In this research the forces exerted on both blank and punch in chipping process are studied. These forces are analyzed initially from pressing force exerted by punch on blank in sheet metal cutting, which is selected according to many factors such as (process type, blank material specifications and dimensions and type of fixtures that means pressure pad if any). This research resulted in an equation used for computing the theoretical value of side force created through the pressing process which may push the end of the punch horizontally. Two sets of practical work include cutting a variable thickness steel 37 plate and (3 mm) thickness punch by using end cutting die. The punch has broken in the 1st set with plate thickness (8) mm due to the side force which is found approximately equal to (0.1718%) of total pressure load. In the 2nd the results show that the (3 mm) punch is broken by the side force equals approximately to (0.2 %) of total pressure load with plate thickness equals to (7.75 mm).