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Slide parallelism is one of the most critical geometric parameters on a servo press. Incorrect parallelism causes uneven die loading, part quality problems, and accelerated die wear.
## What Parallelism Means
Slide parallelism measures how flat and level the slide face is relative to the bolster. A perfectly parallel slide would have zero deviation across its entire face.
Acceptable tolerance: typically 0.02-0.05mm per 1000mm of slide width.
## Four-Point Measurement Method
This method measures parallelism at four corners of the slide, giving a complete picture of tilt in both X and Y directions.
**Equipment needed:**
- Dial indicator with magnetic base (resolution 0.001mm)
- Precision reference block (calibrated flat, 100mm ? 100mm)
- Press must be at TDC with brake engaged
**Measurement points:**
- Point A: Front-left corner (50mm from each edge)
- Point B: Front-right corner
- Point C: Rear-left corner
- Point D: Rear-right corner
**Procedure:**
1. Clean slide face and bolster thoroughly
2. Place reference block on bolster at Point A position
3. Set dial indicator on slide face directly above reference block
4. Zero the indicator
5. Move reference block to Points B, C, D and record readings
**Interpreting results:**
- Front-to-back tilt = average(A,B) - average(C,D)
- Left-to-right tilt = average(A,C) - average(B,D)
- Maximum deviation = max(A,B,C,D) - min(A,B,C,D)
## Adjustment Procedure
Parallelism is adjusted by shimming the gib or adjusting the slide guide blocks. This is a precision operation ??consult the press manual for the specific adjustment mechanism.
**Rule of thumb:** 0.1mm shim change at one corner produces approximately 0.05-0.08mm parallelism change at that corner.
After any adjustment, re-measure all four points and verify the change matches expectation before proceeding.