China Shenzhen Perfect Precision Product Co., Ltd. company news

  The basic concept of CNC programming   When processing parts on the CNC lathe, it is generally necessary to first write the parts processing program, that is, the instruction code in digital form to describe the process of the part being processed, the size of the part and process parameters (such as spindle speed, feed rate, etc.), and then the parts processing program into the CNC device, after the computer processing and calculation, issue a variety of control instructions, control the movement of the machine tool and auxiliary action, automatically complete the The processing of parts. When changing the processing object, just re-write the parts processing program, and the machine itself does not require any adjustment to the parts can be processed.   This is based on the drawings of the parts to be processed and their technical requirements, process requirements and other necessary information for cutting and processing, according to the instructions and format of the CNC system to prepare a sequence of CNC processing instructions, is the CNC machining program, or parts program. To be processed on the CNC machine tool, CNC machining program is necessary. The process of preparing the CNC machining program is called CNC machining programming, referred to as CNC programming (NC programming), which is an extremely important work in CNC machining.   Introduction to CNC programming methods CNC programming methods can be divided into two categories: one is manual programming; the other is automatic programming.   (1) manual programming   Manual programming refers to the preparation of the various steps of the part CNC machining program, that is, from the analysis of the part drawing, process decision, determine the processing route and process parameters, calculate the tool track coordinate data, write the part of the CNC machining program list until the program inspection, are completed by hand. For point processing or geometry is not too complex plane parts, CNC programming calculation is simple, not many program segments, manual programming can be achieved. But the contour shape of the plane parts consisting of complex curves, especially the space complex surface parts, the numerical calculation is quite tedious, the workload is large, easy to make mistakes, and it is difficult to proofread. According to statistics, for complex parts, especially surface parts processing, with manual programming, a part of the programming time and the actual processing time on the machine tool ratio, an average of 30:1. CNC machine tools can not start the reason, there are 20% to 30% is due to the processing program can not be prepared in time and caused. Therefore, in order to shorten the production cycle, improve the utilization of CNC machine tools, effective solution to a variety of molds and complex parts of the processing problem, the use of manual programming can no longer meet the requirements, but must use automatic programming methods.   (2) Automatic programming   When carrying out complex parts processing, the calculation of tool trajectory is very large, and in some cases, even impractical. How to use computer technology to assist people with machining programs has led to the development of automatic programming technology. Automatic programming can be divided into automatic programming methods based on automatic programming languages and automatic programming methods based on computer-aided design with graphic interaction, depending on the input of programming information and the way the computer processes the information.   The automatic programming method based on language is an early automatic programming method, in programming the programmer is based on the programming manual of the CNC language used and the part drawing, in the form of language to express the processing of all the content, and then input all of this content into the computer for processing, to produce the machining program can be used directly for CNC machine tools. Computer-aided design-based graphical interactive automatic programming method is a common method of modern CADCAM integration, in programming the programmer first to the part drawing for process analysis, to determine the composition of the program, followed by the use of computer-aided design (CAD) or automatic programming software itself part modeling function, build out the geometry of the part, followed by the use of computer-aided manufacturing ( CAM) function, the completion of the process plan designation, cutting amount selection, tool and its parameters set, automatically calculate and generate the tool path file, the use of post-processing functions to generate a specific CNC system with machining programs, this automatic programming method is called interactive programming graphics.        This automatic programming system is a combination of CAD and CAM automatic programming system.

  With the development of the economy, the technical improvement of various products, the quality is improving faster and faster, and the product cycle time is getting shorter and shorter, so in the machining, the machining accuracy is required to be higher and higher, and the machining cycle time is shorter and shorter. Some parts hope to achieve all the mechanical processing after a clamping, which puts forward the requirements of composite machining. Turning and milling composite machining is to achieve several different machining processes on one machine tool. Composite machining is the application of the pan, the difficulty of a processing method, that is, turning and milling composite machining. cnc machining center is equivalent to CNC lathe and machining center composite.   A milling parts, often need to go through several clamping, a vertical machining center and a horizontal machining center to complete the parts all processing requirements. As we all know, each after a clamping, will bring a clamping error, the more clamping times, the more errors generated. Therefore, if a vertical machining center and a horizontal machining center are combined together, so that the parts in a single clamping can complete all the milling process, avoiding the errors brought about by multiple clamping.   There are two kinds of composite machining centers, namely, vertical and horizontal conversion machining centers, one is table vertical and horizontal conversion, which is mainly for small parts, and one is spindle vertical and horizontal conversion, which is suitable for medium and large parts.   1 Table vertical and horizontal conversion   There are two structures of table vertical and horizontal conversion, one is to use 45° slope for vertical and horizontal conversion and positioning, the advantage is that 45° slope contact surface is large, table rigidity and load-bearing are better, and vertical and horizontal conversion does not affect the stroke. The positioning surface is not subject to force, which can ensure high accuracy. Another kind is called cradle type table (Fig. 3), because it adopts holding axis for positioning, so the positioning accuracy is poor, and the table's load-bearing is also lighter, which will be subjected to a large torque in the machining, which is unreliable in positioning. It will eat up a large stroke in the table vertical and horizontal conversion. Generally, it is used in the economic type machining center.   2 Horizontal spindle   There are also two types of spindle vertical structures. One is the 45° bevel for spindle vertical and horizontal changeover. Its advantage is that the 45 ° bevel contact surface is large, spindle rigidity is good, positioning using the mouse tooth disc, repeat positioning accuracy is high, and its tool center point position remains unchanged after the vertical and horizontal conversion, convenient programming, of course, its disadvantage is no negative angle.   The other form is A-axis, which has the advantage of a large X-angle, especially suitable for large-angle impeller processing. However, it has the very obvious disadvantage that the vertical and horizontal conversion will eat up the Z-axis travel. Generally speaking, the machine X, Y, Z axis in the Z axis is the shortest, if eaten a little more, it makes the machine tool machining range is greatly reduced. Compared with the traditional CNC machining process, the outstanding advantages of turning and milling machining center are mainly reflected in the following aspects.   (1) Shorten the product manufacturing process chain and improve production efficiency. Turn-mill machining can be realized once the card to complete all or most of the machining process, thereby greatly shortening the product manufacturing process chain. In this way, on the one hand, it reduces the production auxiliary time caused by clamping changes, and at the same time reduces the manufacturing cycle and waiting time of the fixture, which can significantly improve production efficiency.   (2) Reduce the number of clamping times and improve machining accuracy. The reduction of the number of card loading avoids the accumulation of errors due to the change of positioning reference. At the same time, most of the current turning and milling machines have online inspection function, which can realize on-site inspection and precision control of key data during the manufacturing process, thus improving the machining accuracy of products.   (3) Reduce floor space and production cost. Although the single price of turn-mill machining equipment is relatively high, but due to the shortening of the manufacturing process chain, the reduction of equipment required for the product, as well as the reduction of the number of fixtures, workshop floor space and equipment maintenance costs, can effectively reduce the overall investment in fixed assets, production operation and management costs.   Turning and milling machining center through a clamping parts to complete a variety of machining processes, shorten the processing time, improve the processing accuracy, popular among users. CNC turning and milling machine tool is the main type of composite machining machine tool. Usually in the CNC lathe to achieve plane milling, drilling, tapping, milling grooves and other milling processing. With turning, milling, boring and other composite functions, can achieve a clamping, full processing of the processing concept.

In the manufacturing industry, everyone is familiar with the term industrial Internet of things, and the industrial Internet has gradually become a key link to realize smart factories and intelligent manufacturing, which shows the importance of industrial Internet of things. How to deploy and establish the industrial Internet of things has become a problem that every machining enterprise needs to consider. This article will tell you how to deploy the industrial Internet of things. Why do we advocate the industrial Internet of things so much today (related reading: can the industrial Internet of things (iiot) really bring revolutionary changes to enterprises?)? In fact, its real advantage is not in system upgrading, but in developing constant data to collect and evaluate the continuous improvement efficiency of the feedback loop and provide necessary information for the industrial Internet of things strategy. For the construction of industrial Internet of things. First of all, what we should do is: 1. Target setting The main goal of deploying the industrial Internet of things is to reduce costs and improve efficiency (related reading: how to match tools with machine tools), or to achieve remote monitoring of systems and processes. After determining the target, we can analyze the component according to the existing equipment and data. This process is very important. In most cases, it is impossible to replace all the old equipment, and the cost is too high. Therefore, in practice, machining enterprises tend to integrate communication equipment and protocol conversion software to connect all systems, so as to effectively use existing equipment. 2. Device connection The Internet of things is a "network", so it is necessary to realize connection, so enterprises must connect machines and sensors from different manufacturers. For old equipment without communication ability, sensors can be integrated for processing, and a sensor network can be strategically re deployed to meet the requirements of data collection. After the device completes the connection and realizes the communication between the devices, it is also necessary to consider how to push the data. The real power of industrial Internet of things and cloud computing comes from data centralization and integration of applications to extract and process information. Many industrial Internet of things platforms now provide databases with various capabilities, from data storage time processing to equipment supply and reporting. Although they are usually configured for specific applications, many of them are built for simple and rapid implementation. 3. Remove obstacles In the industrial Internet of things, privacy and security are important obstacles to investment in the industrial Internet of things. When collecting and transmitting sensitive data, it must be protected. Therefore, the industrial Internet of things should take special security measures to ensure that the system can safely collect, monitor, process and store data. However, to ensure security, it is necessary to balance the costs related to time and resources with data protection.

Although many people say that business in the machining industry is not easy to do and customers are not easy to talk about, although this situation can not be denied, we need to admit that many enterprises are thriving and making a lot of money. So, what know-how do they have? Let's take a look at how these CNC machining enterprises with good benefits find customers. 1、 Establish and maintain the company's corporate website In the past, machining enterprises only had to decorate their facades, but now the development of network technology has made things have two sides. The company's website is the facade of the enterprise, so the company profile, development, processing capacity, cooperation cases, product display and other contents need professional personnel to maintain them on a daily basis. And enterprise websites have become a standard to measure the quality of enterprises. Therefore, machining enterprises must pay attention to it. 2、 Release the produced products frequently Let users see enterprise products, just like everyone shopping online, they will judge the quality of goods according to many details. The same is true of machining enterprises. Uploading more detailed drawings of manufactured products can prove the quality of their own products on the one hand, and leave a good impression on customers on the other. Therefore, when releasing product pictures, we must pay attention to the clarity of the pictures and show the advantages and features. However, we should also pay attention to avoiding the content involving core technologies and preventing the exposure of enterprise information. 3、 Ingenious use of online resources If you have time, you should go online more to observe business opportunities, visit forums, make friends, and post more essence posts. It can let customers pay attention to you, so as to find you for cooperation, and at the same time, it also advertises its own enterprise. In addition, there are many platforms that communicate with practitioners in the same industry, which are potential business opportunities. 4、 Component community facilitates peer communication Communities are places with rich contacts, such as QQ groups and wechat groups. Don't worry about competing for customers when you communicate with peers. Because it expands the circle of contacts, it not only increases competitors, but also increases the number of customers. Therefore, as long as your goods are high-quality, you will get more customers. 5、 Pay attention to communication problems The machining enterprises should treat the interested customers seriously and attentively, keep records of each customer, track in real time, actively communicate with each other, screen out the target appearance, track and return the targeted customers, and strive to promote the transaction.

With the continuous improvement of human requirements for the living environment, the environmental problems involved in the PCB production process are particularly prominent. At present, lead and bromine are the hottest topics; Lead free and halogen-free will affect the development of PCB in many aspects. Although at present, the changes in the surface treatment process of PCB are not great, which seems to be a distant thing, it should be noted that long-term slow changes will lead to great changes. With the increasing calls for environmental protection, the surface treatment process of PCB will certainly change dramatically in the future. Purpose of surface treatment The most basic purpose of surface treatment is to ensure good solderability or electrical performance. Since copper in nature tends to exist in the form of oxide in the air, it is unlikely to remain as original copper for a long time, so it needs to be treated in other ways. Although in the subsequent assembly, strong flux can be used to remove most of the copper oxides, the strong flux itself is not easy to remove, so the industry generally does not use strong flux. Common surface treatment process At present, there are many PCB surface treatment processes, the common ones are hot-air leveling, organic coating, electroless nickel plating / gold dipping, silver dipping and tin dipping, which will be introduced one by one below. 1. Hot air leveling Hot air leveling, also known as hot air solder leveling, is a process of coating molten tin lead solder on the PCB surface and leveling (blowing) it with heated compressed air to form a coating layer that is resistant to copper oxidation and provides good solderability. After hot air leveling, the solder and copper form copper tin intermetallic compound at the junction. The thickness of the solder protecting the copper surface is about 1-2 mil. PCB shall be immersed in molten solder during hot air leveling; The air knife blows out the liquid solder before the solder solidifies; The wind knife can minimize the meniscus of solder on the copper surface and prevent solder bridging. Hot air leveling is divided into vertical type and horizontal type. Generally speaking, the horizontal type is better, mainly because the horizontal hot air leveling coating is more uniform and can realize automatic production. The general process of hot air leveling process is: Micro etching → preheating → flux coating → tin spraying → cleaning. 2. Organic coating The organic coating process is different from other surface treatment processes in that it acts as a barrier layer between copper and air; The organic coating process is simple and the cost is low, which makes it widely used in the industry. The early organic coating molecules are imidazole and benzotriazole, which play an anti rust role. The latest molecule is mainly benzimidazole, which is the copper that chemically bonds the nitrogen functional group to the PCB. In the subsequent welding process, if there is only one organic coating layer on the copper surface, there must be many layers. This is why liquid copper is usually added to the chemical tank. After coating the first layer, the coating layer adsorbs copper; Then the organic coating molecules of the second layer are combined with copper until 20 or even hundreds of organic coating molecules are concentrated on the copper surface, which can ensure multiple reflow soldering. The test shows that the latest organic coating process can maintain good performance in many lead-free welding processes. The general process of organic coating process is degreasing → micro etching → pickling → pure water cleaning → organic coating → cleaning, and the process control is easier than other surface treatment processes. 3. Electroless nickel plating / gold immersion: electroless nickel plating / gold immersion process Unlike organic coating, electroless nickel plating / gold immersion seems to put thick armor on PCB; In addition, the electroless nickel plating / gold immersion process is not like the organic coating as the anti rust barrier layer, which can be useful in the long-term use of PCB and achieve good electrical performance. Therefore, electroless nickel plating / gold immersion is to wrap a thick layer of nickel gold alloy with good electrical properties on the copper surface, which can protect PCB for a long time; In addition, it also has the tolerance to the environment that other surface treatment processes do not have. The reason for nickel plating is that gold and copper will diffuse each other, and the nickel layer can prevent the diffusion between gold and copper; If there is no nickel layer, the gold will diffuse into the copper in a few hours. Another advantage of electroless nickel plating / gold immersion is the strength of nickel. Only nickel with a thickness of 5 microns can limit the expansion in the Z direction at high temperature. In addition, electroless nickel plating / gold immersion can also prevent the dissolution of copper, which will be beneficial to lead-free assembly. The general process of electroless nickel plating / gold leaching process is: acid cleaning → micro etching → prepreg → activation → electroless nickel plating → chemical gold leaching. There are mainly 6 chemical tanks, involving nearly 100 chemicals, so the process control is relatively difficult. 4. Silver immersion silver immersion process Between organic coating and electroless nickel / gold immersion, the process is relatively simple and fast; It is not as complex as electroless nickel plating / gold immersion, nor is it a thick armor for PCB, but it can still provide good electrical performance. Silver is the little brother of gold. Even when exposed to heat, humidity and pollution, silver can still maintain good solderability, but it will lose luster. Silver immersion does not have the good physical strength of electroless nickel plating / gold immersion because there is no nickel under the silver layer. In addition, silver impregnation has good storage properties, and there will be no major problems when it is put into assembly for a few years after silver impregnation. Silver immersion is a displacement reaction, which is almost submicron pure silver coating. Sometimes, some organic substances are included in the silver immersion process, mainly to prevent silver corrosion and eliminate silver migration; It is generally difficult to measure this thin layer of organic matter, and analysis shows that the weight of the organism is less than 1%. 5. Tin immersion Since all solders are based on tin, the tin layer can match any type of solder. From this point of view, the tin dipping process has great development prospects. However, in the past, the PCB appeared tin whiskers after the tin dipping process, and the migration of tin whiskers and tin during the welding process would bring reliability problems, so the use of tin dipping process was limited. Later, organic additives were added to the tin immersion solution, which can make the tin layer structure take on a granular structure, overcome the previous problems, and also have good thermal stability and solderability. The tin dipping process can form a flat copper tin intermetallic compound, which makes tin dipping have the same good solderability as hot-air leveling without the headache of flatness caused by hot-air leveling; Tin immersion also has no diffusion problem between electroless nickel plating / gold immersion metals - copper tin intermetallic compounds can be firmly combined. The tin immersion plate shall not be stored for too long, and the assembly must be carried out according to the sequence of tin immersion. 6. Other surface treatment processes Other surface treatment processes are less applied. Let's look at the nickel gold plating and electroless palladium plating processes which are relatively more applied. Nickel gold plating is the originator of PCB surface treatment technology. It has appeared since the emergence of PCB, and has gradually evolved into other methods since then. It is to plating a layer of nickel on the PCB surface conductor first and then a layer of gold. Nickel plating is mainly to prevent the diffusion between gold and copper. There are two types of nickel gold plating: soft gold plating (pure gold, the gold surface does not look bright) and hard gold plating (the surface is smooth and hard, wear-resistant, contains cobalt and other elements, and the gold surface looks bright). Soft gold is mainly used for making gold wires during chip packaging; Hard gold is mainly used for electrical interconnection at non soldered places. Considering the cost, the industry often carries out selective plating by image transfer to reduce the use of gold. At present, the use of selective gold plating in the industry continues to increase, which is mainly due to the difficulty in the process control of electroless nickel plating / gold leaching. Under normal circumstances, welding will lead to the embrittlement of the plated gold, which will shorten the service life, so it is necessary to avoid welding on the plated gold; However, since the gold in electroless nickel plating / gold immersion is very thin and consistent, embrittlement rarely occurs. The process of electroless palladium plating is similar to that of electroless nickel plating. The main process is to reduce palladium ions to palladium on the catalytic surface through a reducing agent (such as sodium dihydrogen hypophosphite). The newly generated palladium can become a catalyst to promote the reaction, so that any thickness of palladium coating can be obtained. The advantages of electroless palladium plating are good welding reliability, thermal stability and surface flatness. four Selection of surface treatment process The selection of surface treatment process mainly depends on the type of final assembled components; The surface treatment process will affect the production, assembly and final use of PCB. The following will specifically introduce the use occasions of the five common surface treatment processes. 1. Hot air leveling Hot air leveling once played a leading role in PCB surface treatment process. In the 1980s, more than three-quarters of PCBs used hot-air leveling technology, but the industry has been reducing the use of hot-air leveling technology in the past decade. It is estimated that about 25% - 40% of PCBs now use hot-air leveling technology. Hot air leveling process is dirty, smelly and dangerous, so it has never been a favorite process. However, hot air leveling is an excellent process for larger components and wires with larger spacing. In the PCB with high density, the flatness of hot air leveling will affect the subsequent assembly; Therefore, hot air leveling process is generally not used for HDI board. With the progress of technology, the hot-air leveling process suitable for assembling QFP and BGA with smaller spacing has appeared in the industry, but it is rarely applied in practice. At present, some factories use organic coating and electroless nickel / gold dipping process to replace the hot air leveling process; Technological development has also led some factories to adopt tin and silver impregnation processes. In addition, the trend of lead-free in recent years has further restricted the use of hot air leveling. Although the so-called lead-free hot air leveling has appeared, it may involve the compatibility of equipment. 2. Organic coating It is estimated that at present, about 25% - 30% of PCBs use organic coating technology, and this proportion has been rising (it is likely that organic coating has now surpassed hot-air leveling in the first place). The organic coating process can be used on low-tech PCBs and high-tech PCBs, such as single-sided TV PCBs and high-density chip packaging boards. For BGA, organic coating is also widely used. If PCB has no functional requirements for surface connection or storage period, organic coating will be the most ideal surface treatment process. 3. Electroless nickel plating / gold immersion: electroless nickel plating / gold immersion process Unlike organic coating, it is mainly used on boards with connection functional requirements and long storage life on the surface, such as the key area of mobile phones, the edge connection area of the router shell and the electrical contact area of the elastic connection of chip processors. Due to the flatness of hot-air leveling and the removal of organic coating flux, electroless nickel plating / gold immersion was widely used in the 1990s; Later, due to the appearance of black disk and brittle nickel phosphorus alloy, the application of electroless nickel plating / gold dipping process was reduced. However, at present, almost every high-tech PCB Factory has electroless nickel plating / gold dipping lines. Considering that the solder joint will become brittle when removing the copper tin intermetallic compound, many problems will occur at the relatively brittle nickel tin intermetallic compound. Therefore, almost all portable electronic products (such as mobile phones) use copper tin intermetallic compound solder joints formed by organic coating, silver immersion or tin immersion, while electroless nickel plating / gold immersion is used to form key areas, contact areas and EMI shielding areas. It is estimated that at present, about 10% - 20% of PCBs use electroless nickel plating / gold dipping process. 4. Silver immersion It is cheaper than electroless nickel plating / gold immersion. If PCB has connection functional requirements and needs to reduce costs, silver immersion is a good choice; In addition to the good flatness and contact of silver immersion, the silver immersion process should be selected. Silver immersion is widely used in communication products, automobiles, computer peripherals, and also in high-speed signal design. Silver impregnation can also be used in high-frequency signals because of its excellent electrical properties unmatched by other surface treatments. EMS recommends the silver immersion process because it is easy to assemble and has good inspectability. However, due to defects such as tarnish and solder hole in silver immersion, its growth is slow (but not decreased). It is estimated that at present, about 10% - 15% of PCBs use silver impregnation process. 5. Tin immersion Tin has been introduced into the surface treatment process for nearly a decade, and the emergence of this process is the result of the requirements of production automation. The tin immersion does not bring any new elements into the solder joint, which is especially suitable for the communication backplane. Tin will lose solderability beyond the storage period of the board, so better storage conditions are required for tin immersion. In addition, the use of tin immersion process is restricted due to the presence of carcinogens. It is estimated that at present, about 5% - 10% of PCBs use the tin dipping process. V Conclusion with the higher and higher requirements of customers, stricter environmental requirements and more and more surface treatment processes, it seems that it is a bit confusing and confusing to choose which surface treatment process with development prospects and stronger versatility. It is impossible to predict exactly where PCB surface treatment technology will go in the future. In any case, meeting customer requirements and protecting the environment must be done first!

Parts manufactured by conventional manufacturing processes (casting, forging, etc.) will not explode. However, the explosion of parts made by metal 3D printing is a potential safety hazard. When metal 3D printing is used to manufacture parts, the problem that needs to be paid attention to in this process is the safety hazard. However, only those trapped powders that leave the processing area with the parts in the process of 3D printing metal will bring many safety hazards. Perhaps you have seen operators and technicians wearing respirators and personal protective equipment. This is because the metal powder raw materials used in Metal 3D printing systems are usually small enough and can be easily inhaled and absorbed into the human body with breathing. In fact, some people are also allergic to nickel, which further makes the inhalation of metal powder a major concern. Most people may not realize that once the parts made by metal 3D printing technology are taken out of the construction room and cleaned, the parts may still contain a small amount of powder materials. Because even if the metal part is completely dense, its supporting structure may not be. Most support structures are hollow, so the powder may be trapped inside. When the components are taken out from the building board, one end of these support structures may release the metal powder trapped in the support structures into the atmosphere. This is why it is generally recommended to remove the construction substrate by underwater EDM wire cutting, so that these loose powders can be released into the water. If 3D printed parts are not removed from the substrate using EDM processing technology, secondary cleaning operations, such as vacuuming, are required to remove loose powder trapped in the support structure. However, the difficulty of actual operation is not as easy as it sounds, because powder particles can adhere to the inner wall of the support material or partially melt onto the part surface during stress release. Even if the parts are bumped on the table many times in an exaggerated way, there may still be some powder that has not been removed. Obviously, the method of removing loose powder from parts is very complex, and more research is needed to better understand how to use finishing technologies such as soda blasting, abrasive flow machining (AFM) and electrochemical polishing to help remove loose powder from the inside of the support structure. Among them, abrasive flow machining technology is the latest machining method, which uses abrasive media (a flowable mixture mixed with abrasive particles) to flow through the surface of the workpiece under pressure to deburr, remove flash and grind fillet, so as to reduce the waviness and roughness of the workpiece surface and achieve the finish of precision machining. AFM is the best machining method available for complex manual finishing or complex shape workpieces, as well as parts that are difficult to be machined by other methods. The AFM method can also be applied to the work pieces that are not satisfied with the large-scale processing of rollers, vibrations and other work pieces that will be injured during processing. And the delamination regenerated after the electric discharge machining or the laser beam machining and the residual stress remaining on the machined surface in the previous process can be effectively removed. Electrochemical polishing is also called electrolytic polishing. Electrolytic polishing takes the workpiece to be polished as the anode and insoluble metal as the cathode. Both poles are immersed into the electrolytic cell at the same time, and DC is applied to generate selective anode dissolution, so as to achieve the effect of increasing the brightness of the workpiece surface. It should be noted that some metal powder raw materials such as titanium and aluminum are spontaneous combustion, which means that they will explode. Therefore, professional machining personnel should be careful when handling parts made of these materials, because these powders captured by the parts may be released again. If they sneak into the machine environment, they may explode under the combination of sparks or other conditions. Therefore, special care should be taken when handling and post-processing these parts, and first of all, proper cleaning should be ensured. If loose powder falls during part processing, it cannot be processed. The progress of comprehensively understanding and diagnosing the potential safety hazards related to metal 3D printing is still in progress. If necessary, the local firefighters need to be notified in advance so that they can respond faster in case of emergency. In addition, when 3D printed metal parts are processed on a grinding machine or a turning / milling machine, it must be ensured that the powder in these parts will not explode when sparks ignite during processing.

Nowadays, the hot runner system has gradually entered the market, and various related technologies have also emerged, such as co injection molding technology, insert molding technology, multi-component injection molding technology and so on. As an important part of mold system, hot runner system can effectively improve the quality and production efficiency of plastic mold. The hot runner system originates from the hot runner system. Generally, the nozzle is not always installed on the diverter plate, and it can also be connected to the nozzle flange virtually, but such systems need a fixed plate to maintain the integrity of the system. For most plastic processing processes, because the temperature of the mold is close to 200 ℃, there is a temperature difference between the hot runner and the mold. If the system is connected to the die plate, the temperature will be increased and the heat loss will be increased, and the flow dead angle may also be generated between the diverter plate and the nozzle. When the hot runner needs maintenance, the hot runner must be completely removed from the mold. Since the nozzle is not connected to the diverter plate, the electrical and hydraulic lines must be completely disassembled and connected after the maintenance. Although the hot runner and the injection mold are a whole, their functions and functions are completely different from those of the mold itself. For the independent unit composed of the system, its installation, connection and operation have special high-precision position requirements. For these reasons, the assembly of hot runner system has become a bottleneck of mold installation. Therefore, it has become a very important subject to avoid errors in the installation of the hot runner system, simplify the system connection and save the assembly time. Introduction of combined hot runner system The combined hot runner system is located in the center of the mold and has few connections with the mold. The manufacturing material of the combined hot runner system does not require high thermal conductivity, clamping and pretensioning of the mold piece. This minimal connection provides a high accuracy and stable temperature profile, so the energy consumption is much lower than that of the traditional hot runner system. The combined hot runner system can directly preassemble the hydraulic circuit independent of the mold. The valve gate directly driven by the hydraulic equipment can also be directly installed on the system, so that the control valve on the traditional machine is omitted, making the injection molding more flexible. In addition, electrical and hydraulic circuits can also be configured according to customer requirements. In the combined hot runner system, the nozzle and the splitter plate form a simple unit. The melt flows directly into the nozzle from the diverter plate, so there is no deviation or dead angle. The threaded nozzle is embedded into the diverter plate, eliminating the leakage between the nozzle and the diverter plate. The conventional liner system design generates thermal expansion, and this combined system is particularly effective in eliminating such leakage. Because the system will undergo electrical, temperature, hydraulic or pneumatic testing before delivery, customers will be given instructions on the pre installation system, so that they can be easily installed in the mold and put into production immediately. When the mold or system needs routine maintenance, the combined hot runner system can also be disassembled from the mold by simple steps, so that it can be repaired and tested independently of the mold. The combined hot runner system can reduce the maintenance cost very well, and it is also very convenient in disassembly. The integrated hot runner system can be maintained without disassembly, saving time and cost.

What is the effect of temperature on accuracy in CNC machining? Thermal deformation is one of the reasons that affect the machining accuracy. The machine tool is affected by the change of the workshop environment temperature, the heating of the motor and the friction of the mechanical movement, the cutting heat and the cooling medium, resulting in the uneven temperature rise of each part of the machine tool, resulting in the change of the shape accuracy and machining accuracy of the machine tool. For example, 70mm is processed on an ordinary precision CNC milling machine × For 1650mm screw, the cumulative error of workpieces milled from 7:30 to 9:00 in the morning can reach 85m compared with workpieces processed from 2:00 to 3:30 in the afternoon. But under constant temperature, the error can be reduced to 40m. Another example is a precision double end grinding machine used for double end grinding of 0.6-3.5mm thick thin steel sheet workpieces, which can process 200mm at the time of acceptance × 25mm × The 1.08mm steel sheet workpiece can reach the dimensional accuracy of mm, and the bending degree is less than 5m in the whole length. However, after continuous automatic grinding for 1h, the size change range increased to 12M, and the coolant temperature increased from 17 ℃ at startup to 45 ℃. Due to the influence of grinding heat, the main shaft journal is elongated and the clearance of the front bearing of the main shaft is increased. Therefore, a 5.5kW refrigerator is added to the coolant tank of the machine tool, and the effect is very ideal. It has been proved that the deformation of machine tool after heating is an important factor affecting machining accuracy. However, the machine tool is in an environment where the temperature changes at any time; The machine tool itself will inevitably consume energy when working, and a considerable part of this energy will be converted into heat in various ways, resulting in physical changes of various components of the machine tool. Such changes vary greatly due to different structural forms and materials. Machine tool designers should master the formation mechanism and temperature distribution law of heat and take corresponding measures to reduce the influence of thermal deformation on machining accuracy to Z. CNC machining The temperature rise and temperature distribution of machine tools and the natural climate affect China's vast territory. Most of the areas are located in subtropical areas. The temperature varies greatly throughout the year and the temperature difference in a day is also different. Therefore, the way and degree of people's intervention on indoor (such as workshop) temperature are also different, and the temperature atmosphere around the machine tool varies greatly. For example, the seasonal temperature change range in the Yangtze River Delta is about 45 ℃, and the diurnal temperature change is about 5-12 ℃. Generally, the machining workshop has no heating in winter and no air conditioning in summer. However, as long as the workshop is well ventilated, the temperature gradient of the machining workshop does not change much. In Northeast China, the seasonal temperature difference can reach 60 ℃, and the diurnal variation is about 8-15 ℃. The heating period is from late October to early April of the following year. The machining workshop is designed with heating and insufficient air circulation. The temperature difference inside and outside the workshop can reach 50 ℃. Therefore, the temperature gradient in the workshop in winter is very complex. During the measurement, the outdoor temperature is 1.5 ℃, the time is 8:15-8:35 in the morning, and the temperature change in the workshop is about 3.5 ℃. The machining accuracy of precision machine tools will be greatly affected by the ambient temperature in such a workshop. Influence of surrounding environment the surrounding environment of the machine tool refers to the thermal environment formed by various layouts within the close range of the machine tool. They include the following four aspects: 1) Workshop microclimate: such as the temperature distribution in the workshop (vertical direction and horizontal direction). When the day and night alternate or the climate and ventilation change, the workshop temperature will change slowly. 2) Workshop heat sources: such as solar radiation, radiation of heating equipment and high-power lighting, etc. when they are close to the machine tool, they can directly affect the temperature rise of the whole or part of the machine tool for a long time. The heat generated by the adjacent equipment during operation will affect the temperature rise of the machine tool in the form of radiation or air flow. 3) Heat dissipation: the foundation has a good heat dissipation effect, especially the foundation of precision machine tools should not be close to the underground heating pipe. Once it breaks and leaks, it may become a heat source that is difficult to find the cause; The open workshop will be a good "radiator", which is conducive to the temperature balance in the workshop. 4) Constant temperature: the constant temperature facilities adopted in the workshop are very effective in maintaining the accuracy and processing accuracy of precision machine tools, but the energy consumption is large. 3. Internal thermal influence factors of machine tool 1) Machine tool is a structural heat source. Motor heating such as spindle motor, feed servo motor, cooling and lubricating pump motor and electric control box can generate heat. These conditions are allowed for the motor itself, but they have significant adverse effects on the main shaft, ball screw and other components, and measures shall be taken to isolate them. When the input electric energy drives the motor to run, except that a small part (about 20%) will be converted into the thermal energy of the motor, most will be converted into kinetic energy by the motion mechanism, such as the rotation of the main shaft and the movement of the workbench; However, it is inevitable that a considerable part of the heat will be converted into friction heat during the movement, such as the heat of bearings, guide rails, ball screws and transmission boxes. 2) Cutting heat of the process. During the cutting process, part of the kinetic energy of the tool or workpiece is consumed by the cutting work, and a considerable part is converted into the deformation energy of the cutting and the friction heat between the chip and the tool, forming the heat of the tool, the spindle and the workpiece, and a large amount of chip heat is transmitted to the worktable fixture and other parts of the machine tool. They will directly affect the relative position between the tool and the workpiece. 3) Cooling. Cooling is a reverse measure against the temperature rise of the machine tool, such as motor cooling, spindle component cooling and basic structural component cooling. High end machine tools are often equipped with refrigerators for forced cooling. 4. The influence of the structural form of machine tool on the temperature rise in the field of thermal deformation of machine tool, the structural form of machine tool usually refers to the structural form, mass distribution, material performance and heat source distribution. The structure shape affects the temperature distribution, heat conduction direction, thermal deformation direction and matching of the machine tool. 1) The structural form of the machine tool. In terms of the overall structure, the machine tools are vertical, horizontal, gantry and cantilever, etc., which have great differences in thermal response and stability. For example, the temperature rise of the main axle box of a gear speed lathe can be as high as 35 ℃, so that the main shaft end is lifted up, and the heat balance time needs about 2H. For the precision turning and milling machining center with inclined bed, the machine tool has a stable base. The rigidity of the whole machine is obviously improved. The main shaft is driven by a servo motor, and the gear transmission part is removed. The temperature rise is generally less than 15 ℃. 2) Influence of heat source distribution. It is generally considered that the heat source refers to the motor on the machine tool. For example, the spindle motor, feed motor and hydraulic system are not complete. The heating of the motor is only the energy consumed by the current on the armature impedance when bearing the load, and a considerable part of the energy is consumed by the heating caused by the friction work of the bearing, screw nut, guide rail and other mechanisms. Therefore, the motor can be called the primary heat source, and the bearing, nut, guide rail and chip can be called the secondary heat source. Thermal deformation is the result of the comprehensive influence of all these heat sources. The temperature rise and deformation of a vertical machining center with movable columns during the y-direction feeding movement. The workbench does not move when feeding in the Y direction, so it has little influence on the thermal deformation in the X direction. On the column, the farther away from the y-axis guide screw, the smaller the temperature rise. When the machine moves along the z-axis, the influence of heat source distribution on thermal deformation is further explained. The z-axis feed is farther away from the x-direction, so the thermal deformation has less influence. The closer the z-axis motor nut is to the column, the greater the temperature rise and deformation. 3) Influence of mass distribution. The influence of mass distribution on the thermal deformation of machine tools has three aspects. First, it refers to the size and concentration of mass, usually refers to changing the heat capacity and the speed of heat transfer, and changing the time to reach the heat balance 2、 By changing the arrangement form of mass, such as the arrangement of various ribs, the thermal stiffness of the structure can be improved, and under the same temperature rise, the influence of thermal deformation can be reduced or the relative deformation can be kept small; Third, it means to reduce the temperature rise of machine tool parts by changing the form of mass arrangement, such as arranging heat dissipation ribs outside the structure. Influence of material properties: different materials have different thermal performance parameters (specific heat, thermal conductivity and linear expansion coefficient). Under the influence of the same heat, their temperature rise and deformation are different. Testing of thermal performance of machine tools 1. The purpose of the thermal performance test of the machine tool is to control the thermal deformation of the machine tool. The key is to fully understand the change of the ambient temperature of the machine tool, the heat source and temperature change of the machine tool itself and the response (deformation displacement) of the key points through the thermal characteristic test. The test data or curves describe the thermal characteristics of a machine tool, so that countermeasures can be taken to control the thermal deformation and improve the machining accuracy and efficiency of the machine tool. Specifically, the following objectives should be achieved: 1) Test the surrounding environment of the machine tool. Measure the temperature environment in the workshop, its spatial temperature gradient, the change of temperature distribution in the alternation of day and night, and even the influence of seasonal change on the temperature distribution around the machine tool. 2) Thermal characteristic test of the machine tool itself. Under the condition of eliminating environmental interference as much as possible, the machine tool shall be kept in various operating states to measure the temperature change and displacement change of the important points of the machine tool itself, and record the temperature change and displacement of the key points within a long enough period of time. The infrared thermal phase meter can also be used to record the thermal distribution of each time period. 3) The temperature rise and thermal deformation are measured during the machining process to judge the influence of the thermal deformation of the machine tool on the accuracy of the machining process. 4) The above tests can accumulate a large number of data and curves, which will provide reliable criteria for machine tool design and user control of thermal deformation, and point out the direction of taking effective measures. 2. Principle of thermal deformation test of machine tool thermal deformation test first needs to measure the temperature of several relevant points, including the following aspects: 1) Heat source: including feed motor of each part, spindle motor, ball screw drive pair, guide rail and spindle bearing. 2) Auxiliary devices: including hydraulic system, refrigerator, cooling and lubrication displacement detection system. 3) Mechanical structure: including machine bed, base, slide plate, column, milling head box and spindle. An indium steel measuring rod is clamped between the spindle and the rotary table. Five contact sensors are arranged in the X, y and Z directions to measure the comprehensive deformation under various conditions to simulate the relative displacement between the tool and the workpiece. 3. Test data processing and analysis the thermal deformation test of the machine tool shall be carried out in a long continuous time, and continuous data recording shall be carried out. After analysis and processing, the thermal deformation characteristics reflected are highly reliable. If the error is eliminated through multiple tests, the displayed regularity is credible. There are 5 measuring points in the thermal deformation test of the spindle system, of which point 1 and point 2 are at the end of the spindle and near the spindle bearing, and point 4 and point 5 are respectively at the milling head housing near the z-direction guide rail. The test time lasted for 14h, in which the rotation speed of the main shaft in the first 10h was alternated within the range of 0-9000r / min. from the 10th h, the main shaft continued to rotate at a high speed of 9000r / min. The following conclusions can be drawn: 1) The thermal balance time of the spindle is about 1H, and the temperature rise range after balance is 1.5 ℃; 2) The temperature rise mainly comes from the main shaft bearing and the main shaft motor. Within the normal speed range, the bearing has good thermal performance; 3) Thermal deformation has little influence on X direction; 4) The z-direction expansion deformation is large, about 10m, which is caused by the thermal extension of the main shaft and the increase of the bearing clearance; 5) When the rotation speed is kept at 9000r / min, the temperature rise rises sharply, rising sharply by about 7 ℃ within 2.5h, and there is a tendency to continue to rise. The deformation in Y direction and Z direction reaches 29m and 37m, indicating that the main shaft can no longer operate stably at the rotation speed of 9000r / min, but can operate in a short time (20min). The control of thermal deformation of the machine tool is analyzed and discussed above. The temperature rise and thermal deformation of the machine tool have various influence factors on the machining accuracy. When taking control measures, we should grasp the main contradiction and focus on taking one or two measures to achieve twice the result with half the effort. The design should start from four directions: reducing heat generation, reducing temperature rise, balancing structure and reasonable cooling. 1. Reducing heat generation and controlling heat source are fundamental measures. In the design, measures shall be taken to effectively reduce the heat generation of the heat source. 1) Reasonably select the rated power of the motor. The output power P of the motor is equal to the product of the voltage V and the current I. generally, the voltage V is constant. Therefore, the increase of the load means that the output power of the motor increases, that is, the corresponding current I also increases, and the heat consumed by the current in the armature impedance increases. If the motor we designed and selected works near or greatly exceeds the rated power for a long time, the temperature rise of the motor will obviously increase. Therefore, a comparative test was carried out on the milling head of bk50 numerical control needle slot milling machine (motor speed: 960r / min; ambient temperature: 12 ℃). The following concepts are obtained from the above tests: considering the heat source performance, when selecting the rated power of the spindle motor or the feed motor, it is appropriate to select about 25% higher than the calculated power. In actual operation, the output power of the motor matches the load, and increasing the rated power of the motor has little impact on the energy consumption. But the temperature rise of the motor can be effectively reduced.

The technical requirements for the processing of non-standard parts are generally formulated according to the main functions and working conditions of the shaft, generally including the following: (a) The surface roughness of precision parts is generally ra2.5 ~ 0.63, and the surface roughness of the shaft diameter matched with the transmission parts μ m. The surface roughness of the bearing shaft diameter matched with the bearing is Ra0.63 ~ 0.16 μ m。 (b) The mutual position accuracy of precision parts and the position accuracy requirements of non-standard parts processing are mainly determined by the position and function of the shaft in the machine. Generally, it is required to ensure the coaxiality requirements of the Journal of the assembled transmission parts to the supporting journal, otherwise the transmission accuracy of the transmission parts (gears, etc.) will be affected and noise will be generated. For common precision shafts, the radial runout of the matched shaft section to the bearing journal is generally 0.01 ~ 0.03mm, and for high-precision shafts (such as main shafts), it is usually 0.001 ~ 0.005mm. (c) Geometric accuracy of precision parts geometric accuracy of shaft non-standard parts mainly refers to the roundness and cylindricity of journal, external cone, Morse cone hole, etc. generally, its tolerance shall be limited within the range of dimensional tolerance. For inner and outer circular surfaces with high accuracy requirements, the allowable deviation shall be marked on the drawings. (d) Machining dimensional accuracy of non-standard parts machining the journal with supporting function in order to determine the position of the shaft, it usually requires high dimensional accuracy (it5 ~ it7). The journal dimension accuracy of the assembled transmission parts is generally low (IT6 ~ it9). The precision parts walking type CNC lathe (walking machine / longitudinal cutting lathe) is a kind of CNC machine tool mainly used for the precision machining of shafts and non-standard shafts. It has a qualitative leap in processing efficiency and processing accuracy compared with the CNC lathe. Because of the dual axis arrangement of tools, the processing cycle time is greatly reduced. By shortening the tool exchange time between the tool arrangement and the opposite tool table, The effective axis movement overlap function of thread chip and the direct spindle indexing function during secondary machining can shorten the idle travel time.

Machining process design of aluminum alloy is a means to improve product quality. The heat generated during high-speed cutting of metal will change the physical properties of metal, thus affecting the properties of materials. The normal solution is to reduce the cutting speed to reduce the heat intensity. But better engineers do the opposite. The machining of aluminum alloy increases the cutting speed. As the speed continues to increase, the cutting metal chips are thrown away by centrifugal movement, which takes away most of the heat, and the heat of the processing body itself decreases. This machining design concept fully reflects the role of reverse thinking. Aluminum alloy machining for machine tool processing enterprises, there is a large amount of cutting fluid. Through the use of an effective filtration system, the liquid is monitored and preventive maintenance is carried out. The actual use is a centralized liquid supply system. The aluminum alloy machining mixing dispenser solution is used to ensure the emulsifying effect of the mixture. The experience of adding essence is required for the processing of machined parts every day, so as to maintain the normal concentration effect, concentrate sedimentation, centrifuge and skimming. The filtration is added to the lotion for a certain time and added to other liquid systems as a daily addition solution. There is a system of daily degreasing and conventional slag removal. The waste liquid after machining contains a large number of harmful components and cannot be directly discharged. The rich experience and scientific and reasonable knowledge of machining essence can be summarized through the machining process technology of aluminum alloy in practical engineering. In general, if the machining process is good enough, it requires more advanced equipment and superb machining technology.