Machining PA 6 FR

PA 6 FR is a semi-crystalline engineering thermoplastic of the polyamide family – chemically a PA 6 equipped with a halogen- and phosphorus-free flame-retardant system. This makes it flame retardant and self-extinguishing (UL 94 V-0) and at the same time hard, strong and dimensionally stable. Like all polyamides, PA 6 FR absorbs moisture. Due to the flame retardant, the elongation at break is significantly lower than standard PA 6, i.e. the material is more brittle.

PA 6 FR machines well – turning, milling, drilling and sawing produce clean results. Because of the lower toughness (brittleness) we use sharp tools and adapted cutting parameters to avoid chipping. We take moisture absorption and thermal expansion into account for tight tolerances and condition the stock if required. This lets us reliably produce precision parts – from single parts to series production.

PA 6 FR pays off whenever PA-typical properties have to be combined with fire protection – for example:

• Components for rail vehicles with EN 45545-2 requirements
• Insulators and electrical/electronic components with fire protection
• Holders, housings and covers in public transport
• Guide and sliding parts in railway, transport and factory equipment
• Applications requiring UL 94 V-0 and low smoke generation

PA 6 FR is significantly more expensive than standard PA 6, as the flame-retardant system and the approvals increase the material cost. As a rough guide, semi-finished stock ranges from about 15–30 €/kg. The part price is mainly determined by stock form and dimension, material utilisation (waste), machining effort and batch size. We are happy to quote binding prices on request based on your drawing.

Just as important are the limits of the material:

• Food contact – the FR grade is not intended for the food sector; use standard PA 6 or POM here
• Applications with high impact/shock loading – the elongation at break is low due to the flame retardant (more brittle)
• Highest dimensional accuracy under changing humidity – then POM
• Permanent contact with hot water/steam or strong acids (hydrolysis/attack)
• When no fire protection is required – standard PA 6 is more economical

An honest assessment – and how the disadvantages can be mitigated in practice: Advantages:

Disadvantages:

Practical tip: PA 6 FR shows its strengths wherever fire protection is mandatory – e.g. in rail transport to EN 45545-2. If no flame retardancy is needed, we recommend the tougher and cheaper standard PA 6; for food contact use standard PA 6 or POM.

• Flame retardant and self-extinguishing (UL 94 V-0)
• Halogen- and phosphorus-free flame-retardant system
• Certified to EN 45545-2 (railway fire protection)
• High hardness, strength and stiffness
• Good sliding, abrasion and wear properties
• Low elongation at break – more brittle, sensitive to impact/shock
• Not intended for food contact
• Absorbs moisture – dimensional and property changes
• Lower heat deflection temperature (HDT approx. 65 °C) and higher price