Polygon Solution’s Letter Broach is a new cutting tool used to create letters or numbers in metal parts. The Letter Broach is used in a rotary broach tool holder and is driven in a rotary motion around a fixed pivot point. This rotary motion reduces wear on the cutting tool, and eliminates secondary operations. Letter Broaches may also improve tooling costs and quality systems. Typical methods of marking parts with letters or numbers include stamping presses, hand punches and automated methods which forcefully press a stamp into the metal part. 

This new method of marking eliminates the impact of a high powered press or hammer, and gently displaces the material until the desired depth is achieved. The reduced impact will improve life for the cutting tool, tool holder and machine. Using the Letter Broach within the machine eliminates secondary operations and reduces opportunities for operator error. Cost savings can include less machines, manual labor and tooling costs. The Letter Broaches are designed to fit inside most industry standard rotary broaching tool holders. A benefit of using letter marking broaches in modern CNC machines with a tool holder carousel is the opportunity to mark mixed batches of parts. For example, if one machine is programmed to run three different parts, each can have a dedicated Letter Broach. 

Parts can be clearly marked A, B or C. Parts with similar features not easily seen by the naked eye can be marked with characters for improved quality. Parts marked this way can also be sorted faster. Soft materials including aluminum and brass are ideal for rotary broaching. The nominal broach depth for letter marking is about .005 - .010”. Various characters and symbols can be made, sometimes including multiple characters or custom designs.