Shaping Materials
Bending
Single curvature bending
Compound curvature bending
A material is either bent cold, or heated until is becomes pliable and bent to shape over simple formers or jigs in one direction only
A material is either bent cold, or heated until it becomes pliable and formed in two or more directions at the same time, to make dished shapes
Strip heater
Acrylic line bending (thermoplastic)
Metals
You don't heat it, you just apply pressure on it
Use Box folders
Vacuum forming
Used to form thin plastic sheet material such as polystyrene, ABS, PVC and acrylic
Uses a former
Formers must have draft angles, and rounded corners and edges, in order to release the material after forming
Low-cost process because the former is cheap to make
Dome blowing
Used to form sheet plastics into dome shapes
Material is clamped in the machine beneath a sheet of metal with a hole in it, and heated until it becomes pliable
Press forming
Used to form thicker sheet plastics such as acrylic into dish shapes
Casting (metals)
The pouring of molten metal and thermosetting plastic resins into moulds
Sand casting
The moulding flask is usually made of cast iron, and comes in two parts, the drag and the cope
Easy / 3D shapes
You can only do it once
Die casting
Uses gravity to ensure the flow of the metal into the mold
Steel mould
Moulding (plastics)
Extrusion
The process of forcing a material through a die to produce both solid and hollow shapes. (toothpaste squeezed out)
Injection moulding
Injecting a shot of molten plastic into a mould
Blow moulding
A tube of plastic is extruded between two halves of a mould.
The mould then closes, sealing the base, and air is blown in to inflate the tube to the internal shape of the mould.
Used for bottles
Expensive to set up but low unit cost (mass production)
Lamination
two or more layers of material bonded together to produce a single, larger section
Plywood
bag press
curved shapes
