Enameled wires (magnet wires), are copper/aluminum wires coated with a layer of insulation, mainly used in electrical applications, such as transformers, motors, generators, and inductors. The insulation is of great importance for preventing short circuits and ensuring efficient operation. Here’s a guide to the insulation used on enameled wires:
| THERMAL CLASS | INSULATION TYPE | NEMA STANDARD (MW1000) | IEC STANDARD-60317 | FEDERAL SPECIFICATION (JW 1177) |
| 105℃ | Plain Enamel | NONE | NONE | NONE |
| Formvar* | MW15 (RD) MW18 (SQ & RECT) | 60317-1(RD) 60317-17(SQ & RECT) | JW 1177/ 14 (RD) JW1177/ 16 (SQ & RECT) | |
| Formvar Bondable | MW19 | 60317-5 | JW1177/6 | |
| 130℃ | Polyurethane Nylon Bondable – 130 | NONE | NONE | NONE |
| 155℃ | Polyurethane – 155* | MW79 | 60317-20 | JW1177/41 |
| Polyurethane Nylon – 155* | MWB0 | 60317-21 | JW1177/42 | |
| Polyurethane Bondable – 155* | MW131 | 60317-35 | NONE | |
| Polyurethane Nylon Bondable – 155 | MW 136 | NONE | NONE | |
| Dacron Glass – 155 | MW45 (RD) MW46 (SQ & RECT) | NONE(RD) 60317-60(SQ & RECT) | JW 1177/20 (RD) JW1177/25 (SQ & RECT) | |
| 180℃ | Polyurethane – 180• | MW82 | 60317-51 | NONE |
| Polyurethane Nylon – 180* | MW83 | 60317-55 | NONE | |
| Polyester-imide• | MW30 | 60317-8 | JW1177/ 12 | |
| Polyester-Nylon* | MW76 | 60317-22 | JW1177/38 | |
| Solderable Polyester* | MW77 | 60317-23 | JW1177/39 | |
| Solderable Polyester Nylon• | MW78 | NONE | JW1177/40 | |
| Polyurethane Bondable – 180 | MW132 | NONE | NONE | |
| Polyurethane Nylon Bondable – 180 | MW137 | NONE | NONE | |
| Polyester-imide Bondable | NONE | 60317-37 | NONE | |
| Polyester-amide-imide Bondable* | MW 102 | 60317-38 | NONE | |
| Solderable Polyester Bondable | NONE | 60317-36 | NONE | |
| Dacron Glass High Temp | MW51 (RD) MW53 (SQ & RECT) | NONE(RD) 60317-61(SQ & RECT) | JW 1177/ 32 (RD) JW1177/ 34 (SQ & RECT) | |
| 200℃ | Polyester – 200• | MW74 | 60317-42 | JW1177/43 |
| Polyester A/I Topcoat” | MW35 (RD) MW36 (SQ & RECT) | 60317-13(RD) 60317-29(SQ & RECT) | JW 1177/ 14 (RD) JW1177/ 13 (SQ & RECT) | |
| PolyesterA/I Polyamideimide• | MW73 | 60317-13 | NONE | |
| 240℃ | Polyimide – ML* | MW16 (RD) MW20 (SQ & RECT) | 60317-46(RD) 60317-47(SQ & RECT) | JW 1177115 (RD) JW1177/ 18 (SQ & RECT) |
| THERMAL CLASS | INSULATION CHARACTERISTICS | GENERAL APPLICATIONS |
| 105℃ | Plain Enamel was one of the earliest film insulations developed for automotive ignition coils. Today it is primarily used in musical instruments for pickup coils. It is manufactured to single build dimensions and stocked in sizes 41 to 44 gauge | Pickup coils for guitars and other instruments |
| Formvar was anearly synthetic insulation composed of modified polyvinyl resins designed for continuous operation at 105C. It has excellent abrasion resistance and is compatible with most varnishes and impregnating compounds. | Oil filled transformers, motors, solenoids, superconducting coils or other cryogenic applications | |
| Formvar with a superimposed thermoplastic film for use in heat or solvent activated selfbonding coils. | Relays, yoke coils, self-supporting coils | |
| 130℃ | Class 130°C solderable polyurethane with superimposed thermoplastic polyvinyl butyral film for heat or solvent activated self-bonding coils with excellent bond strength at room temperature. | Voice coils, yoke coils, self-supporting coils |
| 155℃ | Solderable film composed of modified polyurethane resins designed mostly for fine wire applications with excellent resistance to moisture and most solvents. | Relays, high frequency coils and transformers, solenoids, small motors |
| Solderable dual film composed of modified polyurethane resins with a polyamide (nylon) overcoat that provides improvement in severe winding operations. | Appliance motors, relays, torroidal coils, fractional HP motors | |
| Solderable polyurethane or polyurethane with nylon overcoat and a superimposed thermoplastic butyral film for coils requiring Class F service. Coils may be bonded by heat or with denatured alcohol. Generally made as Type 1insulation build equal to heavy overall diameter. | Voice coils, helical coils, inductors, self-supporting coils | |
| Dacron Glass is a combination of glass and polyester fibers applied as a served filament over bare or film coated magnet wire and maybe supplied with an epoxy varnish or as fused unvarnished to prevent fraying of the fibers. | Dry transformers, Class B motors | |
| 180℃ | Polyurethane film designed for applications requiring high thermal resistance and low soldering temperature. | Relays, ignition coils, solenoids, small transformers |
| Polyurethane with polyamide (nylon) overcoat for applications requiring high thermal properties and chemical resistance. Soldering temperatures 430°C (14-23AWG) or 390°C (24AWG and finer). | Relays, pulse transformers, small appliance motors | |
| Film insulation composed of modified polyester resins with excellent chemical resistance. | Solenoids, servo motors, small appliance motors | |
| Dual film composed of modified polyester resins with a nylon overcoat. Combines continuous 1B0’C operating temperature and low coefficient of friction for superior winding and insertion properties. | Motor stators, fractional HP motors | |
| Film insulation composed of modified polyesterimide resins designed to solder at 470°C, generally made at 24 AWG and finer sizes. | High temperature relays, transformers, automotive coils | |
| Dual film composed of modified polyesterimide resins with nylon overcoat for superior pertormance where winding stresses maybe severe. Designed to solder at 470°C, this insulation is made mostly in heavier gauge sizes. | Transformers, automotive coils, appliance motors | |
| One part (Polyurethane) or dual (Polyurethane Nylon) insulation system with superimposed thermoplastic film combining high thermal resistance, solderability, and self-bonding features. | Self-supporting coils, relays, voice coils | |
| These are wires that combine characteristics of various class 180°C film insulations with self-bonding feature. Bonding method depends on choice of bond coat. May be made as Type 1(heavy diameter) or Type 2(triple diameter) construction. | Voice coils, inductors, yoke coils, small motors | |
| Like Dacron Glass 155except treated with high temperature organic varnish. May be served over bare or film coated magnet wire. Available only in shaped or heavy round wire sizes. | Large generators and alternators, dry type transformers | |
| 200℃ | One part film system composed of THEIC modified polyester resins capable of continuous 200°C operating temperature designed specifically for finer size wires. | Coils, relays, small transformers, small appliance motors |
| A dual film insulation of polyester-amide-imide with polyamideimide (A/I) overcoat for superior windability, heat shock resistance, solvent resistance, and overload protection. | General purpose motors, fractional and integral motors (hermetic and open), dry type transformers | |
| A triple film system composed of THEIC modified polyester, a corona resistant shield coat, and polyamideimide (A/I) overcoat designed to withstand severe voltage stresses. Made as heavy build construction in round sizes 12through 24AWG. | Inverter duty motors, high voltage motors | |
| 240℃ | Film composed of aromatic polyimide resin that features high cut through, exceptional chemical resistance, minimal outgassing and capable of continuous operation at 240° C in extremely harsh environments. | High temperature continuous duty coils, hermetically sealed relays, fractional and integral HP motors |
