# 120: Terminology and Surroundings (14) Width of Blanking Bridges
The bridges in blanking are the feed bridge and the edge bridge as shown in [Fig. 1] The minimum values of common bridge widths in blanking operations are shown in [Table 1] The reason why the width of edge bridge is larger compared to feed bridge is the relationship with the material width guide. The material width guide is made slightly wider than the material width so that the material can move smoothly. Although the edge bridge width changes because of this, it is made wider than the feed bridge so that the minimum bridge width is maintained even in the most oblique state.
When the bridge width becomes close to the limit to product formation or becomes so narrow as to exceed that limit as shown in Fig. 2, a constriction or twisting occurs due to the effect of bending or droop caused by a sideward pressure. This effect is large in soft materials. When this phenomenon occurs, the state of the cut cross-section will no longer be normal, and the external appearance of the blank becomes poor. In addition, the wearing out of the punch and die becomes faster speeding up the generation of burrs, and also shortening the maintenance interval of the dies.
However, there are also times when a narrow and long object is to be prepared by blanking. The phenomena described regarding the bridge width in blanking operations occur as they are in such situations. This means that we are expecting contradicting things from the point of view of blanking. The reason is the same phenomena that occur in the bridge width during blanking. It is effective to observe well the phenomena that occur in the bridge width, and to take countermeasures to prevent deformation. As shown in Fig. 3, it is most effective to make the material pressure pad stronger. It is also possible to think of restricting the blanked part in order to prevent slipping. In addition, it is also effective to use a smaller clearance than normal.
Even the bridge width in blanking becomes useful for a different purpose depending on the viewpoint.


- #167 Problems in Punching and their Countermeasures (6) Scrap Processing in Punching
- #166 Problems in Punching and their Countermeasures (5) Trimming of Drawn and Shaped Parts
- #165 Problems in Punching and their Countermeasures (4) Scrap Clogging in Punching
- #164 Problems in Punching and their Countermeasures (3) Bending and Twisting of Narrow Punched Parts
- #163 Problems in Punching and their Countermeasures (2) Bending due to Punching

