Machining of stainless steel turbo housings boosted

The geometry and edge line quality also help ensure reliability and an increased number of components per insert.

Automotive Application Engineer at Sandvik Coromant, Jacques Gasthuys said: “Stainless is becoming a more popular material choice for turbo housings over the conventional cast iron due to its material properties that help improve resistance to exhaust gas temperatures of up to 1300°C, as well as corrosion.”

Gasthuys added: “Approximately 50 million turbo chargers are produced every year – cast iron and stainless – but the cost of machining stainless is often up to 20 times higher as these operations are often characterised by extremely short and irregular insert tool life, as well as uneven wear. With this in mind, our goal was to develop a strong cutter able to help lower component costs. 

The main challenge in roughing turbo exhaust housings is the complex shape of these thin-walled components and their intricate clamping, which together make for a very vibration-prone operation. The new M612 face milling cutter is purpose-designed to help overcome this issue. Its positive geometry provides smooth cutting action, which lowers power consumption and eliminates vibrations in roughing operations.

This permits greater metal removal and quicker cycle times, which in combination with 12 cutting edges, six on both sides, contributes to lower cost per component. The choice of round inserts also adds flexibility for machine shops, while the insert indexation interface delivers both accuracy and repeatability.

In a user case example using grade GC4240 inserts to rough a stainless turbo exhaust housing, the use of an M612 face mill in place of a competitor cutter allowed spindle speed to be increased from 212-273rev/min, cutting speed to be raised from 70-90m/min (230-295ft/min) and feed to be increased from 0.13-0.18mm (0.005-0.007”). At the same 2.5mm (0.098”) depth of cut, the result of the trial showed that the M612 face mill reduced machining time per component by 27%, while tool life increased by as much as 172%.