Machinery's Handbook, 31st Edition
1322 CYLINDRICAL GRINDING act harder. Allow work to “spark-out.” Decrease feed rate. Use proper number of work rests. Allow proper amount of tarry. Workpiece must be balanced if it is an odd shape. 4) Coolant: Use greater volume of coolant. 5) Wheel: Rebalance wheel on mounting before and after truing. 6) Improper dressing: Use same positions and machine conditions for dressing as in grinding. 7) Spindle bearings: Check clearance. 8) Work: Work must come to machine in reasonably accurate form. Inaccurate Work Sizing (when wheel is fed to same position, it grinds one piece to cor- rect size, another oversize, and still another undersize): Sources of trouble are: 1) im- proper work support or rotation; 2) wheel out of balance; 3) loaded wheel; 4) improper infeed; 5) improper traverse; 6) coolant; 7) misalignment; and 8) work. Suggested procedures for corrections of these troubles are: 1) Improper work support or rotation: Keep work centers clean and lubricated. Regrind work-center tips to proper angle. Be sure footstock spindle is tight. Use sufficient work rests, properly spaced. 2) Wheel out of balance: Balance wheel on mounting before and after truing. 3) Loaded wheel: See Wheel Defects . 4) Improper infeed: Check forward stops of rapid feed and slow feed. When readjusting position of wheel base by means of the fine feed, move the wheel base back after making the adjustment and then bring it forward again to take up backlash and relieve strain in feed-up parts. Check wheel spindle bearings. Don’t let excessive lubrication of wheel base slide cause “floating.” Check and tighten wheel feed mechanism. Check parts for wear. Check pressure in hydraulic system. Set infeed cushion properly. Check to see that pistons are not sticking. 5) Improper traverse: Check traverse hydraulic system and the operating pressure. Pre vent excessive lubrication of carriage ways with resultant “floating” condition. Check to see if carriage traverse piston rods are binding. Carriage rack and driving gear must not bind. Change length of tarry period. 6) Coolant: Use greater volume of clean coolant. 7) Misalignment: Check level and alignment of machine. 8) Work: Workpieces may vary too much in length, permitting uneven center pressure. Uneven Traverse or Infeed of Wheel Head: Sources of uneven traverse or infeed of wheel head are: carriage and wheel head, hydraulic system, interference, unbalanced conditions, and wheel out of balance. Suggested procedures for correction of these troubles are: 1) Carriage and wheel head: Ways may be scored. Be sure to use recommended oil for both lubrication and hydraulic system. Make sure ways are not so smooth that they press out oil film. Check lubrication of ways. Check wheel feed mechanism, traverse gear, and carriage rack clearance. Prevent binding of carriage traverse cylinder rods. 2) Hydraulic systems: Remove air and check pressure of hydraulic oil. Check pistons and valves for oil leakage and for gumminess caused by incorrect oil. Check worn valves or pistons that permit leakage. 3) Interference: Make sure guard strips do not interfere. 4) Unbalanced conditions: Eliminate loose pulleys, unbalanced wheel drive motor, uneven belts, or high spindle keys. 5) Wheel out of balance: Balance wheel on mounting before and after truing. Wheel Defects: When wheel is acting too hard, such defects as glazing, some loading, lack of cut, chatter, and burning of work result.
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