Pressure Forming
Pressure forming, also referred to as blow forming, is a type of thermoforming that uses more extreme amounts of air pressure during the forming process. It fabricates products that are much more detailed and textured than products of other types of forming. Pressure forming provides greater precision since the plastic is able to retain a greater definition of shape in the mold due to the increased air pressure. Manufacturers of computer and electronic housings, panels and company logo makers often use pressure formed plastics for their products because it offers injected molded quality but is faster, has sharper edges, a lower cost and more production flexibility. Pressure forming is ideal for complicated products that require multiple textures or some smooth areas on the same part and multi-part assemblies like medical carts or kiosks.
During pressure forming, a clamped plastic sheet is heated and positioned over a mold of the desired part or product, usually female, which is concave in shape, and high amounts of air pressure force the plastic to take the shape of the aluminum mold. Male molds, which are convex, are rarely used in this process. The complex detail is formed on the mold side, which is in this case is the outside since the mold is negative. This process is able to use heavier sheets, ranging in thickness from 0.0375 inches to 0.093 inches. Pressure forming uses ABS, acrylic PVC and polycarbonate plastic sheets, and volumes are typically in the hundreds to high thousands.