FOOLPROOFING in JIGS and FIXTURES with examples

 FOOLPROOFING

Fig. 1  Example of fool proofing.

The location system should be such that it will be difficult for the operator to

incorrectly load the work piece into the location. Fig. 1. illustrates a fouling pin that

indicates to the operator that the long end of the work-piece has been put into the location

instead of the short end. In this example the fool proofing can be made absolute by

designing the clamping system so that the work piece cannot be clamped when the flange is not seated on the face of the bush. Fig. 2. illustrates part of a piece of equipment thatensures correct loading relative to the boss by having a clearance for the boss.

Fig. 2. Example of fool proofing.

Fig. 3. illustrates a work piece that has two holes of the same diameter and equi-distant from the principal locator, so that either will be accepted by the second locator. In this example the flange shape demands that the work piece be accepted in one position only, and so this flange shape is used for fool proofing, by introducing a fouling pin that will not allow the work piece to be incorrectly loaded. Very often the product designer will assist the production engineer by changing the size or position of holes that will allow incorrect loading, and atthe same time foolproof the actual assembly of the product.

Fig. 4. illustrates the six-point location

principle; in this example the work piece, shown as a cube, is to be positioned in a corner and retained there by the clamping force acting towards the corner as shown. Three pads, 1, 2 and 3, are required on the base; these three pads will constrain the work piece along Y-Y, about Z-Z and about X-X. The two pads 4 and 5 will constrain the work piece along Z-Z and about Y-Y. Pad 6 will constrain the work piece along X-X. These six pads, positioned as shown, will

therefore fully constrain the work piece

Fig.4. example