Machinery's Handbook, 31st Edition
CYLINDRICAL GRINDING 1321 Isolated Deep Marks on Work: Source of trouble is an unsuitable wheel. Use a finer wheel and consider a change in abrasive type. Fine Spiral or Thread on Work: Sources of this trouble are: 1) improper operation; and 2) faulty wheel dressing. Suggested procedures for corrections of these troubles are: 1) Improper operation: Reduce wheel pressure. Use more work rests. Reduce traverse with respect to work rotation. Use different traverse rates to break up pattern when making numerous passes. Prevent edge of wheel from penetrating by dressing wheel face parallel to work. 2) Faulty wheel dressing: Use slower or more even dressing traverse. Set dressing tool at least 3 degrees down and 30 degrees to the side from time to time. Tighten holder. Don’t take too deep a cut. Round off wheel edges. Start dressing cut from wheel edge. Narrow and Deep Regular Marks on Work: Source of trouble is that the wheel is too coarse. Use finer grain size. Wide, Irregular Marks of Varying Depth on Work: Source of trouble is too soft a wheel. Use a harder grade wheel. See Wheel Defects . Widely Spaced Spots on Work: Sources of trouble are oil spots or glazed areas on wheel face. Balance and true wheel. Keep oil from wheel face. Irregular “Fish-tail” Marks of Various Lengths and Widths on Work: Source of trouble is dirty coolant. Clean tank frequently. Use filter for fine finish grinding. Flush wheel guards after dressing or when changing to finer wheel. Wavy Traverse Lines on Work: Source of trouble is wheel edges. Round off. Check for loose thrust on spindle and correct if necessary. Irregular Marks on Work: Cause is loose dirt. Keep machine clean. Deep, Irregular Marks on Work: Source of trouble is loose wheel flanges. Tighten and make sure blotters are used. Isolated Deep Marks on Work: Sources of trouble are: 1) grains pull out; 2) coolant too strong; coarse grains or foreign matter in wheel face; and 3) improper dressing. Respective suggested procedures for corrections of these troubles are: 1) decrease soda content in coolant mixture; 2) dress wheel; and 3) use sharper dressing tool. Brush wheel after dressing with stiff bristle brush. Grain Marks on Work: Sources of trouble are: 1) improper finishing cut; 2) grain sizes of roughing and finishing wheels differ too much; 3) dressing too coarse; and 4) wheel too coarse or too soft. Respective suggested procedures for corrections of these troubles are: start with high work and traverse speeds; finish with high work speed and slow traverse, letting wheel “spark-out” completely; finish out better with roughing wheel or use finer roughing wheel; use shallower and slower cut; and use finer grain size or harder-grade wheel. Inaccuracies in Work: Work out-of-round, out-of-parallel, or tapered. Sources of trouble are: 1) misalignment of machine parts; 2) work centers; 3) improper operation; 4) coolant; 5) wheel; 6) improper dressing; 7) spindle bearings; and 8) work. Suggested procedures for corrections of these troubles are: 1) Misalignment of machine parts: Check headstock and tailstock for alignment and proper clamping. 2) Work centers: Centers in work must be deep enough to clear center point. Keep work centers clean and lubricated. Check play of footstock spindle and see that footstock spindle is clean and tightly seated. Regrind work centers if worn. Work centers must fit taper of work-center holes. Footstock must be checked for proper tension. 3) Improper operation: Don’t let wheel traverse beyond end of work. Decrease wheel pressure so work won’t spring. Use harder wheel or change speeds and feeds to make wheel
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