Friday, January 6, 2017

GMT LATHE CHUCK MOUNTING



MOUNTING THE CHUCK
1. Check the location dia. and face of the machine spindle for Radial and Axial Runout using a Dial gauge. Maximum permissible Radial Runout and Axial Runout of the spindle shall not exceed by 0.005 mm.
2. Mount the chuck flange on the machine using the necessary clamping screws or the special provisions made by the manufacturers.
3. Check the flange for true running for Radial and Axial Runout and ensure that these do not exceed 0.005 mm.
4. Connect the drawtube/draw bar to the cylinder. If the drawtube/draw bar is to be fitted into the cylinder piston rod, ensure that the piston rod is retracted. If fitted at the intermediate position, the anti-rotation stop pin of the piston may be damaged.
5. Mount the Cylinder Flange on to the spindle rear side and check the flange for true running for Radial and Axial Runout and ensure that these do not exceed 0.005mm.
6. Mount the cylinder on to the cylinder flange.
7. Connect the pressure ports of the cylinder by hose.
8. Actuate the cylinder at low pressure (4-5kgf / cm2) two or three times and set the piston towards the cover end and switch off the hydraulic power.
9. Remove the cover from the chuck by removing cover clamping screws.
10. Keep the Wedge in fully de-clamped condition (At this position, the jaws will be fully opened).
11. Clean the chuck location diameter and hold the chuck in such a way that the collar just touches the drawtube end. Tighten the collar on to the drawtube using the special spanner provided, until the chuck sits properly on the flange face. Align the chuck clamping holes with the tapped holes provided on the chuck flange.
12. Tighten the collar with drawtube(in case of draw bar, tighten the wedge screw into the drawbar) and chuck clamping screws simultaneously till the chuck location face butts against the flange butting face.
13. True up the periphery of the chuck with the help of plastic mallet.
14. Ensure there is a gap (approximately 0.5 mm) between the wedge face and body inner face by adjusting wedge screw or wedge collar.
15. Reassemble the cover.
NOTE:
1. Before tightening the chuck flange (Adaptor plate for mounting the chuck) with the Taper nose of the machine spindle, ensure that the clearance between the spindle face and chuck flange butting face is not more than 0.03mm.
2. The flatness of the face of the chuck flange after machining on the machine can have only concavity maximum 0.01mm. Convexity is not permitted. Check with the help of straight edge for blue bearing.
3. Actuate the actuator and check the jaws are moving freely and check for the jaw stroke.

GMT CHUCK DISMANTLING PROCEDURE



1.       Remove the hard jaws / soft jaws from the base jaws by loosening the socket head screws along with the T’ Nuts.
2.       Remove the cover  with cover adaptor (if available) from the chuck.
3.       Loosen the chuck clamping screws which are used for mounting the chuck on the flange.
4.       Do not loosen the screw  fully threads must be engaged with flange .
5.       Ensure that a wooden plank is placed below the chuck on the guide ways of the lathe.
6.       Using the special spanner (Provided along with chuck), rotate the collar  till the drawtube is completely disengaged.
7.       If it is special execution chuck, then using the Allen key (provided with the chuck) loosen the wedge screw till it disengages from the draw bar.
8.       Then loosen the chuck clamping screws fully from the flange, so that the chuck comes out from the flange.
NOTE : DO NOT LOOSEN THE COLLAR OR WEDGE SCREW WITHOUT LOOSENING THE CHUCK CLAMPING SCREWS.
9.       After removing the chuck from the machine spindle, keep it in a table and pull out the wedge along with wedge adaptor and collar.
10.   Push the base jaw towards the wedge bore of the chuck and remove them.

NOTE : DO NOT HAMMER THE BASE JAWS WITH STEEL. ALWAYS USE ALUMINIUM OR PLASTIC MALLET.

Tuesday, June 30, 2015

Advantages of lapping


Advantages of Lapping

gmt-lapping-machine

  •  Improves surface finish by eliminating the peaks and valleys. 
  • Create maximum bearing area between the mating surfaces. 
  •  Improves service life of the moving parts which are subject to wear. 
  • Improves geometrical and dimensional accuracies. 
  •  There is absolutely no distortion in the component after lapping since no clamping devices are used. 
  • Minimizes the necessity of re hardening hardened parts because of less heat generation. 
  • Accessible flat surfaces of parts of any shape and size and any type of material can be lapped.        
  • Simple carrier plate design is enough to accommodate the component for lapping (i.e.) complicated fixture is not required. 
  • Any unskilled operator can work on the machine.

Monday, June 22, 2015

Lapping Process



Lapping is the process of rubbing two surfaces together with a lapping medium (Lapping fluid and Lapping Grit) between them.

lapping-process


Lapping is a low pressure abrading process which is employed as a precision finishing operation tooling to achieve high dimensional accuracy, improve geometrical accuracy, fine surface finish and ensure close fit between mating parts.

Peaks and valleys before lapping

lapping-machine

Peaks and valleys after lapping
after-lapping

Tuesday, June 2, 2015

History of Lapping Machine

early-lapping-process
Lapping is the process of rubbing two surfaces together with a #lappingmedium (Lapping fluid and Lapping Grit) between them.

Stone age man (fig-1) used the process of lapping in preparing their tool and implements to the extent that they drilled holes in a work piece by rotating sticks on it sand strewn surface.

A sketch as shown above (fig-2) from the German Museum in Munich, which has illustrated a probable early “Lapping Machine