admin
## Why Parallelism Matters
Slide parallelism is the flatness of the slide surface relative to the bolster. If the slide is not parallel, one side of the die contacts the material before the other, causing uneven forming, die damage, and part defects.
## Acceptable Values
- New press: 0.01mm per 300mm
- In-service: 0.02mm per 300mm (action limit)
- Reject limit: 0.05mm per 300mm (stop production)
## Measurement Procedure
**Equipment:** Dial indicator with magnetic base, precision ground reference bar (1000mm long).
1. Clean bolster surface thoroughly.
2. Place reference bar on bolster in left-right direction.
3. Mount dial indicator on slide, contact tip on reference bar.
4. Jog slide to BDC.
5. Zero dial indicator at left end of bar.
6. Move indicator to right end of bar. Record reading.
7. Repeat in front-back direction.
8. Record all four corner readings.
## Interpreting Results
If left-right parallelism is out: gib wear on one side, or gib adjustment needed.
If front-back parallelism is out: connecting rod length difference, or crankshaft bearing wear.
## Correction
Left-right: adjust gibs on the high side.
Front-back: check connecting rod adjustment (if adjustable) or crankshaft bearing clearance. This is a major repair — contact press manufacturer.