In the machining industry for many years, encountered many customers consulting aluminum alloy processing technology related issues. In the oxidation process of aluminum alloy materials, does it have a definite impact on the accuracy of mechanical parts? Whenever the customer mentioned this problem, we will inform the customer in detail. The oxidation of aluminum alloy has an impact on the accuracy of mechanical parts, because oxidation is a chemical treatment, which can modify the appearance of aluminum and improve the hardness of mechanical parts. This is also chemical coating technology!
In the machining process, how to control the precision of mechanical parts in the process of aluminum oxidation treatment? If there is a precision request for the thickness and process size of fine mechanical parts, you can add the process size or negative deviation size of mechanical parts according to the accurate size after oxidation treatment, so as to ensure that the fine mechanical parts can meet the process request on the drawing after oxidation treatment. In the machining process of mechanical parts, not only the size and thickness of the drawing have accuracy, but also the size request of fine hole, step, hole to edge, etc. These are the same as the processing method of thickness request. The allowance should be changed according to the size in the processing.
In the mechanical processing industry, the materials often come into contact with include aluminum and aluminum alloy, copper, alloy steel, POM steel, carbon steel, etc. the following is about the basic knowledge of the materials often come into contact with in the mechanical processing industry, so as to understand the basic functions:
Machining manufacturers, any parts or tools need to be processed, in the process of assembly or use, often subject to various forms of external forces. For example, the steel cable on the heavy-duty machine is subject to the tension of the suspended object; When the connecting rod of diesel engine transmits power, it is not only affected by tensile force, but also by impact force; Shaft parts are subject to bending moment, torsion and so on. Take a look at the following understanding of different materials:
First understand the common aluminum, aluminum alloy materials. It is made of aluminum and other alloy elements. It is usually processed into castings, forgings, foils, plates, belts, tubes, rods, profiles, etc., and then made by cold bending, sawing, drilling, assembling, coloring and other processes. The main metal element is aluminum, in addition to some alloy elements, improve the performance of aluminum. Common automation equipment accessories, 4G mobile communication accessories, medical equipment accessories processing and so on, most are replaced by aluminum. Because the density of aluminum is small, the requirements for cutting tools are not high, so it is one of the best materials for machining.
Look at copper, which is made of pure copper or copper alloy in various shapes, including bar, plate, strip, strip, tube, foil, etc. The processing methods of copper include rolling, extrusion and drawing. The plate and strip of copper include hot rolling and cold rolling; The strip and foil are cold rolled; Tubes and bars are divided into extruded products and drawn products; There are many specifications of copper, which are often contacted in the process of machining. The main advantage of copper is fast heating.
Alloy steel material has a history of more than 100 years. It is made of alloy steel. In addition to iron and carbon, other alloy elements are added to the steel, which is called alloy steel. The iron carbon alloy is made by adding one or more alloy elements on the basis of ordinary carbon steel. According to the different adding elements and adopting appropriate processing technology, special properties such as high strength, high toughness, wear resistance, corrosion resistance, low temperature resistance, high temperature resistance and non magnetism can be obtained. Mainly because of its high hardness, it has special requirements for cutting tools. Suitable for high hardness parts design requirements.
POM saigang is also plastic. POM mainly refers to polyoxymethylene, which is a linear polymer with no side chain, high density and high crystallinity. Main features: it is not necessary to dry the material before processing. It is better to preheat the material during processing (about 80 ℃), which is good for the dimensional stability of the product. In the machining process, different processing methods are selected according to the requirements of the workpiece. POM saigang is widely used in general fixture fixture. Because of its light material density, the finished product is not heavy and easy to operate.
Finally, look at carbon steel. In the machining industry, carbon steel is also called carbon steel, which refers to iron carbon alloy with carbon content less than 2.11%. In addition to carbon, carbon steel generally contains a small amount of silicon, manganese, sulfur and phosphorus. Materials are mainly used in mechanical parts of non alloy steel, generally after surface heat treatment processing.
So it is the basic understanding of the materials often contacted by the machining industry.
Before the mechanical processing industry, computer gong processing is also known as CNC processing and CNC milling machine processing, computer gong processing is mainly by the machine tool computer code command to make CNC automatic programming processing. Now computer gong processing is commonly known as CNC processing, which mainly processes small batch parts and high-precision mechanical parts, with high precision, stable quality, and high production efficiency. Production and processing technology has obvious advantages!
In the process of machining, computer gong processing is operated by computer programming command. Processing technology is to tell CNC machine tool machining tool model, position coordinates, how to control the tool feed speed and spindle speed, as well as tool converter, coolant and other functions.
The parts produced by computer gong are very accurate and repeatable; Computer gong processing can produce parts with complex shapes that cannot be finished by manual processing. Now the computer gong processing technology has been widely promoted, most of the machining factory workshops have CNC processing (computer gong processing) ability, the most common small and medium-sized machining factory is: CNC processing, CNC lathe processing and slow wire and other precision processing equipment.
The above is the computer gong processing manufacturers about process knowledge
In the field of mechanical processing, in the process of machining precision mechanical parts, not all materials can be processed. Many raw materials have too much hardness, exceeding the hardness of the machined parts, which may damage the machine tool or the workpiece. Therefore, some raw materials are not suitable for precision machining, unless special customized tools are selected.
Among the metal raw materials, one is metal material, the other is non-metal material. For the composition of metal materials, the hardness of stainless steel is the largest, followed by cast iron, copper, and finally aluminum. Ceramics, plastics and other non-metallic materials encountered in machining.
For precision machining parts, the first requirement is the hardness of the material. For some occasions, the higher the hardness of the material, the better. It is only limited to the hardness requirements of machining machine parts. The processed material should not be too hard. If it is harder than the selected tool, it cannot be processed.
Secondly, the soft and hard material is moderate, at least the hardness of the cutting tool should be lower. At the same time, it also depends on the conditions of the processing equipment itself and whether the reasonable processing equipment is selected.
In short, precision machining has certain requirements for raw materials, not all materials are suitable for precision machining, such as too soft or too hard materials, to choose reasonable processing equipment and special tools to complete. After understanding the processing requirements, the most basic point is that before processing, we must pay attention to the density of raw materials. If the density is too large, it is equivalent to the hardness. It depends on that the hardness exceeds the hardness of the tool. If it exceeds the hardness, it is very difficult to process. It will not only damage the parts and processing equipment, but also cause production risk. Therefore, generally speaking, raw materials should be lower than the hardness of the tool, so that it can be easily processed.
The above is the requirement of raw materials for precision mechanical parts processing
In the machining industry, the surface treatment process is needed in the general parts processing technology. Surface treatment is mainly to meet the requirements of corrosion resistance, wear resistance, decoration or other special functions of processed products. For mechanical equipment accessories, automation equipment processing parts, we are more commonly used surface treatment methods are chemical treatment, surface heat treatment, oxidation surface, surface treatment for workpiece surface cleaning, cleaning, deburring, degreasing, descaling and so on. Let’s take a look at the difference between the blackening treatment of aluminum and steel!
Blackening of steel is a common surface treatment process and a common means of chemical surface treatment. The principle is to produce a layer of oxide film on the metal surface to isolate air and achieve the purpose of rust prevention. General mechanical equipment accessories, CNC processing parts appearance requirements are not high, can use blackening treatment, steel processing surface blackening treatment, also known as bluing treatment.
In the field of mechanical parts processing, aluminum is one of the most widely used materials. Aluminum blackening is anodizing aluminum in sulfuric acid electrolyte by current action, forming a thin layer of about 10 micron oxide film on aluminum surface, and then dyeing with black organic dye. Because the artificially formed oxide film has many small pores invisible to the naked eye, melanin can enter all the pores, which turns the silver white aluminum surface into black. In order to achieve black matte, sandblasting can be carried out before oxidation to form matte surface. After oxidation and coloring, it becomes matte black.
Aluminum and steel material density is different, surface treatment is not the same, its common purpose is to remove oil, rust. The above is the difference between machining aluminum and steel blackening treatment
In the field of machining, CNC machining belongs to precision machining equipment. CNC machining center can complete a variety of processes of automatic state of CNC equipment, mainly for some mechanical equipment, mobile phone communication industry, small batch, large batch parts production and processing operations. But for the mold industry, small batch production and processing has no obvious advantage, many mechanical processing factory home CNC machining center when CNC milling machine to use.
CNC machining center has its own tool magazine. It is very simple to use the tool magazine for the cost of CNC system, but the cost of machine spindle and tool magazine, auxiliary air compressor and various tool handles will increase, and it will take time to program and adjust the tool magazine with computer. Therefore, for the production and processing of a small number of workpieces of the same variety, the machining center should not be used as far as possible, because the cost will be high and the efficiency will be low.
Precision CNC machining center is an automatic numerical control equipment, which can use the full-automatic tool setting system. The tool is installed upward, the operation button, the machine tool automatic tool setting, and direct processing. The error is within 0.003 ~ 0.005mm, which is not much slower than the automatic tool changing time. If it is a general machining center, but there is no automatic tool setting device, compared with the machine without tool magazine, but there is automatic tool setting device, the efficiency of the latter is much higher than the former in practice. Improve the efficiency of production and processing!
Nowadays, the domestic machinery manufacturing industry, especially the mold manufacturers, is generally single piece production and processing, and labor resources are sufficient, CNC machining center has no obvious advantage. Only in the mechanical parts processing industry, to a certain small batch processing, precision CNC processing will have obvious advantages. The tool magazine on the machine tool plays an important role!
In the field of machining, the machining of parts with high precision is called ultra precision machining. Ultra precision parts processing mainly includes ultra precision turning, mirror grinding and grinding equipment. In ultra precision lathe, micro turning is carried out with single crystal diamond turning tool after fine grinding. The cutting thickness is only about 1 micron. It is often used to process high precision and smooth surface parts of non-ferrous metal materials, such as spherical, aspheric and flat mirrors. For example, the aspheric mirror with a diameter of 800mm is processed for medical equipment accessories, with the highest accuracy of 0.1 μ m and surface roughness of rz0.05 μ M.
In the process of machining ultra precision parts, when the machining precision is usually nanometer or even atomic unit (atomic lattice distance is 0.1-0.2 nanometer), the machining method of ultra precision parts can not adapt to it. It is necessary to use the machining method of special precision parts, that is, chemical energy, electrochemical energy, thermal energy or electric energy, to make these energies exceed the binding energy between atoms, So as to remove the attachment, bonding or lattice deformation of some atoms on the surface of the workpiece, so as to achieve the purpose of ultra precision machining. This kind of processing includes mechanical chemical polishing, ion sputtering and ion implantation, electron beam exposure, laser beam processing, metal evaporation and molecular beam epitaxy.
The main feature of ultra precision parts machining is that the amount of material removed or added to the surface layer can be controlled very finely. However, to obtain the machining accuracy of ultra precision parts, it still depends on precision machining equipment and precise control system, and uses ultra precision mask as intermediary. For example, the plate making of integrated circuits in the electronic industry is to use the electron beam to expose the photoresist (see lithography) on the mask to make the atoms of the photoresist polymerize (or decompose) directly under the electron impact, and then use the developer to dissolve the polymerized or unpolymerized part to make the mask. Electron beam exposure plate making requires the positioning accuracy of worktable up to 100% ± 0.01 micron ultra precision machining equipment.
The so-called high quality comes from exquisite technology. High quality is inseparable from high quality technology, precision processing equipment and reasonable processing technology.
In the field of machining industry, CNC machining center belongs to precision machining equipment, mainly because of the high precision of the machine tool itself, computer programming command CNC operation. CNC machining center machine tool spindle high precision, look at the requirements of high-speed machining tool understanding
In the process of machining mechanical parts, high-speed CNC machining is very important for the selection of cutting tools. The selection of cutting tools is mainly considered from two aspects,
The first is: the dynamic balance state of the cutting tool under the high-speed rotation state;
The second is: how to ensure the life of the tool. In order to ensure the tool can rotate stably around the axis at high speed;
At present, there are two approaches:
One is: the tool with dynamic balance device is used, which is equipped with mechanical slider or fluid dynamic balance design in the tool sleeve;
Second, the integral tool is adopted, and the tool sleeve and the tool body are integrated to ensure the minimum clearance between the tool body and the tool sleeve in the installation process. From the overall performance point of view, the overall tool in this aspect is the most ideal. However, as the tool sleeve and the tool body are integrated, once the tool body is scrapped, the tool sleeve will be scrapped together, so the cost is higher. In the process of parts processing, different materials have different requirements for tool selection. For example: aluminum processing is the first aluminum knife, there is a hardness of steel need to choose different hardness alloy coating knife. Under the operation of high-speed CNC machining, the overall requirements of CNC tools are balance, advanced materials, high manufacturing accuracy, safety, easy chip removal and multi-purpose.
The above is the understanding of the requirements of high-speed CNC machining tools,
In the field of machining industry, production efficiency is directly related to the order cycle and processing profit, which can not be easily ignored. So how to improve the efficiency of machining production? Let’s take a look at the following
CNC machine tool processing operation, must ensure that the table can bear the most weight, ensure the smooth progress of machining process. Nowadays, the purpose of CNC machine tools is to improve the production efficiency. If the machine table can not meet the requirements of use, it will be affected in production.
In the process of machining, because of the increasing speed of high-speed cutting of CNC machine tools, in order to adapt to the processing method, the radius of the tool should be reduced to improve the moving speed of the main bearing of the machine tool. Meet the use requirements in the process of processing, improve the processing quality.
For some precision mechanical parts processing, CNC machine tools need to achieve high precision, high stability and high speed processing requirements. Only in this way can we improve the machining ability and achieve reasonable production efficiency in the cutting process!
In the machining industry, the surface roughness of mechanical parts is also a part of the quality. How to control the surface roughness in machining, what effect does the surface roughness have on the quality of parts, let’s take a look at it next
In the mechanical parts processing drawings, will indicate the surface roughness processing requirements. If the machining process fails to meet the requirements, the surface roughness of parts has a great impact on the mechanical assembly performance and service life
If the surface roughness of the parts can not meet the requirements, the contact area will be reduced, the pressure per unit area will be increased, the contact deformation will be increased, the friction resistance will be increased, and the wear of the parts will be accelerated;
The surface roughness affects the fit properties. For clearance fit, the surface roughness is easy to wear, resulting in the rapid increase of clearance. For interference fit, during assembly, it can flatten the small convex peaks, reduce the effective interference, and reduce the strength of fit parts;
The surface of the parts is rough and low, and corrosive substances are easy to accumulate at the bottom of the surface, which is difficult to remove, causing surface corrosion;
When the part bears the load, the stress concentration is easy to occur at the concave bottom, resulting in cracks and fracture of the part.
In the machining process of mechanical parts, the machining allowance should be reserved for the parts with high surface roughness.
