ROTRONIC HUMIDITY FUN FACTS Manufacturing

Tires in general Each and every one of us knows what a tire is: a rubber tube, placed around the wheel of most vehicles that are commercially available today. However, the tire is much more complicated than a simple rubber tube. A tire is composed of many varied layers where the only visible one is the rubber that faces the exte - rior of the tire. The layers consist of; A conventional tire is composed of several carcass plies of , set at opposing the outside rubber with the tread, angles of approximately 100 degrees to each other and 40 degrees to the tire center line. (blue and red). the cap, the steel belts, the body ply, and the inner liner. Each part of the tire has a com - it its elasticity. After the “cure pack - must comply with the following plex manufacturing procedure that age” is added the maximum tem - requirements: 23°C ±3°C and 55%rh involves the monitoring of temper - perature in the process is 110°C. ±8%rh. ature and humidity. Step 2—Fabric and steel cord Step 3—Belt and play calendaring: preparation: The fabric cord and the The rubber compound is pressed Why the need to measure steel cord are used to reinforce the on and into the cords. This process relative humidity? rubber compound and provide is critical as the bonding of fabric to strength to the tire. The fabric is rubber or steel to rubber will relate The manufacturing starts with the hygroscopic and will shrink or to the performance of the . The preparation of the raw materials stretch depending on the level of production area must be controlled for the different layers: rubber relative humidity. Thus the fabric at 22°C ±2°C and a relative humidity bales, chemicals, and steel. cord has to be kept in a temperature below 50%. The relative humidity and tempera - and humidity controlled room. The The steps remaining, inner liner ture measurements are critical in steel cord is brass coated and the calendaring, bead component the first three steps of the produc - metal will expand and contract with preparation, and sidewall tion process. fluctuating temperatures. High lev - extrusion operations, tire tread Step 1—Rubber compound mixing els of relative humidity (above extrusion, tire sidewall extrusion, operation: the rubber bales are 70%rh) will cause corrosion. Addi - tire building, tire curing and tire mixed with fillers and chemicals, tionally, if dust or grime is left to inspection are also key steps in the depending on the required charac - accumulate on the steel, there will development of a perfect tire. How - teristics. After the rubber com - be retention of water vapor which ever, there is a lesser requirement pound is prepared, the compound may induce corrosion even in lower for a temperature and humidity goes through a “cure package” levels of relative humidity. There - controlled environment. where the tire is formed and gives fore, the steel wire forming area

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