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Selection and Consideration of CNC Aluminum Parts Machining Tool

With the improvement of people's living standards, people are more and more fond of things with a metallic texture, which also makes aluminum products more and more used in many industries. It is a soft metal compared to steel and superalloys, HRC is not as hard but tougher. Therefore, the requirements for tools are relatively high. If you use a high-hardness tungsten steel milling cutter to cut soft metals, the cutting edge will break and the tool life will be short. High-quality knives with low hardness and non-stick knives are required to complete the machining. Only in this way can the knife increase the speed and efficiency of the machine.

How to choose machining tools for CNC aluminum parts?

In the finishing machining with small allowance, the cutting edge of the indexable insert is usually blunt, which often leads to the "plow" effect, and the cutting edge is also easy to suddenly cut into the workpiece, resulting in a sudden increase in cutting force. The sudden increase in cutting forces resulted in oversized tools and high power requirements. The above problems are compounded by the demands on the cutting edge. Finishing must be done with a sharp positive cutting edge. In order to ensure the metal removal rate during rough machining, the cutting edge is required to have sufficient strength. Therefore, consider cutting forces, cutting edge penetration, chip formation, stability, and insert positioning and clamping.

Machining Geometry

The ultimate goal of machining is to produce the best part that meets the design or customer-specific requirements. Specifications can be in the form of part thickness, load carrying capacity, and dimensions. CNC machines can handle aluminum parts of various sizes and shapes through efficient tool sequencing and manipulation. Increasing production requires the use of indexable tooling. This type of tool allows the operator to change the tool insert when necessary, enabling multiple automated machining of aluminum parts. CNC tool inserts with different cutting edges are available for post-processing operations such as polishing and grinding aluminum parts. In the CNC aluminum machining environment, the performance of the tool insert depends on the shape, relief angle and rake angle of the insert.

Processing shape

Tooling for CNC aluminum parts has specific geometries that affect the quality of the final product. Blades come in different shapes to fit specific CNC tool holders. Aluminum utility blades are available in diamond, round, triangular and square shapes. Better part quality can be obtained with sharp-edged inserts. For example, for high-speed surface machining of forged aluminum parts, it is best to use 30o-35o inserts. Turning wrought aluminum with a diamond blade will achieve a high quality surface finish.

CNC machining of cast aluminum parts, on the other hand, will require operators to use round inserts to improve quality. Rough cast aluminum finish. Machining with sharp tools will result in poor surface finish. The shape of the tool insert affects CNC parameters such as feed rate, depth of cut and tool clearance. Sharper shapes will require lower feed rates and greater tool clearance.

For machining tools, what factors do we need to consider?

Rake angle and approach angle

The rake angle refers to the angle between the tip of the cutting tool on the CNC machine tool and the clamped workpiece. Depending on the position of the knife blade, the angle can be positive or negative. We prefer to machine aluminum parts with positive rake angles. Since it is a soft metal, we had to minimize cutting resistance throughout the production process.

During the machining process, as chips accumulate around the tool, it will affect the final quality of the product. Positive rake angle ensures effective chip handling. It also aids in temperature control by reducing cutting temperatures. This factor helps to provide the best machining conditions for aluminum parts and prolongs the life of the insert.

CNC milling is rarely dependent on rake angles. This is because the approach angle defines the relationship between the part and the position of the tool on the CNC tool holder. We use 90 degree timing due to the machinability of aluminum. It allows our experts to perform different milling processes. These include face milling, slot milling and shoulder milling.

Diameter factor

Regarding the influence of radial cutting force, small and medium diameter tools have poor rigidity and are more prone to deflection, while large diameter tools are more stable and have different requirements for anti-vibration. In addition, it was also found that the feed rate was not the main factor affecting the radial cutting force. Between different feeds of the tool (typically 0.25mm and 0.35mm feed per tooth), the radial cutting force varies only slightly. For a typical aluminum alloy milling cutter with a diameter of 25mm, the margin on the insert is 1° and 0.1mm wide, which perfectly matches the curved cutting edge.

Release angle

This parameter also defines the relationship between the tool and the workpiece clamped on the CNC machine tool. In this parameter, the tool insertion is the reference point. Like rake angle, it can be positive or negative.

When processing CNC aluminum parts, whether it is rapid prototyping or mass production, a positive relief angle is recommended. The use of indexable inserts allows the operator to vary the relief angle. The release angle is between 20o and 30o, which can provide better surface finish for aluminum parts.

Aluminum chip breaker

The accumulation of chips will hinder the high-speed machining of aluminum parts. Often, chips are viscous in nature, which creates challenges when managing machining space on CNC surfaces. The chipbreaker design used in CNC machines is largely determined by the rake and relief angles.

In the mass production of CNC aluminum parts, it is recommended to use a sharp and wide chip breaker, and a wider chip breaker can remove chips of various sizes.