PA6 Polyamide 6 or Nylon 6 Typical applications: Widely used in structural components due to good mechanical strength and stiffness. It has good wear resistance and is also used to make bearings.
Injection Molding Process Conditions: Drying: Since PA6 absorbs moisture easily, special attention should be paid to drying before processing. If the material is supplied in a waterproof material, the container should be kept closed. If the humidity is greater than 0.2%, it is recommended to dry in hot air above 80C for 16 hours. If the material has been exposed to air for more than 8 hours, it is recommended to perform vacuum drying at 105 C for more than 8 hours. Melting temperature: 230~280C, 250~280C for enhanced varieties. Mold temperature: 80~90C. The mold temperature significantly affects the crystallinity, which in turn affects the mechanical properties of the part. Crystallinity is important for structural components, so it is recommended that the mold temperature be 80~90C. For thin-walled, longer-flowing parts, it is also recommended to apply higher mold temperatures. Increasing the mold temperature increases the strength and stiffness of the part, but reduces the toughness. If the wall thickness is greater than 3mm, it is recommended to use a low temperature mold of 20~40C. For glass reinforcement the mold temperature should be greater than 80C. Injection pressure: generally between 750 and 1250 bar (depending on material and product design). Injection speed: high speed (slightly lower for reinforced materials).
Runners and gates: Because the solidification time of PA6 is very short, the location of the gate is very important. The gate aperture should not be less than 0.5*t (where t is the thickness of the plastic part). If a hot runner is used, the gate size should be smaller than with a conventional runner because the hot runner can help prevent premature solidification of the material. If a submerged gate is used, the minimum diameter of the gate should be 0.75 mm.
Chemical and physical properties: The chemical and physical properties of PA6 are similar to those of PA66. However, it has a low melting point and a wide process temperature range. It has better impact resistance and solubility resistance than PA66, but it is also more hygroscopic. Because many of the quality characteristics of plastic parts are affected by hygroscopicity, this should be taken into account when designing products using PA6. In order to improve the mechanical properties of PA6, various modifiers are often added. Glass is the most common additive, and sometimes synthetic rubbers such as EPDM and SBR are added to improve impact resistance. For products without additives, PA6 shrinks between 1% and 1.5%. Adding a fiberglass additive can reduce the shrinkage to 0.3% to 0.5% (but slightly higher in the direction perpendicular to the flow). The shrinkage of the molded assembly is mainly affected by the crystallinity and hygroscopicity of the material. The actual shrinkage is also a function of the plastic part design, wall thickness and other process parameters.
PA66 Polyamide 66 or Nylon 66 Typical Applications: Compared to PA6, PA66 is more widely used in the automotive industry, instrument housings, and other products that require impact resistance and high strength.
Injection Molding Process Conditions: Drying: If the material is sealed before processing, there is no need to dry. However, if the storage container is opened, it is recommended to dry it in hot air at 85C. If the humidity is greater than 0.2%, it is also necessary to carry out vacuum drying at 105 C for 12 hours. Melting temperature: 260~290C. The product for glass additives is 275~280C. The melting temperature should be avoided above 300C. Mold temperature: 80C is recommended. The mold temperature will affect the crystallinity, which will affect the physical properties of the product. For thin-walled plastic parts, if a mold temperature lower than 40C is used, the crystallinity of the plastic part will change with time, and in order to maintain the geometric stability of the plastic part, annealing treatment is required. Injection pressure: usually between 750 and 1250 bar, depending on material and product design. Injection speed: high speed (slightly lower for reinforced materials). Runners and gates: Because of the short settling time of the PA66, the location of the gate is very important. The gate aperture should not be less than 0.5*t (where t is the thickness of the plastic part). If a hot runner is used, the gate size should be smaller than with a conventional runner because the hot runner can help prevent premature solidification of the material. If a submerged gate is used, the minimum diameter of the gate should be 0.75 mm.
Chemical and physical properties: PA66 has a higher melting point in polyamide materials. It is a semi-crystalline-crystalline material. PA66 also maintains high strength and stiffness at higher temperatures. PA66 is still hygroscopic after molding, the extent of which depends primarily on the composition of the material, the wall thickness and the environmental conditions. When designing a product, it is important to consider the effect of hygroscopicity on geometric stability. In order to improve the mechanical properties of PA66, various modifiers are often added. Glass is the most common additive, and sometimes synthetic rubbers such as EPDM and SBR are added to improve impact resistance. PA66 is less viscous and therefore has good fluidity (but not as good as PA6). This property can be used to machine very thin components. Its viscosity is sensitive to temperature changes. The shrinkage of PA66 is between 1% and 2%. The addition of glass fiber additives can reduce the shrinkage to 0.2%~1%. The shrinkage ratio is large in the flow direction and in the direction perpendicular to the flow direction. PA66 is resistant to many solvents, but is less resistant to acids and other chlorinating agents.
