Classification And Specification Of Presses

Classification of Presses:

Presses may be classified as follows:

1. According to the source of power:

(i) Manually operated (Fly) press.

(ii) Electric Motor driven press.

(iii) Pneumatic system driven press.

(iv) Hydraulic system driven press.

2. According to the design of the frame:

(i) Inclined. (ii) Straight side.

(iii) Gap.       (iv) Horn.

(v) Arch.        (vi) Inclinable.

3. According to the drive mechanism:

(i) Crank.                       (ii) Eccentric.

(iii) Rack and pinion.  (iv) Screw.

(v) Toggle drive.           (vi) Knuckle joint.

4. According to the number of slides:

(i) Single action.            (ii) Double action.

(iii) Multiple actions.

5. According to the use:

(i) Shearing.           (ii) Punching.

(iii) Coining.            (iv) Stretching.

(v) Extruding.         (vi) Straightening.

(vii) Bending etc.

Specification of a Press:

The specification of a press involves the following items:

1. Length of stroke:

The length of stroke is defined as the distance between up and down position the ram

2. Shut height:

The shut height is defined as the distance between the top of the bed to the bottom of the ram.

3. Die space:

The die space is defined as the available area for mounting the punch and dies components in the press.

4. Press adjustment:

The press adjustment means the capability of press to adjust the length of stroke as per need, as in the case of rack and pinion-driven presses.

5. Number of ram head:

The number of ram heads provided for simultaneous operations i.e. single- acting, double-acting or multiple-acting.

6. Amount force or press:

The size of any press is determined by the maximum force or pressure that can be exerted by the ram on the work piece without any failure.

7. Capacity of working:

The capacity of mechanical press is determined by the shear strength of the crank shaft material multiplied by the area of the crankshaft bearings. The capacity of mechanical presses ranges from 50 tons to 4000 tons. On the other hand, the capacity of a hydraulic press is determined by the piston area multiplied by the pressure of oil in the cylinder. The capacity of a hydraulic press ranges from 100 tons to 40,000 tons.



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