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Emuge’s Punch Tap enables helical thread forming in cast and wrought aluminum alloys, as well as similar lightweight materials. The short, helical tool path produces internal threads in less than half a second to reduce energy consumption and threading time.

The punch tap is made from an HSSE-PM alloy optimized for toughness and long wear. Its teeth have a geometry that produces threads in a single step. It also features two rows of flutes offset 180 degrees from each other and extending in a helical curve down to a usable application depth. This speeds threading by reducing toolpath length.         

The tool punches into a pre-drilled hole, with the first tooth of each flute producing a helical groove that guides the tap to the application depth. Threading commences by cold forming with a synchronous movement of feed and rotation. The thread is produced with a half left turn in the pitch, and each tooth produces half a thread (approximately 180 degrees). After the threads have been formed, the tool retracts from the hole in a helical motion. The finished, cold-formed thread is interrupted by two helical grooves offset by 180 degrees.

Thread strength is comparable to conventionally-machined threads from a depth of thread of 3×D, according to the company. The tool is custom-designed for coatings and dimensions according to application requirements.

The taps are used on modified CNC machines with a specialized Sync Control System and an Emuge Punch Tap software program. They are reportedly useful for blind and through-holes, and for the production of M4 through M8 metric threads with depths as low as 3×D. Featuring internal coolant supply capability, the tools are suitable for use with emulsion or minimum quantity lubrication (MQL).