Selection and Consideration of CNC Cutting Tools for Aluminum Parts
With the improvement of people's living standards, people are more and more fond of things with metal texture, which also makes aluminum products more and more used in many industries. Compared with steel and superalloy, it is a soft metal. HRC is not hard, but it is more tough. Therefore, the requirements for tools are relatively high. If high hardness tungsten steel milling cutter is used to cut soft metal, the cutting edge will break and the tool life will be very short. It is necessary to use high-quality tools with low hardness and non stick to complete the processing. Only in this way can the knife improve the speed and efficiency of the machine.
How to select machining tools for CNC aluminum parts?
In aluminum alloy CNC machining, especially in small margin cutting and finishing, the cutting edge of indexable inserts is usually blunt, which often leads to the "plough" effect, and the cutting edge is easy to cut into the workpiece suddenly, resulting in a sudden increase in cutting force. The sudden increase of cutting force leads to excessive tool size and high power requirements. Due to the demand for cutting edges, the above problems are more complex. Finish machining must be carried out with a sharp tangential cutting edge. In order to ensure the metal removal rate during rough machining, the cutting edge is required to have sufficient strength. Therefore, cutting force, cutting edge penetration, chip formation, stability, and blade positioning and clamping should be considered.
Machining geometry
The ultimate goal of machining is to produce the best parts that meet the design or customer specific requirements. Specifications can be in the form of part thickness, bearing capacity and size. CNC machine tools can process aluminum parts of various sizes and shapes through effective tool sequencing and manipulation. Increasing production requires the use of indexable tools. This type of tool allows the operator to replace the tool blade when necessary, thus realizing multiple automatic machining of aluminum parts. CNC tool inserts with different cutting edges can be used for post-processing operations, such as polishing and grinding aluminum parts. In the NC aluminum processing environment, the performance of the tool blade depends on the shape, back angle and front angle of the blade.
Processing of aluminum alloy parts
Machining shape
Tools for CNC aluminum parts have specific geometric shapes that affect the quality of the final product. The blades have different shapes to fit a specific CNC tool holder. Aluminum tool blades are diamond, round, triangular and square. Better part quality can be obtained by using sharp blade. For example, for high-speed surface processing of forged aluminum parts, it is better to use 30o-35o blades. High quality surface finish will be obtained by turning forged aluminum with diamond blades.
On the other hand, CNC machining of cast aluminum parts will require operators to use round blades to improve quality. The surface of cast aluminum is rough. Machining with sharp tools will result in poor surface finish. The shape of the tool insert affects CNC parameters such as feed rate, cutting depth, and tool clearance. Sharper shapes will require smaller feed rates and larger tool gaps.
What factors do we need to consider for machining tools?
Front angle and approach angle
The rake angle refers to the angle between the cutting tool tip and the clamped workpiece on the CNC machine tool. Depending on the position of the tool blade, the angle can be positive or negative. We prefer to process aluminum parts with front corners. As it is a soft metal, we must reduce cutting resistance as much as possible in the entire production process.
In the process of machining, the final quality of the product will be affected due to the accumulation of chips around the tool. The positive rake angle ensures effective chip handling. It also facilitates temperature control by reducing the cutting temperature. This factor helps to provide the best processing conditions for aluminum parts and prolong the service life of the blade.
CNC milling rarely depends on rake angle. This is because the approach angle defines the relationship between the position of the part and the tool on the CNC tool holder. Because of the machinability of aluminum, we use 90 degree timing. It allows our experts to perform different milling processes. These include face milling, slot milling and square shoulder milling.
Diameter factor
For 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 require different anti vibration. In addition, it is found that the feed speed is not the main factor affecting the radial cutting force. Between the different feed rates of the tool (usually 0.25 mm and 0.35 mm per tooth), the radial cutting force changes only slightly. For a typical aluminum alloy milling cutter with a diameter of 25 mm, the edge band on the blade is 1 ° and 0.1 mm 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 the front corner, it can be positive or negative.
When machining CNC aluminum parts, whether rapid prototyping or mass production, it is recommended to use straight and back corners. The use of indexable blades allows the operator to change the rear angle. The parting 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. In general, chips are viscous in nature, which poses challenges in managing the machining space on CNC surfaces. The design of chip breaking groove used in CNC machine tools largely depends on the front angle and back angle.
In the mass production of CNC aluminum parts, it is recommended to use sharp and wide chip breaking grooves. The wider chip breaking groove can remove chips of various sizes.