Taps Cut Internal Threads in Half a Second
IMTS 2018: Emuge Corp.’s Punch Tap enables helical thread forming in cast and wrought aluminum alloys and similar lightweight materials.
Emuge Corp.’s Punch Tap enables helical thread forming in cast and wrought aluminum alloys and similar lightweight materials. A shortened toolpath process produces internal threads in less than half a second to reduce energy consumption and threading time.
The punch tap is made from a HSSE-PM alloy optimized for toughness and long wear. Its teeth geometry that produces threads in a single step. It also features two rows of flutes, off-set 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 and the first tooth of each flute produces a helical groove, which 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 ranging to 3xD (inch sizes are also available from #8 thru 5/16). Featuring internal coolant supply capability, the tools are suitable for use with emulsion or minimum quantity lubrication (MQL).
The more common twist drill point geometries often are not the best for the job at hand. By choosing the best point for the material being drilled, it is possible to achieve better tool life, hole geometry, precision, and productivity.
One of the most common methods of tapping in use today on CNC machines is 'rigid tapping' or 'synchronous feed tapping.' A rigid tapping cycle synchronizes the machine spindle rotation and feed to match a specific thread pitch. Since the feed into the hole is synchronized, in theory a solid holder without any tension-compression can be used.
With macros and canned cycles resident in the CNC on most contemporary turning centers, single point turning of OD threads can seem like almost a default process decision. However, for numerous applications, OD thread rolling has inherent advantages as an alternative to cutting threads.