Machine Repair Procedure: Turret Alignment for Mori Seiki SL-25 Turning Center
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SUMMARY: THIS PROCEDURE EXPLAINS A SIMPLE ROTATIONAL ALIGNMENT OF THE TURRET AFTER AN IMPACT.
DETAILS:
After a crash, several items should be checked and noted during machine repair. These are:
- Headstock alignment (parallelism of the spindle centerline with the Z axis). This is done either with a test bar mounted to the spindle or more typically by cutting a part and checking the part for taper. If correction is necessary, align the headstock before performing the turret alignment. We prefer to use a part at least 1 inch in diameter (to avoid excessive part deflection) and at least 5 inches in length.
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Rotational alignment of the turret. This can be done using one of two methods:
- Parallelism of a turning tool pocket to the X axis movement.
- Centering the bore of a boring bar holder to the spindle rotational center in the X axis plane and looking for deviation in the Y axis plane. Mount an indicator to the chuck and rotate the chuck with the indicator stylus inside the boring bar holder. Be sure to note the machine position of the X axis when you have positioned the X axis so that the boring bar holder is centered on the spindle. We prefer this method because if the alignment is done using this check (as opposed to aligning the turning tool pocket with the X axis movement), you will end up with the tool tips centered better on the spindle. Facing will be better as well as drilling on center. It is best to hold the indicator in a piece that is clamped in the chuck, but often times this will not be available. It is possible to use an indicator and magnetic base to do this check (See picture), but the length of this setup should be kept to a minimum to reduce sagging and only a high quality base should be used.
Indicator in boring-bar holder
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Parallelism of the turret bottom with the Z axis movement. Write down the amount and direction of any deviations from “0”. In the case documented in this procedure, the headstock alignment and the Z axis parallelism of the turret were ok and no adjustment was necessary. However, the turret had been rotated by the impact and needed to be aligned. This is done as outlined below:
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Position the turret so that the boring bar holder (use the best, least beat up one you can find, preferably without impact marks or scoring, rust or dents in the bore) is centered on the spindle rotational center. Make a note of the machine position in the X axis. Note the amount of deviation from “0” in the Y axis plane. (See picture above)
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Mark and remove the number plate around the center hub of the turret by taking out the Phillips screws.
Removing the number plate
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Remove the 4 M8 cap screws in the turret center cover and remove the cover. You may need to tap the cover in the CW and CCW direction to get it loose enough to pull out. This will expose the turret center.
Remove the 2 M8 taper pins in the turret. These are located 180 degrees from each other. They are 90 degrees from the “master” pin hole. This is the hole with the small counter-bore.
Removing taper pins witha slide-hammer
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Loosen the (12) 8mm cap screws on the outer bolt circle. These are the bolts that hold the turret-side of the curvic coupling in place. Retighten the screws slightly (a little more than finger tight) to prevent excessive turret movement.
Turret center view-loosen outer bolt circle
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While watching the indicator, strike the turret to rotate it in the needed direction (CW or CCW) with a soft hammer or a piece of sturdy wood. (See picture 6) As you do this, check and adjust the X axis position back to center after seeing any change in the Y axis direction as the centerline will keep changing as the turret is rotated. Continue this process until the indicator reads “0” all the way around the inside diameter of the boring bar holder.
Striking turret with wood block
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Tighten the12 screws on the outside bolt circle in a cross pattern until all are fully tightened. We prefer at least 3 times around the pattern, tightening a little more each time.
Tighten the outer bolt circle
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Check your indicator again to make sure that the tightening of the screws did not move the turret. If you still have “0” all the way around the inside diameter of the boring bar holder, you can proceed. If not, loosen the screws and repeat from step 5. After achieving “0”, note the resulting machine position in the X axis. You will need to know this later to adjust the X axis grid-shift parameter (NC parameter 1850 for X axis).
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After all screws are tight and your indicator reading is “0”, you will need to lightly ream the taper pin holes to remove any bur cause by the pin when the turret was impacted.
Lightly ream the taper-pin holes
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Install new taper pins. Use only the correct size metric taper pin with a tapped hole for later removal. Put a screw into the tapped hole in the pin and lightly strike the screw with a small hammer to seat the pin.
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Check the rotational alignment with the indicator one more time with the indicator to make sure the turret is still correctly aligned.
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Reinstall the center cover and the number plate.
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Using the machine position of the X axis from step 8, calculate the difference between the current X centerline position and the machine specification distance. You will need to adjust the X axis grid shift to get the distance from X zero-return (home) position to the spindle centerline back to the specification distance. The specification distance may vary depending on the machine model and number of turret stations.See below:
Model: SL-25A, 25B, 25MC
10 Station Turret: 250mm or 10 inches
12 Station Turret: 250mm or 10 inches
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