1. Regarding the selection of manufacturers and brands (1) Pay attention to their market share in China and abroad; sales performance and operating conditions in recent years, financial situation; service capabilities, especially remote service capabilities; prevent the risk of manufacturer bankruptcy. For example, a factory purchased a floor-type CNC boring and milling machine from a Spanish company in 1995. Before the machine was installed, the company went bankrupt. (2) Select more than three manufacturers - compare prices. Conduct a comprehensive study on the performance, characteristics, precision, main specifications and prices of their products. In addition to traditional user surveys, manufacturer exchanges and inspections, special attention should be paid to visiting authoritative international machine tool exhibitions held in China, such as CL-MT; at the same time, the role of authoritative and neutral market intermediary organizations at home and abroad should be fully utilized; and the functions of the Internet should be fully utilized. (3) If public bidding is required, the preparation of the tender documents is very important, especially the main technical indicators marked with an asterisk. The principle of "fairness, rationality and advancement" should be adhered to. Fairness, i.e. non-discrimination, is the basis for ensuring that the selected equipment is the best or better, and ultimately you will benefit. At the same time, this is also a prerequisite for passing the national tender document review. • Reasonableness: Avoid setting excessively high specifications, which can lead to waste and deter manufacturers with the best or best equipment. Excessively high specifications can result in both blindly pursuing advanced and all-around capabilities, and insufficient process analysis. • Advanced specifications are crucial to avoid winning bids for low-priced but low-quality, low-performance products. 2. Regarding Price : With the industrialization of CNC machine tools in developed countries and regions, and the gradual price reduction of CNC equipment worldwide, international CNC machine tool prices have decreased by an average of about half over the past decade (therefore, some believe that price reduction is also a development trend in the international machine tool industry). During procurement, we often find that CNC machine tools with similar performance can have vastly different prices. A key reason for this is the large difference in production volume between manufacturers. A manufacturer producing dozens of units annually may have a price difference of up to 100% for purchased components (parts) compared to a manufacturer producing over a thousand units annually. Purchased components account for about half of the total price of a CNC machine tool. Therefore, it can be said that "cheap can also be good." It is essential to research fair international prices to prevent the risk of fraud. Also pay attention to the performance/price ratio—choose equipment with excellent performance at a low price; avoid low-price traps. 3. Regarding the selection and identification methods of positioning accuracy standards The four internationally popular positioning accuracy standards are: ISO, JIS, ASME, and VDI (belonging to the international, Japanese, American, and German standards respectively). In addition, there are China's GB and the UK's BS. Of these six standards, except for ISO, all use a mathematical statistical measurement method with multiple, multi-point measurements, resulting in little difference in measurement results. JIS, however, only requires one measurement, resulting in the lowest accuracy value. For example, a machining center sample provided by the German company HE1 I ER indicates that its positioning accuracy, measured according to JIS and VDI standards, is ±4μm and 14μm respectively; the repeatability positioning accuracy is 2μm and 10μm respectively. The American company BOS-IONDIGITAL has listed a comparison of the accuracy values ​​of machining center positioning using ISO and JIS standards, as shown in the table below. In addition, attention should be paid to the factory accuracy reserve (the actual measured accuracy should not be trusted). 4. Regarding the selection of CNC system Since the application of computer technology to machine tools, it has gone through two stages and six generations of products. That is: the NC (numerical control) stage, including vacuum tubes, transistors, and small-scale integrated circuit systems; and the CNC (computer numerical control) stage, including minicomputers, microprocessors, and PC-based systems. At present, many machine tools in the world use the sixth generation PC-based CNC system. This is because it can develop almost in sync with the world's development level of PCs, and therefore has the following advantages: (1) Thousands of component and hardware manufacturers around the world have developed and improved components for PCs, which can be applied to PC-based CNC systems. Therefore, its component integration is the highest, reliability is good, and performance is high. (2) Technological progress is fast and upgrading is easy. Many PC features, such as touch screen input, voice input, network communication, and large-capacity storage, can be realized on PC-based CNC systems. (3) It provides an open foundation with abundant available hardware and software resources. This expands the CNC functionality. Some factories abroad now use these expanded functions to achieve network manufacturing. (4) For CNC system manufacturers, the advantage lies in having high-performance and diverse development tools and environments, such as the ability to use high-level languages ​​for development; hardware production is simplified (by purchasing externally). Currently, many users prefer FANUC and SIEMENS CNC systems. This is certainly reasonable, as they have a leading market share. However, in the PC-based generation of CNC systems, domestic products are at the same development level as foreign products. 5. Study technological development trends to ensure that the selected equipment will not be obsolete for 10 years. Example: When Guangzhou Peugeot Automobile Company was dissolved, the Chinese side looked for a new partner. Honda of Japan discovered that the Chinese side had a flexible engine production line and quickly reached a joint venture agreement. Another large automobile joint venture, however, found that its new engine production line was outdated as soon as it was put into operation because it was a rigid production line and could not adapt to the requirements of engine upgrades. The obvious contrast between these two events is self-evident, so it is essential to pay attention to the advancement of equipment when purchasing it. Author: Chen Changnian, No. 26, Yuetan South Street, Xicheng District, Beijing, China Machine Tool & Tool Builders' Association, 100085, Tel: (010) 8595924