Dayton Die Cushions - Cushion Types

There are 3 main die cushion types:
* Pneumatic Die Cushions
* Hydraulic Die Cushions
* CNC Die Cushions
Pneumatic Die Cushions are the most popular type. In most cases they operate at either 100 or 200 psi air pressure. However, in case of high tonnage requirement in small bed space, these cushions can be designed to use up to 400 psi air or even higher pressure nitrogen. In order to preserve nitrogen, these cushions can also use the combination of shop air and nitrogen. Pneumatic Die Cushions' tonnage is set by their air/nitrogen pressure. The tonnage increases throughout the stroke as the total air/nitrogen volume of die cushion and surge tank decreases. This pressure increase is defined as pressure build-up that is directly dependent on the size of the surge tank. Dayton Die Cushions are designed to have no more than 17% of pressure build-up throughout the stroke.
Hydraulic Die Cushions generally offer more tonnage in less space as oil pressure can be much higher than air or nitrogen pressure. Similarly to hydraulic press, hydraulic die cushions deliver uniform pressure during the whole stroke. They can also have additional functions added: controlled return or die cushion hold-down. Hydraulic Die Cushion installation usually includes HPU (hydraulic pump unit), cooling and filtration systems, hydraulic reservoir, sometimes accumulators and manifold with valves.
CNC Die Cushions are the most advanced type of die cushions. They are usually built as hydro-pneumatic die cushions offering both advantages of hydraulic and pneumatic die cushion. They offer very high tonnages that can be programmed to change during the stroke - tonnage control. CNC Die cushions also offer position control during return part of the stroke as well as hold-down functions at any point of the stroke. Installation includes HPU, cooling and filtration systems, hydraulic reservoir, accumulator and manifold with valves. It also includes electronic interface to the operator to program tonnage and position curves, set pressures, move cushions, etc.

Standard Pneumatic Die Cushions can be divided into categories based on maximum operating pressure, single or dual chamber design and stroke adjustment.
MAXIMUM OPERATING PRESSURE
Die Cushions can operate at 100, 200 or higher than 200 psi pressure. Low pressure cushions do not require booster pump and can be connected directly to shop air lines. High pressure cushions are suitable when higher tonnage is required as their tonnage is double the tonnage of low pressure cushions. Shop air is pressurized to 200 psi with supplied booster pump. High-high pressure die cushions operate at pressure greater than 200 psi thus they deliver extremely high tonnages.
DIE CUSHION DESIGN
Cushions can have single or double chamber design. Double chamber die cushions deliver twice the tonnage of single chamber cushion working at the same pressure.
STROKE ADJUSTMENT
Some die cushion models offer stroke adjustment feature. It offers stroke variations up to 1 inch for low pressure cushions and up to 2 inches for high pressure cushions. As a result, operator may be adjust the stroke rather than changing pressure pins (for length) when a new job is set-up.