Autoclave moulding

The Manual processes cover methods such as hand lay-up, spray-up, pressure bag and autoclave moulding. 

The following period between 1975 and 1985 was characterized by activities related to the development of prepreg systems for low pressure autoclave moulding, i.e. modification of the resin chemistries to achieve flow, tack and non-volatile cure. These requirements were dictated by the industry to meet the processing techniques already in place for epoxy and polyester resins. 

Autoclave moulding is typically used in the aerospace industry for the production of high-value composites from prepregs. The laminate, which is covered on both sides by a fine polyester cloth peel-ply (for enhancing the surface effect), is built up on the mould surface. The top surface of the laminate is covered by a porous release film and bleeder cloth. The whole assembly is then covered with a non-porous membrane, which is sealed to the mould, and then placed inside an autoclave as shown in Figure 6.19. 

This process has a number of advantages over the more conventional autoclave moulding using pre-impregnated carbon fibre ... 

Autoclave Moulding—A process similar to the pressure bag technique. The lay-up is covered by a pressure bag, and the entire assembly is placed in an autoclave capable of providing heat and pressure for curing the part. The pressure bag is normally vented to the outside. 

Fibres can also be prepared in the form of a mat consisting of randomly oriented short fibres held loosely together hy a chemical hinder, sometimes in a carrier fabric, as a continuous thin flat sheet. Mats are commercially available as blankets of various weights, thickness, and widths, which can he cut and shaped for use as preforms in some closed-mould processes and in hand lay-up, press moulding, bag moulding, autoclave moulding, and in various continuous impregnating processes. 

Autoclave moulding is a modification of the pressure bag method. It is used to produce high quality composites, (i.e., for aerospace applications), where high pressures (up to 0.6 MPa) and high temperatures (up to 700 °C) are used. An autoclave is a pressure vessel inside which the curing reaction occurs. With this process, it is possible to produce composite structures with up to 70 wt% GF reinforcements [5]. However, the autoclave process is rather costly. 

Purslow, D. and Childs, R., Autoclave moulding of carbon fibre-reinforced epoxies . 

A 177 C curing low micro-cracking/low moisture absorbing cyanate resin with a -128 to +121 C service temperature range (without post cure), formulated for press and autoclave moulding. Prepregs in all available fibres and fabrics can be manufactured via hot-melt or solution techniques, a. 1.19 j. 0.96 /o Tg (no post cure) 206"C (with post cure) 258 C... 

A 121 C cure flame retardant, self-adhesive epoxy with a good 71 C dry service temperature, formulated for autoclave moulding although press moulding can be employed. Can be hot-melt or solution impregnated on all available fibres and fabrics. Typical applications include aircraft interiors, seats and control surfaces. 

Prepreg material with balanced warp/weft autoclave moulded ... 

Prepregs laid up at various fibre orientations, autoclave moulding, Vf = 62%. 

AFNOR Aramid fibre Aspect ratio ASTM ATH Autoclave moulding... 

---