For engineering and sourcing teams
Nylon or PBT for a Molded Component?
Shortlist exact PA6, PA66 and PBT grades against the part’s humidity, load, temperature, electrical and approval requirements. A resin-family label cannot decide the finished part.
- For moisture-sensitive fit or electrical geometry, evaluate an appropriate PBT grade and the specified exposure
- For loaded, impact or wear duty, evaluate named PA6 and PA66 grades at the required condition
- Compare molded-part evidence and total project cost, not resin price alone
Request a nylon vs PBT material review → View nylon injection molding services
Two Engineering Plastics, Two Different Worlds
Nylon (polyamide, PA) and PBT (polybutylene terephthalate) are semi-crystalline engineering thermoplastics used in automotive, electrical and industrial parts. Connectors, housings and brackets can make either family worth screening. The decision depends on the named grade, molded geometry, conditioning, load, temperature, fluids and required approvals.
Polyamides absorb moisture; PBT grades generally have lower water uptake, but neither family has one fixed response in every environment. Compare supplier data under like test conditions and validate the finished part after its intended exposure.
PA6 GF30 vs PA66 GF30 vs PBT GF30: What to Verify
Project screening, not a universal property ranking. GF30 identifies nominal glass-fiber content; it does not make PA6, PA66 and PBT grades interchangeable. Use this matrix to identify the evidence to request before approving a material or molded part.
| Part requirement | PA6 GF30 check | PA66 GF30 check | PBT GF30 check | Evidence before approval |
|---|---|---|---|---|
| Tight fit after humidity exposure | Review conditioned dimensions and strength. | Review conditioned dimensions and strength. | Screen lower water uptake; check hot-wet duty separately. | Exact-grade conditioning data and critical dimensions after the specified cycle. |
| Load near heat | Check temperature, load and duration. | Include when a PA6 candidate misses a defined thermal or load criterion. | Compare thermal and aging data at the same criterion. | Like-load HDT or relevant long-term method, then a molded-part test. |
| Electrical housing or connector | Check conditioned electrical data and required recognition. | Check the same; GF30 alone gives no flame rating. | Check fit, electrical data, hot-wet need and recognition. | Exact grade, color and tested thickness on the current document; part-level approval. |
| Fluid or coolant exposure | Test the named grade in the actual fluid. | Test the named grade in the actual fluid. | Ask whether a hydrolysis-resistant variant is needed for hot-wet service. | Exposure fluid, temperature, duration and retained part function. |
| Warp, fit or visible surface | Trial the actual geometry and gate. | Trial the actual geometry and gate. | Trial the actual geometry and gate. | Flow/transverse shrinkage, fiber orientation and measured part geometry. |
Compare dry and conditioned data using the same method, temperature and load; then test the molded part. For example, BASF publishes separate sheets for Ultramid B3EG6 (PA6-GF30), A3EG6 (PA66-GF30) and Ultradur B 4300 G6 HR (hydrolysis-resistant PBT-GF30). These are third-party examples of exact-grade documentation, not Nylon Plastic formulations or approvals. For a recognition requirement, check the specific material record; UL explains what a Yellow Card represents.
For a named-grade review, share the current grade and TDS, drawing or critical dimensions, load, temperature, humidity or fluids, electrical or flame requirements, target tests and quantity. Send the project details through the existing inquiry form.
The Moisture Factor: Nylon’s Defining Characteristic
Polyamides absorb moisture. Conditioning can change stiffness, impact response and dimensions, so dry-as-molded data and conditioned data answer different questions. The size and direction of the effect depend on the exact grade, reinforcement and exposure cycle. Measure critical molded dimensions after the humidity or immersion condition specified for the part.
PBT grades are often screened for moisture-sensitive fit and electrical geometry because of their relatively low water uptake. Low is not zero: hot-wet exposure, hydrolysis and electrical performance still need exact-grade and part-level checks. BASF’s Ultradur brochure describes low water absorption, while its B 4300 G6 HR sheet identifies a specific hydrolysis-resistant PBT-GF30 grade.
Application Selection Guide
Choose Nylon When:
- A named PA6 or PA66 grade meets the specified load, temperature, impact or repeated-load duty in the relevant conditioned state.
- A wear application has been checked against the actual counterface, load, speed and lubrication conditions; a GF30 label alone does not establish a low-friction grade.
- A chemical or fluid exposure test supports the proposed grade and finished-part function.
- The quote for the approved part and quantity supports the selected material and process route.
Choose PBT When:
- A named grade meets moisture-sensitive fit or electrical geometry requirements after the specified conditioning cycle.
- Hot-wet, coolant or other fluid exposure has been checked against the proposed variant; a hydrolysis-resistant grade may be needed.
- The exact grade, color and thickness meet any required electrical or flame documentation, followed by part-level approval.
- Molding trials confirm the required cycle, dimensional results, surface quality and finished-part cost.
Cost Considerations Beyond Material Price
A resin-price comparison cannot establish the cost of an approved molded part. Quote the same drawing, quality target and quantity for each proposed grade and process route. Record:
- Exact grade, purchase quantity and material price at the time of quotation
- Supplier drying instructions and any part-conditioning requirement
- Measured trial cycle, scrap and rework at the required quality level
- Gate, cooling, mold or finishing changes needed for approval
- Inspection, documentation, packaging and agreed delivery terms
Cycle time, warpage, yield and total cost depend on the part, tool and processing window. Compare measured trial data before treating an apparent resin-price or cycle advantage as a purchasing decision.
Why Choose Nylon Plastic for Your Engineering Plastic Needs?
- ✅ 300+ injection molding machines from 50T to 2000T
- ✅ 10,000+ parts per day production capacity
- ✅ ±0.02mm precision tolerance across all materials
- ✅ MOQ just 1 piece for prototyping; scalable to millions
- ✅ 24-hour quoting, 3–15 day lead times
- ✅ ISO 9001 certified quality management system
Related Articles
- Nylon vs POM (Acetal/Delrin): Engineering Plastics Comparison Guide
- Nylon vs Polypropylene: Material Selection Guide for Engineering Applications
- Nylon vs Polycarbonate: Strength, Heat Resistance, and Cost Comparison
FAQ
When should PBT GF30 be shortlisted?
When moisture-sensitive fit or electrical geometry is important, screen a named PBT-GF30 grade. Check hot-wet exposure, the exact electrical or flame documentation and molded-part dimensions before approval.
When should PA6 GF30 or PA66 GF30 be shortlisted?
When the part has a specified load, temperature, impact or wear duty, compare exact PA6-GF30 and PA66-GF30 grades under the relevant conditioning and test methods. Validate the molded part rather than choosing from the polymer name alone.
Are GF30 grades interchangeable?
No. Nominal 30% glass content does not establish identical chemistry, additive package, test results, recognition or processing behavior. Compare named grades and the approved part requirements.
What is needed for a useful Nylon-versus-PBT review?
Share the drawing or critical dimensions, current grade if known, load, temperature, humidity and fluids, electrical or flame requirements, quantity and target approval tests.
