When the sales price of aluminum profiles remains unchanged, the higher the production cost, the lower the profit. At present, under the harsh environment of rising raw material prices, rising wages of workers, appreciation of the RMB, rising energy prices, and increasing tax burdens, the competition in the same industry has entered “white-hot”, and the era of refined cost control has come.
Cost control is the key and core of business management. Only by constantly discovering weak links, tapping internal potential, using all means and ways that can reduce costs, participating in all staff, starting from details, starting from waste reduction, and meticulously implementing cost control of aluminum profiles, we can effectively expand the space for enterprises to survive , to improve the state of enterprise management, so that the enterprise can continue to develop and be in an invincible position.
The aluminum profile cost control is guided by the value chain, and the cost control is divided into design cost, purchase cost, manufacturing cost, sales cost and service cost. Because cost control involves a wide range of content and a lot of content.From the perspective of production and manufacturing, we will talk about how to improve the production yield and reduce production costs.
1. Through data analysis and practice, it has been proved that improving the yield of aluminum alloy profiles is one of the most direct and effective ways to reduce production costs. Taking the extrusion workshop as an example, for every percentage point increase in the yield, the production cost per ton of aluminum will be reduced by 25— 30 yuan, and this reduced part is the pure profit of the enterprise.
How to improve the yield of aluminum profiles, reduce aluminum scrap, and improve productivity? We generalized the extrusion waste:
The waste of aluminum profiles is divided into two categories: geometric waste and technical waste. Geometric scraps are inevitable scraps in the extrusion process of aluminum alloy profiles. Such as the extruded residual material, the chucks at both ends of the product during stretching, and the material discarded due to insufficient length of the fixed-size material, cut out the necessary samples, split the aluminum block remaining in the cavity of the combined mold, and cast the ingot. And products cut aluminum scraps cut by cut-to-length cutting and aluminum ingots consumed during mold trial.
Technical wastes are man-made wastes produced during the production of aluminum alloy profiles due to unreasonable processes, equipment problems, and improper operation by workers. It is different from geometric waste. Through technical improvement and strengthened management, it can effectively overcome and eliminate the generation of technical waste. Technical waste can be divided into:
Tissue waste: over-burning, coarse grain ring, coarse grain, tail shrinkage, slag inclusion, etc.
Unqualified mechanical properties: the strength and hardness are too low, and do not meet the national standards; or the plasticity is too low, and it is not fully softened and does not meet the technical requirements.
Unqualified surface quality waste: layering, bubbles, extrusion cracks, orange peel, tissue streaks, black spots, longitudinal welding lines, transverse welding lines, scratches, metal pressing, etc.
Geometrical size waste: waves, twists, bends, plane gaps, out of tolerance, etc.
The yield is divided into process yield and comprehensive yield.
The process yield generally refers to the main process, which is usually calculated on the basis of the workshop. Casting process (casting workshop), extrusion process (extrusion process), oxidation coloring process (oxidation workshop), powder spraying process (spraying workshop). Its definition is: the ratio of the qualified output of the workshop to the input of raw materials (and possibly semi-finished products) in the workshop.
The yield is related to the quality of the equipment, the quality of ingots, the product structure, the frequency of changing specifications, the advanced degree of process technology, the level of enterprise management and the quality of operators.
The key to improving the yield of aluminum alloy profiles is to reduce and eliminate waste. Geometric scrap, while unavoidable, can be managed to keep it to a minimum. Technical waste is a human factor that can be eliminated or minimized on an item-by-item basis. To this end, the following measures can be taken to effectively control and improve the yield of extruded products.
1. Measures to reduce geometric waste Correct selection of ingot length is the main measure to reduce process waste. The length of the ingot is not calculated after extrusion, but calculated first and then extrusion.
Most enterprises now use long-bar hot-cut aluminum bar heating furnaces. Compared with short-bar heating furnaces, the loss of aluminum chips is reduced. Due to the change of the wall thickness of the mold, the control of the casting length is more flexible and accurate, which greatly improves the yield. However, many companies ignore the calculation of the length of the cast rod after using the long rod hot shear furnace, and directly hand over this work to the operator for control. The operator usually takes the next rod according to experience and observes the length of the material. If the difference is large, continue to adjust, usually it takes about 3 rods to get the accurate length. In this process, a considerable amount of scrap has been generated, which reduces both production efficiency and yield.
The correct way is that when the mold is initially produced, the process control department calculates the length of the ingot. When the mold is produced multiple times, the length of the last production rod recorded on the mold card is slightly increased by about 5-10MM. Observe the length of the material when it comes out. Fine-tune if there is a difference. This way the second stick is very precise. According to some data, the use of long rod hot shears can increase the yield by 4%, and it is completely feasible to increase the yield by 2 to 3% in actual production.
In addition, when selecting the number of fixed lengths or the length of the product, on the premise of ensuring the smooth extrusion of the extruder. When the length of the cooling bed is long enough, the number of fixed lengths or the length of the product should be increased as much as possible, that is, a longer ingot may be selected. It is also an effective way to reduce the percentage of process geometry scrap and improve yield.
2. Measures to improve the yield from the technical level
Improving the level of mold design and manufacturing and reducing the number of mold trials are important technical measures to improve the yield. Generally, 1 to 3 ingots are consumed for each mold test, which reduces the yield by 0.5 to 1%. Due to the design of the mold, the manufacturing level is low, and some products need to be repaired and tested 3 to 4 times or even more times. After the finished product is produced, the yield is reduced by 2 to 5%, which will not only cause economic losses, but also prolong the production cycle due to repeated mold testing.
Modern molds put forward the concept of zero trial mode, that is, after the mold is manufactured, no trial mode is required, and qualified products can be produced directly on the machine. Using simulation design software, finite element analysis, the design can be completed in the computer. It is also possible to simulate the test mode through the computer. The cavity processing is completed in the automatic machining center, and the entire mold processing is completed with high precision, so the quality of the mold is very high. The pass rate on the machine is above 90%. The yield can be increased by 2 to 6%.
3. Appropriately increase the extrusion coefficient of aluminum materials to improve the yield
Each aluminum material factory has a series of machines. Each factory determines the production of the product on the corresponding machine according to the extrusion ratio of the product, the length of the cooling bed, the outer truncated circle of the product, and the length and diameter of the extrusion cylinder. Practice has proved that products of the same specification are produced on extruders of different tonnages. Due to the different extrusion coefficients, the organizational properties and production efficiency of the products will be greatly affected, and the yield will also vary. When the tonnage of the extruder is larger, the extrusion coefficient is larger, the yield is higher, and the extrusion cost is close.
4. Improving the quality of ingots is the premise of improving the yield
The ingot is the raw material for extrusion production. The ingot has a uniform structure, fine grains, no slag inclusion, pores, segregation, cracks and other defects, which can not only reduce the extrusion force, increase the extrusion speed, and improve the intrinsic quality of the product. It can also reduce defects such as air bubbles, pores, scratches, cracks, pitting and other defects on the surface of the product. Smaller slag inclusions can be discharged through the slits of the mold working belt, but will cause cracks on the surface of the profile, resulting in a certain length of waste. The larger slag inclusions will be stuck in the slits of the working belt and cannot be excluded, causing the plug mold or the product to crack, and the mold will be replaced, which will seriously affect the yield. Use corresponding pads when stretching and straightening to reduce the cutting length of the head and tail material
When the profiles are stretched and straightened, many companies have not designed corresponding cushions, especially some large cantilever profiles and hollow profiles. As a result, the deformation of the head and tail of the profile is too large, and when the finished product is sawed, the deformed part must be cut off. This results in a drop in yield.
The cushions can be made of hardwood or aluminum blocks, and the specifications of the cushions should be minimized in the design to increase the versatility of the cushions. For profiles with long cantilever walls and closed cross-sections, when straightening, insert pads into the closed cavity and place a support frame on the cantilever wall. Thereby reducing the amount of deformation in the length direction. Fixtures must be specially designed, managed, and instructed to use by workers.
At the same time, in order to prevent workers from being unwilling to use pads because of trouble, it is necessary to establish a reward and punishment mechanism that links the yield to wages
5. Strengthen the management of aluminum extrusion dies and production original records
The mold card and the original production records are very important. The mold card must be able to truly display the mold nitriding situation, maintenance situation, and material production situation. The original records must be able to truly show that the support weight, casting length and quantity provide a reliable basis for the next production.
Nowadays, many enterprises have also realized computerized data management, but there is still a long way to go in practical application.
6. Use no pressure excess extrusion to reduce geometric waste
The fixed pad is squeezed without excess pressure, which is to fix the squeeze pad on the squeeze rod, and make certain modifications to the two. When the extrusion cylinder does not retreat, the pressure pad is also easily separated from the ingot. The next ingot is then pushed directly into the extrusion barrel. Squeeze together with the remainder of the previous ingot, thus avoiding the need to cut each ingot once. The number of casting shears can be determined according to the quality requirements and the order quantity. Usually 40-50 pieces are cut once.
7. Optimize the extrusion process of aluminum profiles to reduce technical waste
There are many aspects of the extrusion process that affect technical waste and it covers the entire extrusion production process. Mainly include: ingot quality, process temperature, extrusion speed, extrusion tools, molds, transfer loading and unloading, aging heat treatment, etc. In addition to formulating advanced and scientific production processes, it is also necessary to strictly implement operating procedures and improve the proficiency and sense of responsibility of workers.
Minimize the varieties produced in each shift. It is best to arrange only 3 to 5 varieties per shift to increase the production capacity of a single set of molds at one time. The more varieties on the machine, the more mold aluminum is taken away, and the lower the yield.
The influence of the mold on the yield mainly has two aspects: the use of the new mold test and the production mold
The more times the mold is tried, the more aluminum is taken away from the mold, and the lower the yield. Therefore, it is necessary to improve the design and production level of the mold.
The production mold should be carefully maintained, reasonably nitrided, and maintained in time. Guarantee a high pass rate every time you go on the machine. Good formability and high durability. If 3 to 4 varieties fail to be produced on the machine due to unqualified mold maintenance in each shift, the yield will be reduced by at least one percentage point.
Aluminum extrusion tools include: extrusion cylinder, extrusion rod, extrusion pad, die pad, etc. It is mainly to ensure that the extrusion cylinder, rod and die are concentric at three points. The second is to properly maintain the extrusion cylinder, heat it correctly, and ensure that the end surface of the cylinder is flat. Eliminate the phenomenon of poor cooperation between various extrusion cylinders and molds. Regularly clean the residual aluminum on the inner wall of the extrusion cylinder, check whether the inner hole wall is damaged, use the die pad correctly, and improve the support strength of the die.
The extrusion temperature, extrusion speed and cooling have a great influence on the product structure, mechanical properties and surface quality, and also affect the yield. In addition, the three will affect the length of the product. When the casting rod temperature is high, the extrusion speed is fast, and the cooling speed is low, the length of the product after extrusion will increase, and the growth rate can reach 0.5% to 1%, which also affects the profile. Line density, so a stable process can improve yield.
Improve the subsequent extrusion process to avoid technical waste. In the transfer of the subsequent extrusion process, the main attention is paid to the scratches and bumps of the profiles.
8. One-die porous extrusion can improve the yield
When some products are suitable for porous extrusion, porous extrusion should be used as much as possible, which can not only reduce the extrusion coefficient, reduce the extrusion force, but also improve the yield. In the case of zero technical waste, the yield of double-hole extrusion can be increased by 3% to 4% compared with single-hole extrusion.
The extrusion speed is an important process parameter in the extrusion process, which is related to the quality of the product and the level of production efficiency. The extrusion speed is not like mastering the process temperature. Basically, one alloy and one heat treatment process can choose a different temperature, and the extrusion speed is a highly empirical process parameter. Profiles with different alloy states and different sections have different extrusion speeds. The same product is affected by temperature changes during the extrusion process, and the extrusion speeds before and after are different. To properly control the extrusion speed should do:
Master the extrusion speed range of various alloys and sections (including wall thickness) skillfully and flexibly, and pay attention to the influence of extrusion speed on aluminum profiles, such as surface quality, forming degree, etc.
Be familiar with the ability of extrusion equipment to control extrusion speed. Some extruders have constant speed extrusion control and PLC control, some only have PLC control, and some have neither. When an extrusion speed is given, some extruders can start to extrude at this speed. As the billet in the extrusion cylinder gradually decreases, the extrusion force decreases, and the outflow speed of the product will become faster and faster, sometimes It will cause cracks in the back of the product. Therefore, it is necessary to adjust the extrusion speed in time. Only by understanding the state of the equipment, can the extrusion speed be properly adjusted and controlled.
Understand the effect of different dies on extrusion speed. Generally speaking, the extrusion speed of a flat die (solid profile) is higher than that of a split die (hollow profile). However, products of the same type of mold and the same cross-sectional shape have different extrusion speeds due to different design and manufacturing levels. Especially the semi-hollow profiles with different wall thicknesses or openings have a great relationship with the mold. Only a certain extrusion speed designed by the mold is the best, and the speed is too fast or too slow, and it is easy to twist. Opening and closing phenomenon.
9. Reduce the generation of waste by strengthening the first inspection and in-process inspection
The waste products of aluminum profile dimensions, such as excessive wall thickness, twisting, plane gaps, openings or closings, etc., mainly depend on the first rod after the mold trial being checked by the host hand when the material is discharged and the quality inspector checking after stretching. Avoid the generation of such wastes. Generally, the wall thickness tolerance should be controlled from the negative tolerance, because with the continuous production of the product, the wall thickness of the product will gradually become thicker due to the gradual wear of the mold. For profiles with large overhangs, carefully check against the drawings when stretching and straightening, and control a reasonable amount of stretching.
Surface waste such as scratches, orange peel, tissue strips, black spots, bubbles, etc., often not all appear on every product. It is necessary to check each other through the host hand, quality inspector, and the sawing process of the stretched finished product, and jointly supervise the removal of the waste products existing on the surface.
If the quality inspector does not find scratches on the product on the discharge table, and finds scratches on the product when the finished product is sawed, it is necessary to check from the conversion process of the cooling bed, whether the conveyor belt, feeder, etc. There are hard protrusions in the parts, which cause the products to be scratched.
Quality management is the management of all staff and the whole process. Each process must control the quality and achieve a combination of self-inspection, mutual inspection and special inspection, so as to effectively eliminate technical waste in the bud. Artificial control and improve yield.
Through the above measures, geometric waste can be reduced. It can be seen that reducing geometric waste is an important technical management measure for enterprises, which is of great significance to high economic benefits.
To improve the yield of aluminum extrusion billets is a comprehensive and meticulous work process in extrusion production. Not only the technical process should be in place, but the management should also be solid and practical. There is still a lot of room for the improvement of the yield of aluminum profiles in my country. The improvement of the yield will be a continuous process, and the improvement of the yield and the improvement of product quality and output are closely linked. It is a comprehensive reflection of the technical and management level of an enterprise.
Post time: Apr-12-2022