C5 Class Coatings

C-5 coatings provide excellent surface resistivity both before and after stress relief annealing (SRA ). Customer does the SRA after slitting. Presence of organic part ensures improved punch and die life during stamping operations. During annealing the organic component of the coating volatilizes but inorganic part remains to provide an adherent film with a high level of surface resistivity. Correct blend of organic and inorganic avoids yield losses and gives better performance. No significant flaking occurs at the punched edges of laminations. Used for refrigerator motors, small to large sized motors and transformers, large turbogenerators . Also useful where high temperature resistance and weldability are required. Withstands stress relief annealing and other high temperature treatment.

Product Description

FILAMAR ESV U356 is a chrome free C-5 class (ASTM 976) insulation varnish, made up largely of inorganic phosphates in organic polymer complexes designed to provide superior electrical insulation properties along with good weldability, punchability, adhesion and superior stability post stress relieving annealing treatment.

Application Range

  • The product is suitable for coating thickness of 1-3 microns.

  • It is suited for applications in high line speed coating systems.

  • It is well suited for aluminum casting, welding and annealing with good adhesion of the annealed layer at coating thickness lower than 2.5 microns.

  • Chemical reactions of the phosphate groups with steel surface ensure excellent insulation values at small coating thickness.

  • Non-chrome nature, low thickness, high IR, superior punchability & weldability distinguish FILAMAR ESV U356 from other C-5 coatings.

Processing

FILAMAR ESV U356 is hot curing. Optimum curing temperature depends upon the dwell time in the furnace and must be determined for each oven separately. 

For FILAMAR ESV U356, cure pattern is a strip temperature (PMT) of 350 °C for dwell time of 30 seconds inside the curing furnace. This can however, be altered as per customer demands.

Coating Properties

Following properties are for a typical 2 micron coating thickness.

FILAMAR ESV U356 (C-5)
Sr. No. DESCRIPTION TYPICAL PROPERTIES
1 Coating Appearance Grey
2 Insulation Resistance (For 1-3 microns lamination) 30-200 Ohm.cm2/lam
3 Punchability 2-3 times Bright Steel
4 Weldability Good
5 Stress Relieving Annealing (SRA) 815°C



Product Description

FILAMAR ESV ITK/OTK is a two component, chrome based coating, C-5 class (ASTM 976) and withstands SRA (Stress Relieving Annealing) treatment at 815°C. It is typically a combination of chromate and inorganic pigments (ITK) along with acrylic resin (OTK).

Application Range

  • FILAMAR ESV ITK/OTK is suitable for coating thickness of 1.0-1.5 microns.

  • It is designed for applications in both high as well as low line speed coating systems.

  • Due to very good adhesion of the annealed layer at low coating thickness, FILAMAR ESV ITK/OTK is well suited for aluminum casting, welding and annealing. 

Processing

FILAMAR ESV ITK/OTK is hot curing. Optimum curing temperature depends upon the dwell time in the furnace and must be determined for each oven separately. 

For FILAMAR ESV ITK/OTK, cure pattern is a strip temperature (PMT) of 350 °C for dwell time of 20 sec. inside the curing furnace. This can however, be altered as per customer demands.

Coating Properties

Following properties are for a typical 1 micron coating thickness.

FILAMAR ESV ITK/OTK (C-5)
Sr. No. DESCRIPTION TYPICAL PROPERTIES
1 Coating Appearance Greenish
2 Insulation Resistance (For 1 micron lamination) >8 Ohm.cm2/lam
3 Punchability 2-3 times Bright Steel
4 Weldability Good, Non-Porous
5 Stress Relieving Annealing (SRA) 815°C


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