Notching

A shearing or punching process is used in a press, so as to cut vertically down and perpendicular to the surface, working from the edge of a work-piece.

Notching is a low-cost process, particularly for its low tooling costs with a small range of standard punches.

The first punch & die type tool for notching tube & pipe was invented in Chicago by Julius Vogel, who was issued a US patent in 1938.

It's particularly suitable where the metal is otherwise awkward to drill, such as stainless steels, titanium or previously heat-treated aluminium alloys.

The stock to be notched is clamped into a vise and can then be fed slowly and accurately into a rotating, hardened metal, end mill.

This method of end notching is much faster and thus greatly minimizes the chance of damaging the stock either by warping due to heat build up or by squashing as can still happen with a hole saw.

[4] Notching in thin-wall tube may also be carried out by abrasive tools, reducing some of the risk of damage from a hole saw snatching.