9 effective ways to improve aluminum profile yield

9 effective ways to improve aluminum profile yield

9 effective ways to improve aluminum profile yield

In aluminum profiles production, the profit is equal to sales value minus production costs.

The total cost of aluminum profiles is divided into fixed costs and variable costs. Fixed costs such as factory rent, machine depreciation, etc. It is fixed. The variable cost has a lot of flexibility.

When the selling price of aluminum profile remains unchanged, the higher the cost of aluminum profile, the lower the profit will be.

Cost control is the key and core of business management.

Only by continuously discovering weakness, tapping the internal potential, using all the means and ways to reduce costs, full participation, starting from the details, starting from the reduction of scrap, and meticulously implementing the cost control of aluminum profiles, can effectively broaden the enterprise’s living space.

Improve the state of business management, make the company continue to develop, and remain invincible.

From the view of manufacturing, here we are discussing how to increase the production yield and reduce production costs.

Data analysis and practice have proved that increasing the yield of aluminum profiles is one of the most direct and effective ways to reduce production costs.

Taking the extrusion workshop as an example, for every one percentage point increase in yield, the production cost per ton of aluminum profile will be reduced by 5.00-10.00USD, and the reduced part is the net profit of the company. 

To improve the yield of aluminum extrusion, the main task of production is to reduce extrusion scrap.

At present, the price of raw materials is rising, the salary of workers is constantly increasing, the appreciation of the currency, the rise of energy prices, and the heavier burden of taxes and fees have caused competition in the aluminum industry to become hotter today.

How to improve the yield of aluminum profiles, reduce aluminum profile scrap, increase productivity, and reduce the production cost of aluminum profiles, we have summarized the extrusion scrap products:

The scrap products of aluminum extrusion profiles are divided into two categories: physical scrap products and technical scrap products.

Physical scrap is an unavoidable scrap produced in the aluminum extrusion process, such as the residual material of extrusion, both ends of the product during stretching, the material discarded because the length of the fixed-length material is not enough, necessary cutting samples, aluminum stuck in porthole die, aluminum chips scrap in billets and aluminum profiles cutting and mold test aluminum billets.

Technical scrap is considered to be scrap generated during the production process of aluminum profiles due to unreasonable technology, equipment problems, and improper operation by workers. It is different from physical scrap, through technical improvement and strengthening management, it can effectively overcome and eliminate the happening of technical scrap.

Technical scrap as the following:

Structure scrap: Overburn, coarse crystal ring, coarse crystal grain, extrusion funnel, slag inclusion, etc.

Unqualified mechanical properties: the strength and hardness too low and do not meet the national standards; or the plasticity is too low, not fully softened and does not meet the technical requirements.

Surface scrap: layering, bubbles, extrusion cracks, orange peel, structure lines, black spots, longitudinal welding lines, horizontal welding lines, scratches, etc.

Physical dimension scrap: waves, twists, bends, flat clearances, out of tolerances, etc.

The yield is divided into process yield and comprehensive yield.

The finished aluminum rate of the process generally refers to the main process, and is usually calculated based on the workshop.

Casting process (melting and casting workshop), extrusion process, anodizing process (oxidation workshop), powder coating process.

It is defined as the ratio of the qualified output of the workshop to the input of raw materials (or semi-finished products) in the workshop.

The yield rate is related to factors such as the quality of equipment, the quality of billets, the product structure, the frequency of specifications change, the advanced level of process technology, the level of enterprise management and the quality of operating workers.

The key to improving the yield of aluminum profiles is to reduce and eliminate scrap.

Although physical scrap is inevitable, it can be minimized.

Technical scrap is a human factor, which can be eliminated by analyzing one by one, or it can be reduced to a minimum.

Reducing physical scrap is an important prerequisite for improving the yield of aluminum profiles.

1. Improving the quality of aluminum billet

The aluminum billet is the raw material for aluminum extrusion production.

The billet structure is uniform, with small grains, no slag inclusion, no blowhole, segregation, cracks and other defects, which can not only reduce the extrusion force, but also increase the extrusion speed, and improve the internal quality of the product.

Moreover, it can reduce defects such as bubbles, holes, scratches, cracks, and pits on the surface of aluminum extrusion.

Smaller slag can be discharged through the slits of the mold working belt, but it will cause marks on the surface of aluminum extrusion, resulting in a certain length of scrap.

Larger slag inclusions will be stuck in the slits of the working belt and cannot be eliminated, causing mold to stop up or product cracks. Changing molds will seriously affect the yield.

Use the corresponding cushion when aluminum extrusion straightening to reduce the cutting length of aluminum extrusion on both ends.

When the profile is stretched and straightened, many companies do not design corresponding cushions, especially some large sectional aluminum profiles and hollow aluminum profiles.

As a result, the deformation of the aluminum profile on both ends is too large, and when the finished product is sawed, the deformed part must be cut off. This has caused a drop in yield.

Hardwood or aluminum blocks can be used for the cushion, and the specification of the cushion is minimized in the design to increase its versatility of the cushion.

For profiles with long cantilever walls and closed cross-sections, a support frame should be placed on the cantilever when inserting cushions in the closed cavity during straightening.

Thereby reducing the amount of deformation in the longitudinal direction. The fixture must be designed and managed by a special person, and guide workers to use it.

At the same time, in order to prevent workers from being unwilling to use cushions because of troubles, a reward and punishment mechanism must be established in which the yield and wages are linked.

2. Choose the right aluminum billets length for the production

The correct choice of aluminum billet length is the main measure to reduce process scrap.

The length of the aluminum billet is should be calculated first before the extrusion, not calculated after the extrusion.

Most of the aluminum extruders now use long billets heating furnace with hot log shear, which reduces the loss of aluminum chips compared with short billet heating furnaces.

Because the wall thickness is changed after the mold use, aluminum billet length control is more flexible and accurate, and the yield is greatly improved.

However, many companies ignore the calculation of the billet length after using the long-billet furnace with hot log shear, and directly send this work to the operator to control.

The operators usually test the first billet based on experience and observe the length of the material. If the difference is big, continue to adjust. Usually, it takes about 3 billets to get the exact length.

In this process, a lot of scraps have been produced, which not only reduces production efficiency but also reduces the yield.

The correct way is to calculate the length of the billet by the process control department during the initial production of the mold.

When the mold is produced on the machine multiple times, add about 5-10mm length according to the last production billet length recorded on the mold card.

Observe the length of the material when it is extruded, make a slight adjustment if there is a difference. So the second aluminum billet is very precise.

According to data, the use of long billets heating furnace with hot log shear can increase the yield rate by 4%, and it is completely feasible to increase it by 2-3% in actual production.

In addition, when selecting the number of fixed lengths or the length of the product, under the premise of ensuring the smooth extrusion and 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 aluminum billet.

This is also an effective way to reduce the percentage of process physical scrap and improve the yield.

3. Improve mold design and manufacturing level, reduce mold testing time

Improving the level of mold design and manufacturing, and reducing the number of mold final acceptance tests are important technical measures to increase the yield.

Generally, it takes 1-3 pieces of billets for the extrusion die final acceptance test, which reduces the yield rate by 0.5-1%.

Due to the design of the mold and the low manufacturing level, some molds need to be repaired and tested 3-4 times or more, the yield rate will be reduced by 2 to 5%, which will not only cause economic losses but also prolong the production cycle due to repeated mold testing.

The more mold testing, the more aluminum that is stuck in the mold will be taken away, and the lower the yield rate is.

Therefore, the design and manufacturing level of the mold must be improved.

Extrusion molds must be carefully repaired, reasonably nitride and timely maintained. Ensure that the pass rate is high every time, Good shaping production and high durability.

If each shift fails due to unqualified mold repairs, causing 3-4 sets of molds to fail on the aluminum extrusion machine, the yield will be reduced by at least 1%.

Modern molds put forward the “concept of zero test mold”, that is after the mold is manufactured, no test mold is required, and qualified products can be produced directly on an aluminum extrusion machine.

Using simulation design software, finite element analysis, the design can all be completed in the computer. It is also possible to simulate the test mode by computer.

The mold 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.

For mold testing, the qualified rate on the aluminum extrusion machine is above 90%. It can increase the yield by 2-6%.

4. Strengthen the management of extrusion molds and original production records

The mold card and the original production record are very important. The mold card must be able to truly show the mold nitriding, maintenance, and production conditions.

The original record must be able to truly show the weight, billets length and quantity, providing a reliable basis for the next production.

Many companies have also implemented computerized data management, but there is still a long way to go in practical applications.

 5. Appropriately increase aluminum extrusion coefficient

Each aluminum extruder has many sets of extrusion production lines.

According to the extrusion ratio of the product, the length of the cooling bed, the outer circle of aluminum profile, the diameter of the extrusion cylinder, each factory determines the product to be produced on the corresponding aluminum extrusion machine.

The practice has proved that products of the same specification are produced on different tonnages aluminum extrusion machine, due to the difference in extrusion coefficient, the product structure and performance and production efficiency will be greatly affected, and the yield will also be different.

6. Apply remnant-material-free extrusion method to reduce physical scrap

The fixed dummy block remnant-material-free extrusion, which is to fix the dummy block on the extrusion ram and make certain changes to both parts.

When the extrusion container does not retreat, the dummy block is also easily separated from the aluminum billet. Then directly push the next billet into the extrusion container.

Extrude together with the remaining billet of the previous aluminum billet, thus avoiding the remnant material of each billet being cut once.

The number of billets shears can be determined according to quality requirements and order quantity. Usually, 40-50 pieces are cut once.

7. Optimize aluminum extrusion process to reduce technical scrap

 There are many aspects of the extrusion process that affect technical scrap, and it covers the entire extrusion production process.

Mainly includes billet 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 correctly and strictly implement operating procedures to improve the proficiency and sense of responsibility of workers.

Try to reduce the number of specifications produced in each shift. It is best to arrange only 3-5 specifications per shift to increase the output of a single set of molds.

The more specification on the aluminum extrusion machine, the more molds will be applied, and the lower the yield will be.

Aluminum extrusion tools include extrusion container, extrusion ram, dummy block, die backer, etc. Mainly ensure that the extrusion container, ram, and die are concentric at three points.

The second is to maintain the extrusion container reasonably, heat it correctly, and ensure that the container end surface is flat.

Eliminate the phenomenon of a poor fit between various extrusion containers and molds.

Regularly clean the residual aluminum on the inner wall of the extrusion container, check the inner hole wall for damage, and use the mold backer correctly to improve the support strength of the mold.

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 factors will affect the length of the product.

When aluminum billet temperature is high, the extrusion speed is fast, and the cooling rate is low, the length of the product after extrusion will increase, and the growth rate can reach 0.5%-1%, which will affect aluminum profile Linear density, so a stable process can improve the yield.

Improve the following process of extrusion to avoid technical scrap. The transship of aluminum extrusion in the following processes, mainly pays attention to the scratches of the aluminum profile.

For some products suitable for multi-hole extrusion, multi-hole extrusion is used as much as possible, which can not only reduce the extrusion coefficient and pressure, but also increase the yield.

In the case of zero technical scraps, double-hole extrusion can increase the yield by 3% to 4% compared with single-hole extrusion.

The extrusion speed is an important process parameter in the extrusion process, and it is related to the quality of the product and the level of production efficiency.

Extrusion speed is not like mastering the process temperature. A temperature can be basically selected for an alloy and a heat-treatment process.

While the extrusion speed is a very empirical process parameter, for aluminum profiles with different alloy states and different sections, the extrusion speeds are different.

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 be: Master the extrusion speed range of various alloys and various sections (including wall thickness) skillfully and flexibly, and pay attention to the influence of the extrusion speed on the aluminum profile, such as surface quality, shaping, etc.

Familiar with the ability of extrusion equipment to control extrusion speed.

Some extrusion machines have constant speed extrusion control and PLC control, some only have PLC control, and some do not have both.

When an extrusion speed is given, some extrusion press can begin to extrude at this speed.

As the billet in the extrusion container gradually decreases, the extrusion force decreases, and the product flow rate becomes faster and faster.

Sometimes Will cause cracks in the back of the product. Therefore, it is necessary to even adjust the extrusion speed.

Only by knowing the status of the equipment can the extrusion speed be adjusted and controlled appropriately.

Understand the influence of different dies on extrusion speed.

Generally speaking, the extrusion speed of the flat die (solid profile) is higher than that of the porthole die (hollow profile).

However, products with the same type of mold and the same cross-sectional shape have different extrusion speeds due to different design and manufacturing levels.

Especially 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. If the speed is too fast or too slow, it is easy to twist, or with opening and closing defects.

8. Improve the operation details in anodizing production

The anodizing yield rate is a one-time production yield, that is, one-time production without rework.

According to production practice, the cost of reworked profiles is three times the cost of non-reworked profiles, and the surface quality of the profiles cannot be guaranteed.

Of course, the quality of oxidation products starts from the melting and casting workshop.

The following will briefly talk about some of the details of the oxidation production process

The fixing screw between the hanging rod and the conductive beam should be fastened frequently. Before binding aluminum profiles, first, check whether the fixing of the hanging rod is loose.

In addition, the hanging rod will become smaller due to corrosion, and it needs to be replaced in time, because its conductive area becomes smaller, which is easy to cause heat.

At the same time, it must be tightly tied to prevent aluminum profiles from falling into the tank and causing the pole to touch and short-circuit damage the power supply.

At the same time, aluminum profiles that fall into the tank should be cleaned out in time.

If an aluminum profile falls into the alkali washing tank, it will quickly corrode.

Experiments have shown that the alkali consumption is equivalent to the alkali consumption of 50-100 pieces profiles.

Falling into the coloring tank or the sealing tank, due to corrosion, a large number of aluminum ions will accumulate in the tank, which affects the service life of the bath.

It is better to use two specifications for the aluminum wire used for binding.

The thick aluminum wire is used for large materials, and the thinner aluminum wire is used for medium and small materials.

Two specifications of 2mm and 3mm, or 2.2mm and 3.2mm are available. Aluminum wire annealing hardness is preferably 1/2~3/4. Some companies replaced aluminum wire with a clamp for the anodizing.

Before lifting into the oxidation tank, tighten each piece of aluminum profile carefully; when tightening the rework aluminum profiles before oxidation, first tap the end of the aluminum profile with a vise to shift it before tightening the material so that there is no film in the contact area to ensure good electrical conductivity.

When aluminum material is hung on the conductive seat of the oxidation tank and the coloring tank, pay attention to the alignment, otherwise the color difference will easily occur.

After the oxidation is finished, hang up in time after the power is cut off. Staying in the oxidation tank for a few minutes will affect the sealing and speed up the coloring; after oxidation, it will be lifted and stayed in the air for too long. Make the coloring darker, easy to appear color difference at both ends.

The four washing tanks before and after the coloring tank should keep the pH value of each tank relatively stable. Normally, the pH value of the four washing tanks is controlled as follows:

PH value of the first washing tank after oxidation: 0.8~1.5

PH value of the second washing tank after oxidation: 2.5~3.5

The pH value of the first washing tank after coloring: 1.5~2.5

PH value of the second washing tank after coloring: 3.5~5.0

9. Strengthening the first inspection and process inspection

Aluminum profile shape and size scrap products such as wall thickness out of tolerance, twisting, flat clearance, opening or closing, etc., mainly rely on the first aluminum billet after the mold testing is checked by the main operator and the quality inspector checks after the stretching to reduce the generation of such scrap products.

Generally, the wall thickness tolerance should be controlled from the negative tolerance, because as the products are successively produced, the wall thickness of the products will gradually become thicker due to the gradual wear of the mold.

For large cantilever profiles, check carefully against the drawings during stretching and straightening to control a reasonable amount of stretching.

Surface scrap products such as scratches, orange peel, die lines, dark spots, bubbles, etc., often not all appear on every product.

It is necessary to check each other through the main machine operator, quality inspector, and the sawing process of the stretched product, and jointly supervise the scraping of the scrap products on the surface.

If the quality inspector does not find any scratches on the product on the runout table, and finds the product scratched when the finished product is sawed, it is necessary to check during the conversion process of the cooling bed to see if it is transporting belts, feeders, etc. There are hard parts that cause scratches on aluminum extrusion.

Quality management is the management of the whole staff and the whole process.

Each process must be quality controlled, and the combination of self-inspection, mutual inspection and special inspection can effectively eliminate technical scrap in the bud, Artificial control and improvement of yield.

Through the above measures, physical and technical scrap can be reduced.

It can be seen that reducing physical and technical scraps is an important technical management measure for the aluminum extrusion industry, which is of great significance to high economic benefits.

Improving the yield of aluminum extrusion is a comprehensive and meticulous work process in extrusion production.

Not only must the technical process be in place, but also the management will be a must and practical.

Brightstar Aluminum Machinery offers automatic aluminum extrusion auxiliary equipment for our customers, such as aluminum profile shape corrector, aluminum profile automatic packaging machine, aluminum profile automatic film applicator machine, aluminum profile surface defects brushing and cleaning machine, aluminum profile polishing machine, wood grain effect sublimation machine, all these machines can improve the production efficiency, reduce NG rate, save the labor, get more profit.

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July 12, 2022