Machinists know the challenge: Plastic parts rarely match metals like aluminum when it comes to holding tight tolerances. They machine to spec, let it cool, but the parts still shift. Why?
It often comes down to how stable the material is during and right after machining.
Let’s break down what gives Ertalyte™ polyethylene terephthalate polyester (PET-P) an edge over other plastic materials.
Three Key Drivers of Machining Stability
Stability of a material during machining depends on:
- Modulus (stiffness)
- Residual stress
- Coefficient of linear thermal expansion (CLTE)
If two or three of these attributes fall short, stability drops fast. The good news? Ertalyte™ PET-P holds its ground well in every category.
The Highest Stiffness in its Class
Stiffness resists deflections and dampens vibrations. With 15% more stiffness than typical nylon or acetal, Ertalyte™ PET-P machines cleaner with minimal moving, bending, or deforming under load.
Material |
Tensile Modulus (ksi) |
| Ertalyte™ PET-P | 460 |
| Ultra-High Molecular Weight Polyethylene (UHMW-PE) | 80 |
| Cast Nylon 6 | 400 |
| Acetal | 400 |
Low Residual Stress = Better Part Accuracy
Machinists feel residual stress when parts curl, warp, or distort after cutting. Ertalyte™ PET-P has the lowest internal stress of any standard engineering plastic. Why? The difference between its high melting point and softening point allows Mitsubishi Chemical Group (MCG) to create a unique annealing cycle.
We heat treat every shape to drive out stress and lock in stability. That means less distortion, even in non-symmetrical parts, heavy material removal, and multi-axis machining.
Minimal Expansion with Temperature
Thermal expansion can ruin a part’s fit, wear life, or sealing performance. Ertalyte™ PET-P moves less than half as much as conventional nylon or acetal and one-third that of typical UHMW-PE. That difference matters when temperatures fluctuate, tight clearances affect fit or seal, and you need consistent, repeatable results.
Material |
CLTE (in/in/°F from -40 to 150°F) |
| Ertalyte™ PET-P | 3.3 x 10⁻⁵ |
| UHMW-PE | 11 x 10⁻⁵ |
| Cast Nylon 6 | 5 x 10⁻⁵ |
| Acetal | 5.4 x 10⁻⁵ |
Use Ertalyte™ PET-P When You Need:
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We’re here to helpWhether you need tips on setup or help picking the right grade, our team is ready. Let’s talk about how Ertalyte™ PET-P fits your toughest jobs. Contact us. |
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