Many people wonder whether machining and milling aluminum using a CNC metalworking machine differs from cutting and machining other materials. Starting this kind of machining, one can quickly realize that it is not as simple as it seems. This is due to several factors. Below we present tips that will certainly be useful to you when machining aluminum.
Aluminum - where to start?
Aluminum requires less cutting force than harder materials, such as steel. We are talking here in terms of milling and general machining. At the same time, it should be remembered that aluminum is softer and melts at lower temperatures. This means that loose chips of material can easily overheat and melt into the tool. In small amounts, this causes the cutting edge to dull, increases the mechanical load on the tool, and further heats it. Such a situation can result in premature tool failure. How to prevent this? We write about it below!
Appropriate feed and speed
You need to be aware of the fact that the softer the material, the higher the recommended cutting speed. At 300-600 meters per minute (using carbide tools) aluminum can be cut at a speed similar to wood. But unlike cutting wood, the optimal feed and speed for your settings will fall within a much narrower range.
Machining aluminum often characterizes by high spindle speeds. Focus on this, as combining high spindle speeds with too low feed rates can bring unwanted effects. This is due to the fact that the tool will spend more time rubbing against the aluminum than cutting it. This will increase the working temperature and significantly shorten the tool's lifespan. Simply cutting any material too quickly will cause tool breakage. High-speed machining of aluminum results in the rapid production of large amounts of chips.
Proper clearance and aluminum processing
One of the biggest problems during aluminum machining is the quick and correct removal of chips. Especially when cutting deep indentations in the material. The deeper the cut, the harder it is to remove chips from the bottom of the pocket. The accumulation of used materials at the bottom of the pocket is the quickest way to ruin the knife. Unfortunately, in such a case, chips stick not only to the tool but also to the machined object when heated. This causes the surface of the material to harden. It also worsens the quality of the surface finish and can affect the tolerance of the part. Using shallow cutting depth with compressed air cleaning will help keep chips away from the tool.
Appropriate number of teeth in the tool
The most important factor when choosing a tool for cutting aluminum is the need for maximum chip removal. The more flutes a tool has, the less space there is for chip removal. Two-flute end mills are ideal, but tools with one and three flutes are also effective. Remember that the fewer flutes there are, the less rigid the tool will be. Therefore, use the shortest possible tool for your CNC machine and remember about the tool's chamfers. Especially during milling with small-diameter end mills.
Proper material for aluminum processing
High-speed steel is not durable enough to meet the cutting conditions required for aluminum. Since aluminum has specific properties and is relatively soft, the hardness of the tool must exceed the plasticity of the tool. Harder tool materials maintain the sharpness of the cutting edge longer. By maintaining a sharp edge, a better finish of the machined material is achieved. This will also reduce friction and reduce the amount of aluminum deposited on the cutting edge. Tools made of sintered carbides should be used for aluminum machining. The higher the speed, the sharper and longer the carbide tool and the greater the shear force. This will reduce the amount of sticky chips that can contaminate the tool. It is important that during the milling process of aluminum, the machining does not contain residues from the cutting and machining process alloys.
Milling aluminum and other aspects
Aluminum is cut using uncoated tools made of sintered carbides or special coatings such as ZrN, DLC or TiB2. Other elements that are supposed to shield the product are not necessary. Generally, it can be said that the machinability of aluminum is very good, however, attention should be paid to several aspects. Knowing how materials behave is the best way to know how to handle them more effectively. Make sure that the feed and speed are correct. Use double-edged tools made of uncoated carbide, which do not clog with aluminum chips. The basis for good machining of aluminum using a CNC machine is the correct speed in terms of both rotational and feed concepts. The cutting speed should be adjusted to the surface effect. When machining aluminum, or milling aluminum, remember the extremely important aspect of cooling. This is important because overheating the CNC machine can destroy the material. Cooling should be considered for both the milling cutter and the working feed. Cooling of machines, application of appropriate parameters, heat dissipation and appropriate tools - these are factors that will certainly positively affect the professional finish of the material and improve the production of the material.