# Extrusion forming tools

Sheet-metal hole extrusions, pilot-hole and collar geometry, cut versus formed threads, and manufacturer-specific height limits.

Reviewed: 2026-11-02

Tags: tooling, sheet-metal, hole-forming, threading

In **1.2 mm sheet**, Mate's **2.5t** bottom-to-top height convention gives a **3.0 mm** form height. In a separate hypothetical **M4×0.7** joint, **2.1 mm** of fully formed engagement spans **3 pitches**, versus **about 1.71 pitches** across the original sheet. The engagement is an independent assumption. These ratios give pitch intervals. Actual complete threads and pullout strength need separate evidence. [Mate height convention, printed p. 47](https://www.mate.com/wp-content/uploads/2021/03/LIT00682_TechSolutionsGuide_RevE_LR.pdf#page=49).

## What the tool forms

Mate forms a collar by turning the edge of a pre-pierced hole into a die cavity with a radiused punch. Finished bore, height and material determine pilot size. [Mate, Technical Solutions Guide, LIT00682 Rev E 2021, printed p. 47](https://www.mate.com/wp-content/uploads/2021/03/LIT00682_TechSolutionsGuide_RevE_LR.pdf#page=49).

The collar provides the geometry for a separate threading operation.

Wilson Tool’s September 12, 2019 guide describes a tap rotating in the existing punched or extruded hole, with fluid injection synchronized to the press stroke. Thin sheet may need a collar for adequate engagement. [Wilson Tool, Tapping 101](https://wilsontool.com/en-us/resources/tapping-101).

## Three dimensions that have different jobs

| Dimension | Meaning | Why it matters |
| --- | --- | --- |
| Pre-pierced hole diameter | Opening before the collar is formed | Controls the material available to turn into the wall |
| Extrusion inside diameter | Bore after collar forming, before threading | Depends on the intended subsequent thread process |
| Form height | Axial dimension of the collar and sheet in the specified drawing | Depends on the chosen measurement datums |

This is an engineering interpretation of the forming sequence. None of these diameters is automatically the screw's nominal major diameter. Nor does geometric height establish that every part of the wall becomes a complete usable thread.

Mate links pilot burrs to increased stripping force, reduced by lubrication or coatings. Its maximum recommended height is **2.5 × thickness, from sheet bottom to form top**; excessive height can tear the rim, and neighboring features can distort it. [Mate, forming and stripping limits, printed p. 47](https://www.mate.com/wp-content/uploads/2021/03/LIT00682_TechSolutionsGuide_RevE_LR.pdf#page=49).

As engineering synthesis, punch penetration, return/stripping capability, material ductility, edge quality and surrounding geometry are separate influences. Press capacity for piercing alone cannot establish that a collar will form and release cleanly.

## A bounded TRUMPF example

TRUMPF lists **699921 upward** and **699206 downward**, designed for a specified thickness. The downward design covers **0.8–2.0 mm sheet**, **H ≤ 2 × thickness**, and **M2.5–M6** tapping sizes. These bounds apply to that design. [TRUMPF Punching Tools, printed pp. 67–68](https://www.trumpf.com/filestorage/TRUMPF_Master/Products/Services/01_brochures/TRUMPF-punching-tools-catalog-EN.pdf#page=67).

Its downward-tool M4 row illustrates why thread preparation differs:

| Subsequent operation | Listed sheet thicknesses | Extrusion diameter D |
| --- | --- | --- |
| Thread forming | 1.0 / 1.5 / 2.0 mm | 3.70 mm |
| Thread cutting | 1.0–2.0 mm | 3.35 mm |

D names the extrusion bore, not the pilot. The calculated 0.35 mm difference is specific to these entries. [TRUMPF, downward extrusion and thread-size table, printed p. 68](https://www.trumpf.com/filestorage/TRUMPF_Master/Products/Services/01_brochures/TRUMPF-punching-tools-catalog-EN.pdf#page=68).

The sources' height ratios follow their respective drawings; a common acceptance rule would require matching geometry and datums.

## Collar forming versus thread forming

The collar is produced by displacing the sheet around an opening. Subsequent thread forming displaces material again to create the screw profile; thread cutting removes material. Those distinct operations explain why a common nominal screw size can require different bore preparations. This is a geometric explanation of the cited process distinctions, not a tap-drill prescription.

A longer threaded collar can increase engagement length, but it does not by itself establish joint strength. Wall thickness after forming, incomplete entry and exit threads, thread profile, fastener material and loading direction remain separate factors. A collar used as a tube guide may need a different bore finish and geometry from one subsequently threaded.

## Worked example: height and pitch count

**Original illustration.** At t = 1.2 mm, Mate's 2.5t bottom-to-top height is **3.0 mm**. This arithmetic does not qualify a material or tool. [Mate height convention, printed p. 47](https://www.mate.com/wp-content/uploads/2021/03/LIT00682_TechSolutionsGuide_RevE_LR.pdf#page=49).

Separately assume an M4×0.7 thread and an actual fully formed engagement length of **2.1 mm** after allowing for entry, exit and root geometry. The axial length spans **2.1 / 0.7 = 3 pitches**. The same pitch across the original 1.2 mm sheet would span **1.2 / 0.7 ≈ 1.71 pitches**.

The 2.1 mm engagement is an assumption, not something derived from the 3.0 mm total height. These ratios count pitch intervals; they are not an integer guarantee of complete threads or a tensile/pullout rating. They illustrate why total form height and effective engagement must remain distinct.

## Source and application limits

Mate prints LIT00682 Rev E 2021. TRUMPF's catalog prints identifier **1798794_EN_202204_S** and a price-validity date of April 1, 2022; the identifier is retained without assigning every technical claim a revision date. Wilson's article supplies its September 12, 2019 date. Sources were inspected on November 2, 2026.

This reference does not establish universal pilot diameters, collar wall thickness, tonnage, tool mounting compatibility, thread class or joint strength. A named thread size alone does not establish a suitable extrusion tool or a finished connection. The cited manufacturer designs describe particular forming systems and conditions.

## Related reference

[Sheet-metal tooling](index.md)