PA12 processing conditions

PA12 processing conditions

Generic Class

PA12 (Polyamide 12 or Nylon 12)

Typical Applications

Gear wheels for water meters and business machines, cable ties, cams, slides, and bearings.

Injection Molding Processing Conditions

Drying

The moisture content must be below 0.1% prior to processing. If the material is exposed to air, drying in a hot air oven at 85 C (185 F) for 4 -5 hours is recommended (3-4 hours in a desiccant dryer). If the container is unopened, it may be used directly for molding after 3 hours of equilibration to shop floor temperature. 
Melt Temperature  230 - 300 C (446 - 580 F); Not to exceed 310 C (590 F) for standard grades and 270 C (518 F) for flame retardant grades 

Mold Temperature

30 - 40C (86 - 104 F) for unreinforced grades; for thin walled or large surface area components, 80 -90 C (176 - 194 F) may be used; 90 - 100 C (194 - 212 F) for reinforced grades. Increasing the mold temperature increases the crystallinity level. It is very important to precisely control the mold temperature. 

Material Injection Pressure

Up to 100 MPa  Low hold pressures and high melt temperatures are recommended.

Injection Speed

High (high speeds give better finish on glass-filled grades)

Runners and Gates

Runner diameters for unfilled grades may be as small as 3 - 5 mm because of the material's low viscosity. 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 may be used. Small gates for large parts should be not be used, in order to avoid highly stressed components or excessive shrinkage. The thickness of the gate should preferably be equal to the part thickness. When using submarine gates, the minimum recommended diameter is 0.8 mm.

Hot runner molds may be used effectively but precise temperature control is necessary to prevent material drooling or freezing off at the nozzle. When hot runners are used, the size of the gates may be smaller than in the case of cold runners.

Chemical and Physical Properties

PA12 is a linear, semicrystalline-crystalline thermoplastic derived from butadiene. It has properties similar to PA11 but its crystal structure is different. PA12 is a good electrical insulator and its properties are not as sensitive to humidity as other polyamides. It has good resistance to shock and resistant to many chemicals. It is extensively modified with plasticisers and reinforcements. In comparison to PA6 and PA66, these materials have a lower melting point, density, and much lower moisture regain. It is not resistant to strong oxidizing acids.

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.

 


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