Accurate results, high efficiency

Face milling turbocharger components presents a huge challenge for the milling tools used due to the demanding nature of the material – usually refractory cast steel, often containing niobium. In addition to this, the design of turbocharger housings and exhaust manifolds often create unstable machining conditions. This means the tool needs to be very stable and cut effectively to achieve the required quality.

CERATIZIT – a full-range provider in the machining sector – set itself the task of developing a technically optimised, efficient tool system for these kinds of applications, bringing together the expertise of its specialists from Team Cutting Tools. “This collaboration has been a complete success with the MaxiMill 275 face milling system the end result,” confirms Detlef Erdei, Application Manager Automotive at CERATIZIT. “Our development team began the process by designing the cutter body to be extremely stable and have low-vibration. We were then able to optimise the number of cutting edges based on the diameter.” This resulted in the largest MaxiMill 275 with 125 mm diameter featuring 18 teeth, while the smaller 63, 80 and 100 mm diameter variants have 7, 10 and 14 teeth respectively.

Particular attention was paid to accuracy of the insert seat, which keeps the indexable insert firmly and precisely in place using a wedge clamp. This avoids any cutting mismatches and, therefore, the need for any subsequent height adjustment. This is a plus in terms of user friendliness, too.

The indexable inserts have also been refined. The basis for this is a special cutting material, which is designed for the highest thermomechanical demands. The inserts have a positive geometry with a 20-degree rake angle. This enables them to cut effectively and guarantees a smooth tool motion. The fact that they are fully ground around the periphery produces consistent and high precision.

The PVD-coated inserts are positioned in the cutter body in such a way that the cutting edge is horizontally aligned with the holder. This way, in contrast to most other face milling systems, which remove chips with the corner chamfer, a significantly smoother surface is produced like with an integrated finishing cutter. The indexable insert can be used on left- and right-hand cutting tools.

The key features of the MaxiMill 275

• Robust design
• Indexable insert fits stably and firmly in the base body
• Defined, stable cutting edge guide
• 16 usable cutting edges per indexable insert for maximum efficiency
• Low power consumption thanks to positive indexable insert topography
• Integrated cutting edge for high surface quality
• Smooth milling action and reduced spindle load
• High productivity, process security and efficiency

Practical example

For a turbocharger (material: 1.4837+Nb) the flange face is milled with a MaxiMill 275 (diameter 80 mm/8 cutting edges).

The key cutting values:

• f_z = 0.145 mm
• v_c= 100 m/min
• a_p= 1.4 mm
• a_e/D = variable
• Coolant = dry

The tool life achieved is 0.92 m, which is equal to 24 components – in impressive time and quality. The tool life is therefore around 70 percent higher in comparison to competitor products.