Technical Center

Tools to help you with Modular Hard Die Systems and more.

CALCULATING PUNCHING TONNAGE

To calculate punching tonnages use the following shear strength value chart with either the Inch or Metric formulas. To ensure safe operation,
it is recommended that any questionable tonnage conditions be reviewed thoroughly with your press manufacturer.

To do the math faster, download our tonnage calculater tons-1

MATERIAL

TONS PER SQ INCH

METRIC TONS PER SQ CM

Aluminum 1100-0
3003-0, 6061-0

5.0

0.71

Aluminum 2024-0
3004-H36, 5052-H32

10.0

1.41

Brass & Aluminum
2025-T6, 6152-T6

17.5

2.46

Mild Steel & Bronze

27.5

3.87

Stainless Steel

55.0

7.74

Formula – Inches
Linear inches x Material thickness in inches x Tons per square inch = Job Tonnage Requirement
Formula – Metric
Linear centimeters x Material thickness in centimeters x Metric tons per square centimeters = Job Tonnage Requirement

NOTE: Add an additional 10% for stripping pressure (multiply by 1.1).

EXAMPLE:  How many tons are required to punch (15) fifteen .375″ / 9.52 mm diameter holes in 16-gage (.06″ / 1.52 mm) mild steel?

Inch   
Using the formula of Circumference = 3.1416 x Diameter, determine the linear inches of one .375″ diameter hole (.375 x 3.1416 = 1.178″). Multiply by 15 to calculate total linear inches (15 x 1.178 = 17.672″).  Select the proper Shear Strength value from the chart above.

17.672″ X 0.06″ X 27.5 = 29.2 Total Tons
Add 10% for Stripping pressure
29.2 X 1.1 = 32.1 Tons

Metric
Using the formula of Circumference = 3.1416 x Diameter, determine the linear centimeters of one 9.52 mm diameter hole (9.52 x 3.1416 = 29.91 mm, or 2.99 cm).  Multiply by 5 to calculate total linear centimeters (15 x 2.99 = 44.85 cm).  Select the proper Shear Strength value from the chart above.

44.85cm X .152 cm X 3.87 = 26.38 Metric Tons
Add 10% for Stripping pressure
29.2 X 1.1 = 32.1 Tons

CALCULATING DIE CLEARANCE

Die clearance is related to the type and thickness of the material being punched. For mild steel (AISI 1010 or equivalent) we recommend using 10% of material thickness (5% per side) added to the punch size, when punching up to .25″ (6.35 mm) thick material. Clearance should be doubled when punching thicker materials, or when punching Stainless Steels. Use 8% (4% per side) when punching light gage softer materials, like aluminum or copper.  Example: To punch a .500″ (12.7 mm) diameter hole in 11 GA (.120″ / 3 mm) mild steel, the die size will be .512″ (13 mm). (10% x .120 = .012 + .500 = .512).

DXF Layout Tools

Whether you currently use modular hard dies or would just like to review the layout for a possible application, the DXF files below contain each of the tool holders in plan view. You can quickly insert the tool holders into your flat blank CAD drawing and easily determine the number of tools and hits required. “Right Click” the appropriate link to download any of the DXF files and then click “save as” when prompted in the dialog box.

Contact Information

S.B. Whistler & Sons
11023 West Center St. Ext.
P.O. Box 270
Medina, New York 14103
Phone: 585-318-4630
Fax: 585-798-5612
Email Us Today

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