A geometry hard to resist
With shaft speeds of 200,000 rpm and temperatures up to 1,300 °C, modern turbochargers are exemplary for components made of heat-resistant steels.
Alloying elements such as chromium, nickel, molybdenum or titanium influence the properties of the materials in order to withstand high temperatures and stress.
Problem materials in machining
As a consequence, however, short and irregular tool life, uneven wear and problems with chip formation and removal occur during machining of the abrasive material.
A hardening of the edge zones of the bore surfaces and the poor thermal conductivity of the materials also contribute to the difficult machinability. The same applies to the tendency to stick and clamp with increasing nickel content, which results in the formation of built-up edges.
Process-reliable threading tools
In the newly developed HVA geometry, BASS has considered the requirements of heat-resistant high-alloyed steels. The optimized tool geometry ensures that clamping is drastically reduced despite the high elastic deformation components of the machined materials. Sharp cutting edges avoid sticking and the formation of built-up edges.
Accurately fitting macro geometry
In order to achieve long and process-reliable tool life during machining despite the heavy loads on the threading tool, further features have been adapted. The HVA family has a specific macro geometry that has been specially developed for heat-resistant steels. It reduces cutting forces and optimizes chip shape and removal. This is reflected in a considerable reduction and stabilization of the axial forces during machining (see diagram below).
Stable and short cutting edges ensure a long tool life by counteracting the extreme temperatures and the associated crater wear.
Precise micro geometry
In addition to the specially developed macro geometry, a coordinated micro geometry and coating is required. These must have a high toughness and wear resistance. The innovative BT coating is particularly convincing in terms of thermal conductivity, hot hardness and resistance to abrasive wear.
The HVA tools are designed for wet and MQL machining and are available with different chamfer leads and coolant supply.