A survey from 2017 by Ducker made major revelations about the magnitude of growth in usage of aluminum in the automotive sector. It quoted a projected increase of 42 percent in the usage of aluminum in passenger vehicles by 2028. And these are definitely not just numbers proving the point. The increased use of machined aluminum in the news around us, whether it is about the Tesla’s models S and X or light pickup trucks like the Chevy Silverado, proves the exponential rise in its usage. Due to this rapid rise and projected growth, a large number of companies are offering various services regarding milling aluminum and overall machining for aluminum parts.
However, it is vital for you to know which factors play a crucial role in determining which service to go for and we will help you with that throughout this article.
Aluminium Properties
Before diving into the specifics of aluminum machining, let us first have an insight into why aluminum is so useful. The following diagram summarizes the main advantages of using aluminum.
Resistance to Corrosion
Aluminum boasts remarkable resistance to corrosion and chemical damage. Al-6061, which is a popular aluminum grade for CNC machining, has remarkable resistance to oxidation and chemical damage. However, stronger aluminum alloys which consist of copper for instance are not as resistive to corrosion. So, choosing an aluminum alloy is about analyzing the chemical composition and weighing the decision based on strength vs corrosion resistive properties.
Optimal Strength to Weight Ratio
Al-6061 and Al-7075 are good examples of aluminum alloys with extremely favorable strength to weight ratios for the automotive industry. Aluminum is not only a high-strength material but also lightweight simultaneously. Therefore, grades like 6061 are used for creating machined aluminum parts requiring average strength while 7075 is used to machine parts requiring robustness. The strength to weight ratio for aluminum is 1/8 which is twice that of steel.
Good Electrical Conductivity
CNC milling and machining of aluminum parts is adapted in the electronics industry to manufacture some electrical components where the cost of development is more important than achieving very high electrical conductivities. The electrical conductivity of aluminum is 37.7 million siemens per meter. Although this value is considerably lower than copper’s electrical conductivity of 59.6 million siemens per meter, it can still be considered as an option for non-critical electrical components since its cost is lower. Moreover, aluminum is considerably more conductive than several other materials like carbon steel and stainless steel.
Recyclability
Milling aluminum or in general aluminum machining means a lot of waste in form of metal chips. If your business is striving for recyclability, usage of aluminum will help in the reduction of material wastage due to its high recyclability. Astonishingly, aluminum can be recycled indefinitely! Unlike plastics, recycled aluminum is not downgraded in the recycling process. This is why companies like Apple, PepsiCo, and Coca-Cola majorly rely on the usage of recycled aluminum to fulfill their commitment towards a greener tomorrow as well as increase their profit margins. ( Common issues in milling aluminum and tips to avoid them.)
Machinability
The most important factor in choosing aluminum as your go-to material is the ease of machining it. Whether it is the business ordering the part or the machining service offering its expertise, aluminum offers a win-win for both. Aluminum machining, shaping, milling, and other processes, all are really cost and user friendly. Short machining times makes it way easier and cheaper to consider aluminum as the best choice. Furthermore, good machinability means less deformation of the part by the cutting tool. Thus, easier machinability enables tighter tolerances along with precision, accuracy, and repeatability.
Also, you may be interested in another blog: Know Your CNC Aluminum Machining For Maximum Profitability
Anodization
You must have come across aesthetically wonderful looking windowpanes which are so common these days. The use of aluminum is common in applications where aesthetics plays a major role. It can be anodized to provide a fine surface finishing that thickens the oxidized layer on the aluminum. This process helps to give aluminum unique colored outlooks along with more resistance to corrosion and wear and tear.
Increasing Use of Aluminum in the Automotive Industry
There are some key factors that are breeding the growth in usage of aluminum in the automotive industry:
- An increase in demand for luxurious vehicles means the installation of more systems. For instance, heavier entertainment systems, car refrigerators, peripheral vision systems, and installation of other items mean more weight to the car. Simultaneously, there is a demand for more fuel efficiency too. So, to keep both advancements parallel, automotive manufacturers are increasingly moving towards the use of aluminum and aluminum alloys to meet tight constraints. Thus, consumer preference drives evolutionary measures in the industry.
- The most important factor in the increased usage of aluminum is the rise of electric vehicles. Most certainly, the major win factor for the success of an electric vehicle is range. Lighter the body, the more the range on a single charge. Decision-makers and manufacturers weigh in the cost of going for an all-aluminum body vs. an increased battery size. More commonly, they go for an all-aluminum body since battery technology is still very expensive.
Key Notes in Aluminum Machining
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As a decision-maker, it is really important for you to know the issues faced in aluminum machining and how to avoid them. While aluminum has remarkable machinability, it does not necessarily mean this is always good. Good machinability means less hardness and high thermal expansion factors which makes aluminum really deformable when thin parts are involved. So, let us brief you with the keynotes to take care of when machining aluminum.
Thermal considerations: Heat has an adverse effect on the quality of a finished part. The amount of heat generated must be dissipated on a larger surface area in order to reduce the intensity and ultimately avoid thermal deformations. This is possible by the use of symmetrical machining. To help you understand this phenomenon, let us take an example of milling aluminum parts using face milling. The following diagrammatic comparison makes understanding a lot easier. As you can notice, the surface area of the workpiece in contact with the cutter is larger in the symmetrical case which makes the heat dissipation value in W/m2 less than the 2nd.
Twisting of cavity walls: Uneven distribution of force during machining operations is a widespread issue. Specifically, when machining of aluminum plates with cavities is involved, uneven force distribution leads to distortion and twisting of the cavity walls due to high torsional stresses. To counteract with this dilemma, stratified multiple machining is incorporated. This method follows a layer by layer approach. This helps in a more even distribution of force on the aluminum part thus reducing torsional stresses that cause twisting or distortion.
Selection of optimal cutting parameters: Efficient machining requires landing at optimal values of cutting parameters that provide appropriate cutting forces yet reduce heat dissipation to reduce distortion in manufactured parts. If it is about milling aluminum, back-cutting depth plays a key role. Back cutting happens due to tool run-out or uneven tool wear because of machining in two directions over the same workpiece. So, professional CNC machining service providers can provide solutions to this dilemma by use of CNC high-speed milling that increases processing efficiency and reduces the unnecessary magnitudes of cutting forces. Moreover, cutting tool parameters like front angle, rear angle, helix angle, main deflection angle and others need to be optimally selected too.
Pre-drilling followed by milling: Performing machining operations on parts with cavities is always a challenge. Application of a milling cutter does not guarantee a good finish due to insufficient debris space of the milling cutter. Consequently, excessive heat dissipation, deformation and failure of parts may occur. The solution to this is pre-drilling. Drilling with a tool of the same diameter as the milling cutter before actually starting the milling operation saves the day with regard to the finish of the end product.
Thin-walled aluminum parts: Aluminum machining of thin-walled parts is a challenge in itself. Machining requires clamping of the workpiece. However, clamping thin-walled aluminum parts might cause deformations. So, a two-stage compression method is used in this case. In the first stage, machining is performed while clamping the workpiece normally. However, before finishing the final dimensioning, the workpiece is unclamped, and it is clamped in the direction of greatest material rigidity. While this may sound simple, it requires the experience of operators belonging from reputable prototyping services to handle the machining of thin-walled aluminum parts.
The Verdict
The considerations in the machining of aluminum parts are surely diverse. It not only requires experience but also credibility and reputability of providing quality aluminum machining matters a lot. If your business is striving for quality aluminum parts, you can surely contact us for quality CNC prototyping and machining services at the most optimal rates.
