Robotic arms need to carry the main weight during the working process, therefore fracture and deformation are unacceptable. Accordingly, materials with high strength should be chosen.The tensile strength of carbon fiber composite materials can reach 3000MPa above, its comprehensive indicators of tensile strength and specific modulus are better any existing structural materials, can effectively meet the strength requirement. The reduction of robotic arm’s weight could make operation more convenient. The density of carbon fiber composite materials is only L.7g/cm3, less than a quarter of steel. Besides, the carbon fiber composite materials own the property of energy absorption and shock resistance, which could ensure the stability during operation. Robotic arms need to adopt to different surroundings, having certain requirements of operation accuracy. The thermal expansion coefficient of carbon fiber composite materials are quite small, basically it will not undergo deformation along with changing working temperature, having stable size. In contrast, some mental materials will emerge corresponding creeping, which could affect the accuracy of robotic arms operation.
Among the new ightweight materials,carbon fiber reinforced composite materials have become one of the development directions of lightweight materials with a series of advantages. The use of carbon fiber composite materials to lighten the weight of industrial robots can not only reduce the weight of industrial robots themselves, but also reduce the weight of motion and improve the dynamic characteristics,while reducing costs and energy consumption, with greater development prospects and significance.
Carbon fiber (CF for short) is one kind of new material with excellent mechanical performance. CF’s tensile strength ranges from 2GPa to 7GPa, tensile modulus is about 200GPa to 700GPa. The density is from 1.5-2.0g/cm3 which is majorly determined by the carbonizing treatment temperature apart from its original construction. Its density could reach 2.0g/cm3 after graphitization at 3000℃. Besides, it weight is very light, and its specific gravity is smaller than aluminum, less than 1/4 of steel, the specific strength of CF is 20 times larger than steel. The thermal expansion coefficient of CF is different from other fibers and it is anisotropic. CF’s Specific heat capacity reaches 7.12. Its thermal conductivity decreases with the temperature increases. The thermal conductivity paralleled to the fiber direction is negative value(from 0.72 to 0.90) while perpendicular to the fiber direction is positive value (from 32 to 22). The specific resistance of CF is related to the CF type, the high modulus at 25℃ is 775 and high strength CF is 1500 per centimeter. CF owns the highest specific strength and the highest specific modulus among all the high performance fibers. Compared with metal materials like titanium, steel, aluminum and others, CF owns many advantages, such as high tensile strength, high modulus, low density, small linear expansion coefficient and so on and could be called as king of the new material.