Polyamide 12 or Nylon 12 (PA12) is an effective electrical insulator and its properties are not as sensitive to humidity as other polyamides. PA12 has good resistance to shock and many chemicals, and is extensively modified with plasticizers and reinforcements. In comparison to PA6 and PA66, PA12 materials have a lower melting point, lower density, and much lower moisture regain. PA12 is not resistant to strong oxidizing acids.
Runner diameters for unfilled grades can be as small as 3–5 mm because of the low viscosity of the material. Reinforced grades require larger diameters (5–8 mm). The runner shape should be the full round type. Sprues should be as short as possible.
A variety of gates can be used. To avoid highly stressed components or excessive shrinkage, small gates should not be used for large parts. The thickness of the gate should be equal to the part thickness. When using circular tapered gates, the minimum recommended diameter is 0.8 mm.
Hot runner molds can be used effectively but precise temperature control is necessary to prevent material drooling or freezing off at the nozzle. The size of the gates can be smaller when hot runners are used instead of cold runners.
PA12 is a linear, semicrystalline-crystalline thermoplastic derived from butadiene. The properties of PA12 and PA11 are similar, but PA12 has a different crystal structure.
Viscosity is determined by water content, temperature, and residence time. This material flows easily. Shrinkage is of the order of 0.005–0.02 mm/mm [0.5–2%]. This is dependent on the specific grade, wall thickness, and processing conditions.