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.
Typical Applications for Plastic PA12
– gear wheels
– water meters
business machines
cable ties
cams
slides
bearings
Injection Molding Processing Conditions
Plastic PA12 Injection Molding Processing Conditions
| Conditions Name | Value |
|---|---|
| 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 can be used directly for molding after 3 hours of equilibration to shop floor temperature. |
| Melt Temperature | 230°C–300°C [446°F–580°F]; not to exceed 310°C [590°F] for standard grades. 270°C [518°F] for flame retardant grades. |
| Mold Temperature | 30°C–40°C [86°F–104°F] for unreinforced grades; 80°C-90°C [176°F–194°F]for thin-walled or large surface area components. 90°C–100°C [194°F–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 for Plastic PA12 injection molds
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.
Chemical and Physical Properties of PA12
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.
