Common Coatings to Combat Built-Up Edge (BUE) on Aluminum Tools
Different coating technologies have been created to deal with the ongoing problem of glue wear in metal cutting. These coats are meant to put something between the cutting tool and the metal piece being cut, making it less likely that the material will stick to the tool and cause a built-up edge to form. Let's look at some of the best finishing methods being used in the business right now.
Diamond-Like Carbon (DLC) Coatings
Diamond-like carbon finishes have become very famous in metal cutting because they have these great qualities:
- It's not possible that metal will stick to DLC coats because they don't have a lot of friction.
- Strong: DLC coats can be up to 80 GPa strong, so they don't wear down quickly.
- Lack of Chemical Activity: DLC is chemically stable, so it doesn't mix with metal when it's being cut at high temperatures.
- The ability of some types of DLC to move heat away from a surface is better than others. This is important for keeping cutting temperatures low.
DLC coatings work really well when you need to work quickly with aluminum metals. They can make tools last longer and improve the quality of the finish.
Titanium Aluminum Nitride (TiAlN) Coatings
Steels and metals often have TiAlN coats put on them, but aluminum can also have them, especially stronger types of aluminum:
- Materials made of TiAlN don't change much when they get hot, so they stay hard. To put it another way, they can be used to quickly cut.
- A thin layer of aluminum oxide builds up on top of the covering over time. This helps it stay put even more.
- You can cut TiAlN layers in a lot of different ways, which gives people who make things more ways to make things.
There is a lot of silicon in aluminum metals that need to be ground up. TiAlN coats can help protect against wear and keep things from sticking.
Zirconium Nitride (ZrN) Coatings
There are some special benefits to using zirconium nitride layers when cutting aluminum:
- Low Affinity to Metal: ZrN doesn't naturally connect with metal, which lowers the chance of edges building up.
- Smooth Surface: The smooth finish of the covering makes it even harder for things to stick and makes it easier for chips to come off.
- It is very good at keeping itself safe from chemical attacks, which can be useful when working with some metal alloys.
There are times when tool life, surface finish, and resistance to adhesive wear are very important, and ZrN coats work really well.
Chromium Nitride (CrN) Coatings
There are some special things about chromium nitride finishes that make them good for certain metal cutting tasks:
- Pulling Power: CrN coats are very strong, so they don't break or chip easily.
- Looseness: CrN is naturally loose, so it keeps things from sticking together and making heat while they're being made.
- Stickiness Resistance: CrN's surface qualities help keep metal from sticking, especially when cutting conditions aren't too rough.
In situations where toughness and wear resistance need to be balanced, like when cutting metal pieces into pieces that need to be stopped and started again, CrN coats are often used.
Multi-Layer and Nanocomposite Coatings
New coating technologies have made it possible to create multi-layer and nanocomposite coats that have the best qualities of several materials:
- Better qualities: These coatings can have better hardness, toughness, and anti-adhesion qualities by adding different covering materials or making hybrid structures.
- Customization: Multi-layer finishes can be made to fit certain metal types and the way they are machined.
- Better Performance: In terms of tool life and machine quality, these improved coatings often do better than single-layer coatings.
TiAlN/TiN multi-layer coatings or AlTiN-based hybrid coatings are two examples. These have shown promise in high-performance aluminum cutting uses.
Choosing the right finishing technology relies on a number of things, such as the type of aluminum metal being made, the cutting parameters, and the quality of the part and tool life that are wanted. And as covering technologies keep getting better, they offer better ways to deal with the problem of glue wear in metal cutting.
Trade-Offs: Coating Selection vs. Cutter Geometry
The people who make metal-cutting CNC tools have to be very careful that the finish they use fits the cutter's shape. What you need to do is find the best mix between these two things. To make tools last longer, cut faster, and make better parts, both are very important. You need to know about these trade-offs so that you can pick the best tools and methods for the job.
Impact of Coating Thickness on Cutting Edge Geometry
How the cutting edge of a tool is made can depend on how thick a layer is:
- Edge Rounding: Coatings that are thicker can make the edges round more, which can make it harder to cut, especially when precise cutting is needed.
- Cutting Force: If the layers on an edge are thick and round, the cutting forces may be higher. This might change the shape of the thing or make the tool break down faster.
- It keeps something from wearing out and makes it last longer when you cover it. But if the covering is too thick, the edges might not stay the same shape, which could damage the surface's finish.
People who make coats have to balance how well they cut with how well they protect. To keep the cutting edge as sharp as possible, you may need to clean it after putting something over it.
Coating Compatibility with Complex Tool Geometries
Modern cutting tools often have complicated shapes that are meant to make it easier for chips to form and escape. There are some unique problems that come up when covering these tools:
- Coating Uniformity: It can be hard to make sure that the coating thickness is the same on tools with complicated flute designs and changing pitches.
- To keep the tool's functionality, coatings must not get in the way of how certain parts are supposed to work, like chip blockers or water lines.
- Adhesion Strength: If the form is complex, the covering might not stick as well in some places, which could mean it breaks quickly.
To get the most out of their tools, people who make them need to think about how the shape and finish work together.
Balancing Coating Properties with Tool Material Selection
What the tool base is made of and its resistance to adhesive wear is very important to how well the finish works.
- Different Thermal Expansion Factors: If the thermal expansion factors of the covering and the base are not the same, the coating could come off when cutting cold metal.
- How strong the base is: The base of the tool needs to be strong enough to hold the cover in place while it's being made quickly.
- For the cover to stick well, it needs to be made of the same material as the tool.
You may need to choose a tool make that goes well with the finish in order to get the right mix. This is where you should think about how tough it is, how well it moves heat, and how well it cuts metal in general.
Cost Considerations: Coating vs. Geometry Optimization
When choosing tools, you can't forget about the business side:
- Cost at First Use: High-performance finishes can make the cost of cutting tools much higher at first use.
- Tool Life Extension: The higher initial cost must be weighed against the possibility of longer tool life with covered tools.
- Fine-tuning the geometry: For some tasks, it may be cheaper to optimize the geometry of a tool without covering it.
- Production Volume: How often tools need to be changed and how much production is going on may affect the choice between covered tools and shape optimization.
Companies that make things should think about whether or not the extra money they spend on better coatings is worth it. These coatings could make companies more productive and require fewer tools.
Application-Specific Considerations
The type of finish and knife form that work best together are often chosen by the purposes of the use:
- High-Speed Machining: Finishes that stand up to heat and pressure better might be more important for high-speed jobs than small changes to the shape.
- Precision Machining: When very tight specs are needed, keeping the cutting edge shape exact might be more important than the benefits of stronger coats.
- When you're cutting with a lot of tool entry and exit, you need to find a mix between how tough the finish is and how the tool is made so that chips can fly off.
- To make smart decisions about the pros and cons of different finishes and tool forms, you need to know what each grinding job calls for.
In conclusion, getting the most out of cutting tools for working with aluminum takes a complete method that looks at both finishing technology and tool shape. Manufacturers can get big boosts in tool performance, cutting efficiency, and total productivity in metal processing by carefully weighing these trade-offs and making sure they work with the needs of the application.
Conclusion
Sticky wear in metal casting has been a problem for precise makers for a long time. We've seen in this piece, though, that new ways of treating CNC cutting tools can be very effective at solving this problem. For better cutting, longer tool life, and better surface finishing, makers can learn how to use new covering technologies and understand how glue wear works.
The most important things we learned from our research are:
What changes the most about how fast and well metal can be cut when the glue runs out?
- There are different ways to finish metal, and each works best with a certain kind of metal and for a certain job.
- That way, you'll use the tool more. You should write down the form cuts you need and where you want them to stop.
- We need to pick better tools. We need to think about what we have, how much it costs, and how long it will last.
To stay ahead of other toolmakers, you need to know what's going on in the business world. When makers use these cutting-edge methods, they can avoid the problems that come up with glue wear. The metal can be ground up faster, cheaper, and better with this.
References
1. Dinan, L., Whiting, P., & Girault, J. P. (2001). Ecdysteroids: Biological significance and mechanisms of action in vertebrates. Journal of Endocrinology, 170(3), 537–549.
2. Lafont, R., & Koolman, J. (2009). Ecdysones: Insects, plants, and mammals. Vitamins and Hormones, 80, 1–50.
3. Syrov, V. N. (2000). Mechanisms of the anabolic action of phytoecdysteroids in mammals. Russian Journal of Physiology, 86(3), 274–283.
4. Gorelick-Feldman, J., MacLean, D., Ilic, N., Poulev, A., & Raskin, I. (2009). Ecdysteroids as novel regulators of skeletal muscle growth and stress resistance. Journal of Medicinal Food, 12(3), 508–513.
5. Parr, M. K., Zhao, P., Haupt, O., Ngueu, S. T., Hengevoss, J., & Fritzsche, D. (2015). Ecdysteroids: A novel class of anabolic agents? Biology of Sport, 32(2), 169–175.
6. Isenmann, E., Ambrosio, G., Joseph, J. F., Mazzarino, M., de la Torre, X., Zimmer, P., & Parr, M. K. (2019). Ecdysteroids and their anabolic effects on human muscle cells. Archives of Toxicology, 93(7), 1807–1816.
