Tooling Condition
Tooling condition is a factor that is important to keep your eye on. Poor tooling conditions such as punch wear, die sharpness, guidance, and alignment can all affect the life of the tooling and your bottom line. Be sure to sharpen your tooling when needed - sharp tools need less force and absorb less compressive stress.
*TIP*: Inspecting the slugs produced by your tooling can tell you if something is afoot with your die clearance and tool condition. A sharp tool with proper clearance will produce a slug with an even burnished land area, approximately one third of the material thickness in size.
- A. Compare to the uneven land and fracture area, this indicates improper die clearance
- B. Slug indicates that the die clearance may be too tight
- C. Notice the consistent burnished land and even fracture plane on this slug. This slug indicates that the tooling is in good condition and has a correct die clearance.
Stripping Force
'Stripping' refers to the process of removing the punch from the material after the punching process. As the material grips This requires a certain amount of force; a guide to figuring out how much stripping force is require for your application is Shear length x Material Thickness x 3500 = Stripping Force required (in pounds). You will need at least much stripping force in your tooling. However, you should avoid exceeding this force by an excessive amount as too much stripping force unnecessarily increases the force requirement of the application.
*TIP* This is especially important in your Multicyl system as excessive stripping forces can cause the patented self-adjusting stroke (click here for a detailed explanation of this patented process) of the cylinder to enter its power stroke prematurely. If your Multicyl seems to be producing a shortened power stroke, you should investigate the stripping force being applied and the preload on the punch.
Some means of stripping the part from the end of the punch are also required. Common types of strippers for accomplishing this include Fixed, Urethane and Spring. Although fixed strippers and Urethane strippers are sometimes used, the best method is a Spring Stripper. Their main advantage is that as the die closes, they hold the stock strip or part flat and in place during perforating. A spring stripper prevents the part material from lifting or hanging up on the punches at withdrawal. Because the stripper lifts away from the part material after each stroke, you can visually monitor die performance.
*TIP* Although a spring stripper is preferred, too much preload in the stripper assembly can have a negative effect on the performance of your Multicyl. If your cylinder appears to be having problems with its power stroke length you should inspect the stripper assembly for excessive preload.