| Polyurethane enamel (solderable grades) | Commonly 155 or 180 | Suitable for many dry, indoor applications. Resistance to solvents, refrigerants, moisture, and chemicals varies by grade. | Thin coating supports compact winding and good flexibility. Avoid assuming high abrasion or scrape resistance without checking the product specification. | Small transformers, relays, coils, and compact motors where solderability is useful. | Confirm solder-bath conditions and compatibility with the winding varnish, impregnation resin, or operating fluid. |
| Polyester enamel | Commonly 155; some systems are rated 180 | Often used in general-purpose electrical equipment. Chemical, moisture, and thermal endurance depend on the exact formulation and insulation system. | Typically offers a useful balance of flexibility and film toughness for routine winding processes. | General-purpose transformers, motors, and coils operating within the specified thermal limits. | Check the full insulation-system rating, not just the enamel name, especially for impregnated or enclosed equipment. |
| Polyesterimide enamel | Commonly 180 | Often selected for higher-temperature service than standard polyester. Resistance to chemicals and operating fluids is grade-dependent. | Provides a durable coating for many production winding processes; minimum bend radius and abrasion performance should be verified. | Motors, transformers, and coils with elevated operating temperatures. | Compare the wire’s thermal rating with the expected hot-spot temperature and the equipment’s insulation-system requirements. |
| Polyesterimide base coat with polyamide-imide overcoat | Commonly 200 | Often used in demanding thermal environments. The overcoat can improve resistance to some solvents and oils, but compatibility must be confirmed. | Generally offers improved abrasion and cut-through resistance compared with many single-coat constructions; winding tension and tooling still matter. | Higher-temperature motors, generators, and transformers subject to more demanding winding conditions. | Check chemical exposure, overcoat thickness, winding speed, and the applicable thermal-class specification. |
| Polyimide enamel | Commonly 220 or higher, depending on the qualified system | Can suit high-temperature applications. Moisture, hydrolysis, chemicals, and long-term service limits depend on the specific wire and equipment design. | High-temperature performance does not automatically mean easy winding; flexibility, bend limits, and handling requirements should be reviewed. | Specialty coils and electrical equipment designed for very high operating temperatures. | Confirm qualification, processing limits, repair method, and compatibility with nearby insulation materials. |
| Bondable magnet wire (bonding overcoat on a specified base insulation) | Varies by base insulation and bonding system | Environmental capability is determined by the complete wire construction and the bonding material. | Designed to form a bonded winding under specified heat, solvent, or other activation conditions; bonding strength depends on process control. | Self-supporting coils and windings where reducing separate mechanical supports is beneficial. | Verify activation conditions, bond strength, winding geometry, and the final assembly’s thermal and environmental ratings. |
| Important: Thermal classes shown are common examples, not universal ratings. Classification and test requirements vary by wire construction and applicable standards, such as IEC 60317 or NEMA MW 100. Select wire using the manufacturer’s certified specification and the complete equipment insulation-system rating. Consider actual hot-spot temperature, voltage, conductor size, winding process, chemicals, moisture, vibration, and abrasion. |