carbon fiber than Invar.”

Three tools are being trailed right now, one each with BA Systems and The Boeing Co., and a third with an unidentified firm. The next step is development of full production tools.