Material guide
Torlon vs PEEK vs Vespel: Choosing an Extreme-Performance Plastic
Torlon, PEEK and Vespel are the top of the plastics pyramid. Here's how they compare on temperature, strength, wear, chemicals and cost, and when each is worth the price.
Start with PEEK: it covers most high-temperature and chemical jobs and costs the least of the three. Step up to Torlon when you need more strength, stiffness or wear life at high temperature (and the part won't see hot steam or strong bases). Use Vespel when nothing else survives the heat, wear or vacuum, and the budget allows.
The short version
These three sit at the very top of the plastics pyramid. All of them hold strength far above where acetal, nylon or even Ultem give up. The trade-offs are temperature ceiling, strength and wear, chemical and steam resistance, and cost. PEEK is the most versatile, Torlon the strongest, and Vespel the most heat-resistant.
| PEEK | Torlon (PAI) | Vespel (PI) | |
|---|---|---|---|
| Continuous use temp | ~480°F (250°C) | ~500°F (260°C) | ~550°F (288°C), doesn't melt |
| Tensile strength (unfilled) | ~14,000–16,000 psi | ~20,000 psi | ~12,500 psi |
| Wear (bearing grades) | Very good | Excellent | Excellent |
| Steam and hot water | Excellent | Poor at high temps | Poor long-term |
| Chemical resistance | Excellent | Good; avoid strong bases | Good; avoid strong bases and acids |
| Moisture absorption | Very low | Moderate | Moderate |
| Relative cost | $$$ | $$$$ | $$$$$ |
Typical values for common general-purpose grades. Filled grades differ significantly; confirm with the datasheet for your grade.
PEEK: the versatile default
PEEK handles continuous heat around 480°F, nearly every chemical, and long-term hot water and steam. It's the easiest of the three to get, machine and afford, and comes in unfilled, glass-filled, carbon-filled and bearing grades. If PEEK meets the temperature and load, there's rarely a reason to pay more. (Comparing PEEK with Ultem instead? See PEEK vs Ultem.)
Torlon: maximum strength and wear
Torlon polyamide-imide is the strongest and stiffest unreinforced thermoplastic, keeps that strength up to around 500°F, and has outstanding creep and wear resistance. Bearing grades like 4301 are used for thrust washers, seals, bearings and wear rings in aerospace, transmissions and compressors.
The catches: it costs more than PEEK, absorbs some moisture, is attacked by high-temperature steam and strong bases, and is harder to machine. It's also hard on tooling.
Vespel: when nothing else survives
Vespel polyimide doesn't melt. It's rated for continuous service around 550°F with short excursions much higher, keeps its properties down to cryogenic temperatures, and has very low outgassing in vacuum. Graphite-filled grades (like SP-21 and SP-22) are known for excellent wear with no lubrication. It's used in jet engines, semiconductor equipment, vacuum systems and high-temperature seals.
It's the most expensive of the three, is attacked by strong bases and long-term hot water or steam, and is typically bought as stock shapes or direct-formed parts.
Machining notes
- All three machine well with sharp carbide, and diamond tooling helps on filled grades.
- PEEK and Torlon stock may need annealing or drying before tight-tolerance finishing.
- Filled grades are abrasive; budget for tool wear.
- At these prices, scrap is expensive, so pick a shop experienced with high-performance plastics.
When to choose each
PEEK
- Up to ~480°F continuous
- Steam, hot water and harsh chemicals
- Oil and gas, semiconductor, medical
- Best value at high performance
Torlon
- Highest strength and stiffness
- Thrust washers, seals, bearings, wear rings
- Aerospace and transmission parts
- Dry, high-load, high-temp wear
Vespel
- Above ~500°F continuous
- Vacuum, cryogenic and low outgassing
- Jet engine and semiconductor parts
- When nothing else will last
Tip from the counter: ask for the real operating temperature and duty cycle before quoting Torlon or Vespel. Many parts specified that way would run fine in a PEEK bearing grade for far less money.
Common questions
Is Torlon stronger than PEEK?
Yes. Torlon (polyamide-imide) has the highest strength and stiffness of any unreinforced thermoplastic, with tensile strength around 20,000 psi for general-purpose grades, versus roughly 14,000 to 16,000 psi for unfilled PEEK. Torlon also holds that strength to higher temperatures.
Which is more expensive, Torlon, PEEK or Vespel?
Generally PEEK is the least expensive of the three, Torlon costs more, and Vespel is the most expensive, often by a wide margin. Prices vary with grade and size, so get quotes, but expect each step up the ladder to cost noticeably more.
What is Vespel used for?
Vespel (polyimide) is used where other plastics would soften or melt: aircraft engine and jet parts, semiconductor wafer-handling parts, vacuum and cryogenic equipment, high-temperature seals, thrust washers and bushings. It doesn't melt, so it can handle continuous temperatures around 550°F and short excursions far higher.
Does Torlon absorb water?
Yes, more than PEEK. Torlon absorbs moisture over time and grows slightly, so very tight-tolerance parts may need to be dried or designed with that in mind. Torlon is also attacked by high-temperature steam and strong bases. PEEK is the better choice for hot water and steam.
What are Torlon 4203 and 4301?
They're the most common Torlon stock shape grades. 4203 is the general-purpose and electrical grade with the highest strength and impact resistance. 4301 is the bearing and wear grade, filled with graphite and PTFE for low friction. 5530 is 30% glass-filled for maximum stiffness.
Values in this guide are typical figures for common unfilled grades, for general comparison only. Properties vary by manufacturer, grade, filler, and shape. Before you specify, buy or machine a material for an application, check the manufacturer's datasheet and the material certifications for the exact grade you're getting, and confirm suitability with your supplier.
Who stocks and machines it
Distributors that stock these materials and shops that machine or fabricate them, from the Stock & Shape directory.
Torlon (PAI)
- Port Plastics – Phoenix Phoenix, AZ
- Professional Plastics – Portland Tualatin, OR
- AIP Precision Machining Daytona Beach, FL
- Boyd Machine Co. Souderton, PA
- Evolution Manufacturing Hubbard, OR
- Portland Precision Manufacturing Portland, OR
PEEK
- Interstate Advanced Materials – Portland Portland, OR
- Piedmont Plastics – Knoxville Knoxville, TN
- Port Plastics – Albuquerque Albuquerque, NM
- Total Plastics – Chicago Elk Grove Village, IL
- AIP Precision Machining Daytona Beach, FL
- Avion USA Sanborn, NY
- Carlson Tool & Manufacturing Cedarburg, WI
- No Limit Swiss Mentor, OH
Vespel (PI)
- Curbell Plastics – Seattle Fife, WA
- Professional Plastics – Portland Tualatin, OR
- AIP Precision Machining Daytona Beach, FL
- Allied Precision Middletown, DE
- Dover High Performance Plastics Dover, OH
- HD Machining Solutions Elizabethton, TN