Welcome the Multicyl tooling tutorial. We hope the information here is helpful, for any questions or comments about the information please contact us.

Anatomy of a Tool

  • Punch: The punch is the male portion of the punching assembly that penetrates the work piece during the punching process
  • Die: The die is the female portion of the punching assembly provides the cutting edge and accepts the punch as it removes material from the work piece.
  • Stripper: The stripper is that part of the assembly that holds the work piece material in place and in some instances helps to keep the punch rigid during the punching process.
  • Holder: The holder is the body of the system. It holds the punch and die in place and provides the rigidity for the system. This can be a c-frame like in the picture shown here or may also be a traditional die set.

Now lets take a look at some of the important features of the tooling, how they relate to the punching process, and some information and tips to help you along

Die Clearance

Die clearance is the term used to describe the relationship between the size of the punch and the size of the die cavity.

Die clearance is important because it has a direct relationship with both hole condition and tooling life. Too much clearance and the material can draw an excessive burr at the bottom of the hole or become rounded at the top of the hole. Too little clearance and punching force and stress is increased causing premature punch wear and reducing tooling life. Proper balance is very important. Die clearance is often expressed as % of material thickness, and as a rough guide 10% per side is often used.

This chart shows correct die clearances for the materials and thickness listed.

*TIP*: Not only will correct die clearance prolong the life of your tooling, but can also help prolong the life of the seals in your Multicyl by reducing the pressure build up in the cylinder.

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.

Shear Angle

By applying a shear angle to the punch, tonnage requirements can be reduced by up to 30%. Shear on the punch essentially proportions the force being applied by producing an even shearing action through the stroke of the ram rather than by applying all the force at once.

Feed Clearance

Feed clearance refers to the distance between the punch and die when the tooling is in the open position. The minimum feed clearance required in the tooling is determined by the work piece – you need enough feed clearance to feed the part between the punch and die. The feed clearance required in turns tells you how much advance stroke is required of the Multicyl. Click here to for a detailed explanation of how to select a Multicyl with the appropriate stroke and tonnage for your application.

*TIP*: If the feed clearance required by the part allows for it, the patented self adjusting stroke of the Multicyl allows you to thread the cylinder down far enough to eliminate the pinch point at the point of operation. This makes your Multicyl system safe for your operators and allows you to meet OSHA safety standards without the need for guards or expensive light curtains.

Die Sets

Unlike traditional die sets, Multicyls do not have gibs and slides, as such we need to take care in our selection of die sets. The reason for this is that unbalanced loads and transverse forces have the potential to be transferred up the ram into the cylinder where the seals and other components can be adversely affected. The Die set should always have a balanced load condition and should always have oversized pins and bushings. Additionally, when permitted by the application, the die set should have 4 pins instead of 2 and should have self contained lifter springs to return the top shoe rather than attaching it to the ram of the Multicyl.

*TIP*: To prolong the life of both your tooling and your Multicyl use the checklist below when your designing your die set. The more features you incorporate into the design the better off you will be.

  • A. four guide pins wherever possible*
  • B. oversized guide pins and bushings
  • C. built in depth stop
  • D. self contained tool return springs**
  • E. a balanced load and centralized working forces
  • F. minimal acceptable stripping spring pressure

* Although a 4 pin dieset is ideal, 2 pin applications can be done successfully. However, with a 2 pin die set the central position is not necessarily on the center line of the punch, but may be found at any point in the triangle formed by the 2 pins and the center line of the punch.

** Single acting Multicyls are not designed to return die sets, and die sets should not be attached to the ram of a single acting Multicyl. It is possible, however, to return die sets with a double acting Multicyl, such as our DX and DL series of cyliners. An EAC-1000 flexible coupler or 6003/6004 die connector set (available from Multicyl) should be used in all applications where die sets are attached directly to a Multicyl. Click here for information on these components.

Download Tooling Connection DXF