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Slide adjustment is one of the most critical maintenance procedures on a servo press. Incorrect slide parallelism causes uneven die loading, accelerated tool wear, and poor part quality.
## Why Slide Parallelism Matters
The slide must be parallel to the bolster plate within tight tolerances — typically 0.02mm per 300mm for precision work. Even small deviations cause:
- Uneven blanking forces across the die
- Premature wear on one side of the tooling
- Part dimension variation
- Increased noise and vibration
## Tools Required
- Dial indicator with magnetic base (resolution 0.001mm)
- Precision ground test bar or reference block
- Feeler gauges
- Shim stock (0.01mm to 0.5mm)
- Torque wrench
## Measurement Procedure
**Step 1:** Clean the slide face and bolster plate thoroughly. Any debris will give false readings.
**Step 2:** Mount dial indicator on the bolster plate. Zero it at the front-left corner of the slide face.
**Step 3:** Move the indicator to front-right, rear-left, and rear-right corners. Record all four readings.
**Step 4:** Calculate the deviation: maximum reading minus minimum reading. This is your parallelism error.
**Step 5:** For a 4-point measurement, also check the center. Center deviation indicates slide crown or concavity.
## Acceptable Tolerances
| Press Class | Parallelism Tolerance |
|-------------|----------------------|
| General purpose | 0.05mm/300mm |
| Precision stamping | 0.02mm/300mm |
| Fine blanking | 0.008mm/300mm |
## Adjustment Procedure
Most servo presses use gib-based adjustment. The gibs are tapered wedges that control slide clearance and alignment.
**Step 1:** Loosen the gib locking screws on the high side.
**Step 2:** Tighten the adjustment screws incrementally — quarter turns only.
**Step 3:** Re-measure after each adjustment. Do not over-adjust.
**Step 4:** When within tolerance, tighten locking screws to specified torque.
**Step 5:** Run 20 dry cycles and re-measure. Thermal expansion will slightly change readings.
## Shimming for Coarse Adjustment
If gib adjustment range is insufficient, shims can be added behind the gib. Use precision ground shim stock. Calculate required shim thickness from your measurement data.
## Documentation
Record all measurements before and after adjustment. Track trends over time — increasing parallelism error between adjustments indicates accelerating gib wear.