Magnesium has exceptional characteristics, notably low density, and good machinability, for creating corrosion resistance in high-strength parts through CNC machining. However, the process of machining magnesium is quite a challenge because of the flammability of the material. When dealing with magnesium, safety measures are taken to reduce any risks likely associated with it.
The machining of magnesium generates shavings and dust, which can easily be ignited, which is a great danger to CNC machinists. If not well controlled, the machining process will likely cause fires or explosions in the workshop. This article describes the main safety measures for working correctly with magnesium and other flammable metals. It focuses on proper methods of chip clearance and measures and precautionary measures to avoid fire in a machine shop.
Challenges in Magnesium Machining
Working with magnesium alloys is always accompanied by risks that must be managed adequately. These are some of the risks that should be understood when involved in the CNC machining of magnesium.
Fire Hazard
One of the significant problems in machining magnesium alloys is the flammability of the fine chips and dust produced during the process. These particles are highly inflammable, and even tiny sparks or excessive heat can easily cause them to catch fire, which is a big danger in the workshop.
Tool Wear
Due to its soft and abrasive nature, the magnesium material can wear out the cutting tool during CNC machining. This results in a lower machining rate and more tools that must be changed more often than not.
Heat Generation
It is also clear that magnesium alloys have low thermal conductivity, and therefore, heat is localized to the cutting zone. This high cutting temperature also negatively affects the tool’s life. Also, it increases the possibility of warping the workpiece and accelerates the tool wear rate.
Surface Finish Challenges
Achieving a high surface finish on magnesium alloys is challenging due to the presence of burr and machining deformation. All these issues must be addressed by applying the correct machining methods and selecting the right tools to achieve the desired high-quality surface finish. To address these issues, it is required to adhere to all the safety measures, correct use of tools, and information on the characteristics of magnesium and its machining for safety and effectiveness.
Enormous Benefits CNC Magnesium Machining
However, there are some advantages of using CNC machining magnesium despite the above risks. This is why magnesium is appropriate for use in industries that require light, such as the aerospace and automobile industries, whereby it enhances efficiency and fuel usage. It is a very lightweight material, but at the same time it has high strength. Thus, structures can be solid and slim, requiring less material.
Magnesium is easily machined and thus can be produced in large quantities. The tools used are not easily damaged, cutting the cost. Because of its good thermal conductivity, it is suitable for applications where heat is to be conducted away from the product, such as the casing of electronic equipment. Also, magnesium has inherent EMI gasketing characteristics that shield sensitive electronics from interference.
From the environmental point of view, magnesium is in abundance. It can be recycled, and in the machining processes, the amount of emission is negligible. Additionally, the energy used is less than that of other metals. This sustainability, coupled with flexibility in the type of surface finish that can be applied, such as painting or anodizing, makes magnesium a preferred material by manufacturers who desire high performance and, simultaneously want to reduce the impacts of their CNC machining on the environment.
Safety Measures to be Adopted in CNC Machining of Magnesium Alloys
CNC machining of magnesium alloys can be safe if the following measures for machining magnesium safety are observed: Here are vital tips to ensure the safe machining of magnesium.
- Keep Tools Sharp:
One of the challenges that are associated with the machining of magnesium is heat production—using sharp tools when cutting is also essential to avoid heat accumulation. Blunt tools are likely to create a lot of friction and may cause sparks that lead to the ignition of magnesium chips. Carbide-tipped tools are preferred because they are hard and do not spark quickly at high temperatures.
- Avoid Tight Clearance Angles:
One of the crucial things to consider when machining magnesium alloys is to avoid close tolerance angles. High cutting angles result in massive and consecutive chips that increase heat and the possibility of a fire outbreak due to the nature of the element magnesium.
- Produce Broken Chips:
Set up your CNC machine to produce small and intermittent chips. This assists in removing heat from the cutting tool and the workpiece so that there are minimal chances of the material catching an open flame. This should be done by employing small back rake angles, low feed rates, and moderate to high cutting speeds.
- Use Mineral Oil-Based Coolants:
When machining magnesium, it is recommended to use mineral oil coolants instead of water. Mineral oil reduces fire and explosion risks and enhances the surface finish. Aqueous solutions of coolants may corrode magnesium and cause the formation of flammable hydrogen gas.
- Employ Explosion-Proof Vacuum Systems:
Employ explosion-proof vacuum systems to help extract magnesium chips and dust from the CNC machines. Discontinuous magnesium chips are also flammable; removing them in the workshop is crucial without causing a fire outbreak.
- Avoid Water in Case of Fire:
Do not attempt to put the fire out with water during a magnesium fire, as this will only worsen it. Magnesium fires should be fought with dry Class-D fire extinguishers or dry sand. Thus, following the above measures, magnesium cnc machining can be done safely with less risk in the workplace.
Choosing the Right Cutting Tool in CNC Machining of Magnesium Alloy
Selecting the appropriate cutting tools is crucial to achieve the best results and safety when using CNC machining on magnesium alloys. Below is the categorization of the tools that are frequently utilized:
High-Speed Steel (HSS) Tools:
High-speed steel tools are easy to use and relatively cheaper than other tools. Due to their hardness and ability to do interrupted cuts, they are easy to hone and thus suitable for various machining operations.
Carbide Tipped Tools:
Carbide tools are well known for their hardness and, therefore, very hardly worn and have a long tool life. They keep their sharpness well, which leads to improved surface finish, higher machining rates, and, therefore, improved productivity.
Coated Carbide Tools:
Coated carbide tools have carbide as the substrate material, with other materials like titanium nitride being coated with the substrate. These coatings improve the hardness and heat stability giving the tool a longer life span and, at the same time, improving the machining efficiency.
Polycrystalline Diamond (PCD) Tools:
PCD tools are among the most rigid cutting materials in the market, offering the best wear resistance and tool life. It is suitable for high-speed machining operations to retain sharpness for longer and produce many parts accurately.
Why Magnesium for CNC Machining?
However, magnesium is still used in CNC machining due to its desirable properties as long as safety measures are implemented. Here are compelling reasons to consider magnesium:
Exceptional Machinability:
Magnesium alloys are easy to machine and can be easily machined through Computer Numerical Control or CNC. This characteristic reduces the cutting forces hence improving the tool and proper machining.
Complex Geometries:
The material is more accessible to machines than other metals, which allows the creation of complex shapes of parts. CNC machining enables the fabrication of magnesium parts to precise engineering specifications that are essential in today’s industries.
Precision and Consistency:
CNC technology ensures that the designs are reproduced to the smallest detail and even the microstructures. Multi-axis machining is very useful since it enables the contouring of magnesium alloys in all directions to meet the requirements of different projects.
Recyclability:
It’s important to note that magnesium and its alloys are recyclable, which significantly adds to the environmental factor in manufacturing. CNC machining leads to the creation of recyclable magnesium, thus reducing the impact on the surrounding.
Environmental Benefits:
Magnesium is non-hazardous to the environment and can be recycled, making it better than other materials. It is environmentally friendly since it aligns with global trends in minimizing the effects of production on the environment.
Unique Material Advantages:
Besides ease of machining, it is a lightweight material with high strength that enhances fuel efficiency in the automobile and aircraft industries. This is especially true with the surface finish, whereby the tool can deliver high-performance parts.
Various Methods of CNC Machining for Magnesium
CNC machining employs several specialized methods to fabricate magnesium parts across diverse applications effectively.
CNC Drilling:
CNC drilling is drilling holes in magnesium workpieces using rotating cutters or drill bits at a controlled feed rate. This method is advantageous in applications requiring high accuracy in positioning holes and the depth at which they should be made in materials such as aerospace and automobile parts.
CNC Milling:
In CNC milling, a rotating cutter cuts out magnesium’s required shape and profile. It also performs well when producing features with thin fillets and small clearances, vital in applications that require structures such as electronics, medical equipment, and industrial equipment.
CNC Turning:
In CNC turning, a chuck holds the workpiece made of magnesium alloy while the workpiece is rotated, and a single-point tool is used to cut the workpiece. This method is ideal for producing cylindrical goods like shafts, pins, and fittings to fine limits and smooth surface finishes. It is applied in automotive engine parts and hydraulic equipment.
Laser Cutting:
CNC laser cutting involves melting or vaporizing magnesium sheets or plates according to a set cutting path. This method is preferred because it does not involve direct touch, can create sharp edges and delicate features, and is commonly applied to aerospace panels, decorative parts, and electronic casings.
Tapping:
CNC tapping is tapping tools to produce internal threads in the magnesium parts. It also offers reasonable control of the pitch and depth of the threads, which is essential in fasteners and threaded inserts in aerospace structures, automotive assemblies and consumer electronics.
Summing Up
The CNM’s use of CNC machining to work on magnesium leads to the creation of lightweight and durable parts with accurate dimensions and good impact strength. The reasonably good machinability of magnesium can be applied to a wide range of products through various CNC operations. However, operational safety is paramount in magnesium machining as this calls for proper understanding and implementation of safety measures to achieve high-quality production at CNM.
