High-density multilayer PCB layout detail by MCG LLC

Materials Selection Guide - Part 2

Engineering Nylons & Composite Materials

← Part 1: High-Performance Polymers Part 2: Nylons & Composites Part 3: Selection Matrix →

Engineering Nylons & Fiber-Reinforced Composites

This section covers workhorse engineering materials: nylon families (PA6, PA12), polycarbonate, PETG, ABS, and their carbon/glass fiber reinforced variants. These materials balance cost, printability, and mechanical performance for production applications. All materials maintained in climate-controlled dry storage with documented lot traceability.

Nylon Family

PA6, PA12, and fiber-reinforced variants

6 variants

Engineering Thermoplastics

PC, PC-FR for structural applications

2 variants

PETG & ABS Families

Standard & fiber-reinforced composites

6 variants

Nylon (Polyamide) Family

Nylons are the most widely used engineering thermoplastics in FDM printing. Excellent toughness, fatigue resistance, chemical resistance, and low friction. All nylons are hygroscopic - proper drying and storage is critical.

PA6 (Nylon 6)

Mechanical Tough Low Friction

Overview: General-purpose nylon with excellent toughness and wear resistance. Lower cost than PA12, higher moisture absorption. Good for functional prototypes, jigs, fixtures, and wear parts.

Thermal Properties

Glass Transition (Tg)50-60°C
HDT @ 0.45 MPa65-75°C (dry)
HDT @ 1.8 MPa45-55°C (dry)
Service Temp (continuous)80-100°C (dry)
Print Temp240-260°C
Bed Temp70-90°C
Chamber (recommended)50-70°C

Mechanical Properties

Tensile Strength45-55 MPa
Tensile Modulus1.8-2.5 GPa
Elongation at Break30-100% (varies with moisture)
Flexural Strength60-80 MPa
Flexural Modulus2.0-2.8 GPa
Impact Strength (Izod)5-8 kJ/m²

Other Properties

Density1.12-1.14 g/cm³
Water Absorption (24h)1.5-2.5% (high!)
Chemical ResistanceGood (oils, fuels, alcohols)
UV ResistancePoor (yellowing, embrittlement)
Coefficient of Friction0.2-0.4 (low, self-lubricating)
Flammability (UL94)HB (burns slowly)

Common Applications

  • Functional prototypes and end-use parts
  • Gears, bushings, bearings (low friction)
  • Jigs, fixtures, assembly tooling
  • Living hinges and snap-fit assemblies
  • Wear parts and sliding components
  • Automotive under-hood (non-critical)

Design Considerations

  • Moisture sensitivity: Must dry 8-12 hours @ 70-80°C before printing. Store in dry box with desiccant.
  • Dimensional stability: Moisture absorption causes swelling (up to 2% linear). Design with clearances.
  • Warping: Moderate warping tendency. Heated bed + chamber recommended for large parts.
  • Layer adhesion: Excellent when dry. Poor adhesion if wet (steam voids).
  • Post-processing: Can be annealed @ 80-100°C for improved stability. Dyeable with acid dyes.
  • Support removal: Excellent - supports break away cleanly due to toughness.

PA12 (Nylon 12)

Mechanical Tough Low Moisture Preferred

Overview: Premium nylon with lower moisture absorption than PA6. Better dimensional stability, less warping, easier to print. Industry standard for SLS powder, excellent FDM variant. Higher cost justified by performance.

Thermal Properties

Glass Transition (Tg)40-50°C
HDT @ 0.45 MPa50-60°C
HDT @ 1.8 MPa40-50°C
Service Temp (continuous)80-100°C
Print Temp240-270°C
Bed Temp60-80°C
Chamber (recommended)40-60°C

Mechanical Properties

Tensile Strength50-60 MPa
Tensile Modulus1.5-1.8 GPa
Elongation at Break50-300% (highly ductile)
Flexural Strength55-75 MPa
Flexural Modulus1.3-1.6 GPa
Impact Strength (Izod)8-12 kJ/m² (notched)

Other Properties

Density1.01-1.03 g/cm³
Water Absorption (24h)0.5-1.0% (much lower than PA6)
Chemical ResistanceExcellent (oils, greases, fuels)
UV ResistanceFair (better with stabilizers)
Coefficient of Friction0.2-0.3 (very low)
Flammability (UL94)HB

Common Applications

  • Production-grade functional parts
  • Precision gears and mechanical assemblies
  • Automotive interior components
  • Medical devices and healthcare (biocompatible grades)
  • Consumer electronics housings
  • Sports equipment and outdoor gear

Design Considerations

  • Moisture management: Still hygroscopic, but 3-5x less than PA6. Dry 4-8 hours @ 70°C.
  • Dimensional control: Excellent dimensional stability. Moisture-induced swelling <1%.
  • Printability: Easier than PA6. Less warping, better first layer adhesion.
  • Ductility: Highly ductile - excellent for snap-fits and living hinges.
  • Cost: 2-3x more expensive than PA6. Worth it for precision parts.
  • Post-processing: Can be vapor smoothed, dyed, or annealed for stress relief.

PA6-CF (Carbon Fiber Reinforced Nylon 6)

Composite High Stiffness Mechanical

Overview: PA6 reinforced with 15-20% chopped carbon fiber. Dramatically increased stiffness and strength, reduced moisture absorption. Requires hardened steel nozzle (0.6mm+ recommended). Matte black finish.

Thermal Properties

HDT @ 0.45 MPa110-130°C
HDT @ 1.8 MPa90-110°C
Service Temp (continuous)110-130°C
Print Temp260-280°C
Bed Temp80-100°C
Chamber (required)60-80°C

Mechanical Properties

Tensile Strength60-90 MPa
Tensile Modulus5-7 GPa (3x unfilled)
Elongation at Break3-5% (brittle)
Flexural Strength100-130 MPa
Flexural Modulus5-8 GPa
Impact Strength7-10 kJ/m²

Other Properties

Density1.15-1.20 g/cm³
Water Absorption (24h)0.5-1.0%
Chemical ResistanceGood
AnisotropyModerate (fiber orientation)
Surface FinishMatte black, visible fibers
AbrasivenessHigh - wear on brass nozzles

Common Applications

  • Structural brackets and mounting hardware
  • Drone frames and UAV components
  • Tooling, jigs, and manufacturing fixtures
  • Automotive under-hood components
  • Robotic arms and mechanical linkages

Design Considerations

  • Hardened nozzle required: Carbon fiber abrasion destroys brass nozzles in hours. Use hardened steel or ruby.
  • Larger nozzle: 0.6mm minimum to avoid clogging. Chopped fibers can jam 0.4mm nozzles.
  • Anisotropy: Strength varies with fiber orientation. Z-axis strength lower than XY.
  • Brittleness: Much less ductile than unfilled nylon. Poor for living hinges or snap-fits.
  • Surface finish: Rough matte finish. Difficult to sand smooth.
  • Cost: 2-3x more than PA6, but excellent stiffness-to-weight ratio.

PA6-GF (Glass Fiber Reinforced Nylon 6)

Composite High Stiffness High-Temp

Overview: PA6 with 15-30% glass fiber reinforcement. Higher stiffness and HDT than PA6-CF, lower cost. More abrasive than carbon fiber. Natural translucent appearance. Excellent for high-temperature structural applications.

Key Properties

HDT @ 1.8 MPa140-160°C
Tensile Strength90-140 MPa
Tensile Modulus6-10 GPa
Elongation at Break2-4%
Print Temperature270-290°C
Chamber Required60-80°C

Applications

  • High-temperature structural parts (up to 150°C)
  • Automotive engine compartment components
  • Industrial equipment housings
  • Electrical enclosures and insulators

Design Notes

  • Extreme abrasiveness: Even more abrasive than carbon fiber. Hardened steel nozzle mandatory.
  • High HDT: Excellent heat resistance - better than PA6-CF.
  • Brittleness: Very brittle. Prone to cracking under impact.
  • Warping: Significant warping. Enclosed chamber essential for large parts.

Engineering Thermoplastics

PC (Polycarbonate)

Impact Resistant High-Temp Transparent

Overview: Engineering thermoplastic known for extreme impact resistance and optical clarity. Excellent heat resistance (HDT ~135°C). Used in safety glasses, bulletproof windows, and automotive. Hygroscopic - requires drying.

Thermal Properties

Glass Transition (Tg)145-150°C
HDT @ 0.45 MPa135-140°C
HDT @ 1.8 MPa128-133°C
Service Temp (continuous)115-130°C
Print Temp270-310°C
Bed Temp100-120°C
Chamber (required)60-80°C

Mechanical Properties

Tensile Strength60-70 MPa
Tensile Modulus2.2-2.4 GPa
Elongation at Break80-150%
Flexural Strength90-100 MPa
Flexural Modulus2.3-2.5 GPa
Impact Strength (Izod)60-80 kJ/m² (extreme!)

Other Properties

Density1.18-1.22 g/cm³
Water Absorption (24h)0.15-0.35%
Chemical ResistanceFair (attacked by alkalis, solvents)
UV ResistanceFair (yellowing over time)
Optical ClarityTransparent (if printed correctly)
Flammability (UL94)HB to V-2

Common Applications

  • Impact-resistant enclosures and housings
  • Safety shields and machine guards
  • Optical prototypes (lenses, light pipes)
  • Automotive interior trim and bezels
  • Electronic device housings (laptops, phones)
  • Medical devices (sterilizable grades)

Design Considerations

  • Drying critical: Absorbs moisture rapidly. Dry 6-8 hours @ 100-110°C. Wet PC bubbles and delaminates.
  • High print temp: 270-310°C required. All-metal hotend mandatory.
  • Warping: Severe warping without heated chamber. Large parts nearly impossible without enclosure.
  • Bed adhesion: Difficult. Use PEI sheet + high bed temp (110-120°C) + glue stick.
  • Clarity: Can achieve transparency with slow speeds, high temps, and careful cooling. Difficult but possible.
  • Chemical sensitivity: Attacked by acetone, alcohols, alkalis. Do not use alcohol for bed prep.

PC-FR (Flame Retardant Polycarbonate)

Impact Resistant Fire Resistant High-Temp

Overview: PC with flame retardant additives. UL94 V-0 rating (self-extinguishing). Required for electrical enclosures and safety-critical applications. Slightly reduced mechanical properties vs. unfilled PC.

Key Properties

HDT @ 1.8 MPa125-135°C
Tensile Strength55-65 MPa
Impact Strength50-70 kJ/m²
FlammabilityUL94 V-0
Print Temperature275-315°C

Applications

  • Electrical enclosures and junction boxes
  • Power supply housings
  • Automotive electrical components
  • Safety-critical housings requiring fire resistance

Design Notes

  • UL94 V-0: Self-extinguishing. Required for many electrical applications.
  • Cost: 2-3x more expensive than standard PC.
  • Same print challenges as PC: Requires drying, high temps, heated chamber.

PETG & ABS Families

PETG (Polyethylene Terephthalate Glycol)

Easy Print Tough Chemical Resistant

Overview: Modified PET with excellent toughness, chemical resistance, and printability. Easier than ABS (no warping), tougher than PLA. Good clarity. Ideal for functional prototypes and consumer products. Hygroscopic but less sensitive than nylon.

Thermal Properties

Glass Transition (Tg)80-85°C
HDT @ 0.45 MPa70-75°C
Service Temp (continuous)60-70°C
Print Temp220-250°C
Bed Temp70-90°C
ChamberNot required (optional)

Mechanical Properties

Tensile Strength50-55 MPa
Tensile Modulus2.0-2.2 GPa
Elongation at Break50-150%
Flexural Strength65-75 MPa
Impact Strength7-10 kJ/m²

Other Properties

Density1.27-1.29 g/cm³
Water Absorption (24h)0.1-0.2%
Chemical ResistanceGood (acids, oils, alcohols)
UV ResistanceFair
Food SafeYes (FDA compliant grades)

Common Applications

  • Functional prototypes and end-use parts
  • Consumer product housings
  • Food containers and packaging (FDA grades)
  • Transparent or translucent parts
  • Mechanical assemblies and brackets

Design Considerations

  • Easy printing: No warping, good bed adhesion, forgiving temperature range.
  • Stringing: Tends to string/ooze. Requires good retraction tuning.
  • Layer adhesion: Excellent - very strong layer bonds.
  • Moisture: Hygroscopic. Dry 4-6 hours @ 65°C if wet (bubbling, stringing).
  • Heat resistance: Limited to ~70°C. Not for high-temp applications.

PETG-CF (Carbon Fiber PETG)

Composite Stiffness Easier Print

Overview: PETG with 10-15% carbon fiber. Increased stiffness, reduced warping vs. unfilled PETG. Easier to print than PA6-CF or ABS-CF (no chamber required). Good dimensional stability. Matte black finish.

Key Properties

HDT @ 1.8 MPa75-85°C
Tensile Strength45-55 MPa
Tensile Modulus4-6 GPa (2-3x PETG)
Elongation at Break2-4%
Print Temperature240-260°C

Applications

  • Stiff structural parts (not high-temp)
  • Jigs and fixtures
  • Drone frames (low-temp environments)
  • Tooling and manufacturing aids

Design Notes

  • Easier than nylon-CF: No chamber required, less warping.
  • Lower HDT: Only good to ~75°C. Not for high-temp applications.
  • Hardened nozzle required: Abrasive. Use hardened steel.

ABS (Acrylonitrile Butadiene Styrene)

Tough Post-Processable Medium-Temp

Overview: Classic engineering thermoplastic. Good toughness, heat resistance, and chemical resistance. Can be acetone vapor smoothed. Difficult to print (warping, odor). Widely used in injection molding - LEGO bricks, automotive trim.

Key Properties

HDT @ 1.8 MPa95-105°C
Service Temp80-95°C
Tensile Strength40-45 MPa
Tensile Modulus2.0-2.5 GPa
Impact Strength15-25 kJ/m²
Print Temperature230-250°C
Chamber Required40-60°C (essential)

Applications

  • Functional prototypes for injection molding
  • Automotive interior components
  • Consumer electronics housings
  • Tooling and jigs (medium-temp)

Design Notes

  • Warping: Severe warping without heated chamber. Large parts very difficult.
  • Odor: Strong smell during printing. Ventilation required.
  • Acetone smoothing: Can be vapor smoothed for glossy finish.
  • Better alternatives: ASA (UV resistant) or PETG (easier) often preferred.

ABS-CF / ABS-GF (Reinforced ABS)

Composite Stiffness

Overview: ABS with carbon or glass fiber reinforcement. Increased stiffness and HDT. Same warping challenges as unfilled ABS. Requires heated chamber and hardened nozzle.

Key Properties

HDT @ 1.8 MPa100-115°C (CF), 105-120°C (GF)
Tensile Modulus4-6 GPa (CF), 5-7 GPa (GF)
Tensile Strength50-70 MPa
Print Temperature250-270°C

Applications

  • Automotive under-hood prototypes
  • Industrial equipment housings
  • High-stiffness jigs and fixtures

Design Notes

  • All ABS challenges + abrasiveness: Difficult material.
  • Better alternatives: PA6-CF or PA6-GF usually preferred (better properties, availability).

ASA (Acrylonitrile Styrene Acrylate)

Tough UV Resistant Outdoor

Overview: UV-resistant version of ABS. Excellent weatherability for outdoor applications. Same mechanical properties as ABS, but doesn't yellow or become brittle in sunlight. Easier to print than ABS (less warping). Premium cost.

Thermal Properties

HDT @ 1.8 MPa95-100°C
Service Temp80-90°C
Print Temp240-260°C
Bed Temp90-110°C
Chamber40-60°C (recommended)

Mechanical Properties

Tensile Strength40-50 MPa
Tensile Modulus2.1-2.3 GPa
Impact Strength20-30 kJ/m²
Elongation at Break15-30%

Other Properties

Density1.05-1.08 g/cm³
UV ResistanceExcellent (no yellowing)
Weather ResistanceExcellent
Chemical ResistanceGood

Common Applications

  • Outdoor enclosures and housings
  • Automotive exterior trim prototypes
  • Garden equipment and outdoor tools
  • Signage and architectural models
  • Marine applications (above waterline)

Design Considerations

  • UV stability: Best choice for outdoor applications. No yellowing or embrittlement.
  • Less warping than ABS: Easier to print, but still benefits from heated chamber.
  • Cost: 1.5-2x more expensive than ABS. Worth it for outdoor use.
  • Acetone smoothing: Can be vapor smoothed like ABS.
  • Color retention: Maintains color in sunlight unlike ABS or PETG.

Quick Material Comparison

Best General Purpose

PA12: Excellent all-around performance, easy to print, good dimensional stability

Highest Stiffness

PA6-GF: 6-10 GPa modulus, best for structural applications

Best Impact Resistance

PC: 60-80 kJ/m² Izod, extreme toughness

Easiest to Print

PETG: No warping, no chamber, forgiving temperatures

Best for Outdoors

ASA: UV resistant, weatherproof, color stable

Best Cost/Performance

PA6: Good properties at lowest cost for nylon family

Material Selection Decision Guide

Need help choosing the right material? Part 3 provides selection matrices, decision trees, and application-specific recommendations.

Continue to Part 3: Selection Matrix

← Back to Part 1: High-Performance Polymers