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Press specifications can be confusing. Here is what each number actually means and why it matters.
## Nominal Tonnage
The maximum force the press can exert, measured in metric tons or kilonewtons. **Critical:** This is the force available at a specific point in the stroke — typically 6mm or 3mm before BDC for mechanical presses. At higher positions in the stroke, available force is lower.
For servo presses, the tonnage curve is different — some designs can deliver full tonnage throughout a larger portion of the stroke.
## Stroke Length
The total distance the slide travels from TDC to BDC. Longer stroke allows deeper draws and more die space. Typical range: 100mm to 500mm for servo presses.
## Strokes Per Minute (SPM)
Maximum cycle rate. For servo presses, this is the maximum at no-load. Actual production SPM depends on the motion profile and forming requirements. A servo press rated at 60 SPM may only achieve 20 SPM in a deep drawing application.
## Slide Adjustment
The range over which the slide shut height can be adjusted. Larger adjustment range accommodates more die heights without bolster risers.
## Bed Size (Bolster Dimensions)
Left-right x front-back dimensions of the working area. Must be larger than your largest die.
## Throat Depth
Distance from the slide centerline to the frame. Relevant for side-loading operations.
## Motor Power (kW)
For servo presses, this determines the energy available for high-speed or high-force operations. A press with insufficient motor power will fault on overload during demanding applications.
## Slide Parallelism Specification
Factory specification for slide-to-bolster parallelism. Better presses specify 0.01-0.02mm/300mm. This directly affects part quality and tool life.
## Position Repeatability
How consistently the slide returns to the same BDC position stroke after stroke. Servo presses typically achieve ±0.01mm. This is critical for fine blanking and precision forming.