Metalworking technology is a broad technical term that combines industry, science and metallurgy. It is an important fulfillment that integrates culture, race, civilization, and art. The oldest metalworking technique of humans began with the hammering of a hammer and an anvil. It was not until 2500 BC that humans learned the casting process of pouring molten metal into molds. After the Neolithic Era and the inspiration of the Bronze Age, around 1400 BC, humans discovered that ironware had better wear and function than bronzeware. Therefore, iron ore is widely used in various agricultural tools and weapons through the design of different types of metallurgical furnaces and the technology of controlling high temperature. This period is called the "Iron Age" in human civilization, which has become an important era for metalworking.
Until modern times, before mechanical tools were widely used, metalworking is only limited to using chisels, hammers, files, saws and pliers manually, which has high difficulty and low accuracy. Since The Industrial Revolution came out and energy comes from the steam boiler, it has become common to do machining by mechanical power. Metalworking is also divided into milling, turning, grinding, boring, etc., and also has developed various machining tools. For example, milling machines can be divided into universal milling machines, vertical milling machines and horizontal milling machines; while turning machines can be divided into lathes, table lathes, vertical lathes and automatic lathes.
After the invention and evolution of computers, a high precision CNC machining tool has been developed with computing power. The machining accuracy can achieve the range of 1~0.1 microns (µm) and the surface roughness (Ra) of 0.1~0.01 microns (µm), and the limits of precision and surface roughness are continuously improved. Under modern precision machining technology, except ensuring precision, how to avoid accumulated tolerances, how to improve machining efficiency and integrate surface treatment technology are all problems that need to be overcome during the machining process.
The so-called precision machining refers to the precision requirements of workpiece machining features far beyond the standards of general industrial parts. Precision machining is often used in industries that require extremely high precision, such as aerospace industry, national defense industry and medical equipment industry, etc. The precision machining mentioned here is not limited to micron-level dimensional accuracy, but also includes extremely smooth surface roughness and extremely precise geometric accuracy technology.
Upon recognizing that precision machining has the above-mentioned extremely small, extremely smooth and extremely precise machining features, following conditions are how to achieve these machining features. First, reduce the replacement of fixtures or machine tools, as each change increases the cumulative tolerance. In order to avoid the above situation, a turning-milling machining center and multi-axis machine tools were developed, which can complete clamping machining in one action. Besides, temperature such as ambient temperature and temperature changes during operation of the machine tool is also one of the factors. Temperature has a great influence on precision machining. For example, seasonal changes, daily temperature changes, and thermal displacement errors during the operation of the machine tool will affect the accuracy. Finally, external environmental factors such as the level change of the machine tool due to earthquakes or other external forces after positioning, or the structural creep caused by the internal stress of the machine tool due to long-term use, which is also considered as one of the factors that affect the accuracy.
In order to improve the accuracy of precision machining, we have introduced multi-axis compound machine tools, and at the same time improved the machining environment to reduce temperature changes. The online measurement technology we’re importing is more important. Through real-time correction, we can avoid errors caused by wear during the machining, or waste of resources caused by errors that are discovered until the end of the machining process. Except for the above-mentioned factors such as environment and mechanical technology, there is still an indispensable factor that affects precision machining, that is, the quality of personnel. The operators must have a concept of the precision machining process and factors affecting the accuracy, and then use the high-precision machining equipment in the factory to ensure the precision machining quality. After the machining is completed, the control of environmental factors is also important in the stage of assembly and stock. So it can maintain the required accuracy achieved by the machining in the previous stage.
In addition to the aforementioned hardware equipment and personnel quality, there is another factor in precision machining that is not related to the process but will affect the results; that is consensus. The current precision measurement mostly obtains the required data through mathematical operations. If our customers and we do not confirm each other's measurement methods in advance for a consensus, the measurement results obtained by both parties may be different, and even affect the final judgment of accuracy. This does not belong to the field of hardware and software in precision machining, but it is one of the factors that will affect the accuracy.
Based on above conditions, precision machining is an industry that requires a high degree of control over equipment and environmental factors. The specialists must also have background knowledge of precision machining processes and its knowledge base, and effective communication with customers, in order to produce precision machining products that meet customer needs.