# Slitting tools

Punch-press slitting and parting tools, overlapping hits, side loads, guided tooling and edge-quality limits.

Reviewed: 2026-11-02

Tags: tooling, sheet-metal, punching, slitting

In the ideal slitting example, a **50 × 5 mm** rectangular punch advancing **40 mm** per hit overlaps **10 mm**. **Seven hits** cover **290 mm**. At a **10 mm** increment, overlap is **40 mm** and the same length needs **25 hits**. This assumes aligned rectangular footprints on an accessible straight path. Partial engagement, side loading, edge quality and positioning still govern the process.

## Meaning and process scope

Overlapping hits separate parts or trim edges. Mate notes that asymmetric resistance loads the punch laterally and can fold thin sheet into the die. [Mate slitting explanation](https://www.mate.com/technical-resources/punch-press-resources/tips-techniques/punching/techniques/slitting/)

BTU’s coil-slitting arrangement instead draws strip through circular knives and recoils the strands continuously. [BTU coil-slitting principle](https://btu-bridle.com/en/the-processes/slitting/)

## Hit length, pitch and overlap

For an ideal rectangular punch, length along the cut is different from cutting width across it. Let a be the punch length along a straight path, p the programmed center-to-center increment and o the overlap:

```text
o = a − p
Covered length after N aligned hits = a + (N − 1)p
```

**Worked example, assumed geometry:** a 50 × 5 mm rectangular punch advancing 40 mm per hit overlaps by 10 mm. Seven hits cover 50 + 6 × 40 = 290 mm. Each later hit adds only 40 mm of new cut length, although the tool is 50 mm long. A 10 mm increment would instead overlap by 40 mm; covering the same 290 mm would require 1 + (290 − 50)/10 = 25 hits.

This arithmetic assumes perfectly aligned rectangular footprints and an already accessible straight path. It does not determine an acceptable overlap or cycle time. Corner radii, end treatment, machine positioning, clamp clearance and retained tabs can change the actual sequence. More hits do not automatically produce a better cut because each partial hit also changes loading and sheet support.

## Side loads and guided tooling

A partial hit does not load a long, narrow punch like a full-width hole. Resistance on one part of the cutting edge and open space on the other can deflect the tip toward the existing opening. Mate states that increasing the unsupported overlap area increases side loading. [Mate overlap and lateral-load discussion](https://www.mate.com/technical-resources/punch-press-resources/tips-techniques/punching/techniques/slitting/)

Mate's fully guided assembly supports the punch near its tip with a closely fitting stripper. Its guide lists these minimum punch-width-to-sheet-thickness ratios; they describe Mate's tooling guidance, not universal minimum slitting widths. [Mate Technical Solutions Guide, printed p. 19](https://www.mate.com/wp-content/uploads/2021/03/LIT00682_TechSolutionsGuide_RevE_LR.pdf#page=21)

| Material label | Conventional tooling | Fully guided tooling |
| --- | --- | --- |
| Aluminum | 0.75 : 1 | 0.5 : 1 |
| Mild steel | 1 : 1 | 0.75 : 1 |
| Stainless steel | 2 : 1 | 1 : 1 |

The same page warns against notching or nibbling a strip narrower than 2.5 sheet thicknesses. That strip-width limit concerns a partial edge cut; it is different from the punch-width ratios for piercing. A narrow punch that can pierce a complete hole is not thereby approved for shaving an arbitrarily thin strip from an edge. [Mate partial-cut limitation, printed p. 19](https://www.mate.com/wp-content/uploads/2021/03/LIT00682_TechSolutionsGuide_RevE_LR.pdf#page=21)

**Interpretation:** guided support, punch width and remaining material engagement constrain different parts of the operation. Neither a machine's total punching-force rating nor a punch's outside dimensions alone establish its tolerance for lateral force.

## Edge quality and specialized geometries

Wilson Tool's June 19, 2019 article identifies worn guides/keys, station misalignment and positioning accuracy as contributors to parting burrs and witness marks. It describes an obround punch paired with a rectangular die as one way to improve the edge compared with repeated rectangular corner cuts. Its example is for 0.060 inch mild steel; that example is not a universal pairing or clearance prescription for every material. [Wilson Tool parting/slitting article](https://wilsontool.com/en-us/resources/parting-or-slitting-made-easy)

**Interpretation:** an overlap witness, fractured edge, raised burr and sheet scratch are different defects. A tool intended to reduce nibble marks does not necessarily establish acceptable burr height, edge straightness or cosmetic finish. Sheet distortion and tool alignment can matter even when both cutting edges are sharp.

TRUMPF's cataloged tool for cutting close to formed sections is self-stripping, with urethane-stripper or steel-presser-foot variants, optional roof shear, and a die using interchangeable blades. The catalog lists a 0.5–2.0 mm sheet range and requires machine, material, thickness and slitting geometry to define the application. Its brush-equipped die option addresses surface scratching; it is not a quantified edge-burr guarantee. [TRUMPF punching-tools catalog, p. 46](https://www.trumpf.com/filestorage/TRUMPF_Master/Products/Services/01_brochures/TRUMPF-punching-tools-catalog-EN.pdf#page=46)

The catalog's representative 5 × 56 mm and 5 × 76.2 mm tool dimensions describe specific products. They do not turn the article's assumed 50 × 5 mm arithmetic into a TRUMPF product specification or establish a maximum allowable feed increment.

## Material, machine and source limits

Material grade/condition, thickness, cutting width, overlap, corner shape, clearance and stripping determine the application. Remaining tabs, part support and the route for removing cut material also affect whether a separation sequence is workable. The required clear space around an existing form is an assembly geometry, not merely the nominal width of the cutting punch.

Mate's guide is identified as LIT00682 Rev E 2021. Wilson Tool explicitly dates its article June 19, 2019. TRUMPF's catalog carries identifier 1798794_EN_202204_S and price validity from April 1, 2022; that commercial date is not treated as a separate technical revision. No issue date was established for the Mate slitting page or BTU page. Upload and crawl dates are not editions.

This reference provides no universal overlap, punch penetration, material-independent maximum thickness, burr tolerance or production rate. Published tooling features do not establish that a particular press has the corresponding holder, guide, support or options installed.

## Related reference

[Sheet-metal tooling](index.md)