In the CNC machining process for aluminum, the correct choice of coolant can prevent overheating and may extend the useful life of tools and machined parts.
The selection of cutting fluid hinges upon various factors, including lubricity, rust resistance, stability, and ease of maintenance.
In high-speed CNC aluminum machining, the generation of overheating can cause the sticking of tools leading to build-up edges, which can affect the machining roughness of the working part. Besides, excessive heat can also deform the tool, affecting its useful life and the accuracy of the workpiece.
So, the coolant of soluble、straight oils along with synthetic and semi-synthetic fluids can be used to enhance the lubrication and cooling process. Soluble oils usually mix with water and provide lubrication and cooling, while straight oils are pure without water content. For high-speed CNC machined aluminum high content oil is recommended with synthetic fluid to achieve cooling effect.
Challenges in Aluminum Machining Due to Material Properties
Aluminum’s unique chemical and physical properties present challenges in coolant selection for CNC Machining of Aluminum.
Chemically aluminum is highly reactive in acidic or alkaline environments. It is because when it reacts with acids it rapidly releases hydrogen gas while in contact with alkaline, it oxides.
In high-speed CNC machining, aluminum can also cause thermal deformation of the working part due to its high thermal coefficient, which transfers heat to the part easily. Besides, aluminum being soft can cause the sticking of tools leading to build-up edges, which can affect the machining roughness of the working part, and then affect its useful life and the accuracy of the workpiece.
The ductile nature of aluminum makes it harder for the cutting tools to access the target area as it can easily form long strips of cracks.
The physical and chemical properties of aluminum demand a cutting fluid with good lubricity, filtering, and rust resistivity, making the aluminum cutting fluid different from others.
Choosing the Right Cutting Oils
Cutting oils with low viscosity and anti-friction additives offer lubrication and anti-friction properties critical for aluminum machining. This is so that the cutting oil should achieve lubrication and the desired anti-friction properties along with good cooling and filtering. The problem with cutting oil is its low flash point which can be dangerous in high-speed machining where the flash point is low. Here, volatilization can occur quickly, and the cost price soars.
Straight oils are another example of cutting fluids that can be used for the CNC machining of aluminum. As the aluminum tends to be very sticky, we required a large quantity of coolant to keep the chips away. Straight oils also have a base mineral or petroleum which makes them dilute and easy to use during CNC processes such as milling.
In CNC machining of aluminum, Water-based coolants with rust-resistant properties are essential for preventing corrosion in aluminum parts. As the aluminum parts are kept idle for a long time and when in contact with silicon it can produce corrosion. It can be seen as black silicon spots on the surface of aluminum. For such parts, water-based coolants are stored at a pH level of 8-10 and have rust-resistance properties. If the coolant is not anti-resistive the aluminum can easily corrode when exposed to alkaline conditions.
There are different coolant options for each type of CNC machining of aluminum. The coolant should be an anti-friction and low-viscosity oil for the Finishing process. A coolant with emulsified anti-friction or semi-synthetic anti-friction properties can perform well for semi-finishing and rough machining. A synthetic or semi-synthetic cutting fluid can be our choice for a rough grinding process. Likewise, for turning operations the coolant must be rust-resistant and easy to maintain such as soluble oil.
All in all, the coolant of soluble、 straight oils along with synthetic and semi-synthetic fluids can be used to enhance the lubrication and cooling process. Soluble oils usually mix with water and provide lubrication and cooling, while straight oils are pure without water content. For high-speed CNC aluminum machining high content oil is recommended with synthetic fluid to achieve cooling effect.
Coolant Concentration and its Impact
Maintaining optimal coolant concentration is essential in aluminum machining to avoid excessive heating, friction, tool wear, and bacterial contamination. For low concentrations of coolant, the machine and working part can experience excessive heating and friction. This would reduce the tool life and corrosion of the machine and workpiece. In such cases, the tool may also experience some bacterial infection which can alter its performance.
Similarly, the excess working fluid is also bad for the tool life as the waste coolant can concentrate forming residue and reducing the useful tool life. High levels of coolant can also lead to skin irritation among the operators.
Conclusion
In the world of CNC machining, where precision and efficiency are paramount, the selection of cutting fluid for aluminum machining stands as a critical determinant of operational success. From milling to turning and finishing processes, the choice of coolant plays a pivotal role in ensuring optimal performance, tool longevity, and part quality. By considering factors such as lubricity, rust resistance, and thermal stability, manufacturers can tailor their coolant selection to meet the specific demands of aluminum machining.
Whether opting for soluble oils, synthetic fluids, or straight oils, each coolant type addresses unique challenges posed by aluminum’s chemical and physical properties, ensuring smooth machining operations. A good choice of coolant can extend the useful life of the tool and workpiece, making the operations cost-effective.