Magnet Wire Insulation Guide
Thermal Class Insulation Type NEMA Standard (MW1000) Federal Specification (JW1177) Insulation Characteristics
Plain Enamel, known as oleoresinous enamel, was one of the first film
Plain Enamel NONE NONE insulations developed more than 75 years ago and is still in use today in a
variety of electronic components. Plain Enamel wires are manufactured to
single‐build dimensional standards. Available in 40‐44 AWG.
Formvar Enamel is made from vinyl acetal resins produced as a smooth
Formvar MW 15 (RD), MW 18 (SQ/RECT) JW1177/4 (RD), JW1177/16 (SQ/RECT) uniform film. Formvar has excellent mechanical properties such as abrasion
resistance and flexibility.
105C
Bondable magnet wire is insulated copper wire with a superimposed film of
Polyurethane Bondable MW 3 JW1177/44
thermoplastic bonding material. The bonding material is activated by heat
or a solvent making it possible to wind coils in tight and unusual shapes
Formvar Bondable MW 19 JW1177/6 since the wire may be bonded turn‐to‐turn as it is being wound.
Polyurethane Nylon Bondable MW 29 JW1177/30
Polyurethane‐155 is a 155°C thermal class solder strippable insulation
Polyurethane‐155 MW 79 JW1177/41 produced primarily 30 AWG and finer with quick soldering characteristics
at 390C
155C Polyurethane Nylon‐155 is similar to the 155°C Polyurethane with an
Polyurethane Nylon‐155 MW 80 JW1177/42 additional Nylon overcoat to improve the abrasion resistance and heat
shock characteristics for coil and motor windings
Polyurethane‐180 combines the thermal properties of a class 180°C
Polyurethane‐180 MW 82 NONE
insulation, while offering low temperature solderability at 390 C.
Polyurethane Nylon‐180 offers excellent abrasion resistance for ferrite core
Polyurethane Nylon‐180 MW 83 NONE coils and transformers, while exhibiting high temperature thermal stress
and low temperature solderability at 430C
Polyester‐imide magnet wire is insulated with a Class H modified polyester
Polyester‐imide MW 30 JW1177/12 resin. It has excellent thermal endurance, solvent resistance and exhibits a
low coefficient of friction to improve windability.
Polyester Nylon is a film insulation with a modified polyester basecoat and
Polyester Nylon MW 76 JW1177/38 a nylon topcoat. Typical of a dual coat construction, advantage is taken of
the high thermal properties of the polyester and the mechanical properties
180C of the nylon
Solderable Polyester magnet wire is an ester‐imide insulated wire which
Solderable Polyester MW 77 JW1177/39
solders at 470°C.
Solderable Polyester‐Nylon magnet wire is a two‐part insulation system in
Solderable Polyester Nylon MW 78 JW1177/40 which ester‐imide basecoat is overcoated with nylon. This wire solders at
455C.
Polyester‐imide Bondable NONE NONE Self‐bonding polyester actually describes a number of possible
constructions of polyester base insulation with a thermoplastic bond coat.
Polyester‐amide‐imide Bondable NONE NONE The bond coat is heat or solvent activated.
Solderable Polyester Bondable NONE NONE
Both glass and Dacron glass are a served filament on the magnet wire
conductor. They are available as unvarnished or varnished with organic or
silicone varnishes. The fibers may be served over bare conductor or over
Glass Fibers MW 44 (RD), MW 43 (SQ/RECT) JW1177/21 (RD)
film constructions. The glass is a continuous filament glass yarn and the
Dacron glass is a combination of glass and polyester fibers. Glass offers
high resistance to overload burnout and Dacron offers excellent abrasion
resistance and flexibility.
Dacron Glass (DDG) MW 45 (RD), MW 46 (SQ/RECT) JW1177/20 (RD),JW1177/25(SQ/RECT)
Polyester‐200 is a modified theic‐polyesterimide one‐part system. It has
Polyester‐200 MW 74 JW1177/43
200C high temperature thermal properties and good chemical resistance.
Polyester‐amide‐imide magnet wire is a two‐part insulation consisting of a
modified polyester basecoat with a superimposed amide‐imide outer
Polyester‐Amide‐Imide MW 35 (RD), MW 36 (SQ/RECT) JW1177/14(RD),JW1177/13(SQ/RECT) coating. The wire exhibits exceptional windability, heat shock resistance
and ability to withstand overloads. Excellent chemical resistance to most
solvents and insulating varnishes.
Teflon has high heat resistance and excellent resistance to most solvents,
Polytetrafluoroethylene (Teflon) NONE NONE
acids and corrosive chemicals and a high dielectric constant.
ML is a film insulation made of polyimide resins. It is a Class 240 C thermal
rated insulation with exceptional resistance to chemical solvents and
burnout. The wire ability to withstand excessive overloads extends the use
240C Polyimide‐ML MW 16 (RD), MW 20 (SQ/RECT) JW1177/15(RD),JW1177/18(SQ/RECT)
of the magnet wire in extreme conditions. MS is unaffected by prolonged
exposure to varnish solvents.
NOTE: For reference only. Wire manufacturer specifications may vary.
