Aluminum is a material that is globally used, in many different applications; from marine vessels and automotive manufacturing to sign making and flagpole production. Aluminum’s unique properties of strength combined with light weight and its ability to be corrosion resistant makes it one of the most desirable and economical materials to use in manufacturing and fabrication.
To understand how best to cut or mill aluminum, it is important to understand, “what exactly is aluminum”? This non-ferrous metal is “softer” comparably to other metals such as steel. This softness makes aluminum a suitable and desired material for many applications where strength and durability are needed, but extreme hardness is not. Because of these properties, aluminum can be easily machined, cut and formed using the right tools and procedures.
Techno Blog | Sept 2024
Most people who have tried machining aluminum for the first time understand very quickly that aluminum can be very sticky; welding itself to the cutting edge, inevitably breaking the tool if not stopped. This occurs as a result of a number of variables, including heat, cutting force, and friction generated. To put these variables in check and prevent the aluminum from sticking to the cutting tool, machinists and programmers use numerous strategies, fixturing, and tooling to achieve an optimal chip load and to ensure proper chip evacuation from the cut. Below are some of Techno CNC’s “goto” tips and tricks for optimizing cut quality in aluminum, as well as maintaining the sharpness of the cutting tool:
1. Tooling, Tooling, Tooling
Selecting the right cutter is crucial for any machining product, especially a metal like aluminum. Choosing the wrong tool can be a set up for failure before the cut even starts. For aluminum, Techno CNC recommends a specific type of spiral oflute tool specifically designed for aluminum cutting and chip evacuation. These tools are single flute cutters, allowing plenty of room within the cutter for chip evacuation. Look on the website for any cutters starting with the part # “AL” and you will have found yourself the proper tool for cutting aluminum on a CNC router. Browse aluminum cutting CNC router bits here.
2. Coolant Makes Life Much Easier
Whether you are using a spiral oflute tool or choosing to dial in a standard endmill for routing aluminum, using a lubricant or coolant on the tool while it is cutting will ensure the tool and the material are maintaining a reasonable temperature. Coolant also ensures that chips do not stick to the cutter, causing chip welding, and are easily evacuating up and out of the cutting channel. Techno CNC offers a magnetic and a stand-alone micro drop coolant system for these applications as well as replacement coolant available in 1-gallon containers.
3. Calculate Proper Feeds and Speeds
Good feeds and speeds are critical to the cut quality of your parts and the longevity of your tools. With Techno CNC Tools, you have access to chip load data, charts, and formulas used for calculating feeds and speeds for a variety of materials. Don’t be shy; you can also call Techno CNC and speak with an expert applications engineer. Unlike most manufacturers, Techno is confident enough in their tooling and their expertise to advise and walk you through making the right feeds and speeds calculations with their tools.
4. Fixturing is Key
Even with the previous 3 tips and tricks dialed in perfectly, if your parts aren’t held down or fixtured properly, you are doomed for failure. Though aluminum is a soft metal, there are still a lot of forces involved with cutting. Any movement of the piece or vibration on the material can cause poor cut quality or damaged/unusable parts. Your fixturing strategy really all depends on the application. For thinner sheets of aluminum, Techno CNC offers vacuum pumps that draw air through a sacrificial board, holding the sheet goods down tight to the material, preventing any movement or vibration. For thicker, smaller chunks of metal being machined, there are numerous vice set ups and clamping mechanisms available to keep material held solid, allowing for a rigid cutting surface.
5. Steel Machines are the Best Machines
As you can imagine, with the cutting forces involved with milling a metal like aluminum, you will need a good foundation to optimize a cut and have your tools perform well. When cutting aluminum, there is a ton of vibration that is produced. Part of the vibration is absorbed by the material, as long as it is fixtured well, but the majority of the vibration is absorbed by the machine’s spindle, and then transferred throughout the rest of the machine. A CNC machine with a heavy, all steel constructed and welded framework is a necessity for getting good clean cuts through aluminum at efficient feeds and speeds. That heavy steel does nothing but absorb the vibrations produced from a cut and ensures the spindle head stays firm, preventing any tool deflection and premature failure of the tool or spindle. ALL of Techno CNC machines are built just that way. Ranging from a 1500 lb tabletop unit to a 20,000 lb 5 axis machining center, Techno CNC builds their equipment to accommodate manufacturing at any level and guarantees superior cutting experience.
6. Take Shallow Passes
When cuts are too aggressive, spindles can bog down, machines can vibrate, and heat build up can generate; all factors that effect cut quality in a not so good way. Depending on your set up and the type of spindle you have, taking shallow passes, or multiple passes through material to finish your cuts can be a great way to reduce heat, keep cutters sharper longer, and maintain good cut quality across a project. Multiple passes can also help with dust collection and chip removal which we know is key to maintaining your tools and keeping cut quality at a high level.
7. Check your Tool Sharpness
Aluminum can be hard on tooling. It is abrasive in a sense. Checking the tools sharpness is a good habit to get into. It can be easy to forget about when you are cutting multiple projects using the same tooling and everything seems to be going great. A dull tool can easily change that experience; forcing a project to be scrapped, break, or even cause injury, which leads us to our next tip.
8. Stay Safe
Cutting aluminum can produce a number of hazards. Hot chips are flying off the machine at an elevated rate. ALWAYS wear protective safety goggles. Always make sure your skin is covered and loose hair and clothing are secured. Being safe while routing aluminum always makes the experience much better for any end user.
9. Always Run Test Cuts First
The worst feeling is spending money on materials to complete a project, try to run the project, and end up having to scrap the piece and purchase more because the cut did not come out the way it should have. Running test cuts before routing projects helps avoid this. Use scrap materials, run small programs, and make sure all of the machine parameters are dialed in prior to running on the main material. This will help reduce the time of processing and wasted costs on scrapped pieces.
It is important to remember that each CNC machine and the grade of aluminum can be different and experimenting with those combinations is often necessary. To be successful in machining aluminum, it is crucial to address the challenges discussed previously. Using the right tools, calculating proper feeds and speeds, adding coolant to the mix, evacuating chips, fixturing your parts, and using a heavy, rigid machine set up will all help alleviate any difficulties with addressing any of those challenges. I hope this blog is a great tool for you to get started with your aluminum cutting projects and I thank you for reading! Happy Routing
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