Milling aluminum appears to be a very easy process. This is often the case with people who are not directly involved in aluminum machining. They believe that a balanced, sharp, polished tool spinning at maximum speed and set at moderate feed rates is enough to cut aluminum like butter.
Aluminum Machining Characteristics
Compared to steel machining, aluminum and aluminum alloys require less cutting force, so the mechanical load on the milling cutter cutting edge is relatively low. In this article, we will simply refer to aluminum and aluminum alloys as aluminum. Aluminum has a high thermal conductivity, so the chips generated during aluminum machining conduct a lot of cutting heat, resulting in a significantly reduced thermal load on the cutting edge. Due to these properties, aluminum milling can be characterized by very high cutting speeds and feeds. However, this does not guarantee that aluminum milling will be easy.
The material properties of aluminum lead to the formation of built-up edge (BUE) during cutting. This unpleasant phenomenon increases the mechanical load on the cutting edge, making efficient chip evacuation difficult. It also affects the dynamic balance of the rotating tool, making the entire process inefficient.
Using the wrong tool can also affect aluminum chip evacuation. The long chips generated during aluminum milling can clog the tool if the tool flutes do not have enough space for the chips. To overcome this obstacle, tools with fewer teeth or reduced cutting parameters are used; however, this behavior has a negative impact on productivity.
From a machinability point of view, aluminum is not a uniform material. Alloying elements (especially silicon), material type (forged, cast) and material preparation methods all affect cutting performance. Other factors such as workpiece shape, tooling conditions and machining requirements (precision, roughness, etc.) increase their own machining limitations and are necessary considerations when choosing a machining strategy and tool selection. Therefore, in many cases, aluminum machining in general and aluminum milling in particular is often not as simple a task as it seems.
Milling Tools for Machining Aluminum
Tool manufacturers need to consider the specific characteristics of aluminum milling tools when developing tools. The key to success is to find the right combination of cutting geometry, tool material and edge preparation, and to optimize the coolant supply.
When considering aluminum milling applications, large aircraft components such as wing components, cabin doors, cabin window frames, etc. cannot be avoided. Typically, these workpieces are made from a single piece of material, often weighing several tons, and often require 80-85% of the material to be removed to obtain the desired final shape. In contrast, the global automotive industry, which is also a major consumer of aluminum, has introduced a large amount of hard cast aluminum materials into its parts. Although this has led to improved corrosion resistance for these parts, it has the negative effect of more wear on the tools.
SAMHO, a full-line SHD series supplier, has developed a complete range of end mills specifically designed for efficient aluminum machining. Each series of these high-quality tools features a monolithic or lightweight body design, a unique carbide insert clamping mechanism principle, a toolholder with an adjustment structure, a variety of ground and polished tools with different corner radii, and inserts with polycrystalline diamond (PCD) tips, which are very popular in aluminum machining. The SHD series of end mills enable efficient high speed machining (HSM) of aluminum, ensuring high metal removal rates (MRR), high precision and excellent surface quality, meeting all the quality requirements of aluminum component manufacturers around the world.
The metalworking industry manufactures large to small aluminum components, and in many cases requires more modestly sized milling cutters. The size of these tools is not suitable for clamping indexable inserts, and solid carbide tools have a clear advantage. In addition, the high precision of solid carbide end mills makes them unmatched in the precision machining of large components. Therefore, SAMHO remains actively involved in the design and development of advanced solid carbide aluminum milling tools. The latest innovative additions have further enriched the tool product range, once again improving the value brought to users in the global industrial field.
SANHO’s SHD series of solid carbide end mills with four teeth are designed for rough milling operations at high metal removal rates. The technologically innovative end mills have serrated cutting edges that can tear wide chips into narrow chips that are easy to discharge. This design feature, combined with the polished grooves, significantly improves chip evacuation, allowing a significant increase in productivity. The serrated cutting edge not only splits the chips but also improves vibration resistance. The necking design helps to improve cutting stability in machining with large tool overhangs.
Why are most milling cutters only available with three teeth, and not with more teeth? The generation of tool chatter and unwelcome vibrations is the primary and most important factor in the milling of aluminum. Various studies and metalworking practices have shown that the three-tooth structure is the optimal design for solid carbide aluminum milling end mills with a 90° main rake angle. In efficient milling, this layout ensures the chip pocket volume, which is also necessary for chip flow, without increasing tool vibration. The mainstream of aluminum milling end mills is based on this.
However, the desire to improve milling productivity prompted SAMHO to develop a technologically innovative four-tooth end mill. The SHD end mill series, with an additional tooth compared to the three-tooth milling cutter, helps to increase the metal removal rate (MRR) in both roughing and finishing operations. Despite their four-tooth construction, these end mills have impressive vibration resistance, thanks to the combination of unequal helix angles and unequal tooth pitches. In addition, SAMHO’s tool designers have succeeded in creating a four-tooth milling cutter with a core diameter and flute cross-sectional area similar to existing three-tooth end mills of the same diameter.
The mold and die industry and the aerospace industry require small-diameter milling cutters for precision machining of three-dimensional surfaces. SAMHO’s latest solid carbide ball nose end mills with polished flutes and a diameter range of 1-6 mm are designed for such demanding and precise needs.
The Transformer end mill series of combination tools, including different configurations and a variety of replaceable milling heads, are ideal tools for milling aluminum, especially in applications that require large tool overhangs. Large overhang solid carbide end mills are made from high-cost carbide bars with a considerable overall length. Although only the head part of the end mill is directly involved in cutting, it is the entire expensive bar that is discarded after the tool wears or breaks suddenly, which brings obvious economic disadvantages. In contrast, in such cases, users of Transformer end mills only need to replace the cutting head.
In summary, it is fair to say that milling aluminum is easy. But the premise is to process it wisely! Applying efficient processing strategies and correctly using SAMHO’s selected milling cutters can achieve practically successful processing results.