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      No. Troubles Possible Causes Remedies

      Remedies for Troubles of Hydraulic System

      1 Oil does not
      enter into
      the pump
      • Inversion of the motor
      • Reverse the terminals

      • No oil in the oil pump
      • Remove the oil-pipe and add oil into the pump

      • Oil level is too low in the tank
      • Add oil into the tank

      • Oil filter is blocked
      • Clean the oil filter

      • Oil pump is damaged
      • Replace the oil pump

      2 Oil pressure is insufficient
      • Over-flow valve is jammed
      • Repair the valve

      • Oil pump is seriously worn
      • Replace the oil pump

      • Oil plug falls down
      • Fix the oil plug

      3 Creep of worktable
      • There is air in hydraulic system
      • Exhaust air

      • Air leakage in oil supply system
      • Seal the air leakage point

      • Guideway contact is not good
      • Rescrape the guideway

      • Lubrication of the guideway is insufficient
      • Strengthen the lubrication of the guideway

      • Centers of the hydraulic cylinder and guideway are  unparalleled
      • Readjust

      • Guideway oil is not qualified
      • Replace the oil

      4 Dwell time is
      not stable
      • Throttle valve for dwelling is blocked
      • Clean the throttle valve

      • Dwell time is set too long
      • Reset

      5 Worktable does
      not reverse
      • Speed of worktable is too low
      • Adjust the speed

      • Stop-nut of the pilot valve is maladjusted
      • Readjust

      • Rod of reverse valve is stuck or rusty
      • Clean the rod

      • Gap of pilot valve is too large
      • Replace the pilot valve

      6 Noise and vibration
      in the system
      • Air remained in the system
      • Exhaust air

      • Oil pump or the clutch is damaged
      • Replace

      7 Function of automatic recycle fails to work
      • Electrical system or solenoid does not work well
      • Check the system depending on the diagram

      8 Periodic feed
      is incorrect
      • Air is remained in the oil-pine
      • Exhaust air

      Note: No.7 and No.8 are only suitable for semi-automatic model.

      Remedies for Grinding Defects
      No. Grinding Defects Possible Causes Remedies

      1. Straight waves on the surface of workpiece
      • Vibration comes from outside of the machine
      • Eliminate or isolate the vibration

      • Clearance of the spindle is too large
      • Readjust the clearance

      • Grinding wheel is not balanced
      • Rebalance the wheel

      • Grinding wheel is too hard
      • Replace a softer one

      • Grinding is blunt
      • Redress the wheel

      • Workpiece is supported loosely between centers
      • Adjust the tailstock

      • Do not use center rest for thin and long workpiece, or the support force of the center rest is not enough
      • Mount or readjust the center rest

      • The center holes of workpiece do not contact well with the centers
      • Redress the holes or the centers

      • Cross feed is to large
      • Readjust

      • Rotary speed of the workpiece is too high
      • Readjust

      2. Spiral line on the surface of workpiece
      • Due to the large clearance, the spindle is forced to displace and only half area of the wheel is in working
      • Readjust the clearance

      • Due to the thermal deformations of the grinding carriage and headstock, only one side of the grinding wheel is in working
      • Operate the machine when the temperature is stable

      • The out-of-straight of the feeding guideway makes the grinding position inconsonant with the dressed position, so only half area of the wheel is in working 
      • Make the two positions conform with each other as much as possible

      • Rigidity of headstock and tailstock is not enough
      • Find out the reason of weak rigidity and eliminate it

      • Generatrix of the grinding wheel is not straight after dressing
      • Readjust

      • Speed of worktable is too high
      • Appropriately adjust it

      3. Workpiece is convex
      • The workpiece bent over to the feeding direction
      • Mount a center rest

      • Supporting force of the center rest is not enough, or do not adjust the rest when the workpiece becomes smaller
      • Readjust the center rest

      • Grinding wheel feeds too much, or the dwell time is too long at both ends of workpiece
      • Readjust

      • Original accuracy of longitudinal guideway is lost
      • Rescrape the guideway

      4. Workpiece is concave
      • Supporting force of center rest is too much
      • Readjust the center rest

      • Grinding time for the middle part is longer than that of two ends
      • Decrease the grinding time at two ends

      • Original accuracy of longitudinal guideway is lost
      • Rescrape the guideway

      5. Inner hole of workpiece is horn-shaped
      • The grinding wheel is too harder or too fine
      • Replace with the softer or rougher wheel

      • The amount of feed is not proper or the the dwell is occurred at one end of workpiece
      • Readjust the feed amount

      6. Generatrix of taper hole is not straight after grinding
      • Equal-height difference between centers of workpiece and grinding wheel is too much
      • Readjust the machine bed or replace with a smaller wheel

      • Original accuracy of longitudinal guideway is lost
      • Rescrape the guideway

      7. Scratches on the surface of  workpiece
      • Coolant liquid is not clear
      • Replace the coolant  liquid and filter it finely

      • Grains fall down on the workpiece
      • Increase the liquid flow when dressing the wheel

      8. Burnt marks or cracks on the surface of workpiece
      • Grinding wheel is too hard
      • Replace with a softer one

      • Feeding amount is too much
      • Decrease the feeding amount

      • Grinding wheel is not dressed well or becomes blunt
      • Redress the grinding wheel

      • Coolant liquid is not supplied sufficiently
      • Increase the coolant liquid

      9. Surface of workpiece is rough and in fish-scale shape
      • Grinding wheel is not dressed well or becomes blunt, or the surface of wheel is dirty
      • Redress or clean the wheel

      • The hardness of wheel is not even
      • Dress the uneven layer or replace with a new one

      • The wheel is not dressed well due to the unshaped diamond or the shaking of diamond when dressing
      • Sharpen the diamond or eliminate the shaking

      10. Roundness of the cylindrical surface is bad
      • Center hole of workpiece or centers are not round, or they do not match well, or the contact area is dirty
      • Reshape the center holes or clean the centers or replace with new centers

      • Workpiece is not balanced
      • Balance the workpiece

      • Original accuracy of bearing bore of headstock or center sleeve bore of tailstock is lost
      • Check and repair, or replace with new ones
      Maintenance of the Machine
      1. Daily maintenance
        1. Before starting
        2. Fill the specified lubricant into oil basin and all lubricating positions
        3. Check the make sure that the electrical switches are in zero point and connections are in normal condition.
        4. Check and make sure that all clamping screws and protecting shields are tightened.
        5. Make sure that the machine is supplied with sufficient coolant.
        6. After starting
        7.  Check and make sure that the working pressure is normal.
        8.  Make sure that the spindle oil is sufficient.
        9.  Sufficiently lubricate the guideway.
        10.  Idle running for ten minutes before normal operation.
        11.  In terms of semi-automatic machines, turn the switches to specified points and cycle the movements several times before the semi-automatic cycle grinding.
        12.  Before shutting down the machine, stop the coolant firstly, run idly for about five minutes and then stop the grinding motor.
        13.  Clean each part of machine to prevent rust after using.
      2. Weekly maintenance
        1. Change the coolant.
      Clean the coolant tank thoroughly before filling new coolant.
      1. Clean all parts of the machine and smear the rust-proof grease, and cut the power at weekend.
      2. Keep motors clean.
      3. Seasonally maintenance
        1. Change the spindle lubricant.
        2. Change the lubricant in the tank of headstock.
      4. Half-yearly maintenance
        1. Change the hydraulic oil in the tank of machine bed.
      Do not use the cotton yarn but fine rag or foamed plastic to clean the oil tank.
      1. Clean the radiator of hydraulic system. (Only for high-precision machine)
      2. Check the condition of electrical parts.
      3. Yearly maintenance
        1. Remove and clean all rolling bearings in the machine and motors.
      Coat lubricating grease on the bearings and mount them again, and replace the worn ones.
      1. Change the old fuse wires with the same current ones. Never change the current of fuse wires.
      2. Check the quick-wear parts and replace them if necessary.
      3. When changing the nodulized copper filter of workhead, cement the new one to the filter body with glue 402.
      Change the filter if it is blocked.