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Material Information Sheet

Delrin Homopolyer sheets, rods & tubes have many of the same characteristics of industrial metals such as brass, aluminum, zinc, and stainless steel. Some of Delrin's comparable properties include stiffness, dimensional stability, impact resistance, and structural strength. The homopolymer grades have a higher mechanical strength, stiffness, hardness and creep resistance as well as a lower thermal expansion rate and often it also presents a better wear resistance.

Delrin AF Blend is a unique thermoplastic material for use in moving parts in which low friction and long wear life are important. It is a combination of PTFE fibers uniformly dispersed in Delrin acetal resin. This combination offers better wear characteristics than unfilled Delrin. Delrin AF Blend, supplied as a 2:1 blend of Delrin AF100 and Delrin 150 resins, has excellent sliding/friction properties. Bearings made of Delrin. AF Blend can operate at higher speeds while exhibiting reduced wear. These bearings are also essentially free of slip-stick behavior because the static and dynamic coefficient of friction are closer than with most plastics. Delrin AF Blend retains 90% of the strength that is inherent in unmodified Delrin acetal. Some properties are changed due to the addition of the softer PTFE fiber. The natural color of Delrin AF Blend is dark brown.

GENERIC PROPERTY SHEET

SPECIFIC GRAVITY	WATER ABSORPTION	COEFFICIENT OF FRICTION	HARDNESS (ROCKWELL)
1.42 (D792)	0.25 (D570)	0.25 (Dynamic)	94 (D785)

TENSILE STRENGTH	IMPACT STRENGTH	OPERATING/ SPIKE TEMP	MELTING POINT
10,000 (psi) (D638)	1.4-24 (ft-lb/in of notch) (D256)	180°F -	347°F (D3418)

Acetal Copolymer grades tend to be more resistant against hydrolysis, strong alkalis and thermal-oxidative degradation than the homopolymer grades. Acetal provides high strength and stiffness coupled with enhanced dimensional stability and ease of machining. As a semi-crystalline material, acetal is also characterized by a low coefficient of friction and good wear properties –– especially in wet environments. Because acetal absorbs minimal amounts of moisture, its physical properties remain constant in a variety of environments. Low moisture absorption results in excellent dimensional stability for close-tolerance machined parts. In high moisture or submerged applications, acetal bearings outperform nylon 4 to 1. Acetal is ideally suited for close tolerance mechanical parts and electrical insulators which require strength and stiffness. It also offers resistance to a wide range of chemicals including many solvents.

Bonding Acetals Acetal polymers are typically very difficult to bond. Special processes and treatments have been developed to improve bonding of acetal. Typically these processes involve surface etching, flame treatment or mechanical abrasion. Typical etching processes involve chromic acid at elevated temperatures. DuPont has a patented process for treating acetal homopolymer called satinizing which creates anchor points on the surface, giving an adhesive something to grab. There are also processes involving oxygen plasma and corona discharge. Once the surface is prepared, a number of adhesives can be used for bonding. These include epoxies, polyurethanes, and cyanoacrylates. Epoxies have shown 150-500 psi shear strength on mechanically abraded surfaces and 500-1000 psi on chemically treated surfaces. Cyanoacrylates are useful for bonding to metal, leather, rubber and other plastics. Solvent welding is typically unsuccessful on acetal polymers, due to the excellent solvent resistance of acetal. Thermal welding through various methods has been used successfully on both homopolymer and copolymer.

GENERIC PROPERTY SHEET

SPECIFIC GRAVITY	WATER ABSORPTION	COEFFICIENT OF FRICTION	HARDNESS (ROCKWELL)
1.41 (D792)	0.22 (D570)	0.25 (Dynamic)	80 (D785)

TENSILE STRENGTH	IMPACT STRENGTH	OPERATING/ SPIKE TEMP	MELTING POINT
8,800 (psi) (D638)	1.3-20 (ft-lb/in of notch) (D256)	180°F -	335°F (D3418)