Fundamentals of Press Operation
The force through in which press ram is able to exert safely is known as tonnage of the press. Press slides exert a force that is greater than the rated tonnage because of built-in safety factor. The tonnage of hydraulic press is equivalent to the product of the piston area and oil pressure in cylinder. A tonnage is varied by changing the oil pressure. Tonnage of mechanical press is equal to the size of bearings for the crankshaft or eccentric. The tonnage of mechanical press is approximately equal to the product of shear stress of crank shaft material and area of crankshaft bearings. The tonnage of mechanical press is maximum when the slide is near to the bottom of its stroke.
Reciprocating motion of a press slide is known as the stroke. Stroke is expressed as the number of inches among terminal points of the motion. The stroke is constant for mechanical press while it is adjustable for hydraulic press.
A distance from the top of the bed to the bottom of the slide along with the stroke down and the adjustment up is known as shut height.
Die space is the area which is available for mounting dies in the press.