Resin bonded abrasive discs are subject to increased breakdown as the temperature goes up. A rule-of-thumb states that the rate of a chemical reaction doubles for each 18 degrees (F) increase in temperature. If the temperature goes up twice that amount (36 degrees) the rate of breakdown is 2 x 2 or about four times as great. A good example is the cooking temperature inside a pressure cooker that is about 36 degrees higher than in an open pan. Food cooks in roughly one-fourth the usual time at this increased temperature.
The Anchor Bulletin on Coolant Temperature recommends an operating limit of no more than 15 degrees above room temperature. If your coolant temperature increases above this limit by 18 degrees, your disc life could be cut in half. If the temperature is 36 degrees above the recommended limit, your disc life could be cut by three fourths.
Temperature is not the only factor in controlling disc life. Coolant with a high pH can also decrease the life of a disc.