Aluminum plate has advantages of low density, high strength, good extrusion performance and weldability, and high recycling rate. At present, as a popular metal material, it has become a common material for rail vehicles in various countries in the world, especially high speed passenger cars and urban rail vehicles.
Aluminum CNC machining is different from traditional stainless steel processing. Aluminum alloy material has low hardness, high viscosity and easy cutting. But its plastic deformation is large, especially for profiles. We need high speed CNC machine, using high speed powerful cutting tools to improve efficiency and reduce plastic deformation. Also, it can avoid continuous cutting and tearing at thin arms. At the same time, custom aluminum parts are relatively soft, there are many processes for sawing and manual polishing. Therefore, the noise is loud and there is aluminum dust, which needs to make a protection.
The currently used machined aluminum parts are mainly divided into two categories: deformed aluminum alloy and cast aluminum alloy. So what kind of CNC milling cutter do we use to cut aluminum alloy and remove material? Is it better to use aluminum alloy special milling cutter in CNC lathes?
Custom CNC aluminum machining features
The main characteristics of CNC milling aluminum alloy are as follows:
Custom CNC aluminum parts have low hardness
Compared with titanium alloy and other quenched steel, aluminum plate has lower hardness. Of course, the hardness of heat-treated or die-cast aluminum alloy is also very high. The hardness of ordinary aluminum plate is generally below HRC40 degrees. Therefore, the tool load in CNC machine is small during aluminum CNC machining services. Because aluminum alloy has better thermal conductivity, the cutting temperature of CNC milling aluminum alloy is relatively low, which can increase its milling speed.
Custom CNC aluminum parts have low plasticity
It has low plasticity and low melting point. When produce precision machining aluminum parts, the sticking problem is serious. The chip removal performance is poor, and the surface roughness is relatively high. In fact, the main reason for processing custom aluminum parts is the poor sticking and roughness effect. As long as we solve the two major problems of sticking knife and surface quality, there is no problem of custom CNC aluminum parts processing.
The tool is easy to wear
Don’t use unsuitable materials for cutting tools. Because then during aluminum CNC machining, tool sticking and chip removal often lead to faster tool wear.
Milling cutter to process aluminum alloy
CNC machining services provider always uses 3-blade cutting tools to cut aluminum. Then, because of the difference in high quality custom CNC machining conditions, we are likely to use a 2-flute ball-end knife or a 4-flute flat-bottom knife. But in most cases, we adopt a 3-flute flat-bottomed end mill.
Selection of tungsten steel milling cutter for aluminum
The number of blades is generally 3 blades, and the material to cut aluminum is generally YG cemented carbide. This can reduce the chemical affinity between the tool and the machined aluminum parts. General CNC tool brands have special milling cutter products for processing aluminum alloys, such as FAL series from Flandy and AL series from Fraisa in Switzerland.
Coated tungsten steel milling cutter
Aluminum has a low melting point and is easy to stick to chips during the manufacturing process. We recommend to use Flandy’s DLC coated milling cutter for aluminum parts and components. After coating, the friction of the tool is smaller. During processing, chip removal is better, surface quality is higher, and we can make better precision machining for aluminum alloy.
Cutting parameters for milling aluminum alloy
Generally, we can select high-speed and large-feed CNC mill for processing ordinary custom aluminum parts. Secondly, choose a larger rake angle as much as possible to increase the chip space and reduce the phenomenon of sticking. If they are precision machining aluminum parts, water cutting fluid cannot be used to avoid the formation of small pinholes on the machined surface. In general, we can use kerosene or diesel oil as the cutting fluid to produce precision machining aluminum parts.
The cutting speed varies depending on the material and parameters of the milling cutters and the processing technology. We can make high quality custom CNC machining services according to the cutting parameters given by the manufacturer.
Custom CNC aluminum manufacturing process
The cutting performance of CNC aluminum parts and components is good. However, the metal parts are easily deformed if the manufacturing process plan or the setting is improper, causing size errors. We usually adopt the process plan of rough work and fine work. And the specific process flow is as follows: blank → rough turning → rough milling → aging → fine CNC turning → fine CNC milling.
Rough milling process of metal parts cavity
This stage is mainly to remove large margins and lay a good foundation for the subsequent Seiko. It requires milling out the inner contour according to the shown part structure drawing. Also, completing the datum hole required by the precision work in advance.
High speed precision milling process of workpiece cavity
In the process of high-speed milling, we can reduce the deformation of metal parts due to the small cutting force. It is more suitable for cost effective aluminum machined parts. Moreover, the chips are removed in a short time, and they take away most of the cutting heat. Therefore, the thermal deformation of the workpiece is small, which is beneficial to ensure the dimensional accuracy of the CNC machining parts.
Drilling process of workpiece reference hole
For aluminum machined parts, Seiko chooses the center hole as the reference hole. And we make the center hole by boring after CNC turning the outer circle. Besides, completing the datum hole before finishing the cavity.
Improvement of aluminum alloy CNC turning and milling
Reduce the stress and deformation of the blank
If pre-mill the excess part of the blank and remove material to reduce the margin of each part, it can reduce the deformation of the subsequent process. Moreover, it can also release a part of internal stress after placing them for a period of time.
Improve the cutting ability of the tool
The material and geometric parameters of cutting tools have an important influence on the cutting force and cutting heat. The correct choice of tools is essential to reduce the machined aluminum parts deformation.
Selection of tool geometry parameters
Under the condition of maintaining the high strength of cutting edges, a larger rake angle can reduce cutting deformation. The size of the relief angle has a direct effect on the wear of the flank surface and the surface quality.
Improve the structural characteristics of the tool
Aluminum alloy materials have large plasticity and cutting deformation, and require a large chip space. Therefore, the bottom radius of the chip pocket should be larger. And the number of teeth of the milling cutter should be smaller.
Improve the clamping method of the workpiece
Thin-walled custom CNC aluminum parts with poor rigidity can use the following clamping methods to reduce deformation. Thin-walled bushing parts should be compressed by the axial end face with better rigidity. When milling the outer circle, we can avoid clamping deformation and obtain satisfactory accuracy.
CNC aluminum parts cutting oil selection
Cutting oil is a lubricating medium that we must use in the metal cutting process. High precision metal cutting technology has higher requirements for the cooling, lubrication, penetration and cleaning performance of cutting oil. Never use waste engine oil and vegetable oil, instead of special cutting oil. Because it is prone to burrs, scratches, breakage, deformation and other undesirable conditions. And the tool life to cut aluminum will be greatly reduced.
High-efficiency cutting oil has super lubricating performance, lower friction coefficient and higher extreme pressure.
The special cutting oil has strong adhesion. The strong oil film can effectively protect the tool and improve the surface quality of CNC machining parts.
Good cooling performance can effectively suppress temperature rise and reduce sintering and seizure. It has special effects in reducing chipping and broken taps.
Special aluminum alloy cutting oil uses non-corrosive vulcanized additives as the main agent. Therefore, it can effectively avoid problems such as rust and blackening of machined parts and skin allergies.