In this article, you’ll learn how aluminum machining works? and how to machine aluminum alloys effectively, explained everything with practical tips.
Aluminum Alloys are one of the most convenient materials to work with, making it the most common “go-to” material for many applications in a wide range of industries.
In addition to its excellent machinability, aluminum offers a diverse number of alloys and grades that perfectly cater to different demands, from rapid prototypes to precision applications. CNC Aluminum machining boasts a lot of extensive benefits, be it from a cost and material integrity perspective.
Sure, machining this material is easier than most metals out there but it is not always the case. A number of machine shops are facing problems in maintaining the efficiency of their process in machining aluminum alloys.
Some would still struggle thinking about what went wrong along the way that might have caused problems. There are several factors to consider when working with aluminum that are unique from other metals.
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Why Many Choose Machining with Aluminum
Aluminum Alloys are one of the lightest metals that is machinable. With a density range of 2600-2750 kg per cubic meter, Aluminum alloys are around 2.5 times less dense than steel.
One reason why automakers and aviation manufacturers choose aluminum alloys as their material is because of its promising strength to weight ratio. Alloys within the 7000 series have a strength of up to 72,000 pounds per square inch.
Fun fact about aluminum alloys: Theoretically For alloys in the 7000 series, a 300-inch diameter of aluminum wire can suspend a mid-sized SUV.
High Machinability Index
Aluminum is one of the metals with the highest machinability index, making it around three to ten times more machinable than steel. With high machinability index, it is easier to achieve the desired surface finish without going through farther extents of additional processing like that of the harder metals.
One thing about aluminum is that it doesn’t contain iron, which means this metal is safe from the damages that might result from the oxidation of metals. Some aluminum alloys might corrode, but mostly, this corrosion will not be detrimental to the metal itself.
Capability to be Anodized
Aluminum is one of the few metals that are can be anodized. Anodizing such materials would bring forth improved surface finish,improved resistance to corrosion, improved life span, and add a unique array of color.
Aluminum alloys are less expensive compared to other metals that offer similar properties. Aluminum is the most abundant metal in the world making it accessible and cheap. Furthermore, processing this material is not that hard compared to steel making it the most economical material to work with.
Practical Tips to Effective Machining of Aluminum Alloys
Aluminum Alloys in general have the highest machinability rate but many fabrication shops are machining aluminum in such a way that it may be detrimental to the tool life and the finished part as a whole.
It is crucial to choose the right tools, parameters, and set-up to maximize the benefit of processing this metal in order to achieve maximum efficiency. Here are the common problems encountered and practical tips to achieve efficiency in machining aluminum alloys.
Problems Relating to CNC Machining of aluminum:
Trying to achieve the leanest process in machining aluminum could be quite hard because this involves pushing the machine and the tools to their peak performance without damaging these.
Some fabricators often get frustrated in reaching the optimum parameters for their process because in the midst of achieving the peak performance are countless failures including tool pull-up, tool deflection, tool breakage, chatter, and spindle stops.
The main problem that may commonly be encountered when machining aluminum is the adhesion of chips to the cutting tool when engaging with high speeds.
Disasters may arise because of this issue:
This might make the tool too dull to such a point that it would be just rubbing the metal rather than cutting it and as a result, it might melt and destroy the work part and may cause drastic problems for the tool and spindle when not supervised.
One thing that might cause adhesion of metal to the tool is the tooling selection. In the machining industry, it has been a rule of thumb to choose carbide cutting tools when dealing with aluminum.
The main reason for this is that aluminum might get too “sticky” and might cause build-up at the edge of the cutting tool. It is important to take note that not all carbide tools are perfect for machining this material.
Tools with high concentrations of cobalt may not be for machining aluminum because when temperatures get too high, the aluminum may react strangely with the exposed cobalt causing it to bond with each other, hence forming a buildup at the edge of the tool. Choose a cutting tool that is not easily dulled and the best one for this are carbide-tools with larger grains to sway away from higher cobalt contents.
Choose a cutting tool that is coated. These tool coatings include Titanium Nitride, Titanium Carbo-Nitride, Titanium Aluminum Nitride, Chromium Nitride, and other variants depending on the manufacturer. Tool coatings bring in much help for cutting performance bringing in improved hardness, improved wear resistance, and longer tool life.
Take a critical note of the flutes of the tool to be used based on the process it will be involved in. When dealing with the roughing process, chip clearance is a vital specification to be taken into account.
It is important to avoid the choking of the tools from chips in order to avoid material build-up and to avoid undesired finish left on the part. Endmills with 3 flutes is a nice choice to go onto because it has the necessary hardness and chip clearance needed when machining aluminum.
Take into consideration the helix angle depending on the process involved. When roughing, as the rule of the thumb, always use tools with the best chip clearance and cooling.
A 35-degree helix angle will work for this. When finishing on the other hand it is important to achieve a great surface finish and beautiful output. With this it is nice to use tools with a 45-degree helix angle, this will assure you of an accurate finish. On the other hand, when it is planned to use the tool for both roughing and finishing, it may be viable to go with the 40-degree helix angle.
Some fabricators like pushing the limits to achieve faster machining time and sometimes that desire bring in unpleasant results because of the aggression. Feeds that are too fast may have a result on the harmonics and rigidity of the cutting tool making it fail in the midst of the processing.
On the other hand, feeds that are too slow are not efficient and it would be a waste of time and resources. The feed rates and spindle speed would be relative to tooling specifications and parts dimensions. It is important to stick close to the theoretically proven parameters regarding CNC machining established in the Machining handbook.
Key Takeaways about Aluminum Machining
Aluminum machining itself is quite an economically efficient fabrication process for different purposes, but the rate of cost savings will shoot even higher when machining it the right way. Avoiding the issues when it comes to CNC machining of an aluminum alloy may contribute greatly to the cost avoidance brought about by efficient machining.
That’s it, thanks for reading. If you have any questions about “Aluminum Machining” you can ask in the comments. If you like this article please share it.
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