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What is Carbon Fiber and Its Properties
Carbon fiber comprises 5 to 10 microns in diameter strands of fibers consisting of long, closely interlocked chains of carbon atoms in a microscopic crystalline form. These fibers are solid and very light in weight. Carbon fiber is more firm and rigid than steel and lighter than steel.
Carbon sheets are famous for their incredible strength and durability, making them suitable for various sporting, engineering, and aerospace industries and more applications. Carbon fiber is a lightweight composite with excellent toughness, hardness, and resistance to abrasion and corrosion.
Other properties of carbon fiber include:
- Low thermal expansion
- EM transparency
- Appealing cosmetic appearance
- Good electrical conductivity
Application of Machined Carbon Fiber Parts
Carbon fiber is a lightweight material suitable for an extensive list of applications due to its extraordinary mechanical performance, thermal conductivity, and low coefficient of thermal expansion. There are numerous applications of carbon fiber in various industries. Here are some of them:
- Aerospace Industry
The aerospace industry is one of the industries with the highest application of carbon fiber. It was one of the first industries to take carbon fiber as an ideal replacement for titanium and aluminum in specific components.
Carbon fiber aircraft component was made in 1940. Numerous aircraft parts are made with carbon fiber reinforced polymer, often preferred over metal for developing planes because they have an excellent strength-to-weight ratio and last longer. It has influenced a significant reduction in the weight of airplane components.
Aerospace components like gliders, flying jets, or helicopters depend on carbon fiber for improved performance. In addition, the weight-saving property of carbon fiber helps make a significant difference in aircraft fuel consumption.
- Sports Industry
Several professional athletes utilize carbon fiber sheets in their sporting gear – tennis rackets, bicycle wheels, helmets, bicycle frames, archery bows, hockey sticks, golf clubs, and many more.
However, clothing and protective gear such as unique leg- and arm-protector are made of carbon fiber. Also, there are racing or extreme sports where athletes use helmets and firm, lightweight shoes made of carbon fiber.
Carbon fiber is an ideal material for sporting equipment. It offers vast advantages due to its high strength and lightweight. It is much lighter than plastic and wood, making it easy for athletes to use their sporting equipment without difficulty. As a result, athletes can run faster, jump higher, and swim farther.
- Automotive Industry
Carbon fiber has excellent strength and durability, making it a versatile material in the automotive sector. Consequently, automakers utilize carbon fiber in constructing vehicle frames and several other components.
In addition, carbon fiber’s superior strength-to-weight ratio helped influence the manufacturing of faster cars in the automotive sector.
Carbon fiber allows car manufacturers to remove unnecessary metal pieces from the car’s structure, replacing them with lightweight carbon fiber. It helps reduce the costs of manufacturing a vehicle while reducing fuel consumption and CO2 emissions.
- Electronic Industry
The electronics sector benefits immensely from the vast advantages of carbon fiber. Its weigh reducing property is a quality that most customers seek. Likewise, it has an increased natural frequency and maintains dimensional tolerances than metal and plastic enclosures.
Carbon fiber has a thermal coefficient (CTE) equal to invar. As a result, it significantly reduces thermal issues for sensors, sensitive electronics, mirrors, and lasers. In addition to its excellent mechanical properties, carbon fiber is used as a functional material because of its excellent electrical conductivity and non-magnetic properties. It also has essential applications in the electronics industry.
The electronic shielding device made of carbon fiber has a good absorption ability of electromagnetic waves. Carbon fiber and polymer are combined to form a filling composite material, which not only has a good shielding effect but also greatly improves the mechanical properties of the shell material.
How to Machine Carbon Fiber Sheets
Machining carbon fiber composites should be done with the highest accuracy. It is expensive to machine carbon fiber. Hence, wrong cuts or millings should be avoided or mitigated at all costs.
Here are some of the efficient ways of machining carbon fiber sheets:
CNC Turning
CNC turning is a common technique for machining carbon fiber parts in different industries. It offers predetermined dimensional tolerances on components with generally circular surfaces. Possible tools for turning carbon fiber include ceramic, cemented carbide, polycrystalline diamond, and cubic boron nitride.
Turning process parameters such as cutting speed, feed rate, and depth of cut influence the tool life and CNC machining surface quality. However, it is essential to note that the tool’s geometry and the feed rate play crucial roles in determining the surface roughness of the carbon fiber parts.
CNC Milling
Generally, machinists use a router to machine carbon fiber composites. You can cut carbon fiber sheets to size and add the required features. Nevertheless, you can employ standard metal machining methods if needed.
CNC milling carbon fiber composite requires higher spindle speeds than metals and lower feed rates. However, too much heat can affect the quality of the composite parts. As a result, you can adjust the feed rates to reduce the heat generated in the workpiece while machining.
Carbon fiber has a relatively low thermal conductivity which causes the workpiece to retain most of the heat generated, as there are no chips to help disperse the heat during machining. However, this heat generated from the cutting operation may damage the resin.
The tool and the tool path must be used to manage the heat in workpieces while machining since using coolants may not be viable. Also, the fracturing of the fibers causes significant abrasion on the cutting tool. As a result, you need special tooling to machine carbon fiber composites.
Drilling
Drilling is a complicated machining process used in machining carbon fiber composites. These composites comprise material layers that could easily chip or wear away during precision machining. In addition, machining carbon fiber generates conductive dust that can invade and damage electronics, irritating the skin.
Hence consider using a dust mask and gloves when machining carbon fiber. The drilling speed is a crucial factor in dust emission and must be calibrated based on the size and depth of the hole. Using special drill bits specially made for carbon fiber helps prevent delamination when drilling.
Waterjet
Waterjet machining is a fast and reliable technique for cutting carbon fiber composites. The advantage that waterjet cutting has over others is that it requires no special tool to cut carbon fiber materials.
It is an effective dust containment solution as it traps dust particles in the water. However, delamination may occur if you fail to drill a starting hole. Whenever tight tolerances are needed, it is advisable to waterjet the large part and adjusts it to the final dimensions.
Top 3 Tips for Machining Carbon Fiber Composites
There are some helpful tips to consider when machining composites to get the best achievable results. Here are some of them:
Improve the Wear Resistance of the Drill Bit
The cutting temperature is not high when drilling carbon fiber composites, generally between 50~200℃. The tool wear curves are very similar at different cutting speeds. Therefore, the leading cause of tool wear is abrasive wear.
The hardness of carbon fiber is relatively high. The hardness of carbon fiber made of petroleum coke or carbon black is generally up to HS70~ 90 or above. It is equivalent to HRC53~65 Rockwell hardness, while the hardness of an HSS drill is only HRC62~65 at room temperature, very close to that of carbon fiber composite materials.
Therefore, when processing carbon fiber composite materials with an HSS drill, the hard fiber points in the material cause severe abrasive wear on the tool’s surface. For this reason, high-hardness tool materials must be used. High-hardness tool materials include hard alloys, ceramics, cubic boron nitride, diamond, etc.
Prevention and Control of Dust Pollution
Water-based cutting fluid can be added to the drilling process so that the dust particles are removed by water-based cutting fluid and not dispersed to the air. It helps to solve the problem of pollution when making holes.
The test of drilling carbon fiber composites shows that adding water-based cutting fluid does not affect tool durability and hole quality.
However, robot drilling is undoubtedly a better choice to keep people away from the dust pollution environment. Using robot drilling helps monitor the process of hole-making and to further ensures the accuracy of hole-making.
Adopt Reasonable Technology
The test results show that the surface roughness of the holes can be reduced, and the roundness of the holes can be improved effectively by using the Reaming technology after drilling. The surface roughness of carbon fiber composite on the rear wall of Reaming is not less than Ra3.2.
Reaming knife is generally made of hard alloy Reaming knife, and the cutting speed is selected at about 30m/min. In addition, the hole of carbon fiber composite material can be successfully processed using the Reaming composite tool.
Conclusion
Carbon fiber is a compound with a unique appearance and exceptional properties, and it helps reduce components’ weight while retaining strength. A CNC router is ideal for accurately machining carbon fiber sheets as it is more efficient than manual tools. However, consider machining with a CNC machine to avoid bad outcomes and material wastage.
Getting the best results from your carbon fiber machining project requires working with a reliable manufacturing company. AT-Machining offers the perfect combination of machining technology and technical expertise to give the best solution. Contact us today to get your project started.
