Recommended Minimum Distance Between Holes, Between Forms and From Edges of Sheets
If holes and forms are placed any closer to each other or to edges of sheets than is given below, they may distort each other or the material.
- Minimum 2 times material thickness between holes.
- Minimum 2 times material thickness between hole and edge of sheet.
- Minimum 3 times material thickness from form to edge of sheet.
- Minimum 6 times material thickness between forms.
Recommended die penetration is .118”(3,00).
Small Diameter Holes
When punching small diameter or narrow holes, check that tools are properly sharpened and maintained. The following recommendations are provided as guidelines to eliminate machine or tooling complications. In each situation, the user must consider their application, their machine, and their tooling before exceeding these recommendations.
Ratio of Punch to Material Thickness
Material Punch to Material Ratio:
Aluminum .75 to 1
Mild Steel 1 to 1
Stainless Steel 2 to 1
This means that if the material being punched is .078(2.0) thick aluminum, it is reasonable to punch a .059(1,50) diameter hole with the above listed styles of tooling. If the material being punched is .078(2,00) thick mild steel the smallest punch that is recommended is .078(2,00) diameter (or wide shape). If the material being punched is .078(2,00) stainless steel, the smallest punch recommended is .157(4,00) diameter (or wide shape).
Fully Guided Tooling
(Mate MARATHON®, & ULTRA TEC® Fully Guided Tooling)
Material Punch to Material Ratio
Aluminum .5 to 1
Mild Steel .75 to 1
Stainless Steel 1 to 1
This means that if the material being punched is .078(2,00) aluminum, it is possible to punch a .039(1.0) diameter hole using a Mate fully guided product. In mild steel that tool would need to be a minimum of .059(1,50), and in stainless a minimum of .078(2,00) diameter (or wide shape).
Although tooling is available for round holes up to station maximums for the largest station, such holes can exceed press capacities, especially in high shear strength materials. Creating the hole with more than one hit may solve the problem. Using smaller tools to break long perimeters on large tools can cut tonnage by a half or more, without resorting to nibbling the entire periphery. The diagrams above use rounds, double D’s, a quad radius and a biconvex radius. In all three, slugs fall away through the die, leaving no scrap on the punch press table.