A practical comparison page for engineering plastics used in motor insulation systems, bobbins, slot liners, terminal holders, connector housings, sensor carriers, fan parts, brackets, encapsulation structures and molded magnetic components.
Plastic material selection for motors should consider temperature class, dielectric strength, flame rating, dimensional stability, moisture absorption, chemical resistance, creep, vibration, molding flow and compatibility with copper, magnets, steel laminations and potting compounds.
Motor plastics are selected by electrical, thermal, mechanical and process requirements. A material that molds well may not meet high-temperature insulation needs, while a high-performance plastic may be unnecessary for cost-sensitive housings.
Widely used engineering plastic family for molded motor parts that need strength, toughness and cost balance.
Common for electrical insulation and connector components where dimensional stability and dielectric properties matter.
High-temperature engineering plastic with good chemical resistance and dimensional stability.
Thin-wall, high-flow, high-temperature plastic for precision electrical and miniature motor components.
Premium high-performance plastics for severe temperature, wear, chemical and reliability requirements.
Resins and compounds used to protect coils, electronics and magnetic assemblies against heat, vibration and moisture.
Use this table for early-stage material screening. Actual values depend on grade, filler content, flame-retardant package, processing condition, moisture state and supplier datasheet.
| Plastic Type | Typical Grades / Family | Temperature Direction | Electrical / Insulation Behavior | Mechanical Direction | Typical Motor Use | Key Risk |
|---|---|---|---|---|---|---|
| PA6 / PA66 | Nylon, glass-filled nylon, flame-retardant nylon | Medium to good, grade dependent | Good insulation, moisture affects properties | Good toughness and strength | Bobbins, fan blades, brackets, holders, molded supports | Moisture absorption, dimensional change, hydrolysis risk |
| PA46 / High-Temp Nylon | PA46-GF, heat-stabilized nylon | Better high-temperature capability than PA66 | Good insulation with proper grade | Good strength retention | Hot coil formers, terminal holders, compact motor parts | Cost, moisture, molding control |
| PBT / PET | PBT-GF, PET-GF, FR PBT | Medium to good | Good dielectric properties and low moisture uptake | Good stiffness and dimensional stability | Connectors, sensor carriers, terminal blocks, insulation parts | Impact sensitivity, hydrolysis in harsh environments |
| PPS | PPS-GF, mineral-filled PPS | High | Good electrical insulation and chemical resistance | Good stiffness, stable dimensions | High-temperature bobbins, compact motor insulation, holders | Brittleness, cost, tooling and molding temperature |
| LCP | Liquid crystal polymer, glass-filled LCP | High | Excellent for thin-wall precision electrical parts | High stiffness, low warpage | Micro connectors, thin-wall coil formers, precision terminal carriers | Anisotropy, weld line strength, high material cost |
| PEEK | PEEK, glass-filled PEEK, carbon-filled PEEK | Very high | Excellent insulation and chemical resistance | High strength and wear resistance | Extreme-temperature motor parts, wear components, special insulators | Very high cost, processing temperature, over-specification risk |
| PC / ABS / PC Blend | PC, PC/ABS, flame-retardant PC | Medium | Good insulation for housings and covers | Good impact resistance | Covers, housings, electronic enclosures, non-hot structures | Heat limit, chemical cracking, flame rating selection |
| POM | Acetal, POM-H, POM-C | Medium | Insulating but not usually for high-temperature coil areas | Low friction and good wear | Gears, bushings, sliding parts, small mechanical components | Flame behavior, bonding difficulty, thermal limit |
| Potting / Encapsulation Resin | Epoxy, polyurethane, silicone | Grade dependent | Electrical insulation and environmental protection | Depends on hardness and filler | Coil potting, stator encapsulation, electronics protection | Voids, cracking, thermal expansion mismatch, rework difficulty |
This matrix connects plastic choice with electrical insulation, heat exposure, molding process and mechanical load.
| Motor Part | Recommended Plastic Direction | Design Driver | Common Process | Inspection Focus |
|---|---|---|---|---|
| Coil Bobbin / Former | PA66-GF, PBT-GF, PPS, LCP for thin-wall high-temp designs | Insulation, heat, winding force, slot fit | Injection molding, terminal insert molding, winding assembly | CTI, dielectric strength, wall thickness, warpage, terminal position |
| Slot Liner / Insulation Film | PET, PEN, PI film, aramid paper composites | Thermal class, dielectric strength, slot fill | Film cutting, forming, insertion, impregnation | Thickness, breakdown voltage, edge damage, fit and creepage distance |
| Terminal Holder / Connector | PBT, PA66, PPS, LCP, flame-retardant grades | Contact retention, tracking resistance, heat and flame rating | Injection molding, insert molding, plating-compatible assembly | Terminal position, pull force, CTI, UL rating, moisture sensitivity |
| Sensor Carrier | PBT, PPS, LCP, PA66-GF | Dimensional accuracy, magnet gap, thermal drift | Precision molding, insert molding, adhesive bonding | Flatness, position tolerance, warpage, thermal cycling |
| Fan / Impeller | PA6-GF, PA66-GF, PBT-GF, reinforced PP for lower demand | Strength, balance, fatigue, temperature | Injection molding, dynamic balancing, trimming | Runout, balance, blade deformation, impact, aging |
| Encapsulated Stator | Epoxy, thermally conductive resin, PPS/PA overmolding | Thermal transfer, insulation, sealing, vibration resistance | Potting, vacuum casting, overmolding, curing | Voids, adhesion, thermal conductivity, cracks, insulation test |
| Gears / Sliding Parts | POM, PA, PEEK for high demand | Wear, friction, noise, dimensional stability | Injection molding, machining, lubrication selection | Tooth accuracy, wear, creep, noise, temperature limit |
Plastic selection should be linked with temperature class, electrical safety, molding design, moisture conditioning, assembly method and validation testing.
Confirm whether the part is insulating, structural, hot-zone, moving, sealed, overmolded or exposed to chemicals.
Compare temperature rating, CTI, dielectric strength, flame rating, moisture absorption, strength and cost.
Define injection molding, insert molding, overmolding, potting, curing, drying and post-treatment requirements.
Check dimensions, insulation, warpage, aging, thermal cycling, flame rating and assembly fit before release.
Match material rating with winding temperature, hot spot location, ambient condition and safety margin.
Check dielectric strength, CTI, creepage, clearance, flame rating and insulation coordination.
Nylon and some resins change properties with moisture and aging; define conditioning and validation state.
Control shrinkage, warpage, weld lines, glass fiber orientation, terminal position and thin-wall filling.
Check compatibility with copper, magnets, adhesives, varnish, potting resin, oil, coolant and cleaning agents.
Use thermal cycling, humidity, vibration, dielectric test, pull test and aging tests for critical motor plastics.
PA66-GF and PBT-GF are common for many motor bobbins. PPS or LCP may be selected for higher temperature, thinner wall or tighter dimensional stability requirements.
Moisture changes nylon dimensions, stiffness, strength and electrical properties. For precision or insulation-critical parts, conditioning state and humidity exposure should be considered.
PPS and LCP are useful in compact, hot, thin-wall or precision electrical parts where PA or PBT may not provide enough temperature resistance or dimensional stability.
Check temperature rating, flame rating, CTI, dielectric strength, moisture behavior, shrinkage, mold flow, mechanical load, chemical exposure, cost and supplier availability.