Solder wire manufacturing process

The manufacturing process of traditional solder wire roughly includes alloy fusion, casting, extrusion, wire drawing, winding, and packaging. In the production process, each link is more important, and each process should be set up with quality control points, which will be briefly introduced below.

"Alloy fusion" and "casting" "Alloy fusion" refers to the process of smelting and removing impurities from a variety of metals in a certain proportion to make the desired alloy. In practice, "casting" often begins at the same time as the fusion is completed. "Casting" is the operation of pouring the fused alloy into the forming mold (usually cylindrical type), so some people call this semi-finished product "tin cylinder", and the length and thickness of the "tin cylinder" depend on the situation of the press inlet, so it can be easily put into the extruder for extrusion. Here, "fusion" and "casting" are put together, and the equipment required for these two processes is not complicated, and the main equipment includes furnaces, casting molds, forming molds, temperature sensors, etc.

At present, in the fusion process, oil and electric heating are the mainstay, and some manufacturers use coal heating. The use of oil and electric heating requires a special heating furnace that stirs automatically and controls the temperature and time very automatically, thus reducing the occurrence of poor fusion due to human factors. The use of coal heating does not require complex equipment, generally self-built stoves, with cast iron pot heating, some set up electric stirring device, some only rely on manual stirring. In this process, it is difficult to grasp the temperature, stirring and standing time during manual operation, and it is all based on experience, and the arbitrariness of the worker's operation is larger, so the instability of the quality is relatively high. On the whole, oil-electric heating and fusion is higher than coal heating in terms of quality controllability and batch-to-batch stability, but because its cost is higher than that of coal heating, there are still some smaller solder manufacturers using coal heating and fusion process.

Tin-lead alloy fusion preparation procedure and its precautions:

<!--[if !supportLists]-->1.<!--[endif]-->In the production of tin-lead solder alloy, lead should be put in first, and then tin should be put in when the temperature rises to 350 °C, and the middle alloy should be mixed and stirred evenly to remove the slag.

<!--[if !supportLists]-->2.<!--[endif]-->Stirring should be started after the temperature is raised to the specified temperature, and the stirring speed should be uniform, and in order to ensure that there are no stirring dead angles, it is best to install the deflector at the bottom of the furnace about 10 - 20 cm near the part.

<!--[if !supportLists]-->3.<!--[endif]-->Depending on the size of the furnace, every 10-20 minutes of stirring should be adjusted to the opposite direction.

<!--[if !supportLists]-->4.<!--[endif]-->After stirring for about 40 minutes, stop stirring, maintain the temperature in the furnace, and let the alloy in the furnace stand.

<!--[if !supportLists]-->5.<!--[endif]-->Let it stand for 20 minutes and then start stirring again, stirring for about 10 minutes each time, once in the forward and negative directions.

<!--[if !supportLists]-->6.<!--[endif]-->After the above stirring and standing operations are completed, the stirring speed is reduced and the operator begins to cast the tin cylinder. At this time, the temperature of different brands of casting liquid should be operated in strict accordance with the liquid temperature parameter table for details, and the metal liquid in the furnace must be stirred normally to prevent the occurrence of chemical component segregation.

<!--[if !supportLists]-->7.<!--[endif]-->In the process of preparing tin alloys, if you need to change the variety, you must use tools to clean the solder slag in the furnace to prevent the residual material from mixing into the next batch of alloys and affecting its alloy composition.

<!--[if !supportLists]-->8.<!--[endif]-->The area around the ingot mold should be kept tidy, and the tin material splashed on the ground should be cleaned up and not mixed.

<!--[if !supportLists]-->9.<!--[endif]-->When the metal in the furnace has melted into a liquid state, if other cold metal ingots are to be added, they must be dried before adding to prevent the high-temperature melt from splashing and hurting people when it is cold.

<!--[if !supportLists]-->10.<!--[endif]-->When casting a tin-lead alloy with a tin content of <50%, the shrinkage hole must be filled because of the deep shrinkage hole in the center of the circle, and the shrinkage hole should be filled when the center of the melt is not solidified for the first injection, and the surface oxide should be scraped off.

<!--[if !supportLists]-->11.<!--[endif]-->The tin cylinder can only be poured out after it is determined that the inside of the tin cylinder is completely cooled, or after the specified cooling time has been reached, otherwise if the inside is not cooled, it may lead to unformed, which may cause personal injury.

<!--[if !supportLists]-->12.<!--[endif]-->A protective plate should be set up on the ground where the tin cylinder is poured, and the environment should be kept clean without ash and slag.

Extrusion In the whole solder wire production process, the extrusion process is designated as a special process because in the whole production process, extrusion is the key link between the previous and the next. If there are defects or hidden dangers in the extrusion process, it will directly lead to defects in the solder wire product, and this hidden danger is often irreparable in the subsequent wire drawing process, and sometimes even difficult to find. Therefore, from the perspective of the whole process of solder wire, it is necessary to control the extrusion process in order to ensure the production of high-quality products. In the extrusion process, the following aspects need to be noted:

<!--[if !supportLists]-->1.<!--[endif]-->Rosin barrel temperature, air pressure setting and maintenance: Under normal circumstances, the temperature of rosin is about 150°C when the boiling is completed, after pouring into the rosin barrel, after cooling down slightly, turn on the thermostat to set the temperature of the rosin barrel at 70 - 80°C. If the temperature is too low, the rosin will become thick and not easy to flow into the rosin pores; If the temperature is too high or poured in while boiling, it is easy to produce bubbles in the rosin, and once this bubble is pressed into the rosin hole, it will lead to the partial loss of rosin in the subsequent solder wire, resulting in defective products. When the temperature is relatively high, the self-fluidity of molten rosin is better, and the air pressure does not need to be too large. If the temperature is relatively low, the rosin begins to thicken and needs to be pressurized to effectively enter the rosin holes, generally speaking, the air pressure is set at 1.5Kg is more appropriate, and it can be slightly adjusted according to the specific situation.

The daily maintenance of the rosin barrel is also very necessary. After a squeeze is completed, if there is any rosin left in the rosin barrel, it should be released as much as possible; If it really can't be cleaned, the next time you pour in the hot melt rosin, stir to make sure the remaining rosin melts well. If the remaining rosin is not sufficiently melted, it may produce very small lumpy rosin, which will affect the normal inflow of rosin when it enters the rosin hole, and it is very likely to cause uneven rosin or broken rosin. In addition to the above-mentioned rosin should be put away as much as possible when each extrusion is completed, alcohol or other special cleaning agents should be used to clean and maintain the residues inside and outside the rosin barrel to ensure that the rosin barrel can work normally and eliminate possible hidden dangers.

<!--[if !supportLists]-->1.<!--[endif]-->Mold temperature setting and control: In the extrusion process, the setting and control of mold temperature is a very critical link. Under normal circumstances, the mold temperature of lead-free solder wire extrusion should be higher than that of tin-lead solder, which can generally be set at about 170 °C, and the mold temperature of tin-lead solder can be set at 90 - 100 °C during extrusion, and it can be appropriately adjusted by 10 - 20 °C in winter to ensure that the wire is produced normally.

The reason why the setting and control of mold temperature is so emphasized is that improper adjustment of mold temperature will affect the filament effect, resulting in abnormal filament, and the normal filament here is to point out that the filament is uniform, there are no deep stripes on the filament surface, and there are no bubbles. If the mold temperature is too high, there will be streaks on the surface when extruding the tin wire, resulting in the surface is not smooth enough, and it is easy to cause wire breakage in the subsequent wire drawing process; If the mold temperature is too low, the pressure increases during extrusion, and the filament is slow, which sometimes causes the rosin hole to be offset and not centered, which may also leave hidden dangers in the subsequent process.

<!--[if !supportLists]-->1.<!--[endif]-->Surface treatment of tin round casting before extrusion: At present, some manufacturers are equipped with a peeling machine, which strips the surface layer of the cast tin round casting before putting it into the extruder, so that the treated tin cylinder can effectively remove the oxides and impurities on the surface, so as to ensure the reliability of the final product of solder wire.

Regardless of whether the tin cylinder is peeled or not, before putting the tin cylinder into the extruder, a layer of lubricating oil should be rubbed on its surface to ensure that it can pass smoothly when extruding through the mold, reducing the friction between the tin solder and the die hole, which can not only ensure the uniform speed of extrusion filament, but also effectively prolong the service life of the mold. In the process of wiping oil, the quality of the oil is more critical, and the wetting oil of good quality can fully play the role of lubrication, the protective effect is stronger, and the surface of the extruded tin wire is smooth and clean without obvious lines; Poor quality lubricating oil has a short service life, the lubrication effect is not ideal, and the surface of the extruded tin wire is not smooth enough and has obvious lines. It is also worth noting that the amount of oil should be moderate, not too little, and of course not too much, as long as it is fully wiped on the surface of the tin cylinder. If there is too little oil, it will not have a significant effect; If there is too much oil, there will be more lubricating oil residue in the mold, under the strong pressure extrusion of the extruder, bubbles or dark holes may be produced under the surface layer of the extruded tin wire, which is easy to cause bad conditions such as broken rosin in the subsequent drawing, so in order to avoid too much oil, in addition to wiping the oil can not be wiped too much, it is also very necessary to discharge the residual oil in the mold in time.

<!--[if !supportLists]-->1.<!--[endif]-->Adjustment of rosin content and rosin pores: The proportion of rosin in the usual ratio of tin-lead solder can account for 1.8% - 2.3% (this is what we usually call rosin content). According to the provisions of the national standard GB/T3131 - 2001 "Tin-Lead Brazing Metal", the percentage content of brazing agent (commonly known as rosin) is divided into three grades: the first grade is 1.1% - 1.5%, and the minimum value is 0.8%; The second level is 2.2% - 2.6%, and the minimum is 1.5%; The third level is 3.3% - 3.9% and the minimum is 2.6%. Generally, when the extruder is normally extruded, the diameter of the solder wire is 10mm, of which the diameter of the rosin hole is about 2mm, and it is generally easier to pull out the solder wire with a wire diameter of more than 0.8mm in the subsequent wire drawing process. If you need to pull out the tin wire with a wire diameter of less than 0.8mm (such as 0.5mm or 0.6mm or thinner), you need to adjust the rosin hole slightly, generally 0.2 - 0.3mm. The purpose of adjusting the rosin hole is to increase the wall thickness of the tin wire, and when the thinner wire is drawn, the solder ductility is relatively high, so it is possible to pull out the thinner wire; If the rosin hole is large and the tin wire wall is thinner, the solder ductility becomes worse when the thinner wire is drawn, and the wire is easily broken, which affects the wire drawing speed, resulting in a corresponding increase in production costs.

<!--[if !supportLists]-->2.<!--[endif]-->Firing-out speed: The wire drawing process is also an extremely important part of the solder wire production process, and its main role is to further draw the coarser solder wire obtained by the extrusion process to the required wire diameter. During the drawing process, the quality and precision of the drawing die have a significant impact on the quality of the final product. High-quality drawing dies ensure that the tin wire has a uniform diameter and a smooth surface during the drawing process.

First of all, the choice of material for the drawing die is crucial. Different materials have different hardness, wear resistance and corrosion resistance. For example, tungsten carbide drawing dies have excellent wear resistance and are able to maintain the dimensional accuracy of the die for a long time, thus ensuring the consistency of the diameter of the tin wire during the drawing process. For some drawing processes that require high toughness, a die material containing specific alloying elements may be chosen.

Secondly, the lubrication during the drawing process should also not be overlooked. Similar to the extrusion process, the right lubricant can reduce the friction between the solder wire and the drawing die. If the lubrication is insufficient, the tin wire will be subjected to large friction during the drawing process, which may lead to scratches on the surface of the tin wire, and even wire breakage when the tension is too high. At the same time, the cleanliness of the lubricating oil is also critical, as lubricating oil with too many impurities may adhere to the surface of the tin wire and affect its quality.

In addition, the control of the drawing speed is also a key factor. If the drawing speed is too fast, the tin wire may not be evenly deformed, and it is easy to produce uneven thickness, and the excessive speed may aggravate the wear of the mold and shorten the service life of the mold. Conversely, if the drawing speed is too slow, it will affect production efficiency. Therefore, it is necessary to set the drawing speed reasonably according to the material and diameter of the tin wire and the performance of the drawing die.

In the extrusion process, the pressure should be kept equal, so that the filament speed is always kept at a constant speed, not sometimes fast and sometimes slow, if the speed changes suddenly in the normal extrusion process, it should be immediately stopped to check and re-adjusted.

In addition to the above points, it is also necessary to pay attention to other details in daily work, such as the way and method of mold installation should be appropriate and efficient, which can not only ensure the correct installation of the mold, but also ensure the service life of the mold; In the work, we must always be vigilant and carefully observed, especially when the joint or abnormal situation is found, the operation must be stopped in time, and the inspection and adjustment must be carried out; Of course, there are many aspects that need to be constantly summed up in long-term work, so that we can become more and more proficient and ensure product quality.

During the wire drawing process, the quality of the drawn tin wire is also inspected. This includes the precise measurement of the diameter of the tin wire to ensure that it meets the product specifications, typically with a high-precision gauge such as a micrometer. At the same time, it is also necessary to check the finish of the surface of the tin wire, as the tin wire with defects or unevenness on the surface may cause problems during the welding process and affect the welding quality.

<!--[if !supportLists]-->1.<!--[endif]-->Winding process The winding process is to wind the drawn solder wire to the spool in an orderly manner for subsequent packaging and use. The uniformity and compactness of the winding are the key indicators of this process.

For the uniformity of the winding, the accuracy of the winding equipment plays an important role. The high-precision winding machine ensures that the solder wire is wound on the spool according to a predetermined trajectory to avoid crossing, overlapping or loose situations. This not only helps to improve the appearance quality of the product, but also makes it easy for the user to access during use. If the winding is not neat, it may cause the solder wire to be knotted during use or jamming during the pay-off process.

The tightness of the winding also needs to be properly controlled. If the winding is too loose, the solder wire may shake during transportation or storage, causing the solder wire to rub against each other, which will affect the surface quality of the tin wire. If the winding is too tight, it may exert too much pressure on the tin wire, deform the tin wire, and even damage the rosin structure inside the tin wire and affect the welding performance. In the winding process, it is necessary to adjust the tension setting of the winding machine according to the wire diameter, material and spool size of the solder wire to achieve the appropriate compactness.

In addition, the cleaning work during the winding process should not be neglected. The environment of the winding workshop should be kept clean to avoid dust, impurities, etc. from mixing with the solder wire during the winding process. These impurities may adhere to the surface of the solder wire, and welding defects such as virtual soldering may occur during soldering.

<!--[if !supportLists]-->1.<!--[endif]-->Packaging Packaging is the last process in the production process of solder wire, which is not only a simple wrapping of the wound solder wire, but also a kind of protection of the product and the display of brand image.

There are many factors to consider when choosing packaging materials. First of all, the packaging material should have a certain moisture-proof performance. If the solder wire is wet, it may cause problems such as rust on the surface or rosin failure, which will affect the quality of the solder. For example, plastic film or aluminium foil laminates can be used to block the ingress of moisture from the outside. Secondly, the packaging material also needs to have a certain strength to protect the solder wire from external forces such as extrusion and collision during transportation and storage.

In terms of packaging design, in addition to indicating the basic information such as the specification, model, and composition of the product, you can also add some brand logos and instructions for use. Clear product identification helps users quickly identify product characteristics and uses, and makes it easier for users to choose the solder wire product that suits their needs. Detailed instructions for use can provide users with the correct way to use, such as the recommended range of welding temperature, applicable welding objects, etc., which helps to improve the user's experience, and also reduces product quality problems caused by improper use.

From the perspective of the entire solder wire manufacturing process, every process from alloy fusion to packaging is closely linked and indispensable. Each process has its specific requirements and details that need to be paid attention to, and only by strictly controlling the quality in each link can we produce high-quality solder wire products. Whether it's the choice of heating method during alloy fusion, the precise control of various parameters in the extrusion process, or the various operational points in the drawing, winding and packaging processes, all directly or indirectly affect the quality of the final product. Problems in any link may lead to the whole product not meeting the quality requirements, so in the production process of solder wire, a perfect quality control system must be established to ensure that each process can meet the expected quality standards.