Die Clamping Essentials

Die Clamping Essentials

Die Clamp Essentials

Essential qualities to consider in choosing die clamps are the speed of opening and closing, and the ease of inserting and removing. To make your selection you will need to consider:

  • press tonnage and opening force in pounds [lbs]
  • weight of dies
  • stroke per minute (SPM)
  • die change frequency
  • space available for clamps on bolster and ram

Fixed or removable clamps?

This is the question to be answered first and foremost when looking for clamping equipment. Only fixed clamps allow full automation with no further aid. Of course, they require full standardization of the die interface. Removable clamps are more flexible, but prevent full automation of the entire QDX process.

Fixed Clamps

Removable clamps


Standardization is the key to efficient clamping, especially when automation is desired. For all dies in use, the following parameters should be the same:

  • dimensions of die plates
  • clamping stroke
  • clamping positions

Even though our clamps will allow you to handle non-standard situations most efficiently, you should still try to standardize as much as possible.

Clamping force

For standard contract stamping the clamping force should at least be equal to the opening force of the ram — approximately 10% of the striking force. The clamping force is the same on bolster and ram. Divide this force by the number of clamps to be used on either part, bolster or ram, to obtain the capacity of each clamp. For large and heavy dies, and for high strike rates (above 200 per minute), take into account the relevant amount of inertia on moving the ram.

Options for selecting clamps

  • Clamping position: use on bolster or ram, at the sides of the die or on its front and rear.
  • Sensor-control: Some of our clamps are equipped with inductive sensors to ensure proper positioning.
  • Retractable clamping anchor: The die holding parts of the clamp are retracted when the clamp is opened.
  • Embedded: The clamp’s body is recessed into the bolster or ram. The clamping anchor grips the die inside internal slots or holes. Suitable for dies that cover the entire surface of the bolster or ram. — Also allows common clamping points for different die sizes.
  • Roller-bar clamp: embedded twin bars, equipped with rollers on the die’s side — rolling and clamping device in one piece.
  • Clamping height: distance to be spanned by the tightened clamp
  • Clamping stroke: distance by which the gripping parts move when the clamp is tightened; normally in the range of 3/32” to  19/32”.
  • Automation capability: We provide a large variety of clamps suitable for fully automatic clamping.
  • Clamping power: Our clamps can be driven in three different ways: Double-action, hydraulic tightening and releasing — not only allows for optimum efficiency, but, depending on the installation, also for active safety functions or best use of available machine space.
  • Single-action, hydraulic tightening with spring release — a cost-effective solution, which can be used for full automation in certain applications. The pressure can be controlled and monitored to allow additional safety mechanisms.
  • Mechanical tightening, hydraulic releasing — a simple and reliable solution. Clamps must be positioned manually.
  • Hydraulic supply: standard UNF 9/16", also available as G1/4".