It is known that heat checking occurs when grinding with a spindle speed of 6000 rpm, a wheel diameter of 250 mm, and a depth of cut of 0.0375 mm for a feed rate of 0.25 m/s. for this reason, the spindle speed should be kept at 4500 rpm. if a new, 200-mm- diameter wheel is used, what spindle speed can be employed before heat checking occurs? what spindle speed should be used to keep the same grinding temperatures as those encountered with the existing operating conditions?