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Home » NEWS » How to choose a CNC machine tool? Read the practical information first and then choose. I will teach you not to waste money.

How to choose a CNC machine tool? Read the practical information first and then choose. I will teach you not to waste money.

With the development of science and technology, mechanical manufacturing technology has undergone profound changes. As society’s demand for product diversification becomes stronger, the proportion of multi-variety, small and medium-sized batch production has increased significantly, and it is difficult to adapt to the high-efficiency, high-quality, and diversified processing requirements using traditional ordinary processing equipment.

There are three aspects to consider when purchasing CNC machine tools:

The first is whether the machine tool body can meet its own processing requirements and the quality of the machine tool.

Next is the CNC system. There are many types of CNC systems. Choosing the right system is the key to purchasing CNC machine tools.

The last is the drive unit, which is also the key to machine tool control. Different drive units can achieve different processing accuracy. When selecting a drive unit, the appropriate drive unit must be selected according to the accuracy requirements of the workpiece to be processed.

The CNC system is the control center of CNC machine tools and is known as the “brain” of machine tools. Machine tools equipped with CNC systems greatly improve the accuracy, speed and efficiency of part processing.

The function of the CNC system is undoubtedly an important limiting factor for the design and selection of CNC machine tools. The following important factors must be considered when selecting a CNC system:

  1. Driving ability
  2. Fully closed-loop demand and dual-drive demand
  3. Five-axis control requirements
  4. RTCP, the choice will be larger. At the same time, the CNC system suppliers that may be involved in the five-axis function must also carefully consider export licenses, after-sales services, etc.

The following is an analysis from the aspect of CNC system

CNC system options

The CNC system is the “brain” of the CNC machine tool, which calculates and processes the machine tool control information. According to the principles of CNC systems, they can be divided into two categories: economical CNC systems and standard CNC systems.

Economical CNC system. From the perspective of control method, economical CNC system generally refers to an open-loop CNC system. It has the advantages of simple structure, low cost, convenient maintenance and debugging, and low operation and maintenance costs. However, it is limited by the torque frequency characteristics and accuracy of stepper motors. The feed speed and torque restrict each other, and the improvement of performance is limited. Economical CNC systems are often used in CNC wire cutting and some economical CNC lathes and milling machines that do not require high speed and accuracy. They are also widely used in CNC transformation of ordinary machine tools. The open-loop CNC system means that the CNC system itself does not have a position detection device. The CNC system sends a certain number and frequency of command pulses, and the drive unit performs machine tool positioning. In the open-loop system, under the influence of external factors, the machine tool does not move or does not move in place, but the system has reached the designated position when the machine tool has reached the designated position. At this time, the machining accuracy of the machine tool will be greatly reduced. However, due to its simple structure, quick response, stable and reliable operation, convenient debugging and maintenance, and very low price, it still has the largest market in China. Standard CNC system Standard CNC system includes semi-closed-loop CNC system and fully closed-loop CNC system.

The semi-closed loop CNC system generally refers to the position signal (photoelectric encoder) of the machine tool’s servo motor being fed back to the CNC system. The system can automatically perform position detection and error comparison, and can compensate for part of the error. Therefore, its control accuracy is higher than that of the open-loop CNC system. It is higher, but lower than a fully closed-loop CNC system.

In addition to the position feedback of the machine tool’s servo motor, the fully closed-loop CNC system also has the position signal of the machine tool workbench’s position detection device (usually a grating ruler) fed back to the system, thereby forming a full position follow-up control. The system is in the process of processing. Automatically detects and compensates for all position errors.

The machining accuracy of the fully closed-loop CNC system is the highest, but the debugging and maintenance of this system are extremely difficult, and the price of the system is very high, so it is only suitable for medium and high-end CNC machine tools.

Because the price of an open-loop control system is much lower than that of a closed-loop control system, when choosing a CNC system, you must consider the price and cost ratio of the CNC system to the entire CNC machine tool, and then based on the configuration of the machine tool and the requirements of the machine tool itself, , low-end machine tools adopt open-loop control systems, and medium and high-end machine tools adopt closed-loop control systems.

Issues you should pay attention to when purchasing CNC machine tools

Choose CNC machine tools based on product specifications, dimensions, accuracy, etc. When selecting CNC machine tool functions, if you pursue too many CNC machine tool coordinate axes, large worktable and motor power, high machining accuracy, and complete functions, the more complex the system will be and the reliability will be reduced. Low. The purchase cost and maintenance cost will increase, resulting in a corresponding increase in processing costs.

CNC machine tools should be purchased reasonably based on the typical parts that need to be processed. Although CNC machine tools have high flexibility and adaptability, they can only achieve the best results by processing certain parts under certain conditions. Therefore, before deciding to purchase equipment, you must first determine the typical parts to be processed.

The selection of the CNC system must be reasonable and must consider in detail the CNC system that can meet various performance parameter requirements and reliability indicators, as well as ease of operation, programming, maintenance and management. Try to be centralized and unified. Unless there are special circumstances, try to use the same series of CNC systems that are familiar to the unit and produced by the same manufacturer to facilitate future management and maintenance.

Configure necessary accessories and cutting tools In order to give full play to the role of CNC machine tools and enhance their processing capabilities, necessary accessories and cutting tools must be configured. Don’t spend hundreds of thousands or millions of yuan to buy a machine tool that cannot be used normally because it lacks an accessory or tool worth tens of yuan. When purchasing the main machine, you must purchase some wearing parts and other accessories together.

Foreign metal cutting experts believe that the efficiency of a CNC machine tool worth $250,000 largely depends on the performance of an end mill worth $30. It can be seen that CNC machine tools are equipped with cutting tools with good performance. It is one of the key measures to reduce costs and obtain maximum comprehensive economic benefits. Generally, CNC machine tools must be equipped with enough cutting tools to fully utilize the functions of the CNC machine tool, so that the selected CNC machine tool can process multiple product varieties and prevent unnecessary idleness and waste.

Pay attention to the installation, debugging and acceptance of CNC machine tools. After CNC machine tools enter the factory, they must be installed and debugged carefully, which is very important for future operation, maintenance and management. During the installation, commissioning and trial operation of CNC machine tools, technical personnel actively participated and carefully studied the supplier’s technical training and on-site guidance. Conduct comprehensive acceptance of the geometric accuracy, positioning accuracy, cutting accuracy, machine tool performance, etc. of CNC machine tools. Carefully check the various supporting technical information, user manuals, maintenance manuals, accessory instructions, computer software and instructions, etc., and keep them properly. Otherwise, some additional functions will not be developed in the future and it will cause difficulties in the maintenance and upkeep of the machine tool. . Finally, we must comprehensively consider the CNC machine tool manufacturer’s after-sales service, technical support, personnel training, data matching, software support, installation and debugging, spare parts supply, tool systems and machine tool accessories, etc.

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