Ertalyte Grades — Ertalyte Natural, Ertalyte TX & Generic PET-P
Bearing-grade PET-P (Ertalyte) comes in three commercially significant grades: the unfilled Ertalyte natural, the PTFE-plus-solid-lubricant Ertalyte TX, and generic PET-P from alternative compounders. Each grade targets a specific duty cycle. Choosing the wrong grade is the most common mistake in Ertalyte specification — particularly the error of using unfilled Ertalyte where Ertalyte TX would produce dramatically longer bearing life.
At a glance:
- Ertalyte (natural): unfilled, maximum mechanical strength, FDA, translucent off-white
- Ertalyte TX: PTFE + solid lubricant; ~8× lower wear factor than natural; dry-running specialist
- Generic PET-P: meets ASTM D7292; properties comparable to Ertalyte natural; less brand traceability
- Both Ertalyte grades carry FDA 21 CFR 177.1630 for food contact
- Ertalyte TX is opaque white; natural is slightly translucent
- Neither grade is glass-filled or carbon-filled — no reinforced Ertalyte equivalent in standard stock
Ertalyte (Natural/Unfilled)
What It Is
Ertalyte natural is unfilled, semi-crystalline PET-P — the base grade that established PET as a bearing plastic. Mitsubishi/Quadrant's trade name "Ertalyte" refers specifically to this family of bearing-grade PET-P materials, differentiating them from bottle-grade PET (amorphous, lower MW) and from PETG (glycol-modified, amorphous, optically clear).
The material is produced by a solid-state polymerization process that increases molecular weight beyond standard PET, then extruded into rod and sheet stock with controlled cooling to develop the semi-crystalline structure. The result is a hard, stiff, low-moisture-absorption material with:
- Tensile strength: 11,600 psi
- Flexural modulus: 600,000 psi
- Water absorption (24 hr): 0.10%
- Coefficient of friction (dry vs steel): ~0.25
- Wear factor K: ~65 × 10⁻¹⁰
When to Specify Ertalyte Natural
- General-purpose bearings and bushings that run lubricated (oil, water, or process fluid)
- Structural wear components where tensile and flexural strength are also design constraints
- Any application requiring FDA 21 CFR 177.1630 food contact compliance
- Precision machined parts requiring the best surface finish from the PET-P family
- Applications requiring positive identification by the translucent appearance
Ertalyte TX
What It Is
Ertalyte TX is PET-P compounded with PTFE and a proprietary solid lubricant before extrusion. The PTFE creates a transfer film on the mating metal surface that dramatically reduces adhesive wear and friction. The solid lubricant (typically MoS₂ or graphite, exact formulation proprietary to Mitsubishi/Quadrant) supplements the PTFE by maintaining lubricity at higher loads and temperatures.
The tribological improvement is substantial:
| Tribological Property | Ertalyte Natural | Ertalyte TX |
|---|---|---|
| Coefficient of friction (dry vs steel) | ~0.25 | ~0.10 |
| Wear factor K (× 10⁻¹⁰) | ~65 | ~8 |
| Limiting PV, dry (ft·psi/min) | ~3,000 | ~10,000 |
An 8× reduction in wear factor means that at equivalent PV conditions, Ertalyte TX bearings last approximately 8× longer than unfilled Ertalyte. In a production machine running continuously, this translates directly to reduced downtime and maintenance cost.
Mechanical Trade-offs in TX
The PTFE and lubricant additives reduce mechanical properties modestly:
For purely structural parts under high tensile or bending loads, the lower modulus and strength of TX argue for using unfilled Ertalyte instead. For parts where tribological performance — not structural strength — is the governing design constraint, TX is the correct choice.
When to Specify Ertalyte TX
- Dry-running bearings and bushings where re-lubrication is impossible or impractical
- Food and pharmaceutical machinery where lubricant contamination must be completely eliminated (FDA-compliant, clean-dry service)
- High-load, moderate-speed bushings where unfilled Ertalyte's PV limit is insufficient
- Applications requiring noise reduction — TX's lower friction reduces squeal and stick-slip in oscillating motion
- Cam followers and eccentric bushings where low friction at changing load direction is important
Procurement Note on Ertalyte TX
Ertalyte TX is a Mitsubishi/Quadrant-branded product. Generic "PTFE-filled PET-P" from other suppliers should be tested against Ertalyte TX specification sheets before substitution — the performance of PTFE-filled PET depends heavily on PTFE content, dispersion quality, and the presence (or absence) of the secondary solid lubricant.
Generic PET-P
Several compounders offer unfilled bearing-grade PET-P under various trade names that meet ASTM D7292, the standard specification for PET-P extruded shapes. Properties are nominally equivalent to Ertalyte natural. Key considerations when selecting generic PET-P:
- Lot traceability: Ertalyte brand provides Mitsubishi/Quadrant certification documentation. Generic PET-P documentation varies by supplier.
- Crystallinity consistency: Semi-crystalline PET requires controlled extrusion cooling to achieve uniform crystallinity. Established extruders (Mitsubishi, Rochling, Ensinger) produce consistent crystallinity; less-experienced suppliers may produce stock with variable crystallinity that affects dimensional stability and wear performance.
- FDA documentation: Confirm FDA 21 CFR 177.1630 compliance is supported by the specific lot, not just the generic resin grade.
For procurement environments where Ertalyte by name is not required and standard ASTM D7292 PET-P properties suffice, generic PET-P offers a cost-neutral or cost-reduced alternative. For applications citing Ertalyte by trade name, source with Mitsubishi/Quadrant certification.
Grade Selection Decision Guide
- Running lubricated (oil, water, process fluid) + FDA needed → Ertalyte natural
- Dry-running + FDA needed + maximum bearing life → Ertalyte TX
- Maximum mechanical strength from PET-P → Ertalyte natural
- Low friction without external lubrication → Ertalyte TX
- Budget procurement, standard ASTM D7292 → Generic PET-P (verify FDA docs)
- Spec document cites Ertalyte by name → Source with Mitsubishi/Quadrant COC
What Ertalyte Does Not Have
Unlike PEEK or Ultem, Ertalyte is not available in glass-filled, carbon-filled, or ESD grades as standard stock. If these characteristics are needed, consider:
- Glass-filled or CF PEEK for high-temperature + reinforced performance
- Acetal GF (glass-filled Delrin) for cost-effective filled bearing composite
- ESD acetal or PEEK ELS for electrostatic-dissipative bearing applications
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