02-26

What is the effect of temperature and time on the welding effect?

2023-02-26

Weld effect 1. What is the effect of the amount of flux and the temperature and time of welding on the welding effect? With the development of high quality and high efficiency of welding technology, the proportion of welding structure in metal structure is increasing. However, due to the welding thermal cycle, welding residual stress must exist in the welded structure. Generally, the residual stress distribution in the welded structure at room temperature is uneven, especially the residual tensile stress in the weld and near-seam area often leads to the decline of the service performance of the welded structure. Most of the welding temperature control is carried out by the field operator according to the experience, it is difficult to achieve timely and accurate adjustment in one step. The welding temperature is high, the weld is burned, the formation of perforation; low welding temperature, the weld burn through, the formation of incomplete penetration, affecting the quality of the weld, defective products, not only affect the production efficiency of the product, but also cause waste of raw materials. Therefore, controlling the welding temperature and ensuring the welding quality play a decisive role in improving the quality of products. Based on this, this paper analyzes the influence of welding temperature on welding quality. How to improve the welding effect? (1), the use of high precision assembly tooling to improve the assembly accuracy of weldments. (2), the preparation of welding robot special welding process, the size of the parts, weld groove, assembly size for strict process regulations. General parts and groove size tolerances are controlled within ± 0.8mm, assembly size errors are controlled within ± 1.5mm, and the probability of welding defects such as pores and undercuts in welds can be greatly reduced. (3), the weld should be cleaned, no oil, rust, welding slag, cutting slag and other debris, allowing a weldable primer. Otherwise, it will affect the success rate of arc. Tack welding is changed from electrode welding to gas shielded welding, and at the same time, the spot welding part is polished to avoid residual slag shell or pores due to tack welding, thus avoiding arc instability and even spatter.

02-25

What is the purpose of preheating when welding

2023-02-25

Heating weldment What is the purpose of preheating when welding 1. Preheating is an effective measure to prevent cold cracks, hot cracks and hardened tissues in the heat affected zone. When welding carbon steel with high carbon content, low alloy steel, heat-resistant steel, and ordinary low carbon steel components with large stiffness, due to the fast cooling rate of the weld, it is easy to produce hardened structures in the weld and heat affected zone, which leads to cracks. Therefore, the welding parts must be preheated. Preheating can achieve the purpose of slowing down the cooling rate, can prevent the weld crack. 2. When welding the welded joint area with large restraint, shrinkage stress will be generated in the joint area due to rapid cooling and rapid heating, thus causing cracks. Preheating the butt area before welding can reduce the shrinkage stress and prevent cracks. 3, in the low temperature area of welding, in order to prevent cracks, even if the thickness of low carbon steel exceeds the preheating treatment must be carried out. 4, preheating can also remove oil, moisture and other factors affecting the quality of the weld, but also to promote the escape of hydrogen in the weld, so as to prevent the occurrence of pores and other defects to play a corresponding role, but also to prevent the occurrence of cracks. The common preheating methods in welding include overall heating in furnace, flame heating, infrared heating and power frequency induction heating. Among them, when the weldment is extremely thick, local heating takes a long time, or the shape is complicated, the weldment can be placed in the heating furnace for heating as a whole, such as the welding of the boiler drum cylinder and the pipe seat, and the welding of the thick-walled water chamber forgings of the high-pressure heater and the water pipe are all by the method of overall heating in the furnace. The use of oxygen-acetylene flame or city gas or liquefied petroleum gas as a fuel to form a flame heating weldment, is a commonly used local preheating method. According to the shape of the welding parts to be preheated, heating torches of various shapes such as ring and straight lines can be made. The principle of infrared heating is to use fuel combustion or electric energy to heat a specially treated surface to generate far infrared rays with a wavelength of 0.7~20 μm, which is a strong heat source and can be used to heat the welding parts. The device that uses fuel combustion to produce far-infrared rays is called the gas far-infrared heater. The device that uses electric energy to generate far infrared rays is called electric far infrared heater. Power frequency induction heating is the use of industrial frequency alternating current to cause alternating magnetic field on the weldment, forming eddy current and generating heat to heat the weldment.

02-24

Brief description of the welding process is generally divided into several stages?

2023-02-24

Welding process Brief description of the welding process is generally divided into several stages? The welding process can be generally divided into three stages: preparation before welding, welding and inspection after welding. What are the basic methods and steps of manual welding? Welding methods and steps: 1. Preparation for welding: Before welding, check the electric soldering iron. The soldering iron head should be kept clean and in a tin state, which is ready for welding. Generally, the solder wire is held in the left hand and the electric soldering iron in the right hand. The soldering iron head and the solder wire are close to each other and can be welded at any time. At the same time, the position is identified. 2. Heating weldment: contact the soldering iron head with the solder joint of the component to be soldered, and heat the soldering iron head with tin on the solder joint with the lead wire of the component to be soldered along the direction of 45 angle to heat the solder joint. 3. Melting solder: After the component lead is heated to a temperature that can melt solder, touch the solder wire from the opposite side of the soldering iron head to the surface of the soldering place in time along the 45 direction, and the contact solder piece melts an appropriate amount of solder. 4, the withdrawal of solder wire: melt the right amount of solder wire quickly after the solder wire removed. 5. Withdraw the electric soldering iron: the solder on the soldering point is close to full, the solder wire fully infiltrates the solder pad and the soldering part, and the solder leaves in the direction of the most 45 angle, so that a bright and smooth solder joint can be formed, and the time taken to complete the whole process of soldering a solder joint is about 3-5s, which is the best, and the time cannot be too long. Manual welding precautions 1, the selection of appropriate solder, should choose the low melting point solder wire for welding electronic components. 2, flux, with 25% rosin dissolved in 75% alcohol (weight ratio) as a flux. 3. Tin should be applied to the electric soldering iron before use. The specific method is: heat the electric soldering iron, and when the soldering tin can be melted just now, apply flux, and then apply solder evenly on the soldering iron head to make the soldering iron head eat a layer of tin evenly. 4. Welding method: polish the pads and pins of the components with fine sandpaper and coat them with flux. Use the soldering iron head to dip an appropriate amount of solder and contact the solder joint. After all the solder on the solder joint is melted and the component lead head is immersed, the electric soldering iron head is gently raised away from the solder joint along the pin of the component. 5. The welding time should not be too long, otherwise it is easy to burn the components. If necessary, tweezers can be used to clamp the pins to help dissipate heat. 6. The solder joint shall be in the shape of a sinusoidal wave crest, the surface shall be bright and smooth, and the tin quantity shall be moderate. 7. After the welding is completed, the residual flux on the circuit board should be cleaned with alcohol to prevent the flux after carbonization from affecting the normal operation of the circuit. 8. The integrated circuit should be finally welded, and the electric soldering iron should be reliably grounded, or the waste heat should be used for welding after power failure. Or use a special socket for integrated circuits, solder the socket and then plug the integrated circuit in. 9. The electric soldering iron should be placed on the soldering iron rack.

02-23

Basic operating methods of arc welding

2023-02-23

Arc welding Basic operating methods of arc welding The basic operation method of arc welding: when starting the arc, the end of the electrode must be in contact with the surface of the weldment to form a short circuit, and then quickly lift the electrode up a distance of 2~4mm, at which time the arc is ignited; After the arc is ignited, the normal welding process begins. 1. Arc ignition is the generation of arc. Electrode arc welding is the use of low voltage, high current discharge to produce arc, relying on the electrode instantaneous contact with the workpiece to achieve. After the arc is ignited, the normal welding process begins. 3. The movement of the welding rod is called the transport rod. The transport bar is a concrete manifestation of the technical level of the welder's operation. The quality of the weld and the forming of the weld are mainly determined by the transportation strip. 4. At the end of arc interruption and welding, the crater at the end of the end should be filled. If the arc is broken immediately at the end of the tail, a crater lower than the surface of the weldment will be formed. Porosity, cracks, pores, slag inclusion and other phenomena often occur at the crater, so the finishing action when the weld is completed is not only to extinguish the arc, but also to fill the crater. Arc welding refers to the use of arc as a heat source and the physical phenomenon of air discharge to convert electrical energy into the heat and mechanical energy required for welding, so as to achieve the purpose of connecting metals. The main methods include electrode arc welding, submerged arc welding, gas shielded welding, etc. It is the most widely used and most important fusion welding method, accounting for more than 60% of the total welding production. Electrode arc welding is the most widely used welding method in industrial production. Its principle is to use the heat generated by arc discharge (commonly known as arc combustion) to melt the electrode and the workpiece to form a weld after condensation, so as to obtain a firm joint welding process.

02-22

Problems that may occur during welding of galvanized sheets

2023-02-22

Atmosphere protection welding Galvanized sheets produce smoke and white floats during welding. If you want to completely eliminate, it is necessary to use a protective atmosphere welding. For example with CO2 shielded welding. Application of Gas Shielded Arc Welding TIG welding can obtain excellent welding quality of the weld, its disadvantage is that the welding energy is limited, not suitable for welding thick parts, especially the strong thermal conductivity of the metal. In order to overcome this shortcoming, the year produced the molten metal extremely inert gas shielded arc welding (MIG), this method uses the metal welding wire as the electrode, the arc is generated between the welding wire and the workpiece, the welding wire is continuously fed and melted into the weld. Therefore, the welding current used in this method can be greatly improved and is suitable for welding medium and thick plates. Because argon is scarce and welding costs are high, TIG and MIG welding are mainly used to weld non-ferrous metals (aluminum, magnesium and their alloys), rare metals (molybdenum, titanium, nickel and their alloys) and stainless steel. In order to reduce the cost of gas shielded welding, people successfully replaced argon with CO2 gas in, and invented carbon dioxide gas shielded welding (). It is an arc welding method with CO2 gas as a protective medium, with welding wire as an electrode, and welding in an automatic or semi-automatic manner. CO2 welding has low cost, high productivity and wide application range. However, due to the arc atmosphere has a strong oxidizing, easy to make alloy elements burning, will cause pores and welding process is easy to produce metal splash, it must be used to contain deoxidizer welding wire and special welding power supply. At present, CO2 arc welding is mainly used for welding ferrous metals such as low carbon steel and low alloy steel, but it is not suitable for stainless steel, high alloy steel and non-ferrous metals. In the early stage of gas shielded arc welding, a single gas was mainly used, such as argon (Ar), helium (He) and CO2 gas. Later, it was found that after adding a certain amount of another or two gases to one gas, satisfactory results could be obtained in refining the droplet, reducing spatter, improving the stability of the arc, improving the melting depth and increasing the temperature of the arc. Commonly used mixed gases are:(1)Ar + He. It is widely used in the welding of large thickness aluminum plate and high thermal conductivity materials, as well as the high-speed mechanized welding of stainless steel. (2)Ar + H2. Using the reduction of mixed gas to weld nickel and its alloys can eliminate the pores in nickel welds. (3)Ar + O2 mixed gas (O2 content is 1%). Especially suitable for stainless steel MIG welding, can overcome the phenomenon of cathode drift when using argon alone. (4)Ar + CO2 or Ar + CO2 + O2. Suitable for welding low carbon steel and low alloy steel, the weld formation, joint quality and arc stability and droplet transfer are very satisfactory.

02-21

Carbon dioxide shielded welding when the spatter is very big, how to return a responsibility?

2023-02-21

Welding Solutions Carbon dioxide shielded welding when the spatter is very big, how to return a responsibility? 1. The welding does not match according to the process specification, and the welding current and voltage are not matched properly. The voltage is small, the top wire appears, the weld bead is convex, and the spatter is large. The voltage is large, and the weld bead is wide and flat. 2. The wire delivery is not smooth. Unstable wire feeding during welding, resulting in large spatter. Clean the wire feeding hose, adjust the wire feeding wheel and replace the conductive nozzle. 3, the conductive nozzle is too large, resulting in poor contact, resulting in large splash 4. The protective gas has large water content, resulting in large splash 5. Magnetic blow affects the position of the ground wire, and electromagnetic interference in the surrounding environment causes arc offset and splash becomes larger. Solution: adjust the best welding specification to ensure smooth wire feeding, and press down welding according to arc Welding stress causes workpiece cracking, seeking solutions to eliminate welding stress? 1. Aging method: after welding, the workpiece is placed there to be eliminated naturally, which takes a long time and is suitable for larger workpieces; 2. Vibration method: the stress elimination machine is used for vibration, which is the same as the aging method, but the time is shorter, the efficiency is high, and it is suitable for smaller workpieces; 3. Heat treatment method: the workpiece after welding is tempered or other heat treatment methods to eliminate stress. 4. Hawke can stress relief equipment: hand-held equipment, specifically for the weld processing, the size of the workpiece to adapt to a wide range, the elimination of welding stress effect is very good. Generally, there are several commonly used ones, which are selected according to the nature of the workpiece and the conditions of the factory. What kind of solutions can the safest collaborative robot Frady provide for the welding industry? Collaborative Robot Frady aims to provide one-stop solutions, but also aims to broaden the application scenarios of automated welding with efficient, easy-to-use and safe welding solutions, and empower customers to realize intelligent flexible welding.

02-20

Roll welding machine does not belong to melting welding equipment, right

2023-02-20

Fusion welding equipment Roll welding machine does not belong to melting welding equipment, right It is right that the roll welding machine does not belong to the melting welding equipment. Roll welding machine belongs to resistance welding (resistance welding), not fusion welding (melting pole welding). Roll welding, also known as circumferential seam welding, is a method of welding workpieces with a pair of roller electrodes instead of cylindrical electrodes for spot welding. The welded workpieces move between the rollers to produce sealed welds with nugget overlapping each other. AC pulse current or amplitude modulation current is generally used, and three (single) phase rectifier, medium frequency and high frequency DC current can also be used. Roll welding is widely used in thin plate welding of sealed containers in oil drums, cans, radiators, aircraft and automobile fuel tanks, rockets, and missiles. The general welding thickness is within 3mm of the veneer. Principle of roll welding machine The adjustable stroke cylinder is used to pressurize to avoid collision damage of upper and lower electrodes. Using three-phase stepless speed electrode drive, welding speed adjustment is convenient and stable. The ingenious and reasonable internal structure reduces the heat generated by the weakening of the welding performance caused by the silver bearing bush rotating conductive excellent contact. Minimize the loss of power conversion. The seam of seam welding consists of a welding spot, which is divided into roll spot welding or airtight seam welding according to the core melting overlap. The formation process of each solder joint is the same as spot welding, there are three stages of pressure, heating and melting and cooling crystallization, but it is quite different from spot welding. Because there is inevitably a shunt phenomenon, the distribution of current field and thermal field in the welding zone has its own characteristics; and the roller that transmits pressure and is heated by electricity continuously rotates to change the welding position, so that the distribution of current field, thermal field and the crystallization characteristics of the melting zone are related to the speed of the change position. What are the characteristics and characteristics of laser deep penetration welding equipment As far as the laser itself is concerned, it is only a device that can generate a parallel beam with good directionality as a heat source. If it is guided and effectively processed and then shot to the workpiece, its input power has a strong compatibility, so that it can better adapt to the automation process. In order to effectively implement the welding, the laser and other necessary optical, mechanical and control components together to form a large welding system. The system includes a laser, a beam delivery assembly, a device for handling and moving the workpiece, and a control device. This system can be simply manual handling and fixing of workpieces by the operator, or it can include automatic loading, unloading, fixing, welding and inspection of workpieces. The overall requirement for the design and implementation of this system is to obtain satisfactory welding quality and high production efficiency. Features and advantages of laser deep penetration welding. Features:(1) High aspect ratio. As the molten metal forms around the cylindrical high temperature steam chamber and extends toward the workpiece, the weld becomes deep and narrow. (2) Minimum heat input. Because the temperature of the source cavity is very high, the melting process occurs very fast, the heat input to the workpiece is very low, and the thermal deformation and heat affected zone are very small. (3) High compactness. Because the small holes filled with high-temperature steam are conducive to the mixing of the fusion pool and the escape of gas, resulting in the formation of pore-free fusion welding. The high cooling rate after welding is easy to make the weld microstructure fine. (4) Strong weld. (5) Precise control. (6) non-contact, atmospheric welding process. Advantages:(1) Because the focused laser beam has a much higher power density than the regular method, the welding speed is fast, the heat affected zone and the deformation are small, and it can also weld difficult materials such as titanium and quartz. (2) Because the beam is easy to transmit and control, and does not need to replace the torch and nozzle frequently, it significantly reduces the downtime and auxiliary time, so the load coefficient and production efficiency are high. (3) Due to the purification effect and high cooling speed, the weld is strong and the comprehensive performance is high. (4) Due to the low balance heat input and high processing accuracy, reprocessing costs can be reduced. In addition, the dynamic cost of laser welding is also relatively low, which can reduce production costs. (5) easy to achieve automation, the beam intensity and fine positioning can be effectively controlled.

02-19

What tools do you need to weld things?

2023-02-19

Welding tools What tools do you need to weld things? 1. Welding cable quick connector, quick connector Welding cable quick connector, quick connector is a device that can quickly and easily connect welding cable and welding power supply. The main body is made of brass with good conductivity and certain strength, and the outer jacket is made of neoprene. It is determined by the thickness of the welded body before welding and the groove form of the two sides. When welding thicker steel plates, in order to weld through, various shapes of grooves are made at the side so that the welding rod or welding wire can be easily fed. 2. Welding tongs Welding tongs are used to clamp the welding rod for welding tools, the main role is to enable the welder to clamp and control the welding rod, but also plays a role in conducting welding current from the welding cable to the welding rod. 3. Grounding clamp A grounding clamp is an instrument that connects a welding wire or grounding cable to a workpiece. The grounding clamp must be able to form a strong connection and can be quickly and easily clamped to the workpiece. 4. Mask and eye protection glass The mask and eye protection glass is a masking tool to prevent welding spatter, strong arc and other radiation burns on the welder's face and neck. There are two kinds of hand-held and helmet-mounted. These are the welding equipment that welding personnel need to prepare when welding things. In fact, our current welding technology appears with the smelting production of copper, iron and other metals and the application of various heat sources. Welding achieves the purpose of joining through the following three ways: 1. Fusion welding-heating the workpiece to be joined to make it partially melt to form a molten pool, which will be joined after cooling and solidification. If necessary, molten filler can be added to assist. It is a Welding processing suitable for various metals and alloys without pressure. 2, pressure welding-the welding process must apply pressure to the welding parts, which belongs to the processing of various metal materials and some metal materials. 3. Brazing-metal materials with lower melting point than the base metal are used as brazing materials, liquid brazing materials are used to wet the base metal, fill the joint gap, and diffuse with the base metal to realize the link welding parts. It is suitable for Welding processing of various materials, and also suitable for Welding processing of different metals or heterogeneous materials.

02-18

Technical requirements for welding

2023-02-18

Welding technology What is welding technology? Welding, also known as welding, is a manufacturing process and technique for joining metals or other thermoplastic materials such as plastics by heat, high temperature or high pressure. What is welding technology? Welding applications are very wide, can be used for metal, can also be used for non-metal. The welding process is mainly determined according to the material, brand and chemical composition of the welded workpiece, the type of weldment structure and the welding performance requirements. First of all, it is necessary to determine the welding method, such as manual arc welding, submerged arc welding, tungsten argon arc welding, gas shielded welding, etc. There are many types of welding methods and can only be selected according to the specific situation. After determining the welding method, the welding process parameters are formulated. The types of welding process parameters are different. For example, manual arc welding mainly includes: electrode type (or brand), diameter, current, voltage, type of welding power supply, polarity connection, number of welding layers, number of passes, inspection method, etc. Technical requirements for welding Technical requirements: 1. The welding seam shall be smooth during welding, and there shall be no welding defects such as pores and slag inclusion, and the defects shall be repaired in time. The weld height is generally close to the steel plate. When intermittent welding is used, the weld length and interval shall be uniform. 2. When the manufactured parts are required to be sealed and welded continuously, there shall be no blowhole trachoma at the weld. 3. When welding, the height of the weld seam shall not be less than the thickness of the base metal (weldment). When base metal (weldment) of different thickness is welded, the weld height shall not be less than the thickness of the thinnest base metal (weldment). Welding achieves the purpose of joining through the following three ways: 1. Fusion welding-heating the workpiece to be joined to make it partially melt to form a molten pool, which will be joined after cooling and solidification. If necessary, molten filler can be added to assist. It is a Welding processing suitable for various metals and alloys without pressure. 2, pressure welding-the welding process must apply pressure to the welding parts, which belongs to the processing of various metal materials and some metal materials. 3. Brazing-metal materials with lower melting point than the base metal are used as brazing materials, liquid brazing materials are used to wet the base metal, fill the joint gap, and diffuse with the base metal to realize the link welding parts. It is suitable for Welding processing of various materials, and also suitable for Welding processing of different metals or heterogeneous materials. Welding principle: Preheating can reduce the cooling rate after welding, which is conducive to reducing the maximum hardness of the heat affected zone of medium carbon steel and preventing cold cracks, which is the main process measures for welding medium carbon steel. Preheating can also improve the plasticity of the joint and reduce the residual stress after welding. Typically, 35 and 45 steels are preheated at ~ °C. If the carbon content is high or the crack tendency is large due to the large thickness and rigidity, the preheating temperature can be increased to ~ ℃. If the weldment is too large and the overall preheating is difficult, local preheating can be carried out, and the heating range of local preheating is on both sides of the weld ~. 2 Welding rod conditions: acid welding rod is preferred when permitted. 3 groove form: the weldment as far as possible to open into U-shaped groove type for welding. If it is a casting defect, the shape of the groove excavated by the shovel should be smooth, the purpose of which is to reduce the proportion of the base metal melted into the weld metal, so as to reduce the carbon content in the weld and prevent cracks. 4 process parameters: since the proportion of the base metal melted into the first layer of weld metal is up to about 30%, when welding the first layer of weld, small current and slow welding speed should be adopted as far as possible to reduce the penetration depth of the base metal, which is what we usually call burns (the base metal is burned when the current is too large). 5 Heat treatment: After welding, it should be kept at-℃ for 2-6 hours to further slow down the cooling rate, increase plasticity and toughness, and reduce the hardening tendency to eliminate the diffused hydrogen in the joint. Therefore, welding can not be carried out in a cold environment or rain. It is best to perform stress relief heat treatment on weldments immediately after welding, especially for weldments with large thickness, high rigidity structures and weldments working under severe conditions (dynamic load or impact load). The tempering temperature for stress relief after welding is ~ ℃, heat preservation for 1-2h, and then cooling with the furnace.

02-17

What is brazing welding?

2023-02-17

Brazing What is brazing welding? Brazing refers to a welding method that uses liquid brazing material to fill the gap of solid workpieces to connect metals after the brazing material and the welding part which are lower than the melting point of the welding part are heated to the melting temperature of the brazing material at the same time. The brazing methods include: high frequency induction brazing, flame brazing, resistance brazing, furnace brazing, phase brazing, soldering iron brazing, ultrasonic brazing, etc. The brazing deformation is small, the joint is smooth and beautiful, and it is suitable for welding precision, complex and components composed of different materials, such as honeycomb structural plates, turbine blades, carbide tools and printed circuit boards. Before brazing, the workpiece must be carefully processed and strictly cleaned to remove oil and excessive thick oxide film to ensure the interface assembly gap. Most of the flux residue has a corrosive effect on the brazed joint and hinders the inspection of the brazing seam, which often needs to be cleaned up. The residue of the active flux containing rosin can be removed with an organic solvent such as isopropyl alcohol, alcohol and trichloroethylene. The flux composed of organic acid and salt is generally soluble in water and can be washed with hot water. Solder composed of an inorganic acid is soluble in water and therefore can be washed with hot water. Flux containing alkali metal and alkaline earth metal chlorides, such as zinc chloride, can be washed with a 2% hydrochloric acid solution. The borax and boric acid flux residues used for brazing are basically insoluble in water and difficult to remove. They are generally removed by sandblasting. The better method is to put the brazed workpiece into water in the hot state, so that the flux residue is cracked and easy to remove. What is fiber welding It refers to the welding method in which the gap between the solid workpiece is filled with liquid filler metal after the brazing material and the welding part which are lower than the melting point of the welding part are heated to the melting temperature of the brazing material at the same time. When brazing, the oxide film and oil stain on the contact surface of the base metal should be removed first, so as to facilitate the capillary function after the solder melts and increase the wettability and capillary fluidity of the solder. According to the different melting point of the solder, brazing can be divided into brazing and soldering. The brazing deformation is small, and the joint is smooth and beautiful. It is suitable for welding precision, complex and parts composed of different materials such as honeycomb structure plates, turbine blades, hard alloy tools, printed circuit boards, etc. Before brazing, the workpiece must be carefully processed and strictly cleaned to remove oil and thick oxide film to ensure the assembly gap of the interface. The gap is generally required to be between 0.01 and 0.1mm. Brazing application features: (1) The brazing heating temperature is low, the joint is smooth and smooth, the organization and mechanical properties change little, the deformation is small, and the workpiece size is accurate. (2) The same metal or different materials can be welded, and there is no strict limit on the thickness difference of the workpiece. (3) Some brazing methods can weld multiple weldments and joints at the same time, with high productivity. (4) The brazing equipment is simple and the production investment cost is low. (5) the joint strength is low, the heat resistance is poor, and the cleaning requirements before welding are strict, and the solder price is more expensive.