Die cutting is a powerful process for making gaskets, foams, adhesives, and thermal pads at high speed. But like any manufacturing method, it has physical constraints. The interplay between material thickness, feature size, rule support, and kerf spacing determines whether die cutting is efficient—or a headache.
Steel Rule Basics
Steel rule dies are built by embedding sharpened blades (“rule”) into a die board. Common rule sizes are:
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2-point = 0.028″ thick
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3-point = 0.042″ thick
These rule thicknesses define the minimum cutting kerf—the blade is not infinitely thin. That’s why you can’t design walls or features smaller than the physical size of the rule without compromising support or cut quality. Think about bending that rule around a corner. Radii can be challenging to do when you have to bend a radius.
The Rule Needs Support
Every blade segment in a die requires board support. If two rules are placed too close together, there’s no material left to hold the steel in place.
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Side bevels and tricks can sometimes squeeze rules closer together.
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But when walls get too thin, you approach “rule-on-rule” conditions, where two blades nearly touch. This usually ends in premature die failure or unusable parts.
Rule of thumb: if your wall is close to rule thickness, the die will be unstable; if your material is thicker than the wall, the die will jam.
Kerf: Why Parts Can’t Always Be Nest-to-Nest
Unlike CNC machining or laser cutting, most forms of die cutting require a kerf (gap) between parts.
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The kerf accounts for the thickness of the steel rule.
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It also ensures supporting board remains between cavities.
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Designing “part-to-part” with no gap is generally not possible—it will either break the die or prevent proper scrap ejection.
The required kerf usually equals at least the rule thickness (0.028–0.042″), but in practice, more spacing may be needed for stability.
Material Thickness vs. Wall Size
A frequent issue is trying to cut thicker material into designs with thin walls.
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Failure case: .375″ thick foam into parts with .250″ walls. Too much material gets stuffed into too little clearance, causing jams.
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Success case: .125″ foam into .250″ walls. The die clears easily, and the rule has proper support.
Punch Size vs. Material Thickness
Punches also have real-world limits.
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The smaller the punch, the thinner the material needs to be.
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Punches smaller than ~.040″ diameter tend to fail quickly, especially in thick or dense substrates.
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Example: A .040″ punch might be fine in a .010″ adhesive, but it won’t survive long in .125″ rubber.
When micro-holes or dense arrays are required, laser cutting or waterjet are better suited.
When Die Cutting Works Well
Die cutting is most effective when:
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Material thickness is less than the wall size.
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Features are larger than .040″ in thicker stock.
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Kerf spacing is respected between parts.
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The die board provides adequate support for every rule.
When Die Cutting Fails
Die cutting struggles when:
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Walls approach rule thickness, leaving no board support.
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Material thickness > wall size, leading to jammed slugs.
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Punches < .040″ are specified in thick substrates.
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No kerf is designed in, attempting part-to-part layouts.
More Die Cutting Information
Die cutting is fast, repeatable, and cost-effective—but only when its limits are respected:
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Rules have thickness (2-pt = 0.028″, 3-pt = 0.042″).
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Material must be thinner than the narrowest wall.
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Punch size is tied to material thickness—the smaller the hole, the thinner the substrate must be.
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Kerf spacing is required; parts can’t usually be cut wall-to-wall.
At NEDC, we help customers navigate these boundaries. Our custom die cutting services can deliver precision die cut thermal pads and die cut gaskets engineered for demanding applications like telecom modules and industrial systems. If a part design pushes past die cutting’s physical limits, we also offer laser cutting and waterjet cutting, ensuring every design can be manufactured effectively.