Auto Coating & Taping Machine

This process is for the encapsulation of the resistor body, application of colour bands for identification of the value and belting/taping of the resistors.

The machine does the following processes. The belted welded resistors are de-taped by a de-taping head and put on a chain conveyer.

The leads of the resistors are then straightened under rollers where it undergoes a multiple torsion where in case of weak weld joints the leads if any breaks and fall off the conveyer. All the resistors are then subjected to an overload of approximately 3 times the rated voltage which results in the burning off of the resistive film which have some discrepancy of film or cut from the prior processes if any. The resistors are pre heated in an oven duct to disperse any surface moisture and then coated with Phenolic Undercoat (PC 1N) for moisture protection. This coat is then cured in an oven duct after which three coats of lacquer are roller coated of different viscosities, cured stage wise to encapsulate the body of the resistors. The encapsulated resistors are then tested online 100% by an accurate resistance deviation bridge for value and those resistors not complying to the limits are weeded out by a solenoid. The tested resistors are then colour coded with stoving inks for marking as per EIA standards and cured to form an indelible marking impervious to solvents to which they may be subjected to during their use. The marked resistors are once again tested for ohmic value and then taped as per EIA Standard Taping Norms.

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