In the field of hardware machining industry, there will be dimensions and processing steps on the machining drawings of mechanical parts, and the machining accuracy, that is, tolerance requirements, is required for the special position. The precision marked on the production drawing is to ensure that the actual geometric parameters of the hardware after machining are consistent with the size specified on the drawing, and the degree of inconsistency between them is called machining error. In the hardware machining line, the following three aspects should be paid attention to in order to ensure the accuracy tolerance of the production and processing drawings and avoid the machining error:
Datum: select the same datum plane for processing, so as to reduce certain error range in clamping processing of hardware machining parts.
Workpiece shape: for workpieces with special shape, fixture can be designed for positioning processing, so as to continuously achieve accuracy tolerance and improve production and processing efficiency.
Processing technology: in the process of hardware machining, selecting reasonable machining technology can ensure the quality of production and processing, and also improve efficiency!
Reasonable arrangement: according to the machining accuracy on the drawing, different machining equipment can be selected to complete the machining process. While ensuring the workpiece tolerance, it can also show the advantages of machining machine tools!
The above is the basic tolerance concept of hardware machining
In the mechanical parts processing industry, the selection of a reasonable machining process steps, the use of machine tool processing equipment and the selection of tools is also very important, today to see the understanding of cutting conditions in machining tools
Before automatic equipment parts processing or fixture processing, first find the necessary tools and tools, and prepare to start production and processing. In the aspect of cutting, the service life of the cutting tool is affected by the machine tool forward milling and reverse milling. The cutting vibration of forward milling is smaller than that of reverse milling. The cutting thickness of the cutting tool is reduced from the maximum to zero in down milling. After the cutting tool cuts into the workpiece, there will be no springing phenomenon caused by not cutting the chip. The process system has good rigidity and small cutting vibration; In reverse milling, the cutting thickness of the tool increases from zero to the maximum. At the initial stage of cutting, due to the thin cutting thickness, a path will be scratched on the surface of the workpiece. At this time, if the cutting edge meets the hard points in the graphite material or the chip particles remaining on the surface of the workpiece, it will cause the tool to bounce or chatter, so the cutting vibration of reverse milling is larger.
In the process of machining parts, when special materials are encountered, the cutting materials on the surface of the workpiece should be cleaned in time, which is conducive to reducing the secondary wear of the tool, prolonging the service life of the tool, and reducing the influence of some waste materials on the lead screw and guide rail of the machine tool. In the process of machining, select the appropriate high speed and the corresponding large feed.
Based on the above points, the material, geometric angle, coating, edge strengthening and cutting conditions of the cutting tool play different roles in the service life of the tool. A good machining tool should have smooth chip removal groove, long service life, be able to carry out rough and finish machining, and save processing cost.
The above is the understanding of machining conditions of cutting tools.
In the mechanical processing industry, ordinary machining equipment includes lathe, milling machine, grinder, wire cutting, etc., while precision machining equipment includes precision grinder processing, CNC lathe processing, CNC processing, slow wire processing, etc; According to the accuracy requirements of production drawings, to choose a reasonable processing technology and different processing equipment. General processing equipment will be auxiliary accessories, auxiliary accessories also have a different role. Let’s take a look at the application of rotary top of processing equipment accessories
In the process of machining mechanical parts, sometimes auxiliary parts are needed to complete the processing of complex or high precision workpiece. For example, lathe processing shaft parts, with the help of center hole positioning, rotary center is widely used. Because of the high precision of mechanical parts, it is a necessary machine tool accessory for high-speed cutting on small precision lathe.
The above is the application of the rotary center of processing equipment.
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.
