Annealing of Plastics

Arrow uses computer controlled annealing ovens to meet your specifications.

No Stress for Your Plastics or You

We use precision ramping and controlled cooling to remove the stress introduced in plastic during molding, casting, extruding, or secondary finishing like cutting, drilling, or machining.

Mechanical benefits of plastic annealing

Increases dimensional stability
Improves integrity
Reduces shrinkage and expansion
Improves chemical resistance
Reduces cracking
Tighter tolerance capability
Improves wear resistance

Crazing

Crazing is a network of fine cracks under the surface of the material, also called hairline craze.

Different conditions and effects occur on different types of plastics.

In our experience we see it most commonly on materials such as ABS, Acrylic, Polycarbonate and Polystyrene.

Plastics are more susceptible to cracking and crazing when exposed to liquid chemicals and solvents.

This condition can occur months after processing.

To help prevent cracking and crazing, annealing works by reducing internal stresses and increasing the strengths of the joints and the system as a whole.

Post Machining Air Annealing Guidelines
Material	Heat Up	Hold	Cool Down
ABS	50°F per hour to 200°F	30 minutes per 1/4” thickness	50°F per hour
Acrylic	2 hours to 180°F	30 minutes per 1/4” thickness	50°F per hour
Acetal copolymer	4 hours to 310°F	30 minutes per 1/4” thickness	50°F per hour
Delrin® acetal homopolymer	4 hours to 320°F	30 minutes per 1/4” thickness	50°F per hour
Ardel® polyarylate	50°F per hour to 330°F	30 minutes per 1/4” thickness	50°F per hour
Ertalyte® PET-P	4 hours to 350°F	30 minutes per 1/4” thickness	50°F per hour
Halar® ECTFE	50°F per hour to 225°F	30 minutes per 1/4” thickness	50°F per hour
HDPE (Polyethylene)	2 hours to 200°F	60 minutes per 0.4” thickness	10°F per hour
Hydex® 4101 PBT-P	4 hours to 300°F	60 minutes per 1/4” thickness	50°F per hour
Kynar® PVDF	2 hours to 275°F	30 minutes per 1/4” thickness	50°F per hour
LDPE (Polyethylene)	2 hours to 175°F	30 minutes per 1/4” thickness	10°F per hour
Noryl® PPO	50°F per hour to 250°F	30 minutes per 1/4” thickness	50°F per hour
Noryl® PPO (30% glass filled)	50°F per hour to 260°F	30 minutes per 1/4” thickness	50°F per hour
Nylon - type 6	4 hours to 300°F	30 minutes per 1/4” thickness	50°F per hour
Nylon - type 6/6	4 hours to 350°F	30 minutes per 1/4” thickness	50°F per hour
Nylon - glass-filled	4 hours to 375°F	30 minutes per 1/4” thickness	50°F per hour
PCTFE (formerly Kel-F®)	3 hours to 225°F	60 minutes per 1/4” thickness	50°F per hour
PEEK polyetheretherketone	2 hours to 300°F then 2 hours to 375°F	60 minutes per 1/4” thickness 60 minutes per 1/4” thickness	50°F per hour
Polycarbonate (unfilled)	4 hours to 275°F	30 minutes per 1/4” thickness	50°F per hour
Polycarbonate (glass-filled)	4 hours to 290°F	30 minutes per 1/4” thickness	50°F per hour
Polyethylene (LDPE)	2 hours to 175°F	30 minutes per 1/4” thickness	10°F per hour
Polyethylene (HDPE)	2 hours to 200°F	30 minutes per 1/4” thickness	10°F per hour
Polyethylene (UHMW)	2 hours to 220°F	30 minutes per 1/4” thickness	10°F per hour
Polypropylene	2 hours to 185°F	30 minutes per 1/4” thickness	50°F per hour
Polystyrene	50°F per hour to 170°F	30 minutes per 1/4” thickness	50°F per hour
PTFE (Teflon®)	3 hours to 525°F	60 minutes per 1/4” thickness	50°F per hour
Radel® R polyethersulfone	4 hours to 390°F	30 minutes per 1/4” thickness	50°F per hour
Ryton® PPS	4 hours to 350°F	30 minutes per 1/4” thickness	50°F per hour
Techtron® PPS	4 hours to 350°F	30 minutes per 1/4” thickness	50°F per hour
Torlon® PAI	4 hours to 300°F then 4 hours to 420°F then 4 hours to 470°F then 4 hours to 500°F	1 day 1 day 1 day 3 to 10 days	50°F per hour
TPX® polymethylpentene	50°F per hour to 200°F	30 minutes per 1/4” thickness	50°F per hour
Udel® polysulfone	4 hours to 330°F	30 minutes per 1/4” thickness	50°F per hour
UHMW (Polyethylene)	2 hours to 220°F	30 minutes per 1/4” thickness	10°F per hour
Ultem® PEI (unfilled)	4 hours to 390°F	30 minutes per 1/4” thickness	50°F per hour
Ultem® PEI (20%, 30% glass filled)	4 hours to 400°F	30 minutes per 1/4” thickness	50°F per hour
Please note: These are only guidelines. It is up to the purchaser to call out the processes needed on the purchase order. Courtesy of Boedeker Plastics.

FAQs

Plastic annealing is commonly used for thermoplastic manufactured parts, including HDPE and LDPE polyurethane, nylon pebax, polycarbonate, and acrylic. Annealing plastics is an ideal process to strengthen or harden the materials.

Annealing involves heating and slow cooling plastics.

Advantages of annealed machined plastics and metals are:

Prevents warping from prolonged exposure to elevated temperatures
Increased dimensional stability
Reduced shrinkage and expansion
Hold tighter tolerances

Arrow Finishing maintains ovens that are programmable up to 500°F, annealing your plastics and metals to exact specification. The entire annealing cycle is recorded to provide quality assurance.

Acrylic and Ultem benefit from the annealing process after vapor polishing to prevent crazing.