Reference

Plastic Properties Comparison Chart

Tensile strength, service temperature, and key traits for the plastics shops machine most, so you can match the material to load, heat, and environment.

Machining plastics range from cheap and easy to premium high-performance. This chart compares the plastics shops cut most by tensile strength, maximum continuous service temperature, and the property that usually drives the choice. As a starting point: ABS and acrylic for cosmetic and prototype parts, polycarbonate for impact resistance, nylon and acetal for wear and gears, PTFE for low friction, HDPE for chemical resistance on a budget, and PEEK when you need strength and heat together.

Common machining plastics compared

Typical values for unfilled grades at room temperature. Glass- or carbon-filled grades raise strength and stiffness, and moisture, fillers, and grade all shift the numbers, so treat these as representative.

Plastic	Tensile (MPa)	Max service temp (C)	Key properties	Typical use
ABS	40-50	80-90	Tough and impact-resistant, easy to machine, sand, and glue; not UV-stable	Enclosures, prototypes, consumer housings
Polycarbonate (PC)	60-70	115-125	Very high impact strength, optically clear, dimensionally stable	Guards, transparent covers, glazing
Nylon (PA6/66)	70-85 (dry)	80-120	Wear- and abrasion-resistant, tough, low friction; absorbs moisture	Bushings, gears, wear pads, rollers
Acetal / Delrin (POM)	65-80	90-100	Stiff, low friction, dimensionally stable, machines cleanly	Precision gears, bearings, small mechanical parts
PEEK	90-100	~250	High strength, chemically inert, heat- and wear-resistant; premium cost	Aerospace, medical, high-temperature seals
PTFE	20-35	~260	Lowest friction, chemically inert, wide temp range; soft and cold-flows under load	Seals, gaskets, low-friction bushings, insulators
HDPE	25-33	~80	Chemically resistant, low moisture pickup, low cost; hard to bond	Tanks, cutting boards, chute and wear liners
PMMA (acrylic)	70-80	70-90	Optically clear, rigid, UV-stable; brittle and prone to chipping	Displays, light pipes, signage, windows

Typical values for unfilled grades. Service temperature is continuous; short-term peaks can be higher. Nylon strength drops as it absorbs moisture. Confirm the specific grade with the shop.

How to read the numbers

Tensile strength is how much stress the plastic takes before it breaks; most machining plastics fall in the 20-100 MPa range, well below metals. Maximum service temperature is the temperature a part can run at continuously without losing strength or creeping. Two traits that do not appear as a single number often decide the choice: impact toughness (polycarbonate and nylon are high, acrylic is brittle) and friction/wear (PTFE, acetal, and nylon are the low-friction bearing plastics).

Picking a plastic for the job

Match the material to the dominant requirement. For clear parts, choose polycarbonate when it must survive impact and acrylic when optical clarity and rigidity matter more than toughness. For moving parts, acetal gives precision and stiffness while nylon handles shock and wear. For chemical or heat exposure, PTFE and PEEK lead, with PEEK carrying load and PTFE reducing friction. For low-cost, chemically resistant tanks and liners, HDPE is hard to beat. ABS remains the go-to for inexpensive enclosures and prototypes.

Values compiled from published datasheets (MatWeb, MakeItFrom, and material suppliers) for unfilled grades at room temperature. Filled grades, moisture, and specific formulations shift the numbers, so verify against the grade datasheet for load-bearing parts.

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Frequently Asked Questions

What is the strongest machining plastic?

Among common unfilled machining plastics, PEEK is the strongest and most heat-resistant, at roughly 90-100 MPa tensile and about 250 C continuous service. Glass- or carbon-fiber-filled grades of PEEK, nylon, and others push strength and stiffness higher still, at added cost.

Which plastic is best for gears and bearings?

Acetal (Delrin/POM) is the usual pick for precision gears and bearings thanks to its stiffness, low friction, and dimensional stability. Nylon is preferred where the part sees impact or shock loading, and PTFE where the lowest possible friction matters more than strength.

What is the difference between polycarbonate and acrylic?

Both are clear, but polycarbonate is far more impact-resistant and handles higher temperatures (about 115-125 C), while acrylic (PMMA) is stiffer, more scratch- and UV-resistant, and optically clearer but brittle. Choose polycarbonate for toughness and safety guards, acrylic for display-quality clarity.

Does nylon really lose strength from moisture?

Yes. Nylon absorbs water from the air, which lowers its strength and stiffness and causes slight dimensional growth while improving toughness. Datasheet tensile values are typically quoted dry (as-molded), so design with the conditioned (moist) properties for parts that run in humid or wet environments.

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