LMT Fette 'modular' XChange tap enables threading head to be changed in situ

The XChange name derives from the concept behind the tool which enables the threading head to be quickly changed in-situ via a locking screw. The coated carbide threaded head with straight flutes, initially ranged between M8 by 1.25 p and M12 by 1.75 p, will self-centre via a precision ground serrated coupling that also provides the drive from the HSS shank. A further advantage of having a separate shank and head is that shanks of different length can be provided by LMT – in addition to the standard 90 and 100 mm lengths giving improved access to difficult to reach threaded features on a component. The productivity associated with the toughness of a coated carbide tap is enhanced by the process stability factor of the XChange's HSS shank. This is able to absorb the torsion generated through the cutting action and, in particular when the spindle is reversed, to exit the tool from materials such as high grade cast iron. According to LMT around 90% of taps used in production are still made from lower cost HSS, although problems like edge chipping, rapid wear and frequent breakage lead to loss of production time, machine stoppage, quality issues and higher tool inventory and cost. The carbide head of XChange is coated with LMT's latest multi-layered Polaris – LC620M which has a high toughness suitable for wet or dry machining. As the coated thread form initially contacts the material to be threaded, a burnished finish is created on the tool that minimises the levels of friction between the material being threaded and the tool and helps to produce a superior level of surface finish. In a recent trial producing a M8 blind thread 15 mm deep in cast iron using 8% coolant emulsion, the machine spindle was able to be run at 60 m/min (2,400 rpm). The recommended cutting speed for LMT's Polaris-coated XChange taps when threading cast iron and short chipping aluminium alloys is up to 60 m/min, copper 50 m/min and plastics 30 m/min.