Problems in External Grindings: |
INDICATION |
CAUSE |
REMEDY |
CHATTER MARKS :short, close & evenly spaces marks. | Loose wheel spindle bearing. | Tighten or refit bearing. Check axial and radial play. |
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Regularly spaced marks. | General vibration. | check for loose coupings and be sure that motor and spindle are in balance. |
Long regularly speed chatter marks forming checker board pattern. | Wheel out of balance. | Re-balance carefully repeat after dressing. If trouble persists run wheel without coolant to throw off excess of water. |
Wheel out of round. | True before and after balancing: True to face. | |
Chatter marks fairly long wide and evenly spaced at wide intervals and generally discolored : wheel glazed or loaded. | Work centres or work rest 12. | Check fit of centre. |
General | Dressing | use sharp diamond rigidly held close to wheel. |
Scratching of work narrow and deep regular marks. | Wheel too coarse. | Use finer grit. |
Wide regular marks of varying depth. | Wheel too soft. | Use harder grade. |
Widely spaced spots on work. | Oil stoped or glazed area on wheel face. | Balance and true wheel. Avoid getting oil on wheel face |
Fine spiral or thread on work. | Faulty wheel dresser. | Replace cracked or broken diamond : set dresser at correct angle : turn diamond every third dressing : tighten holder of diamond dress with less penetration : do not allow diamond to dwell in contact with wheel : do not start dressing cuts on face , locate tool on face but start cuts from edge : Traverse diamond across face of wheel evenly : round off wheel edges. |
Faulty operation | Prevent penetration of advancing of following edges of wheel by being careful to dress wheel race parallel to work : reduce wheel pressure : provide additional steady rest : reduce traverse in relation to work rotation : when making numerous passes make slight change in traverse rate each pass to break up pattern. | |
Wavy traverse lines.
|
Ragged wheel edges. | Round off wheel edge |
Isolating deep marks. | Coarse grit or foreign matter in wheel face | Dress out |
Spirals on work : Spirals (Traverse lines ) same lead on work as rate of traverse. | Turning | Having turn tool set exactly on work wheel contact line, but pointed down 10 degree round on edge of wheel face. |
Wheel grinding effect, lack of cut, glazing buring of work, chatter. | Wheel too hard in effect. | Increase work and traverse speed , decrease wheel spindle speed and width of wheel face. open up wheel by sharper dressing : increase wheel pressure (infeed) : Use thinner coolant : avoid dwelling at end of traverse : avoid gummy coolants use coarser grit & use coarser softer bond. |
Wheel marks : short wheel life : not holding cuts : tapered work. | Wheel too soft in effect. | Decrease work and traverse speed & wheel pressure (infeed) . Increase spindle sped. wheel diameter and width of wheel face.Dress with slow traverse & slight penetration.Use heavier coolants. Do not pass off work at end of traverse. |
Wheel loading : metal lodged on grains or in wheel porous. | Incorrect wheel | Use coarse grit or more open bond to provide chip clearence : use abrasive that fracture more easily : use more coolant. |
Faulty dressing. | Use sharper dresser : Dress faster : Clean wheel after dressing. | |
Faulty coolant | use more cleaner and thinner coolant. | |
Faulty operations. | Manipulate to soften effect wheel : use less infeed. | |
Wheel glazing : shiny appearance. | Improper wheel | Use coarse grit, softer bond : manipulate wheel to soften effect. |
Improper dressing. | Keep wheel sharp with sharp dresser. Faster traverse . | |
Faulty coolant | use less oil coolant. use more coolant. | |
Faulty operation | use greater infeed | |
Gummy coolant | Increase soda content if water is hard : do not use soluble oils in harder water. |