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Gib clearance is one of the most critical maintenance parameters on a servo press. Too loose and you get part dimensional variation; too tight and you get premature wear and overheating.
## What Are Gibs?
Gibs are the sliding contact surfaces between the press slide and the frame uprights. They guide the slide vertically and resist off-center loading from the die.
Types of gibs:
- Bronze gibs: traditional, self-lubricating, replaceable
- Roller gibs: lower friction, used on high-speed presses
- Hydrostatic gibs: oil film bearing, used on precision presses
## Measuring Gib Clearance
Required tools:
- Dial indicator with magnetic base (0.001mm resolution)
- Feeler gauge set
- Torque wrench
Measurement procedure:
1. Remove the die from the press
2. Mount dial indicator on the press frame, contact point on the slide
3. Apply a lateral force to the slide (use a pry bar against the slide, not the die area)
4. Read the dial indicator - this is the total gib clearance
5. Repeat on all four sides (front, back, left, right)
Acceptable clearance values:
- Standard stamping: 0.03-0.08mm per side
- Precision forming: 0.01-0.03mm per side
- Fine blanking: 0.005-0.015mm per side
## Adjusting Gib Clearance
Most presses use tapered gibs adjusted by a set screw or wedge mechanism.
Adjustment procedure:
1. Loosen the gib lock screws
2. Turn the adjustment screw clockwise to tighten (reduce clearance)
3. Check clearance with feeler gauge after each quarter turn
4. When clearance is correct, tighten lock screws to specified torque
5. Run the press for 10 minutes at slow speed and recheck - gibs settle slightly after initial adjustment
## Signs of Worn Gibs
- Part dimensions drifting over the shift (clearance increasing as gibs wear)
- Unusual noise during the forming stroke (metallic clunking)
- Visible scoring or galling on the gib surface
- Gib temperature above 60C during normal operation (check with infrared thermometer)
## Gib Lubrication
Gibs require continuous lubrication. Most presses use a centralized lubrication system with oil delivered every 15-30 minutes.
Check:
- Oil flow to each gib point (use the manual pump to verify flow)
- Oil viscosity: typically ISO VG 68 or VG 100 depending on press speed
- Oil temperature: above 50C indicates insufficient flow or wrong viscosity