Custom PA66 (Nylon 66) Injection Molding
PA66 is the engineering plastic for parts that move and carry load: gears, bearings, clips and under-bonnet components where wear and heat decide the part life. Its weakness is moisture, which changes both its dimensions and its properties, so the part is designed and measured after conditioning rather than straight from the tool.
Free Consultation24h
Rapid Quote
100 pcs
Molding MOQ
to 250 degree C
Heat Deflection (filled)
above 80 MPa
Tensile Strength
Materials
| Grade | Properties | Typical Applications |
|---|---|---|
| Natural PA66 | High strength, good fatigue and wear resistance with a sharp melt, but moisture sensitive: properties and dimensions shift as it conditions. The base grade for gears, rollers and clips. | Gears, sprockets, rollers, fasteners, general mechanical parts |
| Glass Filled PA66 (30 percent) | Stiffness, heat deflection and creep resistance raised sharply by glass fibre, with lower and more stable shrinkage. Weld lines weaker and the surface abrasive on tooling. | Structural brackets, automotive under-bonnet parts, load bearing frames, pulleys |
| Heat Stabilised PA66 | Additives resisting thermal ageing so the part keeps properties at temperature over time. Essential for under-bonnet and around-heat applications. | Connectors, under-bonnet clips, heater adjacents, lighting surrounds |
| Impact Modified PA66 | Elastomer modified for low temperature and notch impact, trading some stiffness and heat for toughness where the part is dropped or cold. | Tool handles, sport and outdoor parts, clips subject to shock |
| Mineral and Reinforced PA66 | Mineral filled for dimensional stability and lower warpage at moderate stiffness, a balance grade for large flat parts that must stay flat. | Appliance bases, large covers, panels, housings needing flatness |
| Lubricated PA66 (PTFE or MoS2) | Internal lubricant lowering friction and wear for moving parts without external grease. Used where a greased joint is undesirable. | Bushings, bearings, gear trains, sliding wear pads |
Process Parameters
| Parameter | Standard Range |
|---|---|
| Drying Requirement | 80 to 100 degree C for 4 to 6 hours, target moisture below 0.1 percent |
| Melt Temperature Window | 260 to 290 degree C depending on grade and filler |
| Mould Temperature | 60 to 100 degree C, higher for filled grades and to reduce weld line risk |
| Injection Pressure | 700 to 1,400 bar depending on flow length and wall |
| Recommended Wall Thickness | 1.5 to 3.0 mm; reinforce thin areas with ribs |
| Mould Shrinkage | 1.5 to 2.0 percent natural, 0.2 to 0.5 percent glass filled |
| Clamp Force Requirement | 2 to 5 tonnes per square centimetre of projected area |
| Cycle Time | 25 to 70 seconds per part depending on wall and size |
| Part Tolerance | plus or minus 0.05 mm standard, tighter by agreement after conditioning |
| Maximum Moulded Part Size | up to 700 x 500 x 400 mm |
Surface Finishes
As-moulded Texture
Functional matte surface straight from the tool, the default for mechanical parts where appearance is secondary to function.
SPI Polish (B-1)
Smoother, lower friction surface for parts that slide or seal, also improving the look of cosmetic mechanical components.
Vapour Polish
A solvent vapour smooths the surface for improved sealing and a cleaner finish on parts such as valve bodies and medical components.
Laser Marking
Permanent part numbers, traceability codes and logos marked directly, which cannot be scraped off in service and survives wear.
Blackening and Colour
Pigmented resin or a surface treatment for colour identification of grades and functions, common on gears and clips in assemblies.
PTFE or MoS2 Coating
A surface lubricant layer reducing running-in wear on bearings and bushings where the moulded lubricant alone is not enough.
Design for Manufacturing (DFM)
- Dry PA66 thoroughly and confirm it, because moisture causes splay and, more seriously, weakens weld lines that carry load in gears and brackets
- Design for 0.2 to 0.5 percent post-mould shrinkage on filled grades and about 1.5 to 2.0 percent natural, and model warp because the two shrink differently
- Use 1.5 to 3.0 mm walls and reinforce thin areas with ribs rather than thickness, because thick sections sink and lengthen cycle time
- Specify dimensional callouts after conditioning to a stable moisture level, since natural PA66 grows as it absorbs humidity and moves off drawing
- Gate to avoid weld lines on loaded sections; a weld line across a gear tooth or a bracket root is a planned failure, not a cosmetic mark
- Allow for moisture uptake in service: natural PA66 can absorb a few percent water, which raises impact but lowers stiffness and size
- Use heat stabilised grades for any part near a heat source, because unstabilised nylon ages and embrittles over time at temperature
- Consider lubricated grades for moving parts so the joint runs without external grease and stays clean
- Avoid trapped water in features and design for drainage, because standing water accelerates property loss in service
- Upload STEP, IGES or DXF and receive a free material and DFM review within 24 hours covering grade, gate, shrinkage and conditioning
Tooling & Capacity
| Type | Lead Time | Suitable For |
|---|---|---|
| Aluminium Soft Tooling | 2 to 3 weeks | 25 to 1,000 pieces, pilot runs and design validation. Glass filled grades abrade a soft cavity, so steel is preferred for those |
| Production Steel Tooling | 4 to 6 weeks | Annual volumes above roughly 10,000 pieces and any filled or heat stabilised grade |
| Polished Steel Tooling | 4 to 6 weeks | Low friction and cosmetic mechanical surfaces where the cavity finish defines the part finish |
| Multi-Cavity Tooling | 5 to 7 weeks | High volume small parts such as clips, connectors and fasteners where cycle time dominates |
Quality Assurance
- Moisture check on incoming material before processing, recorded rather than assumed, since this controls weld line strength and splay
- Melt temperature verified at the nozzle, because a machine setting is not the true material temperature
- First article inspection with dimensional report after conditioning, because natural PA66 dimensions shift with humidity
- Wall thickness and shot weight are checked per cavity to catch short shots and flash early
- Weld line position and strength reviewed on loaded features at trial, not discovered in service
- Visual inspection for splay, burn and sink on every setup change
- Hardness and tensile checked on samples from the lot where the part has a structural requirement
- Colour and grade verified against the reference, with lot recorded
- PA66 lot traceability is kept per production run with the supplier certificate filed to match
- A dimensional report, material certificate and Certificate of Origin ship with every PA66 lot; SGS, Bureau Veritas or TUV third-party inspection is arranged on request
Applications
- Gears, sprockets and rollers in mechanisms
- Bearings, bushings and wear pads
- Automotive under-bonnet clips, connectors and brackets
- Electrical connectors and housings
- Fasteners, clips and cable ties
- Industrial machine parts and jigs
- Appliance bases and structural frames
- Sport and outdoor equipment components
- Valve bodies and fluid handling parts
Why Choose FHY Precision
All PA66 families moulded in house: natural, glass filled, heat stabilised, impact modified and lubricated, so the grade is matched to load and temperature
Process control tuned to moisture: drying, weld line placement and conditioning are treated as design inputs, not afterthoughts
Dimensions called out after conditioning, so the part you measure is the part that ships and the part that fits
Free PA66 material and DFM review within 24 hours, including grade selection where the right choice is unclear
Pilot quantities of 25 pieces in aluminium tooling come before production steel
Marking, colour and lubricant options quoted with the moulding so the finished part is one purchase order
Lot traceability for resin is retained, with SGS, Bureau Veritas or TUV third-party inspection on request
PA66 moulded in-house in China and quoted factory-direct, no trading layer
FAQ
1. What is the difference between PA66 and PA6?
PA66 has a higher melting point and better heat resistance, stiffness and fatigue at temperature, while PA6 absorbs slightly more moisture and is a little tougher and cheaper. For under-bonnet and load carrying parts PA66 is usually the safer choice; for a low cost clip PA6 can do. We compare both against your temperature and load targets at review.
2. Why does PA66 have to be dried before moulding?
Because moisture in the melt causes splay and, more importantly, weakens weld lines where two flow fronts meet. On a gear tooth or a bracket root that weld line carries load, so a wet material is a planned failure. Drying at 80 to 100 degree C for 4 to 6 hours down to below 0.1 percent moisture prevents this, which is why it is a process control.
3. How does moisture affect PA66 dimensions in service?
Natural PA66 absorbs a few percent water from the air and swells, growing in size and gaining impact while losing some stiffness. We design and measure the part after conditioning to a stable moisture level, so the drawing matches the shipped part rather than the just-moulded part. Filled grades absorb far less and move less.
4. When should I use glass filled PA66?
When stiffness, heat deflection and creep resistance govern the design. Thirty percent glass roughly doubles stiffness and pushes heat deflection toward 250 degree C, at the cost of weaker weld lines, more tool abrasion and anisotropic warp. If the part fails on deflection or at temperature it is the right answer; if it fails on impact it usually is not.
5. Do you mould heat stabilised PA66?
Yes, and we specify it for any part near a heat source. Unstabilised nylon ages and embrittles over time at temperature, so a connector or clip under a bonnet needs the stabiliser to keep its properties for the service life. We select the stabiliser package from the operating temperature.
6. When should I use lubricated, internally greased PA66?
Where the part moves against another surface and you do not want external grease, such as a bushing, bearing or gear train. An internal PTFE or MoS2 lubricant lowers running-in wear and keeps the joint clean, which matters in food, medical and consumer mechanisms. We select the lubricant grade from the speed and load, and we can add a surface coat where the moulded lubricant alone is not enough.
7. Can PA66 replace a metal gear or bushing?
Often yes for low to moderate load and where weight, corrosion and noise matter. PA66 gears run quieter and need no grease with a lubricated grade, and they resist corrosion. The honest limit is peak load and temperature: give us the load path, speed and temperature and we will size the section and pick the grade, and tell you where metal is still required.
8. How chemical resistant is PA66?
Good against most oils, fuels and solvents, and it is a common under-bonnet plastic for that reason. It is not resistant to strong acids and some phenols, and it absorbs water as noted. We review the service fluid and temperature at DFM stage and select the grade and any coating accordingly.
9. How does PA66 compare with POM (acetal)?
POM has lower friction, better dimensional stability and less moisture uptake, but lower temperature resistance and impact. PA66 is stronger, tougher at temperature and cheaper in filled form. For a quiet low friction bushing POM can win; for a structural gear near heat PA66 usually does. We compare both against your duty cycle.
10. What tolerances can I hold on PA66 parts?
Plus or minus 0.05 mm standard on critical features, tighter by agreement, but the key is conditioning: natural PA66 is measured after humidity stabilisation, filled grades nearer the moulded size. We mark which dimensions are moisture controlled on your drawing during DFM review so the part fits in assembly.
11. How long does PA66 tooling take?
Aluminium soft tooling takes 2 to 3 weeks and suits pilot and low volume work, though glass filled grades prefer steel. Production and multi-cavity steel tooling takes 4 to 7 weeks. Trial moulding and first article approval after conditioning add about a week before release.
12. What is your minimum order quantity for PA66 parts?
Standard moulding MOQ is 100 pieces. For pilot runs we machine aluminium soft tooling and produce from 25 pieces. Filled and heat stabilised grades run in steel from the start where the volume justifies it, because they abrade a soft cavity quickly.
13. Can you mould PA66 automotive parts?
Yes. Heat stabilised and glass filled PA66 are standard for under-bonnet clips, connectors and brackets. We select the grade for the temperature and load, place weld lines away from loaded sections, and keep lot traceability. Where a part sits in a hot zone we move to heat stabilised filled PA66 rather than expecting natural material to hold.
14. Should PA66 parts be annealed?
For precision mechanical parts, yes sometimes. A controlled thermal cycle relaxes moulded in stress and stabilises dimensions before the part is machined or assembled, which matters on gears and brackets held to tight size. We specify annealing where the duty cycle and tolerance call for it, since it is cheap relative to a field fit problem.
15. Can PA66 parts be welded or bonded?
Yes. PA66 welds by ultrasonic and vibration methods and bonds with the right adhesive after surface preparation. Joint design matters more than the equipment, so we review the shear joint geometry at DFM stage rather than discovering a weak joint after tooling exists. Laser marking gives permanent traceability on the part.
16. Do you arrange third-party inspection for PA66 parts?
Yes. We arrange SGS, Bureau Veritas or TUV at any stage you specify, including incoming resin verification, dimensional checks after conditioning and weld line review. For automotive and connector programs this is often what your end customer needs, so we build the inspection point into the order.