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Computer gongs – electrode requirements

Modern mold enterprises, almost no lack of EDM, because EDM can effectively process all kinds of special-shaped, all kinds of cavities or high hardness parts, so it has become an indispensable processing means in mold manufacturing and metal processing industry.

According to the feedback information from the enterprise, the accuracy has reached ± 0.002 mm, and the roughness Ra = 0.4 μ M. In order to pursue the machining accuracy, the condition of the WEDM machine tool should be checked at the beginning. The deionization degree of ionic water, the temperature of ionic water, the perpendicularity of wire cutting, the tension force, the cutting wire and the material of the workpiece to be cut should be checked to ensure the good processing speed and accuracy. For WEDM, it is a kind of cutting or cutting material from a whole blank. Therefore, the original stress balance is destroyed in the process of processing, resulting in stress concentration at the corner. When the radius r of the inner corner is less than 0.2, the design department should be advised to improve the die structure. The method of dealing with stress concentration can apply the principle of vector translation. The allowance of 0.8-0.9mm should be reserved before finishing, and the approximate shape of the cavity should be pre processed, and then heat treatment should be carried out to release the machining stress as much as possible before finishing, so as to ensure the thermal stability.

When processing punch, the cutting position and path of cutting wire should be carefully considered. The position of clamping blank should be selected after the first feeding, the workpiece does not form a hanging wall, which always makes the workpiece in good stress state and does not affect the subsequent processing; for the punch with high requirements, the blank can be drilled and threaded, and the processing effect is better than that of cutting in the shape. Now high-precision workpieces, in order to ensure the quality of the parts, four times of cutting is generally used. When there is a part of taper machining in the thickness direction of female die, in order to pursue efficient machining, the straight edge is usually roughened for the first time, tapered for the second time, and then finished for the third time. This process feature is that there is no need to finish the existing taper edge vertically, only the straight edge of the edge section is finished, and the edge of the straight edge is refined after the fourth pass.

Rough and fine electrodes should be made respectively in EDM. The shape of the finishing electrode is required to meet the requirements of the cavity, and the good precision electrode has been processed by CNC machine tool. In terms of electrode material selection, copper electrode is mainly used for general steel parts processing; Cu-W alloy electrode has good comprehensive performance, especially the electrode loss during processing is obviously smaller than that of red copper electrode. Under good chip removal conditions, it is suitable for finishing difficult to machine materials and parts with complex cross-section shape; Ag-W alloy electrode has better performance than Cu-W alloy electrode because of less resources and high price In addition, graphite electrode has been widely used. At present, there are domestic graphite and imported graphite. Imported graphite has the advantages of low loss, high hardness, fast electro etching speed and low surface roughness, and has been applied in many complex parts finishing. When designing the electrode, the clearance and the number of electrodes are calculated. When machining large area or heavy electrode, the workpiece and electrode clamping should be stable and have certain strength to prevent loosening during processing. However, the surface after EDM is more difficult to grind than the surface after conventional machining or heat treatment. Therefore, before the end of EDM, the surface should be trimmed with precision gauge to remove the hardened thin layer formed on the surface.

Surface treatment of mould parts

The content of forming surface treatment includes no porosity on steel surface, uniform hardness, small difference in anisotropy characteristics, low inclusions and stress concentration places such as tool marks and grinding marks left on the surface of parts during processing. Therefore, after the end of processing, it is necessary to strengthen the surface of the parts, through mechanical polishing, fitter grinding, polishing, processing hidden dangers. Blunt the useless edge, acute angle and orifice of the workpiece. Generally, there will be 6-10 μ m metamorphic hardened layer on the surface of EDM, which is gray white in color. This layer is brittle and has residual stress. Before use, the hardened layer should be eliminated completely by polishing the surface and polishing off the hardened layer. In order to obtain high-quality polishing effect, the material, shape, hardness and surface quality of cutting must be fully considered. It is necessary to have high-quality polishing tools, high-quality polishing materials, correct polishing process, rigorous and consistent personnel quality, and good cleaning environment.

Assembly of mould parts

In the process of grinding and electrical machining, the workpiece will be magnetized to a certain extent, with weak magnetic force, which is easy to absorb some small impurities. Therefore, before assembly, the workpiece should be fully demagnetized and the surface should be cleaned with ethyl acetate. During the assembly process: (1) first understand the assembly drawing and complete all kinds of parts; (2) list the assembly sequence of each part; (3) check the dimensional accuracy of each part and make clear the matching requirements; (4) complete the required tools, and then start to assemble the mold; (5) assemble the guide pillar and guide sleeve of the mold base and the assembly of the cavity forming block; (6) assemble the mold (7) open and close the mold, check whether the mold action is reliable.

Computer gong processing – automobile mold

The domestic and international markets have more and more stringent requirements on the quality and cost price of automobile forgings, such as draft angle, weight tolerance, size, machining allowance, etc., and the price is not ideal, but the batch is large. In order to meet the needs of the market, this paper analyzes the process and repeated practice, and finds an ideal process, which is of great significance to the production of similar products.

Introduction of products and determination of process plan

Product introduction

The arm body is a part used on the brake pump of a heavy vehicle, and the structure is shown in Fig. 1. There are several difficulties in forging: (1) the draft angle is small, only 3 ° outside and 5 ° inside, while the ejection device only has one place in the ∮ 62 hole; (2) the machining allowance is small, only boring and broaching are used for ∮ 62 and square groove of 23.2mm; (3) 10 – ∮ 6.2 * 5 these 10 nails are difficult to fill, and the location requirements are high, and the root fillet of the nails is r0.2, which makes the die wear faster and easy to bump and cause deformation in the production process.

Determination of process plan

In order to adapt to mass production and improve efficiency, we have determined the following processes: (intermediate frequency furnace) heating / (cross wedge rolling) / (25000kN hot die forging press) bending / pre forging / forging / (3150kN double-point Press) punching / trimming / normalizing / shot peening / precision pressing. In the technological process, two pieces at a time are used for heating billet, the handle of the part is long and thin, and the blank making efficiency of single piece by free forging is low. The cross wedge rolling billet (as shown in Fig. 2) is adopted and cut into two pieces on the rolling mill at the same time. Because the cross-section of the parts changes greatly, from ∮ 55 to ∮ 23, it takes two wedging to complete, so it is difficult to process and repair the rolling die.

In addition to ensuring the size of the head and shank, it is more important to correct the position of the 10 nails, the fillet of the root and the bending of the handle. Therefore, two standard platens with 5 holes are used to ensure the position of nails and the root fillet, and improve the service life of forging die.

Key points of mould design and manufacture

Generally, the bending die design only considers that the shape of the extruded blank is consistent with that of the forging. Due to the large difference in the thickness between the big end and the handle of the arm body, the handle of the bending billet will be suspended when it is put into the pre forging die. During the pre forging, the transition between the handle and the big head will be folded. Due to the suspension of the handle of the bending billet, the metal flow in this part is too large.

Shape and position tolerance of computer gong machining

1、 Interchangeability of parts

Precision parts manufacturers introduced that after long-term production and operation of the machine, some parts are bound to wear, deformation and scrap, replaced with new parts. These parts are called accessories or spare parts. Accessories or spare parts without repair or selection, installed on the machine can run, known as interchangeability.

In order to achieve interchangeability, the size and geometry of parts should be consistent when manufacturing parts. The so-called consistency does not mean that the score is exactly the same (this is neither economical nor possible). As long as the size and geometric shape of the parts are controlled within an allowable range, it is necessary to make the parts and other parts have the same binding performance. The allowable error range is the geometric tolerance.

2、 The machining quality of precision parts is expressed by machining precision

Geometric accuracy

Geometric accuracy refers to the accuracy of geometric shape of each surface or axis, such as whether the line is straight, whether the surface is flat, whether the normal section on the cylinder is circular, etc. The allowable variation range is represented by “geometric tolerance”. The smaller the geometric tolerance number is, the higher the shape accuracy is.

Dimensional accuracy

According to the analysis of precision parts processing manufacturers, the dimensional accuracy refers to the accuracy of the size of the parts after processing, which is represented by “dimensional tolerance”. When the dimensions of parts are the same, the higher the accuracy, the smaller the tolerance number.

Position accuracy

According to the introduction of precision parts processing manufacturer, position accuracy refers to the accuracy of mutual position between the surfaces of parts, such as whether the two planes are parallel, whether they are vertical, whether the two axes are coaxial, and so on, which is represented by “position tolerance”.

The tolerance of the above shape and position is referred to as “form and position tolerance”.

Troubleshooting of four axis machining

Analysis and processing of four axis machining: the alarm may be caused by the poor SQL3 of the table loosening position sensor or the CNC did not receive the clamping signal of the turntable, because similar faults occurred before were caused by poor plug contact. To confirm, open the side cover of the turntable, and close a small saw blade to the end of SQ13: the SQL3 lamp is on, which proves that SQL3 is normal. Meanwhile, the data of PLC and ladder iaxbul can be highlighted, indicating that the system can receive signals. Therefore, it is suspected that there are problems in the hydraulic part, such as insufficient hydraulic pressure, oil leakage of hydraulic cylinder rising the turntable, mechanical stagnation when the turntable rises, which makes the turntable rise not in place. The hydraulic pressure of four axis machining is checked. When the machine stops moving, the pressure is 5.5mpa. When the turntable or machine is manually operated, it is found that the pointer of the system pressure gauge is shaking obviously and the hydraulic pump has obvious noise. Therefore, it is suspected that the hydraulic pump inhales air: check the oil level of the oil tank and find that the oil tank is empty. After filling the tank, turn the turntable again, normal. The variable pump is used to supply oil in the hydraulic system. When the hydraulic pressure is not operated, the system keeps pressure, the hydraulic pump absorbs less oil, and the oil level of the oil tank basically meets the requirements. When the hydraulic pump is operated, the hydraulic pump shall supply oil. Because the oil tank is not enough, the system pressure is insufficient, which leads to the failure of the turntable to rise in place. Half an hour later, the machine alarm again, and then look at the oil level, and the oil is gone, indicating that the hydraulic system leaks oil: finally, it can find the oil pipe of the turntable rising is broken and leaking; after replacement, the fault is completely eliminated.

CNC machining of revolving parts

CNC lathe machining center is a common name of CNC lathe. The key difference between turning and milling is that it is mainly used for the machining of rotary parts such as shafts, ring parts, disk parts and threads.

CNC lathe can be divided into horizontal CNC lathe and vertical CNC Lathe according to spindle configuration. There are many kinds of horizontal CNC lathe. The function of early CNC lathe is relatively simple, only x, Z axis linkage function to achieve digital control turning processing. Based on the need of expanding the processing range on the CNC lathe, the power tool is added to the tool holder of the NC lathe, and the milling function is increased. On this basis, the turning and milling machining center is developed. However, the processing range of the traditional turning and milling machining center is limited due to the fact that the cutting tool of the CNC lathe always faces the rotation center of the spindle Drilling, reaming, reaming, etc. toward the spindle rotation center. With the continuous development of numerical control technology, as well as the requirements of new product development and rapid response, the main structure of CNC equipment forms serialization and modularization, increases Y-axis and its rotation axis, and develops into a real turning and milling machining center.

As one of the important parts of CNC lathe, the turret determines the overall layout and working performance of CNC lathe. There are turret turret and linear array turret. Turret turret is the most common horizontal CNC lathe.

Numerical control lathe is very popular in the factory, and it plays an important role in the field of processing as the machining center. Industrial statistics show that CNC lathes are generally considered to be relatively simple compared with machining centers, although CNC lathes can produce high-quality parts. CNC lathe is mainly used to process high-precision, good surface quality requirements of rotary parts, so it needs few programs and start-up operation, but this does not mean that CNC lathe can not be used for processing short cycle and ordinary parts, just because the ratio of parts to be machined by turning is much higher than that by milling.

Characteristics of CNC lathe

(1) CNC lathe can automatically complete the following operations: spindle speed change, forward and reverse rotation, start or stop, feed and rapid movement in two coordinate directions, release, rotation and clamping of tool rest, switch of cutting fluid, etc.

(2) The feed of NC turning tool must be connected with the rotation of the spindle, because the turning of NC lathe is calculated by the number of pulse equivalent that the turning tool moves along the feed direction when the spindle rotates a circle.

(3) Since the dimension marking and measurement of part design drawings are diameter values, in order to improve the accuracy of radial dimension and facilitate programming and measurement, X-direction pulse equivalent is taken as half of Z-direction, so when the diameter direction is programmed with absolute value, x-coordinate value is expressed as diameter value. When using incremental programming, the program is programmed by twice the actual radial displacement, and the direction symbol is attached.

(4) When machining parts with horizontal CNC lathe, based on the needs of surface quality and machining accuracy of the parts, the spindle must have a large speed range, which can adopt either constant surface speed or constant speed.

(5) It has the function of tool compensation and skip instruction.

(6) CNC lathe is usually a two coordinate machine tool, which can realize two coordinate (x, z) linkage processing of revolving body contour parts.

(7) Due to the large machining allowance of blank and die forging, CNC lathe often has different forms of fixed cycle function, which can carry out a variety of turning cycles

Factors of deformation and crack of parts

In the production practice, the author found that the deformation and crack in WEDM are related to the following factors.

1.1 it is related to the structure of parts

1) The size of deformation is related to the complexity of shape, the ratio of length to width, and the ratio of cavity to frame width. The more complex the shape, the larger the ratio of length to width and the ratio of cavity to frame width, the greater the deformation of the die. The law of deformation is that the middle part of the cavity is shrunk in, and the punch is usually warped;

2) It is easy to crack or even explode in the sharp corner of quenching cavity with complex shape and clear angle. The frequency of its occurrence is related to the material composition and heat treatment process;

3) Cylindrical parts with thin wall thickness are easy to deform if they are cut on the inner wall, which generally changes from round to ellipse. If it is cut through the notch, it is easy to crack when it is about to be cut through;

4) The deep notch cut in from the outside of the part is easy to deform. The deformation law is that the mouth is retracted. The deformation amount is related to the depth of the notch and the material properties.

1.2 related to hot working process

1) The parts whose initial forging temperature is too high or too low and the final forging temperature is low when forging die blank;

2) When the final forging temperature is too high, the grain grows up, and the cooling rate is too slow after final forging, and there are net carbide precipitated in the die blank;

3) The forging billet annealing is not carried out according to the spheroidizing annealing process, and the parts with spheroidized pearlite more than 5 grades are annealed;

4) When the quenching temperature is too high, the austenite grain is coarse, which reduces the strength and toughness of the material and increases the brittleness;

5) The quenched parts are not tempered in time and the parts with insufficient tempering.

1.3 related to machining process

1) If the die with large area is cut off in the middle without hollowing out in advance, the size of the frame will be deformed due to cutting off the larger volume in the frame;

2) No matter what the shape of punch tempering and shape is, it is easy to deform, especially for the quenched part, which has to be cut in from the outside of the blank;

3) For the grinding parts after heat treatment, there are no process requirements such as grinding wheel granularity, feed rate, cooling mode, etc., and the parts with defects such as burn and microcrack on the surface after grinding.

1.4 material related

1) There is serious carbide segregation in raw materials;

2) Materials with poor hardenability and easy deformation, such as T10A, T8A, etc.

1.5 related to wire cutting process

1) It is easy to deform due to improper selection of WEDM path; Dongguan computer gong Processing Factory Dongguan Mechanical Parts Processing Factory Dongguan plastic mold factory Shenzhen computer gong Processing Co., Ltd

2) It is easy to deform due to unreliable clamping method and improper selection of clamping points;

3) Improper selection of electric gauge may lead to cracks.

Machining and polishing of mechanical parts

The basic principle of electropolishing is the same as that of chemical polishing, that is, the surface is smooth by selectively dissolving the small protruding part of the material surface. Compared with chemical polishing, the effect of cathode reaction can be eliminated and the effect is better. The electrochemical polishing process is divided into two steps: (1) macro leveling solution diffuses into the electrolyte, and the geometric roughness of the material surface decreases with RA > 1 μ M. (2) The results show that the surface brightness is improved and RA is less than 1 μ M.

1.4 in ultrasonic polishing, the workpiece is put into the abrasive suspension and placed in the ultrasonic field together, and the abrasive is ground and polished on the surface of the workpiece by the oscillating action of the ultrasonic wave. The macro force of ultrasonic machining is small, which will not cause deformation of workpiece, but it is difficult to make and install tooling. Ultrasonic machining can be combined with chemical or electrochemical methods. On the basis of solution corrosion and electrolysis, ultrasonic vibration is applied to stir the solution to separate the dissolved products on the surface of the workpiece, and the corrosion or electrolyte near the surface is uniform; the cavitation effect of ultrasonic in the liquid can also inhibit the corrosion process and facilitate the surface lighting.

1.5 fluid polishing fluid polishing is to achieve the purpose of polishing by washing the workpiece surface with high-speed flowing liquid and abrasive particles. The common methods are abrasive jet machining, liquid jet machining, hydrodynamic grinding and so on. Hydrodynamic grinding is driven by hydraulic pressure to make the liquid medium carrying abrasive particles flow through the workpiece surface at high speed. The medium is mainly made of special compound (polymer material) with good flowability under low pressure and mixed with abrasive. The abrasive can be silicon carbide powder.

1.6 magnetic abrasive polishing magnetic abrasive polishing is the use of magnetic abrasive under the action of magnetic field to form abrasive brush to grind the workpiece. This method has the advantages of high efficiency, good quality, easy control of processing conditions and good working conditions. The surface roughness can reach ra0.1 μ m with proper abrasive.

The basic method of mechanical polishing in plastic mold processing is different from the surface polishing required in other industries. Strictly speaking, mold polishing should be called mirror processing. It not only has high requirements for polishing itself, but also has high standards for surface flatness, smoothness and geometric accuracy. Surface polishing generally requires only a bright surface. The standard of mirror machining is divided into four levels: Ao = ra0.008 μ m, A1 = ra0.016 μ m, A3 = ra0.032 μ m, A4 = ra0.063 μ M. due to the fact that it is difficult to accurately control the geometric accuracy of parts by electrolytic polishing, fluid polishing and other methods, and the surface quality of chemical polishing, ultrasonic polishing, magnetic abrasive polishing and other methods can not meet the requirements, so the mirror processing of precision mold is mainly mechanical polishing.

The development trend of heat flow path

The components of the heat flow path technology show several main development trends.

It’s the miniaturization of components. Miniaturization of the components can realize the first mock exam of small products and multi gate filling of large products. By reducing the nozzle space, more cavity can be arranged on the mold, which can improve the product production and injection machine utilization rate, which is very important for the modern plastic processing industry with “time is money”. Moldmaters, an international famous mold enterprise, has developed nozzles for small parts, including integral heater, needle tip and melt channel, with a volume diameter of less than 9 mm, and gate spacing of only 10 mm, and can be molded into products with a quality of 1-30 G.
It is component standardization. At present, the user requires that the die design and manufacturing cycle is shorter and shorter, and standardizing the hot runner elements is not only conducive to reducing the repetition of design work and reducing the cost of the mold, but also for the replacement and maintenance of vulnerable parts. Nozzles, stem and diverter plates from companies such as Husky, Presto and moldmaters are standard, which facilitate rapid replacement and delivery of moulds. Now, the mold can be delivered only four weeks abroad.
It is the reliability of design. Nowadays, the design of hot runner plate and the research and development of pressure distribution, temperature distribution and sealing of the heat nozzle joint are paid great attention to by the major mold companies at home and abroad. The development and utilization of the injection mold for laminated hot runner are also hot spots. The number of cavity can be increased effectively by the stack mold, but the requirement of the injection machine die closing force only needs to increase by 10% – 15%. The stack hot runner mold has been industrialized in some developed countries abroad.
It is the accuracy of temperature control system. In the mold molding of hot runner, developing more precise temperature control device and controlling the temperature of molten resin in hot runner plate and gate are effective measures to prevent resin from overheating degradation and product performance reduction.

The wide application of heat runner technology is a great change of plastic mold. In the aspect of injection molding, it has many incomparable advantages. With the technology becoming more mature and the manufacturing cost is reduced, the heat flow path technology will show more and more great advantages. In recent years, the world famous hot runner technology suppliers have entered the Chinese market in various ways, which shows the huge development potential of the hot runner mould Market in China.

During the forming process of hot runner, the temperature of plastic melt is controlled accurately in the runner system. Plastic can flow into each cavity in a more uniform and uniform state, and the result is the parts of the same quality. The quality of gate of hot runner is good, the residual stress is low after demoulding and the deformation of parts is small. So many high quality products in the market are produced by hot runner die. For example, many plastic parts in the familiar Motorola mobile phone, HP printer and Dell notebook are made by hot runner die.

Eliminating the subsequent processes is conducive to production automation.

The finished product is finished after the hot runner mold is formed. There is no need to trim the gate and recycle the cold runner. It is conducive to production automation. Many foreign manufacturers combine heat flow path with automation to greatly improve production efficiency.

CNC computer gongs thread milling method

CNC computer gong processing needs to be proficient in horizontal processing, and large gantry (moving beam, top beam) processing. Must have good fixture foundation and measurement technology level. The difficulty of fixture analysis is that it can only be qualitative and difficult to quantify. The operation also pays attention to the handle.

In the CNC computer gongs processing process, there is a method called thread milling method, which specifically refers to it? Thread milling is to use thread milling tool, machining center three axis linkage, namely x, Y axis arc interpolation, Z axis linear feed milling method.

Thread milling is mainly used for machining large hole thread and thread hole of difficult to machine material. It has the following characteristics:

(1) high speed, high efficiency and high precision. The material is generally cemented carbide material, and the cutting speed is fast. The manufacturing precision of cutting tool is high, so the precision of thread milling is high.

(2) milling tools are widely used. As long as the pitch is the same, whether it is * * thread or right-hand thread, one tool can be used, which is conducive to reducing the cost of the tool.

(3) milling is easy to chip removal and cooling. Compared with the tap, the cutting condition is better. It is especially suitable for the thread processing of difficult to machine materials such as aluminum, copper, stainless steel, etc., especially for the thread processing of large parts and components of valuable materials, which can ensure the quality of thread processing and the safety of the workpiece.

(4) because there is no tool front-end guide, it is suitable for machining blind holes with short thread bottom holes and holes without undercut groove

Computer gong processing parameters

The gear parameters of the front center are: modulus M = 4, number of teeth z = 9, addendum height coefficient ha = 1, addendum clearance coefficient C = 0.25, radial modification coefficient X = 0.4, number of teeth across k = 2, common normal line wn = 19.5 + 0.2 + 0.1 (mm). CAXA does not provide professional gear modeling command, and can model through function curve, but this method is cumbersome and more difficult to model with modification coefficient.

It is not easy to ensure the size of the curve groove at the lower end of the front of the part, and the two 90 ° gaps are not closed. It is necessary to do auxiliary line closure before programming.

There are two ellipses with different directions on the inner contour edge of the back, the inner and outer hexagonal petals formed by arc, and two arc curve islands on the upper and lower sides. These elements need to be rounded in the processing, so it is more convenient to choose a reasonable shape.

1、 Analysis of parts processing technology

When CAXA is used to manufacture engineering parts, there is no need to draw complete parts for reprocessing. Firstly, the downtime is long and the processing time is wasted. Secondly, when selecting local processing, the elements of parts will interfere, which makes it inconvenient to get the program path.

When machining plane contour elements, the software supports only drawing out the contour line of parts for rough and finish machining. Surface machining can be programmed by solid or surface machining. Surface must be used to realize local machining, and some finishing commands can only use curved surface to select machining.

The rough machining command can not only realize rough machining, but also be used as finishing command.

The finishing command can use the track translation to form multiple levels, and the connecting track becomes a whole rough machining command; the rough machining command can change a layer of machining track into a finishing command by setting the layer height.

The plane contour elements of “CAXA Manufacturing Engineer” can use plane area rough machining and contour line finishing to finish the rough and finish machining of parts, and can also use contour finishing to do rough machining. Surface roughing can use equal height rough machining, or two finishing commands of parameter line finishing and three-dimensional offset surface for rough and finish machining.

Due to the high dimensional accuracy in the drawing, it is decided to use rough machining, semi finishing and finishing to achieve dimensional accuracy. Semi finishing and finishing use the same cutting tool and cutting parameters, which can correct various geometric errors of the cutter and elastic deformation of parts, and ensure the size easily. It is also necessary to finish the important bottom surface.

The part is processed by FANUC CNC machining center. All tool paths are generated according to FANUC post format, and the transmission uses CAXA’s own communication function according to FANUC settings. The larger surface program is processed online. The later processing programming ends with tool path. For parts such as box, bracket and connecting rod, the plane should be machined first and then the hole should be processed. In this way, the hole can be processed by plane positioning, which ensures the accuracy of plane and hole orientation, and brings convenience to the processing of holes on the plane.

2、 Machining datum plane first

In the process of parts processing, the surface as the positioning reference should be processed first, so as to provide the precise reference for the subsequent processing as soon as possible. It is called “benchmark first”.

3、 Finishing

The finishing of the primary surface (such as grinding, honing, finishing grinding / rolling, etc.) should be carried out at the final stage of the process road. After processing, the surface finish should be above ra0.9um, and slight bumping will damage the appearance. In Japan, Germany and other countries, after finishing, it is necessary to use flannelette for maintenance. It is absolutely forbidden to touch the workpiece directly with hands or other objects to avoid polishing The appearance of the finishing process is damaged by the transfer and installation between processes.

4、 Distinguish processing stages

The appearance with high machining quality is divided into three stages: rough machining, semi finishing and finishing. The first is to ensure the quality of processing; it is conducive to the rational use of equipment; it is convenient to organize the heat treatment process; and it is convenient to find the defects of the blank.