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Shut height and die space are the most commonly misunderstood specifications when selecting a servo press for a new application. Getting this wrong means the press cannot run the die.
## Definitions
Shut height: the distance from the slide face to the bolster face when the slide is at bottom dead center (BDC) and the slide adjustment is at maximum.
Die space: the working area of the bolster (length x width).
Stroke: the total travel of the slide from TDC to BDC.
## The Common Mistake
Engineers specify the die height and check it against the press shut height. But they forget to account for:
1. Slide adjustment range: the shut height specification is at maximum adjustment. If you need to run the die at a specific shut height, verify the adjustment range covers it.
2. Bolster plate thickness: if you are adding a bolster plate or riser, subtract its thickness from the available shut height.
3. Die cushion: if the press has a die cushion, the cushion pins take up space in the bolster. Verify the pin pattern matches your die.
4. Minimum shut height: presses have a minimum shut height as well as maximum. If your die is too short, the slide cannot reach BDC.
## Calculating Required Shut Height
Required shut height = die closed height + any riser plates + safety margin (5-10mm)
Verify: minimum press shut height < required shut height < maximum press shut height
## Die Space Considerations
For progressive dies, the die space must accommodate:
- Die length (in feed direction)
- Die width
- Feed clearance on the entry side (typically 200-300mm)
- Scrap chute clearance on the exit side
For transfer dies, also consider the transfer mechanism width.
## Servo Press-Specific Considerations
Servo presses often have a larger stroke than equivalent mechanical presses. This means:
- The slide travels further, requiring more clearance above the die
- The shut height range is wider, giving more flexibility
- But the press height is greater, which may require a pit or higher ceiling