Five Strategies for Extending Tool Life in Indexable Milling

By Rick Crabtree 

 Speed. Efficiency. Performance. These key factors guide decisionmakers at automotive manufacturers as they face production demands and tighter deadlines. Particularly in shoulder and face milling operations, where components get their critical edges and surface finish, every productivity gain counts. 

But where does cutting tool life fit in? In the realm of indexable milling tools, focusing on reducing tool wear can usher in a host of additional benefits. The more durable and dependable your cutting tool inventory, the less time you spend swapping out inserts and the lower your cost per unit. In this way, extending the productive life of your milling tools is an effective strategy to gain a competitive edge. 

 The Challenge 

As aluminum captures an increasing share of both internal combustion engine (ICE) and electric vehicle (EV) automotive components, indexable milling operations meet several hurdles in dealing with this material. Vibration in the machining process can create imperfections and scars in the component while slowing down operations and wearing out tools. Similarly, surface conditions in the cutting zone, such as temperature and chip formation, greatly impact the quality of the finish and the replicability of machining the part. Addressing these factors will not only help manufacturers create more reliable components but also prolong the life of their tools. 

 Strategies for Extending Tool Life — and Boosting Productivity 

1. Leverage the strength of polycrystalline diamond (PCD): The proliferation of laser technology allows cutting tool manufacturers to produce more exact shaping of PCD inserts, resulting in sharper and truer edges. Whether shop owners elect to use a solid PCD insert or simply a PCD-coated carbide insert, the added strength and precision will enhance accuracy and prolong tool life. This adjustment is particularly relevant when machining aluminum with a high silica content or other metal additives like copper or titanium. Know your material and equip your inserts to handle it appropriately.
   
2. Consider the tool body: While many tool bodies are constructed from aluminum, opting for machine heads that employ a steel ring surrounding the indexable pocket can help reduce chip wash and boost tool life. Avoid direct aluminum-to-aluminum contact wherever possible.
   
3. Utilize dampening devices: Handling the vibration challenge is paramount. Solutions like Sandvik Coromant’s SilentTools™ tool holders effectively absorb shock from the cutting zone and alter the frequency of the vibration, with some users seeing significant increases in productivity as a result.
   
4. Expand your coolant arsenal: The obvious first choice for indexable milling operations is high-pressure coolant. This keeps the cutting surface at a suitable temperature and can help wash away chips as they form. However, the coolant conversation is evolving rapidly, particularly in EV applications. To avoid leaving semiconductive coolant residue in components like battery trays, some manufacturers are bypassing coolant altogether, potentially at the expense of tool life. Instead, try implementing minimum quantity lubrication (MQL) or even pressurized air to help stave off insert wear and maintain the integrity of the component.
5. Choose innovative solutions: Standard cartridge-based cutters can create sizable burrs and variable insert wear patterns, both of which can lead to premature tool wear. Instead, select tools that offer predictable, smooth finishing. For example, Sandvik Coromant’s M5B90 face milling cutter for aluminum uses a rotary broach technique to provide burr-free machining and outstanding surface finish at high feed rates. In one case, a customer using the M5B90 for automotive cylinder heads increased their tool life from 30,000 components on average up to 45,000 components. 

 By facing the vibration challenge and cutting zone conditions head-on through the lens of tool life, shop owners will see a commensurate uptick in component quality, surface finish and ultimately, total production. Whereas some machine shops view tool life as a nice-to-have, it’s worth reframing this as a top priority and a means to achieve every other operational KPI.