CNC machining (Computer numerical control machining) is a method of machining using computer-controlled CNC machine tools, which is widely used in parts manufacturing in various industries. It realizes the machining of the workpiece by controlling the machine tool to cut along the specified path through the pre-written machining program. The following will introduce the process flow of CNC machining.First, design and develop the processing technologyBefore CNC machining, it is first necessary to design the product and develop the processing technology. According to the requirements and functions of the product, the designer uses CAD (computer aided design) software to design the product. Then, the process engineer develops the processing technology according to the shape, material and processing requirements of the product, including the selection of the appropriate cutting tools, cutting parameters, cutting paths, etc.Secondly, write the processing programMachining program is the core of CNC machining, it contains the machine tool action instructions, cutting parameters, cutting path and other information. Writing the machining program requires the use of CAM (Computer aided manufacturing) software to convert the design file of the product into the machining program. When writing the processing program, it is necessary to consider the cutting performance of the material, the rationality of the process and other factors to ensure the efficiency and quality of the processing process.Then, the machine tool and tool clamping are carried outBefore CNC machining, the workpiece needs to be clamped on the machine tool and the appropriate tool is selected for cutting. Machine tool clamping is the process of fixing the workpiece to the machine tool, which needs to consider the shape, size and processing requirements of the workpiece. Tool clamping is the process of installing the tool on the machine tool, and it is necessary to select the appropriate tool type and specification, as well as the correct installation method. The accuracy and stability of machine tool and tool clamping has an important impact on machining accuracy and efficiency, so it needs to be carefully adjusted and checked.Next, the processing operation is carried outAfter the machine tool clamping and tool clamping are completed, the CNC machining operation can begin. The operator inputs the written machining program into the CNC machine tool controller, and then through the controller's instructions, the machine tool cuts in accordance with the path and speed specified by the program. During the machining process, the operator needs to monitor the machining status and adjust the cutting parameters and tools in time to ensure the machining quality and efficiency.Finally, the processing inspection and finishing are carried outAfter the completion of CNC machining, the workpiece needs to be inspected and trimmed. Measurement tools and equipment can be used to test the size, shape and surface roughness to verify that the workpiece meets the requirements. Finishing is the process of dressing, grinding or polishing the workpiece to eliminate possible processing defects and improve the accuracy and surface quality of the workpiece.In summary, the CNC machining process covers the design and development of machining technology, writing machining procedures, machine tool clamping and tool clamping, processing operation, and processing inspection and dressing. Each link requires accurate operation and strict control to ensure the efficiency of the processing process and the quality of the workpiece.The development of CNC machining has provided high-precision and high-efficiency parts manufacturing solutions for various industries. Compared with traditional manual operation and conventional machining, CNC machining has the following advantages:1, high precisionCNC machining through the precise control of CNC machine tools and high-speed rotation of tools, high-precision parts can be machined. Processing accuracy can reach sub-millimeter or even higher levels to meet the requirements of complex parts.2. High efficiencyCNC machining adopts computer programming and automatic control, which can realize automatic continuous processing and greatly improve production efficiency. The time and workload of manual operation are reduced, and production efficiency and capacity are improved.3. FlexibilityCNC machining can be flexibly processed according to different product requirements and design requirements. Just modify the processing program and adjust the tool, you can realize the processing of different parts, avoiding the trouble of replacing equipment in traditional machining.4. RepeatabilityCNC machining by writing processing programs and automatic control, can achieve accurate cutting path and processing parameters, to ensure the consistency and repeatability of processing. It is not affected by the technical level and experience of the operator, reducing the influence of human factors on the processing quality.5. VersatilityCNC machining enables a variety of machining operations, such as milling, turning, drilling, tapping, etc. A CNC machine tool can complete a variety of processing tasks, reducing equipment investment and floor space.In summary, CNC machining provides a part manufacturing solution with high efficiency, high precision, flexibility, repeatability and versatility. It is widely used in various industries, such as aerospace, automotive, electronics, medical equipment, mold manufacturing and so on.In the aerospace field, CNC machining can manufacture complex shaped aerospace parts, such as turbine blades, engine parts, aerospace structural parts, etc. Due to the high precision and repeatability of CNC machining, the quality and performance requirements of parts can be ensured.In the automotive industry, CNC machining can manufacture automotive engine parts, chassis parts, body parts, etc. Through CNC machining, high precision and consistency of parts can be achieved, improving the performance and safety of vehicles.In the field of electronics, CNC machining can manufacture electronic parts, circuit boards, shells, etc. Due to the high efficiency and flexibility of CNC machining, it can meet the rapid development and production needs of electronic products.In the field of medical equipment, CNC machining can manufacture medical device parts, artificial joints, dental equipment, etc. The high precision and repeatability of CNC machining can ensure the quality and safety of medical equipment.In the field of mold manufacturing, CNC machining can manufacture various types of molds, such as injection molds, die casting molds, stamping molds, etc. Due to the versatility of CNC machining, high-precision machining of complex molds can be achieved.Overall, the development of CNC machining provides high efficiency, high precision and flexible parts manufacturing solutions for various industries. It can control the machine tool through the computer program for automatic processing, which greatly improves the production efficiency and product quality.One of the advantages of CNC machining is high precision. Thanks to the use of computer program control, very precise machining can be achieved to achieve micron level accuracy requirements. This is very important for some parts that require a precise fit, such as gears, threads, etc.Secondly, CNC machining has a high degree of flexibility. By changing different tools and adjusting the processing path, a variety of complex shapes of parts can be manufactured. Moreover, the production of different products can be achieved only by modifying the program, without the need to redesign and manufacture new tooling.CNC machining is also repeatable. Once the correct machining procedures and parameters are set, the machine can operate continuously and maintain consistent machining quality without manual intervention. This is important for high volume production to ensure that each part meets the specified size and quality requirements.In addition, CNC machining is versatile. By choosing different tools and processing methods, drilling, milling, cutting, turning and other processing operations can be achieved to meet the processing needs of different parts. This makes CNC machining a versatile manufacturing process.Overall, CNC machining is an efficient, precise, flexible and reliable part manufacturing solution. With the continuous development of technology, CNC machining will play an increasingly important role in various industries, promoting the progress and development of manufacturing.

As long as there is a current flowing through an electronic device, the energy loss will be manifested as heat, and the greater the loss, the more heat will be generated. In semiconductor devices, the gate has been reduced to the size of nanometers, and a single bare chip can now contain millions of gates formed by billions of transistors, which is a test for heat dissipation.The effect of overheating on semiconductorsSemiconductor materials change with temperature due to the electromigration effect, and the performance of the device will be reduced beyond the temperature limit of the device. In addition, semiconductors rely on bonding connections, and if exposed to high temperatures, the integrity of the bond can be compromised. Semiconductor devices are usually composed of chips on an insulated substrate, and overheating will cause different levels of deformation in the semiconductor devices, reducing the service life; Or due to the expansion of the packaging material and stress on the chip, resulting in premature failure of the device, which adversely affects reliability, so the higher the operating temperature, the lower the reliability.Cooling solutionThe typical PCB heat dissipation method is passive cooling, where a low thermal resistance copper sheet placed under and around the semiconductor takes away the heat of the device and distributes it to other parts of the PCB board if the space and components allow.Another way to dissipate heat from semiconductors is to install radiators, which are generally made of aluminum and covered with fins on the substrate to maximize the surface area, and then rely on air convection to dissipate heat. Compared to the first method, the heat can be dissipated from the device more efficiently.If the radiator is unable to dissipate excess heat, a fan can be installed to force heat dissipation. The advantage is increased air convection to speed up heat transfer, the disadvantage is that this arrangement will suck dust and pollutants into the equipment, which may affect the overall reliability or potentially reduce the thermal efficiency of the radiator.If space is limited, another solution is heat pipe cooling. As an off-the-shelf material, heat pipes provide a reliable and cost-effective way to passively transfer heat from hot spots on the plate to cooler locations. Typically, heat pipes contain a small amount of endothermic liquid, such as pressurized nitrogen, ammonia, or acetone. The fluid absorbs heat and turns into vapor, which flows down the pipe to the condenser, where it condenses back into a liquid state and then returns to the heat source for re-circulation. Heat pipes have the advantage of passive construction, no moving parts, and no maintenance requirements.Other solutions include using liquid-cooled cooling plates or Peltier effect cooling plates, but add cost and design complexity.PCB heat dissipation recommendations1. Provide natural ventilation for the circuit board, so that the air freely flows through the surface of the circuit board, which can minimize the uneven cooling.2. If the PCB is installed in the housing, try to choose the housing made of low thermal resistance materials; Fins, ridges, or simple raised designs can be used to maximize the surface area of the shell. If the enclosure of the device allows, the direction of the PCB can be adjusted vertically, using the principle of hot air rising and cold air sinking to increase the airflow rate of natural convection.3. If a fan is installed, place the fan at one end of any natural convection channel to ensure free air flow; In addition, if the device is running in an area with dust or contaminants, install a filter.

In an electric car, a battery discharge generates heat, and the faster it is discharged, the more heat it generates. Batteries work on the principle of voltage difference, and at high temperatures, the electrons inside are excited, which reduces the voltage difference between the two sides of the battery. If there is no cooling system to keep it within the working range, the battery will stop working, and if the internal temperature difference is large, it may cause the charge and discharge rate of each cell to be different, thereby reducing the performance of the battery pack. If the battery overheats or the temperature distribution in the battery pack is not uniform, there may be potential thermal stability issues, such as capacity loss, heat loss and fire and explosion, and in the face of life-threatening safety issues, the electric vehicle industry is constantly innovating to improve battery cooling systems.A research team compared four different methods of lithium-ion soft-pack battery cooling: air, indirect liquid, direct liquid, and fin cooling systems. The results show that the air cooling system needs 2 to 3 times more energy than other methods to maintain the same average temperature. Minimum temperature climb of indirect liquid cooling system; The fin cooling system increases the battery weight by about 40%. Indirect liquid cooling is a more practical form than direct liquid cooling.In a liquid cooling system, whether the battery is immersed in the liquid or whether the liquid is pumped through a pipeline divides direct and indirect cooling.Direct cooling systems, which put the battery pack in direct contact with the coolant, are not currently used in cars on the market, and this solution is in the development stage, because of the need for new coolants, direct cooling is more difficult to achieve. And the battery is in contact with the liquid, the coolant needs to have low or no conductivity.Indirect cooling systems are similar to ICE cooling systems in that both circulate liquid coolant through a series of metal tubes. However, the structure of the cooling system will look very different in an electric vehicle, achieving uniformity of the cooling temperature and the structure of the cooling system will vary depending on the shape of the battery pack.Due to the widespread use of electric vehicles, there are also higher requirements on battery life and power output, and in order to achieve this, battery thermal management systems need to be able to transfer heat away from the battery pack at higher rates of charging and discharging. While some companies are already using indirectly cooled battery packs, ongoing research and development on battery packs and coolants is needed to improve the safety of electric vehicles.

1. Battery cooling and battery water cooling plateIn battery cooling system applications, liquid cooling has become the mainstream cooling treatment. The heat generated by the car battery in the work is contacted by the electronic device components and the surface of the water-cooled plate, and is eventually taken away by the coolant in the internal flow channel of the cold plate.The design of the water-cooled plate has a variety, mainly according to the battery type and the overall layout. In order to ensure the temperature uniformity of the high energy battery pack, the longer the cooling channel, the more difficult the temperature uniformity control is.2.The process changes of the battery water cooling plateElectric vehicles have developed from ordinary oil in the early days to electricity, and the water-cooled plate process is also changing.The first generation of products - extruded aluminum profile water cooling plateThe material used for water-cooled plate is generally 6 series aluminum, cold plate forming process is complex, if you want to make a large plate, no large mold, you need to put two or three plates friction stir welding together, so the whole process is more and more complex, plus the welding head is also consumable, so the cost is higher.The second generation of products - small stamping plate and harmonica tubeThe performance of the water-cooled plate directly affects the performance of the battery pack, thus affecting the durability of the electric vehicle. Because the water-cooled plate can easily weigh more than 10 to 20 kilograms, the performance of the battery is greatly limited.The market has turned its attention to lighter stamping plates and harmonica tubes, and water-cooled plates using brazing technology have entered the public's field of vision. Brazing is widely used and mature in the automobile industry. The front radiator, condenser and plate heat exchanger of automobile all adopt this process. Generally, after coating the welding surface of 3-series aluminum with solder or solder sheet, it is welded in a vacuum brazing furnace at high temperature (about 600℃), and mature brazing technology is the key to the success or failure of the product.The third generation of products - liquid cooling plate integration and integrationWhen the energy density of a single unit reaches a certain bottleneck, in order to insert more battery cells into the battery pack, the module becomes larger and larger, and even the concept of the module is cancelled, and the box on the battery pack is directly inserted, that is, the CTP. At the same time, the battery water cooling plate is also in the direction of the large panel, either integrated into the box or module, or made into a large punching plate placed flat on the bottom of the box or covered on the top of the battery.3.The battery water-cooled plate welding processStamping and welding of liquid cooled plates can be relatively complicated. No matter what kind of water-cooled plate processing process we use, welding is a very important process. Nowadays, the welding process of water-cooled plate can be mainly divided into vacuum brazing and friction stir welding, because the structural design of vacuum brazing liquid cooled plate is more flexible, higher welding efficiency and other characteristics, so it is widely used in the field of electric vehicles.At present, with the diversification of the liquid cooled plate structure, the requirements for welding processes are becoming higher and higher, and the welding process is also developing in the following directions:1) Improve welding energy efficiency and reduce welding costs;2) Improve the mechanization and automation level of the workshop, improve the stability of welding quality;3) The development of new industries continues to promote the development of welding technology;4) Research and development of heat sources;5) Energy saving technology is still a common concern.