Custom tooling and die design · Lesson 2 of 4

Custom tooling and die design: materials, standards and design constraints

Tool steel and hardness, load ratings per length and the factors that raise force, the geometry rules tool makers publish, protecting prefinished faces, punching clearance and force, and AFS's envelope.

You will be able to: Identify what tools are made of and who sets their hardness, read a tool rating per length, and apply the published V-opening, leg, radius, angle, offset, hem, surface and punching limits, alongside AFS's own fabrication envelope.

12 min · 12 slides · 8 questions

All lessons in this module

Slide 1 of 12

What tools are made of

ASTM A681-24 covers alloy tool steels, products normally fabricated into tools and dies.

Hardness is measured by the Rockwell method of ASTM E18-25.

WILA deep-hardens its tools to 56-60 HRC to a depth of 4 mm, and notes that a nitrided layer is very thin.

A681 sets requirements for the tool steel as supplied; the working hardness of a finished tool is the tool maker's value.

Sources

ASTM A681-24 Standard Specification for Tool Steels Alloy (scope page) - ASTM International
ASTM A681-08(2022) Standard Specification for Tool Steels Alloy, historical (scope page) - ASTM International
ASTM E18-25 Standard Test Methods for Rockwell Hardness of Metallic Materials (scope page) - ASTM International
Prevent damage and wear (knowledge article) - WILA (press brake tool manufacturer)

Videos for this lesson

What this video shows: Mate, a punch tool maker: per its description, what die clearance is and how proper clearance gives a clean hole and longer tool life.

Video: Punching Holes with Optimal Die Clearance - Mate Precision Technologies by Mate Precision Technologies, on YouTube. AFS checked its description against this lesson.

Glossary

Tool steel (ASTM A681): Wrought alloy tool steel; ASTM A681-24 covers these products, normally fabricated into tools and dies.
HRC: Rockwell C hardness, measured by the methods of ASTM E18; WILA quotes 56-60 HRC for its deep-hardened tools (a maker's value).
Load capacity: The most load a press brake tool takes per unit length, for an evenly spread load; WILA states it in kN/m.
V-opening: The width of a press brake die's groove; WILA suggests about 6 to 8 times the sheet thickness for steel sheet up to about 3 mm thick.
Natural radius: The inside radius air bending forms by itself, set by the material, angle and V-opening rather than by the punch tip (WILA).
Shoulder radius: The rounded entry edge of a die groove; a larger one marks the sheet less (WILA).
Tooling factor: Bystronic's multiplier on air-bend force for special tools: 4.0 for a hemming tool, 5.0 for offset bending.