Questions with Rick Crabtree

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Sandvik Coromant’s automotive applications specialist discusses how applying rotary broaching principles has created burr-free milling cutters.

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April 7, 2021

1) What challenges were Sandvik Coromant engineers trying to solve with M5 milling cutters?

Aluminum is easy to machine but can leave burrs and sharp edges. Manufacturers were using milling cutters with lots of teeth, so tool setup was taking half an hour. Then, cutting in the same area for a length of time causes a burr to form pretty quickly.

We adapted technology from rotary broaching, which is typically used for finishing. We eliminated most of that setup time by using fixed-pocket inserts, so you don’t need to be in the tool room for long.

2) What are the results of the new cutter designs?

There’s been a huge increase in tool life. I’ve been to manufacturers who were getting 10,000 cycles per tool and are now getting 50,000 cycles. So, they’re saving on the consumables, but the bigger savings are in hours. We’ve eliminated setup time at the start, and they don’t have any bench time at the end of machining to deburr the workpieces. Surface quality is better too (Rz1 to Rz3). A lot of the aluminum part designs we’re seeing have really thin walls, and vibration becomes a big problem during machining. The broach-style tool can push down on the workpiece, keeping everything secure.

M5C90

3) What options is Sandvik Coromant offering with this approach?

The M5B90 requires no setup or adjustment, allowing high feed rates with no burring. We can then combine step technology with periphery inserts (M5C90) to rough and finish at the same time, reducing cycle times and boosting throughput.

For die-cast companies, we have the M5Q90 burr-free cubing cutter. As eMobility requires lightweight materials and components, Sandvik Coromant also has developed solutions for thin-walled components, a brazed-in compact cutter, the M5F90, for electric engine housings and battery boxes. The M5R90 offers a cartridge-based solution for square shoulder milling.

4) Many modern engines use aluminum cylinder blocks with gray cast iron liners. How do you approach bi-metal milling?

In rough machining, it’s common to machine liners or cast-iron material first, leaving 50?m of stock, then rough the aluminum with an M5C90 to leave about 0.5mm of stock. We developed the M610 cutter as a stand-alone product for finishing milling bi-metal materials. We dry cut up to 3,000m/min, or we can use minimum quantity lubrication (MQL). Customers using traditional PCD cutters who have switched to the M610 saved 50% on cycle time and 80% on costs. Tool life went from 400 engine blocks to more than 4,000 engine blocks.

5) What are some machining strategies that optimize productivity with these newer tools?

M5Q90

Programming strategies, such as roll-on and roll-off techniques when entering the part, create a smooth corner radius by engaging the cutter correctly. Don’t run the toolpath in the center of the cut/part. These techniques benefit surface quality and reduce the marbling effect that can sometimes occur when machining aluminum castings because of their high silicon content. Most of the major CAD/CAM providers are aware of these cutters and have added toolpaths and programming support for them.

For more information: www.sandvik.coromant.com