WHAT IS REDUNDANT LOCATION ? how it apply?

 REDUNDANT LOCATION

A redundant location is said to be present when more than one locator is used to constrain a freedom; redundant location must be avoided. Fig. 1. shows a location system that includes a redundant location. The duty of the location system is to position the work piece relative to axis A-A and to control its position along A-A; in the upper illustration two faces are attempting to control the position of the work piece along A-A

Fig. 1. Redundant location and how it can

be avoided.

This would only be successful if the location system and the work piece were without any error, and so only one of these faces must be used for location, as shown in the lower illustrations. The choice of face used depends upon the dimensional requirements of the work piece, and whether the work piece is to be supported under the flange.

Fig. 2. illustrates another system that

includes a redundant location. The duty of this system is to control the position of the work piece using the two holes as location points. Pin I will, on its own, constrain all the freedoms except that of rotation about axis Y-Y, and it is intended that pin 2 controls this freedom. But as this pin is full form, it too is attempting to control movement along X-X, thus introducing a redundant location. Pin 2 must be specially shaped so that it will not influence any freedom except that of rotation about Y -Y 

Fig. 2. A location system with redundant

location

Fig. 3. also illustrates a system that

includes redundant locationlocation In this example the work piece is located from a cylindrical feature and the two fixed flatted locators are attempting to control freedom of rotation about the axis of the cylinder. Two redundant locations are present in this example because the cylindrical location and the flatted locators are both attempting to fix the position of the cylinder axis and at the same time the two-flatted locators are competing for the control of rotation. The work piece should be located from the cylinder and one flat, and to avoid redundant location the flatted locator should be adjustable or alternatively a pin locator be used to control the rotation.

Fig. 3. A location system with two

redundant locations