What Is an ASTM D412 Cutting Die Used For?

ASTM D412, published by ASTM International, is one of the most widely used standards for testing the tensile properties of vulcanized rubber and thermoplastic elastomers. It measures tensile strength, elongation at break, tensile stress at a given elongation, and tensile set. Before testing, rubber sheets must be cut into standard dumbbell-shaped specimens, often called dog bone specimens.

The reliability of your tensile data depends heavily on specimen quality. Burrs or nicks along the specimen edge can cause premature breaks at the defect, resulting in low readings and poor repeatability. A cutting die made to standard dimensions is the first step toward trustworthy results.

Kind Snail cutting dies are made of hardened alloy tool steel (HRC 55-60) and precision cut by electrical discharge machining (EDM). With a cutter wall of at least 5 mm, the die resists deformation and keeps every specimen consistent.

Typical users: Rubber compounders, tire and seal manufacturers, hose and belt producers, and testing laboratories, for R&D and incoming or outgoing quality control.

How to Choose ASTM D412 Die A–F

ASTM D412 defines several dumbbell dies, Die A through Die F. They differ mainly in overall length and the width of the narrow section:

・Die C: The most commonly specified die for rubber tensile testing
・Die D: A smaller specimen, useful when sample material is limited
・Die A, B, E, and F: Used when required by a specific product specification or customer

Always follow the die required by your product specification or customer. Tell us your material and application, and we will help you choose the right die.

ASTM D412 Specimen Dimensions

About Kind Snail Cutting Dies

・Material: Alloy tool steel, ensuring accurate cavity dimensions and a long service life
・Cutter wall: At least 5 mm thick to prevent deformation during cutting
・Hardness: HRC 55-60
・Machining: Precision cut by electrical discharge machining (EDM)
・Compatible machines: Kind Snail manual cutting press and pneumatic cutting press
・Custom service: Non-standard dies can be made from your drawing or sample (send us your drawing or requirements, and our specialist will assist you)

What’s in the Box

・Cutting die × 1 (as ordered)
・Dimension inspection report × 1
・Technical document × 1

※ Cutting press and cutting pad are sold separately. Compatible with Kind Snail manual and pneumatic cutting presses.

ASTM D412 Cutting Die FAQ

Q: Which ASTM D412 die is most commonly used?
A: Die C is the most commonly specified die for rubber tensile testing. If your specification does not name a die, Die C is usually the default choice. When in doubt, contact us and we will help you confirm.

Q: Are ASTM D412 Die C and ASTM D638 Type IV the same?
A: The two specimens have essentially the same dimensions, which is why ASTM D638 Type IV is often used for comparing nonrigid plastics with elastomers. Please follow the standard specified in your requirements.

Q: Can I use an ASTM D412 die for ISO 37 testing?
A: No. ISO 37 dumbbell specimens have different dimensions and tolerances. Your test report must state which standard was followed, so you need a die made for that standard. Kind Snail also supplies ISO 37 dumbbell cutting dies.

Q: Do I need a cutting press for an ASTM D412 die?
A: We recommend it. A manual or pneumatic cutting press applies even, vertical force, producing cleaner specimen edges and protecting the cutting edge from damage.

Q: What is the lead time? Do you make custom dies?
A: Common types are usually in stock and ship quickly. Otherwise, standard dies take about 1 month and custom dies about 2 months, depending on complexity. Custom dies can be made from your drawing or sample. Contact us for details.