Tool coatings are often made from a variety of materials.

Die Clearance

gap causes

The clearance is the distance between the punch and die, and a large gap causes a large shear droop and inclination in the fracture cross-section. The clearance values used in blanking operations are shown in Table 1. As the thickness of the plate increases, the clearance values should become larger. If the clearance is too small, the hole will be dimpled.

optimal die clearance

The optimal die clearance depends on the type of material and the thickness of the material. The optimal gap is about 7 to 12 percent on each side. For soft materials, the gap is much smaller. For hard materials, the ideal gap is greater, with a range of seven to 12 percent. Thinner gauge materials can operate at the lower end of the optimal die clearance range, but thicker gauge materials should always use the recommended percentage.

Proper clearance between the punch and die is essential to punching success. A lack of it will result in a poor edge quality and a reduced tool life.

The correct amount of die clearance allows the fractures to connect properly, releasing the punching force. 

Moreover, operators must carefully follow the directions given by the manufacturer of the punches.

Using a hammer to punch a hole will also damage your sheet metal. Another method of making holes in sheet metal is using a Jeweler’s saw or hacksaw.

These two tools are great for creating holes of different sizes and shapes and will work best for smaller diameters. You can even use a stencil to get the desired shape.

You can use a compass to mark the center of the hole, and you can also use a centre punch to strike the exact location of the hole.


Regardless of the material being punched, the operators of punch presses must observe certain safety precautions. These precautions include choosing the correct punch size and angle. In addition, damaged punch points should be repaired before they are used again. A punch has a maximum capacity to ensure safe, dependable operation over a long period of time.

Basics of Metal Punching.


When you're making holes in sheet metal, it's important to know where to position the center of the hole.

Flat Punch

These charts are based on flat punch points, so they will not be useful for more complex shapes.

Tools Listed

In general, the tools listed on this site have rated capacities based on the strength of the design.