China Shenzhen Perfect Precision Product Co., Ltd. company news

(1) Trial cut method That is, first try to cut a small part of the machined surface, measure the size obtained by the test cutting, properly adjust the position of the cutting edge of the tool relative to the workpiece according to the processing requirements, try to cut again, and then measure. After two or three times of test cutting and measurement, when the machined size meets the requirements, cut the entire surface to be machined. The trial cutting method is repeated until the required dimensional accuracy is reached through "trial cutting - measurement - adjustment - trial cutting". For example, the trial boring of the box hole system. The precision achieved by the trial cutting method may be very high, and it does not require complex devices. However, this method is time-consuming (it requires multiple adjustments, trial cutting, measurement and calculation), inefficient, depends on the technical level of workers and the accuracy of measuring instruments, and the quality is unstable, so it is only used for single piece small batch production. As a type of trial cutting method - matching, it is a method of processing another matching workpiece or combining two (or more) workpieces for processing based on the processed workpiece. The final size to be machined during matching is subject to the matching requirements with the machined parts. (2) Adjustment method Accurately adjust the relative positions of the machine tool, fixture, cutter and workpiece with samples or standard parts in advance to ensure the dimensional accuracy of the workpiece. Because the size is adjusted in place in advance, it is unnecessary to cut again during processing. The size is automatically obtained and remains unchanged during the processing of a batch of parts. This is the adjustment method. For example, when using a milling fixture, the position of the tool is determined by the tool setting block. The essence of the adjustment method is to use the fixed distance device or tool setting device on the machine tool or the preset tool holder to make the tool reach a certain position accuracy relative to the machine tool or fixture, and then process a batch of workpieces. It is also a kind of adjustment method to feed and cut according to the dial on the machine tool. This method needs to determine the scale on the dial according to the trial cutting method. In mass production, tool setting devices such as fixed distance stop, sample piece and sample plate are often used for adjustment. The adjustment method is more stable than the trial cutting method in processing accuracy, has higher productivity, and has lower requirements for machine tool operators, but has higher requirements for machine tool adjusters, which is commonly used for mass production and mass production. (3) Sizing method The method of using the corresponding size of the cutter to ensure the size of the part to be processed is called sizing method. It is processed with standard size tools, and the size of the machined surface is determined by the tool size. In other words, tools with certain dimensional accuracy (such as reamers, reamers, drills, etc.) are used to ensure the accuracy of the parts (such as holes) to be processed. The sizing method is easy to operate, with high productivity, stable processing accuracy, almost independent of the technical level of workers, and high productivity. It is widely used in various types of production. Such as drilling, reaming, etc. (4) Active measurement In the process of processing, measure the processing size while processing, and compare the measured results with the size required by the design, or make the machine tool continue to work, or make the machine tool stop working, this is the active measurement method. At present, the values in the active measurement can be displayed digitally. The active measurement method adds the measuring device to the process system (i.e. the unity of machine tool, tool, fixture and workpiece), and becomes the fifth factor. Active measurement is a development direction with stable quality and high productivity. (5) Automatic control method This method is composed of measuring device, feeding device and control system. It is an automatic processing system composed of measuring device, feeding device and control system, and the processing process is automatically completed by the system. A series of work such as dimension measurement, tool compensation adjustment, cutting and machine tool stop are automatically completed, and the required dimension accuracy is automatically achieved. For example, when machining on a CNC machine tool, parts control the machining sequence and accuracy through various instructions of the program. There are two specific methods of automatic control: ① Automatic measurement means that the machine tool is equipped with a device to automatically measure the size of the workpiece. When the workpiece reaches the required size, the measuring device will send a command to make the machine tool automatically retract and stop working. ② Digital control means that there are servo motors, rolling lead screw nut pairs and a complete set of digital control devices in the machine tool to control the precise movement of the tool rest or workbench. The acquisition of dimensions (the movement of the tool rest or the movement of the workbench) is automatically controlled by the computer digital control device through the pre prepared program. The initial automatic control method is completed by using active measurement and mechanical or hydraulic control systems. At present, it has widely adopted the program pre arranged according to the processing requirements, the program control machine tool that the control system sends instructions to work, or the digital control machine tool that the control system sends digital information instructions to work, and the adaptive control machine tool that can adapt to the changes of processing conditions in the processing process, automatically adjust the processing amount, and optimize the processing process according to the specified conditions to automatically control the processing. The automatic control method has stable quality, high productivity, good processing flexibility, and can adapt to multi variety production. It is the development direction of mechanical manufacturing and the basis of computer aided manufacturing (CAM).

(1) Trial cut method That is, first try to cut a small part of the machined surface, measure the size obtained by the test cutting, properly adjust the position of the cutting edge of the tool relative to the workpiece according to the processing requirements, try to cut again, and then measure. After two or three times of test cutting and measurement, when the machined size meets the requirements, cut the entire surface to be machined. The trial cutting method is repeated until the required dimensional accuracy is reached through "trial cutting - measurement - adjustment - trial cutting". For example, the trial boring of the box hole system. The precision achieved by the trial cutting method may be very high, and it does not require complex devices. However, this method is time-consuming (it requires multiple adjustments, trial cutting, measurement and calculation), inefficient, depends on the technical level of workers and the accuracy of measuring instruments, and the quality is unstable, so it is only used for single piece small batch production. As a type of trial cutting method - matching, it is a method of processing another matching workpiece or combining two (or more) workpieces for processing based on the processed workpiece. The final size to be machined during matching is subject to the matching requirements with the machined parts. (2) Adjustment method Accurately adjust the relative positions of the machine tool, fixture, cutter and workpiece with samples or standard parts in advance to ensure the dimensional accuracy of the workpiece. Because the size is adjusted in place in advance, it is unnecessary to cut again during processing. The size is automatically obtained and remains unchanged during the processing of a batch of parts. This is the adjustment method. For example, when using a milling fixture, the position of the tool is determined by the tool setting block. The essence of the adjustment method is to use the fixed distance device or tool setting device on the machine tool or the preset tool holder to make the tool reach a certain position accuracy relative to the machine tool or fixture, and then process a batch of workpieces. It is also a kind of adjustment method to feed and cut according to the dial on the machine tool. This method needs to determine the scale on the dial according to the trial cutting method. In mass production, tool setting devices such as fixed distance stop, sample piece and sample plate are often used for adjustment. The adjustment method is more stable than the trial cutting method in processing accuracy, has higher productivity, and has lower requirements for machine tool operators, but has higher requirements for machine tool adjusters, which is commonly used for mass production and mass production. (3) Sizing method The method of using the corresponding size of the cutter to ensure the size of the part to be processed is called sizing method. It is processed with standard size tools, and the size of the machined surface is determined by the tool size. In other words, tools with certain dimensional accuracy (such as reamers, reamers, drills, etc.) are used to ensure the accuracy of the parts (such as holes) to be processed. The sizing method is easy to operate, with high productivity, stable processing accuracy, almost independent of the technical level of workers, and high productivity. It is widely used in various types of production. Such as drilling, reaming, etc. (4) Active measurement In the process of processing, measure the processing size while processing, and compare the measured results with the size required by the design, or make the machine tool continue to work, or make the machine tool stop working, this is the active measurement method. At present, the values in the active measurement can be displayed digitally. The active measurement method adds the measuring device to the process system (i.e. the unity of machine tool, tool, fixture and workpiece), and becomes the fifth factor. Active measurement is a development direction with stable quality and high productivity. (5) Automatic control method This method is composed of measuring device, feeding device and control system. It is an automatic processing system composed of measuring device, feeding device and control system, and the processing process is automatically completed by the system. A series of work such as dimension measurement, tool compensation adjustment, cutting and machine tool stop are automatically completed, and the required dimension accuracy is automatically achieved. For example, when machining on a CNC machine tool, parts control the machining sequence and accuracy through various instructions of the program. There are two specific methods of automatic control: ① Automatic measurement means that the machine tool is equipped with a device to automatically measure the size of the workpiece. When the workpiece reaches the required size, the measuring device will send a command to make the machine tool automatically retract and stop working. ② Digital control means that there are servo motors, rolling lead screw nut pairs and a complete set of digital control devices in the machine tool to control the precise movement of the tool rest or workbench. The acquisition of dimensions (the movement of the tool rest or the movement of the workbench) is automatically controlled by the computer digital control device through the pre prepared program. The initial automatic control method is completed by using active measurement and mechanical or hydraulic control systems. At present, it has widely adopted the program pre arranged according to the processing requirements, the program control machine tool that the control system sends instructions to work, or the digital control machine tool that the control system sends digital information instructions to work, and the adaptive control machine tool that can adapt to the changes of processing conditions in the processing process, automatically adjust the processing amount, and optimize the processing process according to the specified conditions to automatically control the processing. The automatic control method has stable quality, high productivity, good processing flexibility, and can adapt to multi variety production. It is the development direction of mechanical manufacturing and the basis of computer aided manufacturing (CAM).

CNC machining has become a pillar of manufacturing industry. More and more machine shops use this form of processing in their operations. Although many machinists have been used to this form of processing, not everyone knows the logic behind it. Compared with other forms of machining, the main advantages of using CNC machining are as follows: 1. More automatic than conventional As the name implies, CNC stands for computer numerical control - this form of processing relies heavily on computer control. This means a higher level of automation, which is the best solution for high-precision work. Compared with traditional production methods, the main differences and advantages of using CNC machining are that more processing processes are automated, reducing the occurrence of human errors, and meeting people's demand for higher accuracy. The main function of machining is to create something else from a piece of plastic or metal. Although traditional CNC processing can achieve these goals, the automation used in CNC processing makes the processing efficiency higher, the speed faster, the production speed higher, and the error space less, which reduces the cost of many enterprises. 2. Different types of CNC machining Modern CNC machine tools are suitable for various cutting methods. CNC turning makes it possible to manufacture complex external and internal geometric shapes. For example, CNC turning and CNC milling. In the process of CNC turning, raw materials are processed with the development of processing, making it possible to manufacture "complex external and internal geometric figures, including the generation of various threads". CNC milling is better for manufacturing holes, slots, and repetitive motions to create complex 3D shapes. Milling is versatile, easy to set up repeated movements, commonly used to manufacture plastic injection molding molds. 3. Meet all your needs There is no tool in this industry that can handle all the manufacturing needs, but CNC is the closest. It can create curves and angles where they once were flat and smooth. It can add slots and threads to create locking mechanisms. It can be stamped and engraved, cut and drilled, and added textures and contours. Since it is run by a computer program, you can customize it to do almost anything you can imagine. The computer programming process uses computer aided design (CAD) to create a model of the final product. With the progress of the process, this is a rough draft. It can also identify any problems in the design. The prototype is then photographed, which creates a copy and inputs it into the machine. 4. Safety Although operators play an important role in CNC machining, they do not operate on the machine by hand, but operate on the computer. This creates a safer working environment for all and reduces workplace accidents. This is particularly important, because the repetitive manual work in the past was undertaken by workers. CNC machining ensures that the products produced are consistent to meet the quality control criteria. Human operation errors and insufficient sleep are a common hidden danger, which will lead to accidents. It is unnecessary to worry about using CNC machining. 5. Convenient and fast Because the CNC machining process is efficient and computer oriented, it is easy to mass produce. You only need to have multiple machines running on the same program. For many enterprises, it is a challenge to expand the scale while maintaining a good profit margin. CNC machining has the function of storage, so you don't have to worry about reloading the program every time, and you don't have to re-enter the command every time you produce products. Numerically controlled machining has many advantages that make it the best choice for manufacturers.

In order to improve the finishing quality of annular thin parts, according to the relationship between the rigidity of the lathe processing system, clamping force, machining error mapping and the workpiece to be machined, a finishing process scheme for annular thin parts is proposed. In this scheme, the locating point of the clamping is set on the axial direction of the annular thin part, so that the workpiece will not have radial deformation due to clamping; The specially made process equipment is used to avoid the radial external force load on the machined parts, and the annular thin parts with the ratio of the outer diameter to the annular wall thickness of more than 40 are processed to the required size, while ensuring the coaxiality and surface roughness of the workpiece. The qualified rate of a batch of workpieces processed according to the special tooling scheme is 95%. Typical disk parts are widely used in machine manufacturing, and are one of the main hardware accessories. Typical disc parts have the functions of torque transmission, component movement, transmission component support, etc. At the same time, they can also process various basic mechanical equipment in the application process, and the quality of parts processing has a great impact on the operation performance of mechanical manufacturing equipment. Therefore, according to the processing technology requirements of typical disc parts, combined with specific processing drawings, the mechanical manufacturing processing technology should be analyzed.

The surface quality of mechanical parts plays a very important role in the overall quality of parts, and the surface waviness is also one of the important factors affecting the surface quality of parts. The influence of surface waviness on the performance of mechanical parts is similar to that of surface roughness, but also has its own characteristics, especially for some products. Then, what are the effects of surface waviness on the surface roughness of parts? First, we need to know how the ripples are produced. Let's take a look at the analysis of the accelerated screening: 1. Causes of surface ripples According to the rapid screening analysis, there are two main reasons for waviness in cutting: one is the simple reproduction of tool vibration marks on the workpiece surface; The other is that cutting vibration and waviness are causal. 2. Influence of surface waviness on surface roughness of parts (1) Rolling bearing The vibration of bearing during operation is the main factor causing surface waviness. The shape error mainly reflects the low-frequency component of the part surface, and the influence of these low-frequency components on the bearing vibration is much smaller than the high-frequency component. The waviness of the ball will also cause the vibration value of the steel ball to rise, resulting in greater overall vibration and noise of the rolling bearing. The greater the vibration and noise of rolling bearings, the higher the surface waviness of mechanical parts. The waviness has a great impact on the performance of rolling bearings. Therefore, controlling the surface waviness of bearing raceways and rolling elements within a certain range plays a very important role in improving the machining accuracy of rolling bearings and extending the service life of bearings. (2) Mechanical contact seals With the increase of surface waviness, the fluid film will bear more load, and at the same time, the leakage will increase. From the view of seal design and use requirements, for a working condition, the ripple amplitude should be kept at the optimal value. (3) Optical medium surface The influence of surface waviness on light scattering from optical media surface cannot be ignored. When the surface roughness of the optical medium is very high and has reached the nanometer level, if the reflectivity does not improve significantly, the main reason is due to the influence of waviness. 3. How to improve the cutting waviness (1) Reduce or eliminate the vibration of the process system: the vibration of the process system is the main cause of waviness, so try to reduce or eliminate the vibration. (2) Change the cutting amount: In grinding, the waviness can be reduced by increasing the wheel speed without affecting the vibration of the process system. (3) Correctly select the grinding wheel and improve the hardness of the workpiece: the type of grinding wheel abrasive has an impact on the grinding waviness. If the waviness does not meet the requirements, the grinding wheel of different brands can be replaced. (4) Trim the grinding wheel and use the cooling lubricant.

In CNC machining, the essence of tool "compensation" and "offset" is the same, but they are called differently. They can be regarded as two expressions of a problem, and we do not need to investigate their differences. The offset screen of FANUC 0i CNC system is called "offset", but it is often called "compensation" in practice. If you want to investigate too much, you can refer to the statement in the FANUC official manual, that is, the tool position movement is called "offset", and the tool radius deviation correction is called "compensation". This article will specifically introduce the application skills of tool compensation in CNC machining. In modern CNC system, tool offset is generally divided into two parts: profile offset and wear offset. Profile offset generally controls the tool installation deviation or shape deviation, which is large; The wear offset is mostly used for tool wear compensation and fine adjustment of machining size, and its value is small. The actual tool offset is equal to the algebraic sum of profile offset and wear offset. In addition, profile offset is often used to establish the workpiece coordinate system. The concept of offset vector is often used in offset trajectory analysis. The so-called offset vector is actually the composite vector of X and Z offset sub vectors (signed offset components) in offset memory. Programming application skills and taboos of tool compensation in CNC machining: (1) System parameter No 5002 # 1 (LGN) is used to set whether the profile offset number and wear offset number of the tool are the same. The default setting is the same (LGN=0). (2) System parameter No 5002 # 2 (LWT) is used to set whether tool wear compensation is realized by tool movement or coordinate system offset. The default setting is to compensate by tool movement (LWT=0). The compensation action must be realized in the tool linear movement program section. (3) System parameter No 5002 # 4 (LGT) is used to set whether the tool profile compensation is realized by tool movement or by coordinate system offset. The default setting is to use coordinate system offset for compensation (LGT=0). At this time, it has nothing to do with LWM setting, and it is compensated in the T command program section. The offset action is realized by moving the coordinate system. At this time, the tool generally does not move, only the coordinate value changes (that is, the coordinate system moves). (4) System parameter No 5002 # 5 (LGC) is used to set whether to cancel the tool profile compensation when 00 offset number is set. When LGC=0, it is not canceled (LGC=0). (5) System parameter No 5003 # 6 (LVC) is used to set whether to cancel the offset when pressing the Reset key. When LVC=0, it is not to cancel the offset. Share:

First, machining accuracy refers to the actual value of the relevant workpiece including size, geometry and mutual position of the surface parameters after machining, and its pre-designed ideal geometric parameters should have the degree of conformity; machining accuracy usually includes dimensional accuracy, shape accuracy and position accuracy, etc., dimensional accuracy is used to limit the dimensional error between the machined surface and its benchmark, shape accuracy is used to limit the macro geometric shape error of the machined surface, position accuracy is used to limit the parallelism, perpendicularity, coaxiality and other mutual position errors between the machined surface and its benchmark. The dimensional accuracy is used to limit the range of dimensional error between the processing surface and its reference, the shape accuracy is used to limit the macro geometric shape error of the processing surface, and the position accuracy is used to limit the parallelism, perpendicularity, coaxiality and other mutual position errors between the processing surface and its reference. Second, due to the performance of processing machinery, technical methods, production conditions and other factors of different influences, mechanical processing out of the relevant parts in its size, shape and surface mutual position parameters and ideal parameters always exist a certain deviation error, in the value of the size of the processing error is usually used to indicate the processing accuracy. Machining accuracy and surface quality of mechanical components and other processing quality, is to ensure that the relevant mechanical product assembly quality of the basis, the size of the machining error reflects the level of machining accuracy.   Third, although mechanical processing can not be zero error, but some of the errors in its processing can be completely avoided through technical reform and processing rigor and other methods. Especially now people's requirements for machining accuracy is getting higher and higher, how to improve the accuracy of machining has become an urgent problem to be solved.   Fourth, in order to reduce machining errors, the need to produce the error of each original error analysis, according to the different circumstances of the main original error caused by processing errors to take different measures. Construction drawings of multi-faceted consideration is the most basic. A good mechanical design product must have a very precise and multifaceted consideration of the consciousness in it. Minimize the original error. Fifth, do your best to improve the geometric accuracy of the machine tools, jigs and gauges used in processing mechanical products, and control the deformation caused by heat, cutting forces and internal stresses in the process system are means to reduce the original error. For those precision parts, in order to reduce the original error, every effort should be made to improve the rigidity and accuracy of precision machine tools. In addition, there are two most ingenious methods: transfer of the original error and error compensation method.   Six, transfer the original error, in essence, is to transfer the original error from the error-sensitive direction to the error non-sensitive direction to go. A variety of original error reflected in the degree of error on the parts processing and whether it is in the error-sensitive direction has a direct relationship. If in the process of processing can try to transfer the original error to the non-sensitive direction of the processing error, it can greatly improve the processing accuracy.   Seven, some of the original error of the process system, you can take the error compensation method to control its impact on the parts machining error; implementation of error compensation, is to artificially create a new original error, so as to compensate or offset the original process system inherent in the original error, in order to reduce the processing error, improve the processing accuracy.

We know that precision machining has high requirements for accuracy. Precision machining has good rigidity, high manufacturing accuracy and precise tool setting, so it can process parts with high accuracy requirements. So what are the parts suitable for precision machining? The following is introduced by the editor to introduce you. First of all, compared with ordinary lathe, CNC lathe has constant linear speed cutting function, no matter for turning end face or different diameter outer circle can be processed with the same linear speed, that is to ensure the surface roughness value is consistent and relatively small. While ordinary lathe is constant speed, the cutting speed is different for different diameters. Under the condition that the material of workpiece and tool, finishing allowance and tool angle are certain, the surface roughness depends on the cutting speed and feed speed.   When processing the surface with different surface roughness, a small feed speed is chosen for the surface with small roughness, and a larger feed speed is chosen for the surface with large roughness, with good variability, which is difficult to be achieved in ordinary lathes. Parts with complex contour shapes. Any plane curve can be approximated by a straight line or arc, cnc precision machining with arc interpolation function, can process a variety of complex contours of the parts. cnc precision machining needs the careful use of the operator's good or bad. CNC precision machining mainly has fine turning, fine boring, fine milling, fine grinding and grinding processes.   (1) fine turning and fine boring: most of the precision light alloy (aluminum or magnesium alloy, etc.) parts of the aircraft are mostly processed by this method. Generally with natural single crystal diamond tool, the radius of the cutting edge circle is less than 0.1 micron. In high-precision lathe processing can obtain 1 micron accuracy and average height difference of less than 0.2 micron surface unevenness, coordinate accuracy can reach ± 2 micron.   (2) Fine milling: It is used to process aluminum or beryllium alloy structural parts with complex shapes. Rely on the accuracy of the machine's guide and spindle to obtain high mutual position accuracy. High-speed milling with carefully ground diamond tips can obtain accurate mirror surfaces.   (3) Fine grinding: used for machining shaft or hole type parts. Most of these parts are made of hardened steel, which has high hardness. Most high-precision grinding machine spindles use hydrostatic or dynamic pressure liquid bearings to ensure high stability. The ultimate accuracy of grinding is influenced by the machine tool spindle and bed stiffness, but also by factors such as the selection and balance of the grinding wheel and the machining accuracy of the center hole of the workpiece. Fine grinding can obtain a dimensional accuracy of 1 micron and an out-of-roundness of 0.5 micron.   (4) Grinding: The principle of mutual grinding of mating parts is used to selectively process the irregular raised parts on the machined surface. The grinding grain diameter, cutting force and cutting heat can be precisely controlled, so it is the processing method to obtain the highest precision in precision machining technology. Hydraulic or pneumatic mating parts in precision servo parts of aircraft and bearing parts of dynamic gyro motors are machined by this method to achieve 0.1 or even 0.01 micron accuracy and 0.005 micron micro-unevenness.

Precision machining, not what materials can be precision machined, some materials are too hard, more than the hardness of the machined parts, it is possible to crash the machine, so these materials are not suitable for precision machining, unless it is a special material made of machine parts, or laser cutting. So what are the requirements of precision parts processing material? Here we come together to understand it. For precision machining materials are divided into two categories, metal materials and non-metallic materials.   For metal materials, the hardness of stainless steel is the largest, followed by cast iron, followed by copper, and finally aluminum.   The processing of ceramics, plastics and other non-metallic materials belong to the processing.   1, first of all, the requirements of the material hardness, for some occasions, the higher the hardness of the material is the better, just limited to the hardness requirements of the processing machine, the processing of the material can not be too hard, if harder than the machine is unable to process.   2, secondly, the material soft and hard moderate, at least one grade lower than the hardness of the machine, but also to see what the role of the processed device is to do with a reasonable selection of materials for machine parts. In short, precision machining of the material requirements or some, not what material is suitable for processing, such as too soft or too hard material, the former is not necessary for processing, and the latter is not processed.   Therefore, before processing must pay attention to the density of the material, if the density is too large, equivalent to the hardness is also very large, and if the hardness exceeds the hardness of the machine parts (lathe turning tool), it is impossible to process, not only will damage the parts, but also cause danger, such as turning tool flying out of the crash injury. Therefore, generally speaking, for mechanical processing, the material material should be lower than the hardness of the machine tool, so that it can be processed.

Precision machining industry has been labor-intensive, capital-intensive and technology-intensive industry, the industry threshold is high, the average enterprise even if established but not up to a certain scale, it is difficult to generate profits. Large-scale enterprises can reduce costs through large-scale procurement and production, through business coordination, build a regional sales market, covering different regions and different industries. Therefore, the precision machining industry has a large constant strong characteristics of the future of this industry aspects of the integration, regional integration, industry chain integration and strategic integration is mainly. Among them, regional integration is the same area of precision machining enterprises united together, so you can focus on the application of policy and management advantages, resulting in good synergy and cooperation effect. Industry chain integration is a single function of the machining industry united, or downstream manufacturing enterprises can work together with key component suppliers to solve the technical bottlenecks faced by complex components; strategic integration is the introduction of automotive, military and other strategic partners to more accurately grasp the downstream demand, the development of targeted products, and reduce unnecessary losses in the research and development process.   Precision parts processing process has extremely strict requirements, processing a slight inadvertence will lead to the workpiece error out of tolerance, the need to re-process, or declare the blank scrap, greatly increasing the cost of production. Therefore, today about precision parts processing what requirements, can help us improve production efficiency. First of all, the dimensional requirements, must strictly follow the drawing of the form tolerance requirements for processing. Although the enterprise processing production parts in practice and the size of the drawings will not be exactly the same, but the actual size in the tolerance range of theoretical dimensions, are qualified products, is able to use the parts. Secondly, the equipment requirements, rough and finish machining should be used for different performance of the equipment. As the roughing process is to cut most of the parts of the blank, the workpiece in the case of large feed, cutting depth will produce a large amount of internal stress, then it can no longer be finished. Workpiece in a certain period of time after the finishing process, should be in a higher precision machine tool work, so that the workpiece can reach a high degree of accuracy.   Again precision parts processing often have surface treatment and heat treatment process, surface treatment should be placed after precision machining. And in the process of precision machining, should be considered to leave a thin layer of thickness after surface treatment. Heat treatment is to improve the cutting properties of the metal, so need to be placed in the machine before processing. These are the requirements that need to be followed for precision parts processing.