Polymer coated rollers are used in the CRM / service centers / CTL lines. These rollers are being utilized mainly in areas where chemicals are used in steel processing. The chemicals will corrode the bare metallic barrels & the polymer coating acts as a protective sheath inhibiting corrosion. Certain polymers also provide effective protection against wear. These rollers are generally used in the light gauge lines.
Squeeze (wringer) roller, Bridle roller, Work (pinch) roller, Snubber roller, Guide roller, Idle (Idler) roller, Roller shaft.
The polymer coated rollers are mission critical & the polymers have to be selected suitably (to be able to withstand simultaneously withstand the combination of wear & corrosion) for effective functioning of the equipment. This reduces down time & improves metal strip product quality.
The process chemical, temperature & wear are the key properties to be considered for material selection. The polymer which can withstand the process chemicals at the given temperature are used to coat the barrels of these rollers. The shell is generally fabricated from carbon steel (stainless steel can also be used). The dynamic loading of the roller is used to determine the thickness of the shell / lining.
The shells / bars are ND tested (in proof machined condition) to determine surface / internal defects. The selected polymers are then coated on the barrel & vulcanized. The various test prescribed by the appropriate standards are carried out on a test piece (vulcanized in the same lot / heat as the roller). After completion of testing, the roller barrel is ground. The polymer hardness & TIR readings are measured & recorded, ensuring optimal performance.
After all quality parameters are satisfactorily met, a coat of anti-rust chemical is applied on the bearing journals / ends. The barrel of the roller is wrapped with plastic paper & then with a runner. The rollers are then packed in individual sea-worthy wooden boxes (or as mutually agreed).