How to improve the yield of aluminum profiles and reduce aluminum waste

How to improve the yield of aluminum profiles, reduce aluminum waste, improve productivity, and reduce the production cost of aluminum profiles, we have summarized extruded waste:

Scrap for aluminium extruded profiles is divided into two main categories: geometric scrap and technical scrap. Geometric scrap is the inevitable scrap product produced during the extrusion process of aluminum alloy profiles. For example, the extruded residual material, the chuck at both ends of the product during stretching, the material discarded because the cut-to-length material is not enough to set the length, the necessary samples are cut, the aluminum blocks remaining in the shunt cavity in the shunt combination mold, the aluminum chips consumed by the saw edge of the ingot and the product cut to the cut-to-length material, and the aluminum ingots consumed during the mold test.

Technical waste is considered waste due to unreasonable technology, equipment problems, and improper operation of workers in the production process of aluminum alloy profiles. It is different from geometric waste, through technical improvement and strengthening management, it can effectively overcome and eliminate the generation of technical waste. Technical waste can be divided into:

Tissue waste: overburning, coarse crystal rings, coarse grains, tail shrinkage, slag inclusion, etc.
　　
Unqualified mechanical properties of waste products: strength, hardness is too low, does not meet the national standards: or plasticity is too low, not sufficiently softened does not meet the technical requirements.

Surface waste: lamination, bubbles, extrusion cracks, orange peels, tissue strips, black spots, longitudinal weld lines, transverse weld lines, abrasions, metal pressing, etc.

Geometrical rejects: waves, twisting, bending, plane clearance, dimensional out-of-tolerance, etc.

The yield rate is divided into process yield rate and comprehensive yield rate.

The finished aluminum rate of the process 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). It is defined as 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 rate is related to the quality of the equipment, the quality of the ingot, the product structure, the frequency of the change of varieties and specifications, the advanced degree of technology, the level of enterprise management and the quality of the operators.
　　
The key to improving the yield of aluminum alloy profiles is to reduce and eliminate scrap. Geometric rejects, while inevitable, can be managed to keep it to a minimum. Technical waste is a human factor that can be eliminated on a case-by-case basis or minimized. To this end, the following can be used to effectively control and improve the yield of extruded products.

6.1.3.1 Reducing geometric waste is an important prerequisite for improving the yield rate
　　
Measures to reduce geometric rejects
　　
Choosing the right ingot length is the main measure to reduce process waste. The length of the ingot is not calculated after extrusion, but before extrusion.

Now most enterprises use the long rod hot shear aluminum rod heating furnace, compared with the short rod heating furnace, reduce the loss of aluminum chips, due to the change of mold wall thickness, the casting length control is more flexible and accurate, and the yield is greatly improved. However, many enterprises ignore the calculation of the casting length after using the long rod hot shear furnace, and directly hand over this work to the operator to control. The operator is often based on experience to first next a rod, observe the length of the material, if the difference is large, continue to adjust, usually need about 3 rods to get the accurate length. In this process, a lot of waste has been generated, which not only reduces the production efficiency, but also reduces the yield rate.

The correct approach is that during the initial production of the mold, the process control department calculates the length of the ingot, and when the mold is produced on the machine for many times, according to the length of the last production rod recorded on the mold card, slightly add about 5-10mm, and observe the length of the material when discharging. Fine-tune if there are differences. So that the second stick is very precise. There is data to show that the use of long rod hot shear can improve the yield of 4 percentage points, and it is completely feasible to increase 2-3 percentage points in actual production.

In addition, when selecting the number of fixed lengths or the length of the product, on the premise of ensuring that the extruder can be extruded smoothly. When the length of the cooling bed is sufficiently long, increase the number of fixed lengths or the length of the product as much as possible, that is, it is possible to choose a longer ingot. It is also an effective way to reduce the percentage of process geometry and increase the yield.

Measures to improve the yield from a 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 rate. Generally, there is no such mold trial all cost 1-3 ingots, so that the yield is reduced by 0.5-1%, due to the design of the mold, the manufacturing level is low, some products have to repair the mold, try the mold 3-4 times or even more times to produce the finished product, virtually reduce the yield rate by 2-5%, which will not only cause economic losses, but also due to repeated mold trials, will prolong the production cycle.
　　
Modern mold puts forward the concept of zero mold trial, that is, after the mold is manufactured, there is no need for mold trial, and qualified products can be directly produced 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 mold through computer simulation. The mold cavity processing is completed in the automatic machining center, and the processing of the entire mold is completed with high precision, so the quality of the mold is very high. The pass rate of the machine is more than 90%. It can increase the yield by 2--6%.

Appropriately increase the extrusion coefficient of aluminum to improve the yield rate

Each aluminum factory has a series of machines, and each factory determines the production of products on the corresponding machines according to the extrusion ratio of the product, the length of the cooling bed, the outer truncation 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, and due to the different extrusion coefficients, they have a great impact on the microstructure and production efficiency of the products, and their yield will also be different. When the tonnage of the extruder is larger, the extrusion coefficient is larger, the yield is higher, and the extrusion cost is close.

Improving the quality of ingots is a prerequisite for improving the yield
　　
Ingot is the raw material for extrusion production, the ingot structure is uniform, the grain is fine, there is no slag inclusion, porosity, segregation, cracks and other defects, which can not only reduce the extrusion force, improve the extrusion speed, and improve the internal quality of the product. Moreover, it can reduce defects such as bubbles, porosity, scratches, cracks, and pittings on the surface of the product. Smaller slag inclusions can be discharged through the slits of the mold working belt, but they can cause pear marks on the surface of the profile, resulting in a certain length of waste. The larger slag inclusion will be stuck in the slit of the working belt and cannot be excluded, causing the mold plug or product cracking, and the mold will be replaced, which will seriously affect the yield rate. When stretching and straightening, use the corresponding pad to reduce the length of the head and tail material

When the profile is stretched and straightened, many companies do not design the corresponding pads, especially some large overhanging profiles and hollow profiles. As a result, the deformation of the head and tail of the profile is too large, and the deformed part must be cut off when the finished product is sawing. As a result, the yield decreased.
　　
The mats can be made of hardwood or aluminum, and the design minimizes the size of the mat and increases the versatility of the mat. For profiles with long overhangs and closed sections, when straightening, the cushion is inserted into the closed cavity and the support frame is placed in the overhanging part. This reduces the amount of deformation in the length direction. The fixture must be designed and managed by a special person, and the workers must be instructed to use it.
　　
At the same time, in order to prevent workers from being reluctant to use cushions because of trouble, it is necessary to establish a reward and punishment mechanism that links the yield rate with wages.

Reduce geometrical scrap with no-pressure extrusion
　　
The fixed pad is fixed on the extrusion rod without residual pressure, and the two are modified to a certain extent. When the extrusion cylinder does not retreat, the pressure pad is also easy to separate from the ingot. The next ingot is then pushed directly into the extrusion cylinder. Extrude with the remainder of the previous ingot so that you don't have to cut the rest of each ingot once. According to the quality requirements and the order quantity, it can be decided how many casting shear surpluses are pressed once. Usually 40-50 pieces are cut once.
　　
Optimize the extrusion process of aluminium profiles and reduce technical waste
　　
There are many aspects to 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 technology, it is also necessary to correctly and strictly implement the operating procedures and improve the proficiency and sense of responsibility of workers. 　　

Minimize the varieties produced per shift, and it is best to arrange only 3-5 varieties per shift, so as to increase the production capacity of a single set of molds on the machine at one time. The more varieties on the machine, the more mold aluminum is taken away, and the lower the yield rate.