Polyamide 6, Nylon 6, or polycaprolactam (PA6) is one of the major engineering thermoplastics. PA6 is tough, has excellent abrasion resistance, good chemical resistance, fatigue endurance, lubricity, impact strength, high strength, and rigidity.
Since PA6 absorbs moisture readily, take care to ensure its dryness before molding. If the material is supplied in watertight packaging, keep the containers closed. If the moisture content is >0.2%, drying in a hot air oven at 80 C [176 F] for 16 hours is recommended. If the material is exposed to air for more than 8 hours, vacuum dry it at 105 C [221 F] for more than 8 hours.
Mold temperature significantly influences the crystallinity level which in turn affects the mechanical properties.
Generally between 75MPa 125 MPa (depends on material and product design)
High (slightly lower for reinforced grades)
The gate location is important because of fast freeze-off times. Any type of gate can be used; ensure that the aperture is not less than half the thickness of the part. When hot runners are used, the size of the gates can be smaller than when cold runners are used. When using circular tapered gates, ensure that the minimum diameter of the gate is 0.75 mm.
The molecular structure of polyamides consists of amide (CONH) groups joined by linear aliphatic sections (based on methylene groups). The toughness, rigidity, crystallinity, and thermal resistance of polyamide materials are due to the strong interchain attraction caused by the polarity of the amide groups. The CONH groups also cause much moisture absorption.
Polymerization of caprolactam produces Nylon 6. The chemical and physical properties are like the properties of PA66. However, its melting point is lower than PA66 and it has a wider processing temperature range. Its impact strength and solvent resistance are better than PA66, but its moisture absorption is higher. Moisture absorption affects many properties, which you must take into account when designing with these grades. Various modifiers are added to improve mechanical properties; glass is one of the most commonly used fillers. The addition of elastomers, such as EPDM or SBR, improves impact resistance.
For unfilled grades, shrinkage is of the order of .01 .015 mm/mm [1 1.5%]. The addition of glass fibers reduces the shrinkage to as low as 0.3% in the flow direction. This factor could be as high as 1% in the cross-flow direction. Mainly the mainly by the crystallinity level and moisture absorption affect post-molding shrinkage. The actual shrinkage is a function of part design, wall thickness, and processing conditions.