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December 16, 2024Aluminum is one of the most commonly used materials for machining today. In fact, the CNC machining process for aluminum is second only to steel in terms of frequency of use.
In its high-purity form, the chemical element aluminum is soft, ductile, non-magnetic, and has a silvery-white appearance. However, this element is not used only in its pure form. Aluminum is often alloyed with various elements, such as manganese, copper, and magnesium, to form a variety of aluminum alloys with significantly improved properties. The most common machined aluminum alloys and their grades in different standards can be found here.
Advantages of using aluminum for CNC machined parts
While there are countless aluminum alloys with varying degrees of characteristics, there are some basic characteristics that apply to basically all aluminum alloys.
Workability
Aluminum can be quickly shaped, fabricated, and machined by a variety of different processes. Aluminum can be cut quickly and easily by machine tools because it is soft, easy to cut, inexpensive, and requires less effort than steel. These characteristics are great advantages for both machinists and customers ordering parts. Furthermore, aluminum’s superior machinability means that it is less likely to deform during machining. Given that it allows CNC machines to achieve a higher degree of resistance, their accuracy will be higher.
Strength of Aluminum
Aluminum is about one-third the density of steel, making it relatively lighter in mass. Despite its light weight, aluminum is very strong. This combination of strength and weight is called the specific strength of the material. Aluminum’s high specific strength makes it suitable for parts needed in many industries, such as the automotive and aerospace industries.
Corrosion resistant
Aluminum resists scratching and corrosion in conventional marine and atmospheric environments. This property can also be enhanced by anodizing. It is important to note that the corrosion resistance of different grades of aluminum varies. The most regular and common CNC machined grades instead have the strongest resistance.
Low Temperature Performance
Most materials lose some of their quality properties below freezing. For example, carbon steel and rubber become brittle at low temperatures. Aluminum, on the contrary, retains its softness, ductility and strength at very low temperatures.
Conductivity
The electrical conductivity of pure aluminum is about 37.7 million Siemens/meter at room temperature . Although aluminum alloys are less conductive than pure aluminum, they are sufficient for applications in electronic components. On the other hand, if the desirable properties of a machined part are not electrical conductivity, aluminum would not be a suitable material for it.
Recyclability
Since the CNC machining process is a subtractive manufacturing process, it generates a large amount of chips, also known as scrap. Aluminum is highly recyclable and requires relatively little energy, effort and cost to recycle. This makes it a favorite among those who want to recoup expenses or reduce material waste. It also makes aluminum a more environmentally friendly material to process.
Anodizing possibilities
Anodizing, a surface machining process, improves the material’s resistance to wear and corrosion, which is extremely easy to achieve with aluminum. This process also makes it easier to color machined aluminum parts.
CNC machining process for aluminum
Aluminum is machined through some of the existing CNC machining processes. Some of these processes are listed below.
CNC Turning
In a CNC turning operation, the workpiece rotates while the single-point cutting tool remains stationary along the axis. Both the workpiece and the tool will rely on the machine tool to perform feed movements against each other to achieve material removal.
CNC Milling
CNC milling is the most common process used when machining aluminum parts. These processes involve the rotation of a multi-point cut along an axis, while the workpiece remains stationary along the axis. The cutting action and subsequent material removal is realized by a feed motion, either of the workpiece or of the cutting tool or a combination of both. This action can be carried out along multiple axes.
Notching
Recess machining, known as recess milling, is a form of CNC milling used to machine a hollow recess in a part.
End face machining
Face machining involves the use of face turning or face milling to create a flat cross-section on the surface of a workpiece.
CNC drilling
CNC drilling is the process of punching a hole in a workpiece. In this process, a multipoint rotary cutting tool of a specific size is perpendicular to the surface to be drilled and moves in a straight line to effectively punch the hole.
Tools for machining aluminum
In the choice of CNC machining tools for aluminum, there are so many influencing elements.
Tool Design
The different styles of a tool’s shape affect its efficiency in machining aluminum. One of them is the number of grooves in the tool. In order to avoid difficulties in discharging chips at high speeds, a cutting tool for CNC machining of aluminum should have 2-3 grooves. Too many notches means narrower chip discharge passages, which can lead to large chip jams from aluminum alloys. When cutting forces are low and chip removal is critical to the process, you should use a tool with 2 notches. If you want to achieve the perfect balance of chip removal and tool strength, you should use a 3-notch tool.
Helix angle
The helix angle is the angle formed between the center axis of the tool and the straight line cut along the cutting edge. It is an important feature of cutting tools. Although a larger helix angle clears part chips more quickly, it increases friction and heat during the cutting process. In high-speed CNC machining of aluminum, this can result in chips fusing to the surface of the tool. On the other hand, a smaller helix angle generates less heat and may not be as effective at removing chips. For machining aluminum, a 35- or 40-degree helix angle is suitable for roughing, while a 45-degree helix angle is best for finishing.
Clearance angle
The clearance angle is another important factor for a tool to function properly. Too much angle can cause the tool to drill into the workpiece and make a gurgling sound. On the other hand, too little of an angle can cause friction between the tool and the workpiece. The best clearance angle for CNC machining of aluminum is between 6 and 10 degrees.
Material of the tool
Tungsten carbide is the material of choice for use as a cutting tool for CNC machining of aluminum. Because aluminum is a soft cut, it is important that the tools used to cut aluminum are not hard, yet retain the ability to cut sharp edges. Carbide cutting tools have this ability, mainly by two points: alloy grain size and binder ratio. Although a larger grain size makes the material harder, a smaller grain size ensures that the material is more resilient and impact resistant, which are the properties we really need. Smaller grains allow cobalt to achieve a fine grain structure and material strength.
However, cobalt and aluminum react at high temperatures to form aluminum chip tumors on the tool surface. The key to minimizing this reaction is to use carbide tools with the right amount of cobalt (2 to 20%) while still maintaining the required strength. Carbide tools can usually withstand the high speeds of CNC machining of aluminum better than steel tools. In addition to the material of the tool, coatings are an important factor in cutting efficiency. Zirconium dinitride, titanium diboride and diamond-like coatings are all suitable tool coatings for CNC machining of aluminum.
Feed and speed
The cutting speed is the speed at which the cutting tool is rotating. Aluminum can withstand very high cutting speeds, so the cutting speed of aluminum alloys depends on the limits of the machine tool used. This speed should be as fast as the actual speed at which the aluminum is CNC machined, as this reduces the possibility of chip-rule formation, saves time, reduces part temperatures, improves chip breakage and improves finishing finishes. The exact speed used varies depending on the aluminum alloy and tool diameter.
The feed rate is the distance the workpiece or tool moves for each revolution of the tool. The choice of feed is dependent on the degree of finish, strength and stiffness of the workpiece desired. Rough cutting requires a feed rate of 0.15-2.03 mm/rev, while finish cutting requires a rate of 0.05-0.15 mm/rev.
Cutting fluid
Even if aluminum is a good machinable, never cut it in a dry state, as this will encourage the formation of chip tumors. Suitable cutting fluids for CNC machining of aluminum are oil-based emulsions and mineral oils. Avoid cutting fluids that contain chlorine or reactive sulfur, which can stain aluminum.
Post-Processing Flow
After finishing machining an aluminum part, there are specific processes you can perform to enhance its physical, mechanical, and aesthetic properties. The most widely used processes are listed below.
Pearlized and sandblasted finishes
Pearlizing is a finishing process with a decorative effect. The process consists of a high-pressure air gun spraying small glass beads onto the machined part, effectively cleaning the material and ensuring that the surface of the part is smooth and flat and that the aluminum can have a smooth or matte finish. The main operating parameters of the bead finishing process are the size of the glass beads and the amount of high or low air pressure used. This process is only suitable if the dimensional tolerances of the part are not critical. Other processes, including polishing and lacquering, are also available in addition to bead-blasting, i.e. cleaning the material with a high-pressure stream of sand.
Protective layer
This process covers the use of other materials such as zinc, nickel, and chrome plating to overcoat aluminum parts. This is done to perfect the machining of the part and may be possible through an electrochemical reaction process.
Anodic oxidation
Anodizing is an electrochemical process in which an aluminum part is immersed in a dilute sulfuric acid solution and a voltage is applied to both the positive and negative terminals. This process effectively transforms the exposed surface of the part into a hard, non-reactive aluminum oxide coating. Both the density and thickness of the resulting coating depend on the consistency of the solution, the length of the oxidation, and the current. You can also use anodizing to color parts.
Powder Coating
The powder coating process consists of coating the parts with colored polymer powder using an electrostatic spray gun. The parts are then stored at a temperature of 200 degrees Celsius. Powder coating improves strength and resistance to abrasion, corrosion and impact.
Hot treatment
Parts made of heat-treatable aluminum alloys receive heat treatment to improve their mechanical properties.
CNC Machining of Aluminum Parts in Industry
As mentioned above, aluminum alloys possess many desirable properties. Therefore, CNC machining of aluminum parts is indispensable in many industries, as follows:
Aerospace: Given the high specific strength of aluminum alloys, many aircraft components are made from machined aluminum.
Automotive: Similar to the aerospace industry, many components in the automotive industry, such as driveshafts and other components, are made of aluminum.
Electrical: CNC machined aluminum parts are often used as electronic components in household appliances due to their high electrical conductivity.
Food/Pharmaceuticals: Aluminum parts do not react with most organic substances, so they play an important role in the food and pharmaceutical industries.
Sports: Aluminum is often used to make sports equipment such as baseball bats and sports whistles.
Cryogenic: Aluminum retains its mechanical properties at temperatures below freezing, making it popular for low-temperature applications.
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December 9, 2024Aluminum Processing Industry Overview
According to the different processing techniques, aluminum processing products can be divided into two major categories;
One is the use of fusion casting – extrusion process production of aluminum profiles:
Aluminum rods extruded into aluminum profiles using the hot extrusion process; hot extrusion is the earliest of several extrusion processes used in the extrusion molding technology, it is in the hot forging temperature with the help of the material plasticity good characteristics of the metal for a variety of extrusion molding. At present, hot extrusion is mainly used in the manufacture of ordinary cross-section of long parts, profiles, tubes, bars and various machine parts. Hot extrusion can not only form good plasticity, relatively low strength of non-ferrous metals and their alloys, low, medium carbon steel, etc., but also can be formed into high strength high carbon, high alloy steel, such as structural special, stainless steel, high-speed tool steel and heat-resistant steel, etc.. As the billet must be heated to hot forging temperature for extrusion, often accompanied by more serious oxidation and decarburization and other heating defects, affecting the dimensional accuracy and surface roughness of the extruded parts. In general, machine parts hot extrusion molding, and then use cutting and other machining to improve the dimensional accuracy and surface quality of the parts.
Melting process flow:
Furnace loading → melting → stirring complete melting → add scrap → melting → add scrap → complete melting → sprinkle covering agent and slagging agent → slagging → stirring → sampling, pre-furnace analysis → add Al-Si (Sl-Cu, Cr additives), Mg ingot → stirring → sampling, post-furnace analysis → composition adjustment → refining → slagging re-covering → resting
The other is aluminum sheet and strip and aluminum foil produced using the hot rolling – cold rolling process. Among them, aluminum profiles are mainly used in construction and industrial fields, while aluminum sheet and foil are mainly used in home appliances, food and beverage, and battery fields:
Continuous casting slab or initial rolling slab as raw material, heated by a step heating furnace, high-pressure water dephosphorization into the roughing mill, roughing material by cutting the head, tail, and then into the finishing mill, the implementation of computer-controlled rolling, final rolling that is, after laminar cooling (computer-controlled cooling rate) and coiling machine coiling, become straight hair rolls. The head and tail of the straight hair coil is often tongue and fishtail shape, thickness, width accuracy is poor, there are often wave-shaped edge, folded edge, tower and other defects. Its volume weight is heavy, the inner diameter of the steel coil is 760mm. (General pipe making industry like to use.) The straight hair coil by cutting head, tail, cutting edge and more than one straightening, leveling and other finishing line processing, and then cut plate or re-roll, that is to become: hot rolled aluminum plate, flat hot rolled aluminum coil, longitudinal cut strip and other products. If the hot rolled finishing coils are pickled to remove oxidized skin and coated with oil, they will become hot rolled pickled coils.
With hot rolled aluminum coil as raw material, after pickling to remove the oxide skin for cold rolling, the finished product is rolled hard coil, due to continuous cold deformation caused by cold hardening of rolled hard coil strength, hardness, toughness and plastic index decline, stamping performance deterioration, can only be used for simple deformation of the parts. Rolled hard coil can be used as raw materials for hot-dip galvanizing plant, because the hot-dip galvanizing unit are set with annealing line. Rolled hard coil weight is generally 6 ~ 13.5 tons, aluminum coil inner diameter of 610mm. general cold rolled plate, coil should be continuous annealing (CAPL unit) or hood furnace for de-annealing treatment to eliminate cold hardening and rolling stress, to achieve the mechanical properties specified in the standard index. Cold rolled aluminum plate surface quality, appearance, dimensional accuracy are better than hot rolled plate.
Industry chain analysis: the main products in the midstream for aluminum profiles and aluminum sheet and foil
Aluminum processing industry chain is directly upstream of the production of electrolytic aluminum and renewable aluminum industry, at present, China’s renewable aluminum industry, although the development of faster, but still lagging far behind the developed countries, in the context of the global carbon neutrality, renewable aluminum may usher in the policy support; industry chain for the production of processed aluminum products in the middle of the industry chain, the products are mainly for the aluminum extrusion and aluminum sheet with foil; products downstream of the application of processed aluminum products in the fields of construction and decoration, packaging containers, aerospace, transportation and so on. Decoration, packaging containers, aerospace, transportation and so on.
China’s national economy and high-tech stable, sustained and rapid development, prompting China’s aluminum smelting and aluminum profile processing industry is developing very rapidly. China’s aluminum aluminum alloy profile industrial aluminum profile production in 2006 has reached 8.793 million tons, more than the United States to become the world’s first; 2007 production of up to 12.508 million tons, an increase of 42.45% compared with 2006, hitting a new record high; 2007 imports of 690,000 tons of industrial aluminum, an increase of 0.6% compared with 2006; exports of 1.853 million tons of industrial aluminum profile, an increase of 49.3% compared with 2006 million tons, an increase of 49.5% over 2006, the net export of aluminum alloy profiles 1.163 million tons; in 2007, China’s apparent consumption of industrial aluminum 11.345 million tons. In January-June 2008, China’s aluminum industry production, alumina production of 11.129 million tons, an increase of 7.1% over the same period in 2007, is expected to 2008 annual production of 23 million tons; electrolytic aluminum production of 6.620 million tons, an increase of 12.9% over the same period in 2007, it is expected that the annual production of 2008 will reach 14.5 million tons; aluminum processing material 6.879 million tons, an increase of 38.3% over the same period in 2007; aluminum alloy profiles net exports of 1.163 million tons. the same period of 2007, an increase of 38.3%, is expected to 2008 annual output will reach 14 million tons.
Since the reform and opening up, especially since the new century, China’s non-ferrous metal industry continues to develop rapidly, has become the world’s largest producer and consumer of non-ferrous metals, the overall strength of the industry has been significantly enhanced, and the influence of the same industry in the international arena is increasing. The main performance: the total output and consumption continue to grow rapidly, in 2008, the total output of ten kinds of non-ferrous metals 25.2 million tons, for seven consecutive years ranked first in the world, of which copper production and consumption accounted for 20% and 24% of the world; electrolytic aluminum, lead, zinc production and consumption accounted for more than 30% of the world’s total. Economic benefits have been greatly improved. In 2008, enterprises above designated size are expected to realize sales revenues of more than 2.1 trillion yuan, and profits of more than 80 billion yuan. The pace of optimization and upgrading of industrial structure has been accelerated, and backward self-baking aluminum electrolytic tanks were all eliminated in 2005; at present, the capacity of advanced smelting technology for copper, lead and zinc accounts for more than 85% of the total production capacity; and the processing capacity of copper and aluminum has been greatly improved. The capability of independent innovation has been significantly enhanced, and the 350 kA and 400 kA large-scale prebaked electrolytic cell technologies developed independently with independent intellectual property rights are at the advanced level of the world’s aluminum industry and have been exported abroad; high-precision copper tubes with internal threads, high-grade aluminum alloy architectural profiles, and aluminum materials for high-speed trains with a speed of 350 km/h not only meet the domestic demand, but also have been exported to a large number of developed countries and regions. A new round of mineral search in domestic mines and the development of overseas mineral resources has made breakthrough progress, and the effectiveness of the search for minerals in the margins and depths of the existing nine major mining areas has been remarkable; a number of large-scale enterprise groups with strength have made substantial steps in overseas resource development and the acquisition and reorganization of overseas mining enterprises, which has effectively strengthened the ability to safeguard mineral resources.
Industry History: New Growth Points in the Industry
Since 1954, China’s aluminum processing industry officially started, although a late start, but rapid development, aluminum processing products production increased year by year. 2001, China’s electrolytic aluminum production capacity for the first time exceeded the United States, as of now, China has become the world’s highest production capacity of the aluminum industry in the world. 2020, the new energy automobile industry outbreak, the battery energy density enhancement rate is still not enough to meet the market demand, the quality and strength of the aluminum-based materials have been recognized by the market. The quality and strength of aluminum-based materials have to be recognized by the market, lightweight demand led to a new growth point in the aluminum processing industry.
Aluminum and its alloys are suitable for metal matrix composite material matrix, aluminum matrix composite material reinforcement can be continuous fiber, can also be short fiber, can also be from the spherical to irregular shape of the particles. Aluminum matrix composite reinforcing particles are SiC, AL2O3, BN, etc. Intermetallic compounds such as Ni-Al, Fe-Al and Ti-Al are also used as reinforcing particles.
Composites can be divided into three categories: polymer matrix composites (PMCs), metal matrix composites (MMCs), and ceramic matrix composites (CMCs). Metal matrix composites matrix is mainly aluminum, nickel, magnesium, titanium and so on. Aluminum has many characteristics in the production of composite materials, such as light weight, low density, good plasticity, aluminum-based composite technology is easy to master, easy to process. In addition, aluminum composite material has high specific strength and stiffness, good high temperature performance, more fatigue and wear-resistant, good damping performance, low coefficient of thermal expansion. Like other composite materials, it can combine specific mechanical and physical properties to meet the needs of products. Therefore, aluminum matrix composites have become one of the most commonly used and important materials in metal matrix composites. According to the different reinforcement, aluminum matrix composites can be divided into fiber reinforced aluminum matrix composites and particle reinforced aluminum matrix composites. Fiber-reinforced aluminum matrix composites have a series of excellent properties such as high specific strength, high specific modulus, good dimensional stability, etc. However, they are expensive and are mainly used in the field of aerospace, as the structural materials of space shuttle, artificial satellite and space station. Particle reinforced aluminum matrix composites can be used to manufacture satellites and aerospace structural materials, aircraft parts, metal mirror optical systems, automotive parts; in addition can also be used to manufacture microwave circuit plug-ins, inertial navigation systems, precision parts, turbocharged propellers, electronic packaging devices.
Industry Policy Background: Recycled Aluminum Gets Attention
In order to reduce carbon emissions from the aluminum processing industry and meet the demand for lightweighting in the downstream industry, numerous important policy documents released in recent years have mentioned the establishment of technical R&D support and industry planning for the aluminum processing industry. For example, the “Guiding Opinions on Comprehensive Utilization of Bulk Solid Waste in the 14th Five-Year Plan” issued in March 2021 encourages the recovery of iron, alkali and alumina from red mud, the recovery of valuable components such as rare and sparse metals and rare and precious metals from smelting slag, the enhancement of the efficiency of the utilization of mineral resources, the safeguarding of the security of the country’s resources, and the gradual increase in the comprehensive utilization rate of smelting slag. Utilization rate of smelting slag.
Current status of industry development
1.China’s aluminum production hit a new high
In 2017-2021, China’s aluminum production was first reduced and then increased. 2017 production reached the highest value before 2021, 58,324,400 tons, an increase of 0.63%; in 2018, China’s aluminum industry deepened the supply-side structural reform, strict control of new production capacity of electrolytic aluminum, and promote the exchange of electrolytic aluminum production capacity; at the same time by the impact of the impact of trade friction, the cost of production Continuously improving, China’s aluminum production fell sharply, down 21.91%; in 2019 and 2020, aluminum production improved, and in 2020, the output reached 57.793 million tons, an increase of 10.03% year-on-year; in 2021, aluminum production was further improved, reaching 61.052 million tons, the highest value in history.
2.Highest proportion of aluminum extrusion
According to the statistics of China’s total output of aluminum fabricated materials and the output of subdivided varieties in 2021, the comprehensive output of China’s aluminum fabricated materials was 44.7 million tons in 2021. Among them, the output of aluminum sheet and strip (including aluminum foil gross) is 13.35 million tons, accounting for 29.87%; the output of aluminum foil is 4.55 million tons, accounting for 10.18%; the output of aluminum extrusion is 22.02 million tons, accounting for 49.26%; the output of aluminum wire rod is 4.4 million tons; the output of aluminum powder is 0.16 million tons; and the output of aluminum forgings and others is 0.22 million tons.
3.Battery aluminum foil stands on the wind
From 2017 to 2021, the production of battery aluminum foil is on a growing trend. Affected by the long cycle of new production lines and the high impact of process difficulty, battery aluminum foil expansion is more difficult, in 2020, affected by the outbreak of the new energy automobile industry, the demand for battery aluminum foil industry in 2020 grew faster, and 2021 ushered in the release of battery aluminum foil production reached 140,000 tons, a year-on-year increase of double.
Industry Competitive Landscape
1. Regional competition: Shandong Province has the highest number
From the point of view of the regional distribution of China’s aluminum processing industry chain enterprises, the province with the largest number of aluminum processing industry chain enterprises is Shandong Province, followed by aluminum processing enterprises mainly distributed in the eastern region, and relatively few in the western region. There are many ports in the eastern region, which is convenient for export, at the same time, the eastern region has convenient transportation, and the downstream market is more developed, and the distribution of aluminum processing enterprises in the eastern region can help reduce transportation costs and form industrial clusters.
2.Enterprise competition: the first echelon production more than 1 million tons
Aluminum processing industry has a large number of enterprises, and the production of the head enterprise is relatively higher. From the perspective of the 2021 production situation of aluminum processing enterprises, it is mainly divided into three competitive echelons: the first echelon’s production exceeds 1 million tons.
Industry Development Prospects and Trends
1. Production is expected to exceed 100 million tons in 2027
Despite the increased environmental pressure, low-carbon requirements on aluminum production to form a suppressive effect, but the “14th Five-Year Plan” period, the new energy automotive industry into the sales surge period, at the same time, electronic consumer products in the 5G and chip technology continues to innovate under the influence of the iterative cycle to shorten the demand for aluminum products, aluminum production is expected to be in 2027 More than 100 million tons.
2.The future of China’s aluminum processing industry award facing industrial upgrading and transfer
The core of the upgrading of the aluminum processing industry should be to change the development mode to ensure the sustainable development of the industry. The specific embodiment of the transformation of the development mode should be the adjustment of production capacity, the rational layout of the industry, product structure adjustment, the use of applicable technology routes, etc., to promote the optimization and upgrading of the industrial structure. […]
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December 5, 2024Aluminum is a non-ferrous metal in the largest amount of use, the most widely used metal materials, and its scope of application is still expanding. The use of aluminum production of aluminum products is a wide variety, countless, according to statistics has more than 700,000 kinds, from the building decoration industry to the transportation industry and aerospace and other industries have different needs. Introduce the processing of aluminum products and how to avoid processing deformation.
The superiority and characteristics of aluminum are as follows:
1.Low density. The density of aluminum is about 2.7g/cm3. it is only 1/3 of the density of iron or copper.
2. High plasticity. Aluminum has good ductility and can be made into various supplies by extrusion, stretching and other pressure processing means.
3. Corrosion resistance. Aluminum is a highly negatively charged metal, in natural conditions or anodic oxidation of the surface will generate a protective oxide film, with much better corrosion resistance than steel.
4. Easy to strengthen. The strength of pure aluminum is not high, but its strength can be improved by anodic oxidation.
5. Easy surface treatment. Surface treatment can further improve or change the surface properties of aluminum. Aluminum anodic oxidation process is quite mature, stable operation, has been widely used in the processing of aluminum products.
6. Good conductivity, easy to recycle.
Stamping of aluminum products
1.Cold Punch
Material used: Aluminum pellets. Using an extruder table and die for one-time molding, it is suitable for column-shaped products or product shapes that are difficult to achieve with the stretching process, such as oval, square, and rectangular products.
The tonnage of the machine used is related to the cross-sectional area of the product, the gap between the upper die punch and the lower die tungsten steel is the wall thickness of the product, and the vertical gap between the upper die punch and the lower die tungsten steel to the lower dead center at the completion of the press fit is the top thickness of the product.
Advantages: shorter molding cycle, lower development cost compared to stretching molds.
Disadvantages: Longer production process, large fluctuation of product size during the process, high labor cost.
2.Stretching
Use material aluminum skin. Using continuous mold machine table and molds for multiple deformation to make it reach the demand of shape, suitable for non-cylindrical body (products with curved aluminum).
Advantages: more complex and multiple deformation products in the production process of dimensional control is stable, the product surface is more polished.
Disadvantages: high cost of molds, relatively long development cycle, high requirements for the selection and accuracy of the machine.
Surface treatment of aluminum products
1. Sandblasting (shot blasting)
The process of cleaning and roughening metal surfaces using the impact of a high-speed sand stream.
This method of surface treatment of aluminum parts enables the surface of the workpiece to obtain a certain degree of cleanliness and different roughness, so that the mechanical properties of the surface of the workpiece can be improved, therefore improving the fatigue resistance of the workpiece, increasing the adhesion between it and the coating, prolonging the durability of the coating film, and also contributing to the leveling and decoration of the coating. This process we often see in Apple’s various products.
2.Polishing
The use of mechanical, chemical or electrochemical effects, so that the surface roughness of the workpiece to reduce, in order to obtain a bright, flat surface processing methods. Polishing process is mainly divided into: mechanical polishing, chemical polishing, electrolytic polishing. Aluminum parts using mechanical polishing + electrolytic polishing can be close to the stainless steel mirror effect, the process, giving people a high-grade simple, fashionable future feeling.
3.Drawing
Metal drawing is the manufacturing process of repeatedly scraping lines out of aluminum sheets with sandpaper. Wire drawing can be divided into straight wire drawing, messy wire drawing, spinning wire drawing, thread drawing. The brushed metal process can clearly show each and every fine silk trace, thus making the metal matte with a fine hairline luster, and the product is both fashionable and technological sense.
4.High light cutting
The use of engraving machine will be diamond knife reinforced in the high-speed rotation (general speed of 20,000 rpm) of the engraving machine spindle to cut parts, in the product surface to produce localized highlights area. The brightness of the cutting highlights is affected by the speed of the milling drill, the faster the drill speed, the brighter the cutting highlights, and vice versa, the darker and prone to knife lines. Highlight highlight cutting in the use of cell phones in particular, such as iphone5, in recent years part of the high-end TV metal bezel using a high-gloss milling process, coupled with anodized and brushed process makes the TV set overall full of fashion sense and sharp sense of science and technology.
5.Anodic oxidation
Anodic oxidation refers to the electrochemical oxidation of metals or alloys. Aluminum and its alloys form a layer of oxidized film on aluminum products (anode) due to the action of applied current under the corresponding electrolyte and specific process conditions. Anodic oxidation can not only solve the defects of aluminum surface hardness and abrasion resistance, but also prolong the service life of aluminum and enhance the aesthetics, which has become an indispensable part of aluminum surface treatment, and it is the most widely used and very successful process at present.
6.Double color anode
Two-color anodizing refers to anodizing a product and giving different colors to specific areas. The two-color anodizing process is less used in the TV industry because of the complexity and high cost of the process; however, the contrast between the two colors better reflects the high-end and unique appearance of the product.
Process measures and operating techniques to reduce aluminum machining distortion
Aluminum parts processing deformation of many reasons, and materials, part shape, production conditions and so on have a relationship. There are mainly the following aspects: deformation caused by internal stress in the blank, cutting force, cutting heat caused by deformation, deformation caused by clamping force.
1.Reduce the internal stress of Mao Pei
Internal stresses in the blank can be partially eliminated by natural or artificial aging and vibration treatment. Pre-machining is also an effective process. For fat head and ears of the blank, due to the large margin, so the deformation after processing is also large. If pre-processing off the excess part of the blank, reduce the allowance of each part, not only can reduce the processing deformation of the later process, and pre-processing after placing for a period of time, but also can release part of the internal stress.
2.Improve the cutting ability of the tool
The material and geometric parameters of the tool have an important influence on the cutting force and cutting heat, and the correct selection of the tool is essential to reduce the deformation of the part machining.
(1) Reasonable selection of tool geometry parameters.
①Front angle: under the condition of maintaining the strength of the cutting edge, the front angle is appropriately chosen to be larger, on the one hand, it can sharpen the edge, and on the other hand, it can reduce the cutting deformation, make the chip removal smooth, and then reduce the cutting force and cutting temperature. Do not use negative front angle tool.
② rear angle: the rear angle size of the rear face wear and processing surface quality has a direct impact. Cutting thickness is an important condition for selecting the rear angle. Rough milling, due to large feed, heavy cutting load, heat generation, requiring good tool cooling conditions, therefore, the rear angle should be selected smaller. Precision milling, the requirements of sharp edges, reduce the friction between the rear face and the machined surface, reduce elastic deformation, therefore, the rear angle should be selected larger.
③ Helix angle: In order to make milling smooth and reduce milling force, the helix angle should be chosen as large as possible.
④ Main deflection angle: Appropriate reduction of the main deflection angle can improve the heat dissipation conditions, so that the average temperature of the machining area decreases.
(2) Improvement of tool structure.
① Reduce the number of teeth of milling cutter and increase the chip space. Due to the greater plasticity of aluminum materials, cutting deformation in the processing of large, need a larger chip space, so the bottom radius of the chip slot should be larger, fewer milling cutter teeth is good.
②Precision grinding cutter teeth. Roughness value of the cutting edge of the teeth to be less than Ra = 0.4 um. In the use of new knives before, should use a fine oil stone in front of the teeth, behind the knife gently ground a few times to eliminate the edge of the teeth of the knife when the residual burrs and slight serration pattern. In this way, not only can reduce the cutting heat and cutting deformation is relatively small.
③ Strictly control the standard of tool wear. After the tool wear, the surface roughness of the workpiece increases, the cutting temperature rises, and the deformation of the workpiece increases. Therefore, in addition to the selection of wear-resistant tool materials, tool wear standard should not be greater than 0.2mm, otherwise it is easy to produce chip tumors. When cutting, the temperature of the workpiece should generally not exceed 100 ℃ to prevent deformation.
3、Improve workpiece clamping method
For thin-walled aluminum workpieces with poor rigidity, the following clamping methods can be used to reduce deformation:
① For thin-walled bushing parts, if the three-jaw self-centering chuck or collet chuck is used to clamp from the radial direction, the workpiece is bound to be deformed once it is loosened after machining. At this point, you should use the rigidity of the better axial end face compression method. Positioned in the hole of the part, a threaded self-contained through the center of the shaft, set into the parts of the hole, with a cover plate on the end of the compression face and then backed with a nut tight. Processing of the outer circle can be avoided when the clamping deformation, thus obtaining satisfactory machining accuracy.
② thin-walled sheet workpiece machining, it is best to use vacuum suction cups, in order to obtain a uniform distribution of clamping force, and then a smaller amount of cutting to process, can be very good to prevent deformation of the workpiece.
In addition, the filling method can also be used. In order to increase the rigidity of the process of thin-walled workpieces, the workpiece can be filled with medium inside the workpiece to reduce the clamping and cutting process of the workpiece up to deformation. For example, to the workpiece filled with 3% to 6% potassium nitrate urea melt, after processing, the workpiece will be immersed in water or alcohol, the filler can be dissolved and poured out.
4、Reasonable arrangement of work processes
High-speed cutting, due to the large machining allowance and intermittent cutting, so the milling process often produces vibration, affecting the machining accuracy and surface roughness. Therefore, the CNC high-speed cutting machining process can generally be divided into: roughing – semi-finishing – clear angle machining – finishing and other processes. For parts with high accuracy requirements, it is sometimes necessary to carry out a second semi-finishing process, followed by finishing. After rough machining, the parts can be naturally cooled to eliminate the internal stresses generated by rough machining and reduce deformation. The margin left after rough machining should be larger than the amount of deformation, generally 1 ~ 2 mm. finishing, parts finishing surface to maintain a uniform machining margin, generally 0.2 ~ 0.5 mm is appropriate, so that the tool is in a smooth state in the machining process, you can greatly reduce the cutting deformation, to obtain a good surface finish quality, to ensure the accuracy of the product.
Operational techniques to reduce machining distortion
Aluminum parts material parts deformed during processing, in addition to the above reasons, in practice, the operation method is also very important.
1.For the machining of large parts, in order to make it in the process of machining have better heat dissipation conditions, to avoid heat concentration, processing, it is appropriate to use symmetric processing. If there is a 90mm thick plate needs to be processed to 60mm, if milling a good side immediately after milling the other side, a machining to the final size, then the flatness of 5mm; if the repeated feed symmetric machining, each side of the two times to the final size of the machining, can ensure that the flatness of 0.3mm.
2. If there are more than one cavity on the plate parts, processing, should not be used a cavity a cavity sequence of processing methods, which is likely to cause uneven force and deformation of the parts. The use of multi-layer processing, each layer as far as possible at the same time processing to all the cavities, and then process the next level, so that the parts are uniformly stressed, reducing deformation.
3.By changing the cutting amount to reduce the cutting force, cutting heat. In the three elements of the cutting amount, the back draft has a great impact on the cutting force. If the machining allowance is too large, the cutting force is too large, not only will make the parts deformed, but also affect the rigidity of the machine tool spindle, reduce the durability of the tool. If you reduce the amount of back draft, and will make a big difference in productivity. However, in CNC machining are high-speed milling, can overcome this challenge. In reducing the amount of back draft at the same time, as long as the corresponding increase in feed, increase the speed of the machine tool, you can reduce the cutting force, while ensuring the machining efficiency.
4.The order of tool walking should also be careful. Roughing emphasizes the improvement of processing efficiency, the pursuit of the removal rate per unit of time, generally can be used inverse milling. That is, the fastest speed, the shortest time to excise the excess material on the surface of the blank, the basic formation of the geometric contour required for finishing. And finishing emphasizes the high precision and quality, it is appropriate to use downstream milling. Because the cutting thickness of the cutter teeth gradually decreases from the maximum to zero, the degree of work hardening is greatly reduced, while reducing the degree of deformation of the parts.
5.Thin-walled workpieces in the processing of deformation due to clamping, even if the finishing process is difficult to avoid. In order to minimize the deformation of the workpiece, you can reach the final size in the finishing process before the pressurized pieces of loose, so that the workpiece is free to return to its original state, and then slightly pressed to just be able to clamp the workpiece shall prevail (entirely by feel), so that you can get the desired processing results. In short, the action point of the clamping force is best in the bearing surface, the clamping force should act in the direction of good rigidity of the workpiece, under the premise of ensuring that the workpiece does not loosen, the smaller the clamping force the better.
6. In the processing of parts with cavity, processing cavity try not to let the milling cutter like a drill directly down into the parts, resulting in the milling cutter chip space is not enough, chip removal is not smooth, resulting in parts overheating, expansion, as well as chipping, tool breakage and other unfavorable phenomena. To use the same size as the milling cutter or a larger drill bit to drill down the hole, and then use the milling cutter milling. Alternatively, CAM software can be used to produce a spiral undercut program. […]
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From our leaders
January 22, 2025Elimination of tax rebates on aluminum exports. It is not an exaggeration to say that China’s announcement made the world tremble.
On November 15, the Ministry of Finance and the State Administration of Taxation issued an announcement that since December 1 this year, the export tax rebate for aluminum and other products will be abolished, and the aluminum products involved almost cover the main aluminum profiles, aluminum sheet and strip foils, aluminum bars and rods and other aluminum products.
As of now, China is the undisputed absolute hegemon of the global aluminum industry, and China’s aluminum exports reached 5.287 million tons in 2023, accounting for about 35% of the total global trade.
In terms of production, China’s absolute dominance is even more terrifying, in which primary aluminum production accounts for 59% of the world, aluminum production accounts for about 66%, electrolytic aluminum accounts for 60%, and smelted aluminum is also close to 60%.
According to statistics from the United States Geological Survey (USGS), China’s smelting aluminum production in 2023 will be ten times that of the second-ranked India, and the total production of other countries in the world is only 70% of China’s.
As an extremely important basic resource, aluminum products play a key role in industries such as construction, rail transit, automobiles, and cables. Due to the super status of Chinese aluminum products in the world, countries around the world can hardly bypass China when using aluminum products.
Even though the United States has imposed various trade measures such as anti-dumping duties, countervailing duties and tariffs on my country in recent years, it remains the world’s largest buyer of Chinese aluminum products and the world’s largest importer of aluminum to this day.
The aluminum industry chain, especially electrolytic aluminum, is a “power-eating behemoth” with a huge appetite, which seriously restricts the development of the aluminum industry in other countries and regions. Based on my country’s aluminum exports last year, at least 740GW of electricity was consumed. By the end of September this year, my country’s total photovoltaic installed capacity had reached this figure.
Due to geopolitical conflicts and the pursuit of reducing carbon emissions by mainstream countries around the world, the power supply is insufficient and the energy crisis has emerged. The electricity left for electrolytic aluminum will only become less and less. China’s reduction in aluminum exports will mean a large number of chain reactions for countries around the world, and a subsequent reassessment of China’s industrial capabilities.
1.Electricity-Eating Monster
Aluminum was once more precious than gold.
Aluminum was a very rare metal more than a hundred years ago due to the difficulty of refining. In order to show his lofty status, Napoleon III specially made an aluminum crown, and only he could use exclusive aluminum tableware, and others could not. Only gold or silver cutlery may be used.
Aluminum itself is the most abundant metal element in the earth’s crust. It was not until 1889 that Austrian scientist Bayer invented a method of extracting aluminum oxide from bauxite, and then invented the electrolytic production method, which officially opened the prelude to the large-scale industrialization of aluminum. Currently, almost all aluminum companies in the world use the “Bayer process”.
The efficiency of aluminum smelting has been greatly improved, but the disadvantage of electrolytic aluminum is that it consumes huge amounts of electricity, making it a “power-consuming monster.” It takes 13,600 kw/h of direct current (nearly 14,000 degrees) to produce one ton of electrolytic aluminum. Once upon a time, my country had to use more than 7% of its annual electricity to produce electrolytic aluminum. This was just one link in the electrolytic aluminum industry. The electricity consumption of the entire industry chain was an extremely huge number.
In 2023, the national production of 41.513 million tons of electrolytic aluminum, this calculation, power consumption of up to 564.6 billion kWh of electricity, equivalent to 5646GW, last year’s aluminum exports of 5.287 million tons of power consumption close to 740GW.
To know, at the end of last year, China’s cumulative installed capacity of photovoltaic power generation is less than 610GW, the global cumulative capacity of 1546GW. to June this year, China’s photovoltaic cumulative total of 713.5GW, as of the end of September, only to reach 770GW, that is to say, just China’s exports of aluminum will need to be powered by all of the photovoltaic in China.
At the end of last year, Europe’s cumulative installed capacity of photovoltaic climbed to 263GW, the United States 162GW, India has just exceeded 60GW. relying only on photovoltaic clean energy, the gap is very huge.
Aluminum electrolysis at the same time is still a high-emission industry, smelting process carbon emissions had accounted for about 5% of China’s total carbon emissions, second only to steel and cement. Such a huge amount of carbon emissions is unaffordable for any country pursuing a green energy transition.
In November 2018, the European Union proposed to achieve carbon neutrality by 2050, and has since further established a target of 55% emission reduction (compared to 1990) for member states by 2030; the United States plans to reduce greenhouse gas emissions to half of the 2005 level by 2030, and to achieve “net-zero” emissions by 2050. “emissions by 2050.
Of course, this goal may become recurring as new administrations come to power.
That’s why India, the world’s second-largest aluminum producer, is the world’s third-largest carbon emitter after China and the United States. In order to realize the completion of 500GW of clean energy in 2030, India is frantically mounting photovoltaic projects, and in the first half of 2024, its photovoltaic new installations of 14.9GW, a year-on-year surge of 282%, a record high for the same period in history.
And China is the world’s top PV country, with a complete whole industry chain absolute advantage, India 80% of PV components rely on Chinese manufacturing.
Have no choice, there is news that even India’s second largest aluminum group Indian Aluminum Industries has begun planning to enter the field of solar modules. The company also at the end of last year, plans to invest 80 billion rupees to establish a battery foil manufacturing plant.
Therefore, China’s tightening of aluminum exports this announcement, so that the world vibration, will pay more attention to China’s industrial capacity, whether it is traditional industrial products or photovoltaic, wind power and other new energy products.
2.The world can’t do without Aluminum China
Countries around the world are basically dependent on Chinese aluminum products.
Based on its huge scale advantage, Chinese aluminum products are making inroads into the world.
Especially the United States. Even though it has introduced various trade restrictions, it is still the largest buyer of Chinese aluminum products.
As early as 2018, the United States initiated a 301 tariff review of China, involving 33 sub-divisions of aluminum products; in October 2023, the U.S. Department of Commerce announced that it had imposed a preliminary anti-dumping duty of 167.16% on China’s ordinary aluminum alloy plates, 59.31% on China’s aluminum profiles, and a countervailing duty rate of up to 137.65% on Chinese companies involved in the case;
September 13 this year, the United States and decided to China’s exports of electric vehicle batteries, key minerals, steel, aluminum, masks and other products, the tariff rate will be raised to 25%.
The rounds of tax increases, almost all of the aluminum is covered. It can be said that the United States of China’s aluminum products for a full range of non-discriminatory “comprehensive blow”. But because the United States is extremely dependent on aluminum imports, to 2023, the United States is still China’s largest export market for aluminum products, exports to the United States totaled 694,000 tons, exports of 3.79 billion U.S. dollars.
Due to the continued increase in demand from the automotive lightweight, rail transportation and other industries, Goldman Sachs expects the global aluminum market will also see a shortfall of 7.24 million tons this year.
However, due to the constraints of zero carbon emission targets, China’s electrolytic aluminum has been close to the ceiling of compliance capacity. Some brokerage calculations, electrolytic aluminum compliance capacity limit value of 44.67 million tons, the expansion of space has been little.
According to the previous departments to clean up and rectify the electrolytic aluminum illegal and irregular special action provisions, where the electrolysis process contains the project, must be implemented electrolytic aluminum capacity replacement, that is, “the construction of electrolytic tanks, must be replaced”.
Overseas, in Russia played “cut off” king bomb, Norway Hydro decided to close Slovakia aluminum smelter, Germany’s large aluminum rolling company Speira announced a cut of its German smelter half of the production capacity of Europe’s largest aluminum smelter France Dunkirk Aluminum also said that the production reduction of 22%.
By incomplete statistics, the overseas capacity closure in 2022-2023 is as high as 1.581 million tons, superimposed on the impact of dual-carbon policy and energy issues, further production cuts are more likely.
In fact, the main force of new overseas production capacity or Chinese enterprises, Huaqing Aluminum, Huayou Holdings, Nanshan Aluminum, Shandong Weiqiao / China Liqin and other overseas investment and construction of up to 6,050,000 tons of production capacity scale, the new production capacity of aluminum enterprises in other countries is only 714,000 tons, but also face a lot of uncertainty.
In order to bypass the trade sanctions in Europe and the United States and other countries, China’s aluminum companies also accelerated overseas production, especially Indonesia landed a number of projects, superimposed on the rebound in aluminum prices, the domestic aluminum company performance, Nanshan Aluminum industry in the first three quarters to achieve a net profit of 3.49 billion yuan, an increase of 62.94%; Aluminum Corporation of China in the first three quarters of the ho earned 9.017 billion yuan, an increase of 68.46%; China Hongqiao first half of the storm earned 9.155 billion yuan, a jump of 2.7%. billion yuan, a year-on-year surge of 2.7 times.
At present, the world’s top fifteen electrolytic aluminum producers, China alone accounted for seven seats, respectively, Chinalco, Hongqiao, Xinfa, Guodian Investment, Oriental Hope, Jiujiang Steel and Shenhuo, production accounted for 37% of the global total.
And Alcoa (Alcoa) due to soaring energy and other costs, sustained losses since 2022, after the permanent closure of the Intalco aluminum smelter located in Washington State, production has withdrawn from the world’s top ten.
The crisis of the United States and European aluminum companies, the United States of America’s dependence on Chinese aluminum products will further deepen.
3.The bottom line of industrial scale
The global aluminum industry landscape is solid.
The huge scale of the aluminum industry allows China to hold ample trade leverage, allied with the South in one hand and exported to developed countries in the other.
China’s aluminum manufacturing capacity dominates the world, but its upstream resources rely heavily on overseas imports. China’s bauxite and alumina reserves account for only 2% of the world’s total, and currently around 70% of bauxite needs to be imported.
The world’s bauxite is concentrated in Guinea, Vietnam, Australia, Brazil, Indonesia and other countries, which together account for 65% of the world’s reserves. In particular, Guinea is world-famous for its high-grade, large-scale bauxite resources. It has been the main source of global bauxite growth in recent years and is currently the largest source of minerals for my country.
In October this year, Chinalco’s mining volume in Guinea hit a record high for a single month, and the amount of ore shipped back to China hit the best level in the same period in history; Tianshan Aluminum recently stated that the company’s bauxite project in Guinea has entered the production and mining stage and will soon be shipped to China. , the cost of bauxite raw materials can be greatly reduced in the future.
Judging from the distribution of source countries of my country’s imported bauxite in recent years, my country’s dependence on Guinea has increased rapidly. In the first nine months of this year, 74.5% of the bauxite came from Guinea, and its dependence on Australia has decreased significantly.
Another core country is Indonesia. In June 2023, Indonesia issued a bauxite export ban policy, requiring local resources to be tied to local alumina production capacity, landing projects domestically, creating more jobs and national income. Therefore, China’s aluminum Many companies have set up factories directly in Indonesia to reap the cost benefits brought by the local low-priced bauxite.
Jinjiang Group has planned a 6 million ton alumina production capacity in Indonesia in five phases. The first phase of 1 million tonnes was put into construction in April this year. The 2 million tonnes alumina project of Tianshan Aluminum, the world’s second largest alumina producer, was listed as Indonesia’s national strategic project; Nanshan Aluminum is also promoting a 2 million ton alumina expansion project and a 250,000 ton electrolytic aluminum project; Shandong Innovation Group also plans to build a 2 million ton alumina project in Indonesia.
Under the impetus of Chinese enterprises, advanced smelting technology, complete industrial chain have stationed in Indonesia, formed the upstream bauxite, alumina and electrolytic aluminum production in Indonesia, the domestic focus on aviation panels, automotive panels, and other high barriers, high value-added products development pattern.
Made in China to help, rough estimates, Indonesia’s alumina production capacity this year may exceed 50 million tons, is expected to increase to 80 million tons in 2026, become a global alumina production power, more China’s midstream and downstream aluminum products strategic back.
Currently, the economic development of the world’s countries is extremely unbalanced, many southern countries have rich reserves of upstream resources, but lack of mining, smelting and processing technology and market capacity. China is the combination of manufacturing capacity, advanced technology and the resources of the southern countries, mutual benefit and win-win; on the other hand, by virtue of the crushing supply advantage, so that the developed countries have to purchase.
The global aluminum industry pattern is the best embodiment of this pattern.
4.Conclusion
China is the only country in the world that has all the industrial categories, complete, prosperous and powerful, is the distinctive label of China’s industrial manufacturing resonates globally.
Compared with the comprehensive, complete, people generally overlooked, it is the huge scale advantage, so that China’s industrial products – including such as electrolytic aluminum, such as primary industrial products, can be in the price relative to global competitors have enough advantage. In Europe and the United States erected trade barriers against China at the moment, the value of scale, is the Chinese products continue to expand in the global killer app.
Based on the huge scale of manufacturing, China can, on the one hand, work in solidarity with developing countries to purchase resources; on the other hand, it can manufacture high-level, cost-effective industrial products for global distribution. And in the energy side, and formed a photovoltaic, wind power and other clean energy industry chain advantages, leading the global industrial civilization forward, but also from the side to enhance the barriers to industrial production.
Even in the global energy low-carbon transformation of domestic, other countries have to buy China’s new energy products.
It is no exaggeration to say that in the context of increased global economic turmoil, no country dares not think about the consequences of China’s restrictions on the export of certain industrial products. Starting with various rare earth and aluminum products, the world will have a clearer understanding of this. […]
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