2020 – Page 94 – CNC Machining & Turning, Milling, Metal parts

What should be paid attention to in CNC machining?

Nowadays, with the continuous improvement of science and technology, our industry needs to use a variety of processing, in the process of processing, we will inevitably have a variety of problems, or we need to comply with the problem, Dongguan CNC parts processing is one of them, so what should be paid attention to CNC parts processing?

1. Observe the operation regulations of machining center.

2. Before work, wear protective equipment and cuff as required. Scarf, gloves, tie and apron are not allowed. Women’s hair braid shall be tied in the hat.

3. Check whether the tool compensation, machine zero point, workpiece zero point, etc. are correct before starting the machine.

4. The relative position of each button shall meet the operation requirements. Carefully compile and input numerical control program.

5. Check the operation conditions of the protection, safety, signal, position, mechanical transmission part, electrical, hydraulic digital display and other systems on the equipment, and carry out cutting under all normal conditions.

6. Before the CNC parts are processed, the test run of the machine tool shall be carried out to check the operation conditions of the lubrication, mechanical, electrical, hydraulic, digital display and other systems, and the machining can be carried out under normal conditions.

7. After the machine tool enters the processing operation according to the program, the operator is not allowed to contact the moving workpiece, cutter and transmission part, and is not allowed to transfer or take tools and other items across the transmission part of the machine tool.

8. When adjusting the machine tool, clamping workpiece and cutter, and wiping the machine tool, stop the machine.

9. Tools or other articles shall not be placed on electrical appliances, operation cabinets and protective covers.

10. It is not allowed to remove iron chips directly by hand, and special tools shall be used for cleaning.

11. In case of abnormal condition and alarm signal, stop the vehicle and ask relevant personnel to check. CNC machining center.

12. It is not allowed to leave the work position when the machine tool is running. If you want to leave for some reason, put the workbench in the middle position, return the cutter bar, stop the machine, and cut off the power supply of the main machine.

What are the technical requirements in machining?

Machining is mainly precision machining, because precision machining can highlight the importance of machining products at work. Now machining is important for every project and technology. Now machining is getting better and better, and technology is also better. Now, there are more purchases of machining raw materials. With the development of society, we are With continuous development, many machining industries are expanding at a fast speed.

(1) Remove oxide skin from parts.

(2) There shall be no scratch, scratch and other defects on the machined surface of parts.

(3) The tolerance of undeclared shape shall meet the requirements of gb1184-80, and the allowable deviation of undeclared length dimension shall be ± 0.5mm.

(4) The tolerance zone of casting is symmetrical to the basic dimension configuration of rough casting.

(5) It is allowed to heat the assembled rolling bearing with engine oil, and the temperature of the oil shall not exceed 100 ℃.

(6) When assembling the hydraulic system, it is allowed to use sealing filler or sealant, but it shall be prevented from entering the system.

(7) The parts and components to be assembled can be assembled only after they have the certificate of inspection department.

(8) Parts must be cleaned and cleaned before assembly, without burr, flash, oxide skin, rust, chip, oil stain, colorant and dust, etc.

(9) Before assembly, the main fitting dimensions of parts and components, including interference fit dimensions and relevant accuracy, shall be rechecked.

(10) Parts shall not be knocked, bumped, scratched or rusted during assembly.

(11) When screws, bolts and nuts are tightened, it is strictly prohibited to strike or use improper screwdrivers and wrenches. After fastening, the screw slot, nut, screw and bolt head shall not be damaged.

(12) The fasteners with specified tightening torque shall be tightened with torque wrench according to the specified tightening torque.

(13) Excess adhesive shall be removed after bonding.

(14) The semicircle holes of the bearing outer ring, the open bearing seat and the bearing cover shall not be stuck; the semicircle holes of the bearing outer ring, the open bearing seat and the bearing cover shall be in good contact. During the color coating inspection, they shall be in uniform contact within the range of 120 ° symmetrical to the center line and 90 ° symmetrical to the center line.

(15) After the bearing outer ring is assembled, it shall be in even contact with the end face of the bearing cover at the locating end.

(16) After the rolling bearing is installed, it shall rotate flexibly and stably by hand.

(17) The joint surface of the upper and lower bearing shells shall be closely pasted and cannot be checked with a 0.05mm feeler gauge.

(18) When fixing the bearing bush with the locating pin, the reaming and pin distribution shall be conducted under the condition that the opening and closing surfaces and the end face of the bearing bush mouth and the end face are flush with the opening and closing surfaces of the relevant bearing holes and the end face package. The pin shall not be loose after driving.

(19) When the surface of the alloy bearing liner is yellow, it is not allowed to use it, and there is no phenomenon of nucleation within the specified contact angle. The area of nucleation outside the contact angle shall not be greater than 10% of the total area of the non-contact area.

(20) The reference end face of gear (worm gear) and the end face of shaft shoulder (or locating sleeve) shall fit, and the 0.05mm feeler gauge shall be used to check whether they can not enter. The perpendicularity of the gear reference end face and the axis shall be ensured.

General principles of precision parts processing

Today I would like to add the general principle of precision parts processing, that is, the general principle of precision parts processing process, which is mainly elaborated from the following four points:

1. Benchmark first

That is to say, the datum plane should be processed first. In the process of machining, the surface as the positioning datum should be processed first, so as to provide the precision datum for the subsequent processing as soon as possible.

2. Division of processing stages

The appearance with high machining quality request can be divided into three stages: rough machining, semi finish machining and finish machining. The main purpose is to ensure the processing quality; to facilitate the scientific application of equipment; to facilitate the arrangement of heat treatment process; and to facilitate the detection of blank defects.

3. Face before hole

For the box, bracket, connecting rod and other parts, the plane shall be machined before the hole is machined. In this way, the hole can be machined by plane positioning, ensuring the position accuracy of plane and hole, and bringing convenience to the machining of hole on plane.

4. Finishing

Finishing of main surfaces, such as grinding, honing, finishing, rolling, etc., shall be placed at the end of the process route. The general principle of drawing up the processing route of precision parts and the formulation of the processing procedure of precision parts can be roughly divided into two parts. First of all, it is to draw up the process route of parts processing, and then determine the process size of each process, used equipment and process equipment, cutting specifications, working hours quota, etc.

Processing requirements for precision parts

Mechanical parts processing industry is the pillar industry of the national economy, with a very considerable prospect. In the processing of precision mechanical parts, the processing factory will have many requirements and regulations on the processing technology to ensure the qualified rate of the parts. So do you know the requirements of precision machining technology? Let’s take a look at it!

1. Parts shall be free of oxide skin, scratches, scratches and other defects that may damage the surface of parts, and burr and flash shall be removed;

2. After quenching and tempering, the parts are quenched at high frequency, tempered at 350-370 ℃, hrc40-45, carburized at a depth of 0.3mm, and aged at high temperature.

3. The tolerance of undeclared shape shall meet the requirements of gb1184-80, the allowable deviation of undeclared length dimension shall be ± 0.5mm, and the tolerance zone of casting shall be symmetrical to the basic dimension configuration of rough casting;

4. The radius of undeclared fillet R5, undeclared chamfer are 2 × 45 °, sharp angle is blunt;

5. The temperature shall not exceed 100 ℃, after the gear is assembled, the contact spot and side clearance of the gear surface shall meet the provisions of GB10095 and gb11365;

6. When assembling the hydraulic system, it is allowed to use sealing filler or sealant, but it shall be prevented from entering into the system. The parts and components (including purchased parts and outsourced parts) that enter into the assembly must have the qualification certificate of the inspection department before assembling.

How to inspect precision machining parts?

Precision machine parts require precision. In the actual production process, we must reach the relevant standards for precision and try to improve it. At present, how to improve the precision of precision mechanical parts has become a key issue for related enterprises. The problems of deburring and polishing in the process of machining will directly affect the accuracy of parts, and it is also a difficult problem to solve in the current production automation. What I want to explain to you today is how to inspect precision machining parts?

One、 Basic requirements for inspectors:

1. To have professional knowledge and practical work experience, but also need to meet the requirements of the first product inspection work.

2. The measuring instruments used shall be verified by the measuring department and within the specified verification period.

3. Before product acceptance, it is necessary to be familiar with relevant drawings and technical documents, and understand the key dimensions of parts and key points of assembly.

4. The parts shall be determined in strict accordance with the requirements of drawings and technical documents.

5. Mark the products in process in the workshop according to the regulations.

Two、 Inspection system:

1. First inspection system: for the first part processed by each operator, it is necessary to conduct all-round inspection and keep it.

2. Inspection system: ensure that key parts will be able to obtain the whole process of controlled state.

3. Sequence transfer inspection system: for parts to be transferred to the next process, inspection shall be carried out to avoid unqualified products flowing into the next process.

4. Completion inspection system: the completion inspection shall be carried out for the products to be warehoused after the completion of production, including size and shape, whether there is missing processing procedure, etc.

Knowledge of CNC turning and milling machining

Composite machining is one of the processing technologies in the field of machining. It is an advanced manufacturing technology. Compound machining is to realize several different machining processes on one machine tool. Compound machining is the most widely used and most difficult, which is turning milling compound machining. Turning milling compound machining center is equivalent to the compound of a CNC lathe and a machining center.

brief introduction

Turning and milling compound machine tool is the fastest developing and most widely used numerical control equipment in compound machine tool. Machine tool compounding is one of the important directions of machine tool development. The compound machine tool also includes turning milling compound, turning milling compound, milling compound, cutting and 3D printing compound, cutting and ultrasonic vibration compound, laser and stamping compound and other various forms. The compound purpose is to make a machine tool have multi-function, can complete multi tasks at a time, improve processing efficiency and processing accuracy

advantage

Compared with the conventional NC machining process, the outstanding advantages of composite machining are mainly shown in the following aspects.

(1) Shorten product manufacturing process chain and improve production efficiency. Turning milling compound machining can complete all or most of the processing procedures by one-time loading, thus greatly shortening the product manufacturing process chain. On the one hand, it can reduce the auxiliary production time caused by the change of fixture, and reduce the manufacturing cycle and waiting time of fixture, which can significantly improve the production efficiency.

(3) Reduce floor space and production cost. Although the price of a single turning milling complex processing equipment is relatively high, due to the shortening of manufacturing process chain and the reduction of equipment required for products, as well as the reduction of the number of tooling and fixtures, the floor area of workshop and equipment maintenance costs, it can effectively reduce the investment, production operation and management costs of the overall fixed assets.

Characteristic

1. The turning milling compound machining center uses high-precision internal spindle;

2. The free mobile operation panel improves the working efficiency;

3. The machine is mainly used for mass production of various small parts and complex parts with high-speed processing and diversified processing;

4. In particular, the long and thin complex process can be processed and formed at one time, and the automatic feeding device can be configured to improve the efficiency;

5. Material details: cutting, copper, iron, aluminum alloy, stainless steel, Teflon and other materials.

Development status

Most of the turning and milling complex machining is completed in the turning center, while the general turning center only changes the ordinary turret tool rest of the CNC lathe into the turret tool rest with the power tool, and the spindle adds the c-axis function. Due to the limitation of turret structure and dimension, the power of the power head is small, the rotating speed is not high, and the larger tool can not be installed. This kind of turning center is mainly for turning, milling and drilling functions are only for some auxiliary processing. Because of the high cost of power tool holder, the cost of turning center remains high. The price of domestic tool holder is generally more than 100000 yuan, and that of imported tool holder is more than 200000 yuan, which can not be afforded by general users. Most of the economical turn milling composites are XZC axis, that is, a rotating C axis is added to the chuck to realize the basic milling function.

There are many kinds of equipment in the market, such as WFL, DMG, Dalian machine tool, Taiwan Taiyu precision machine, Doosan (Doosan machine tool), all of which have high-end equipment; the well-known software of the market is Edgecam, UG NX, etc.

Machining of CNC turning and milling composite parts

In order to improve the machining efficiency and accuracy of complex special-shaped products, technologists have been seeking for efficient and precise machining methods. The appearance of turn milling compound machining equipment provides an effective solution for improving the machining accuracy and efficiency of aerospace parts.

Machining efficiency and precision is the eternal goal in the field of metal processing. With the continuous development of numerical control technology, computer technology, machine tool technology and processing technology, the traditional processing concept can not meet the requirements of processing speed, efficiency and accuracy. In this context, composite machining technology came into being. Generally speaking, composite processing refers to the general term of processing technology that can complete different processes or different process methods on a single processing equipment. There are two different types of compound processing technology, one is the combination of different processing methods based on energy or motion mode; the other is the combination based on the principle of process concentration and mechanical processing technology. Turning milling compound processing is one of the processing methods that have developed rapidly in recent years.

Aviation product parts are characterized by many varieties, small batch, complex process, and widely used as a whole thin-walled structure and difficult to process materials. Therefore, there are many bottlenecks in the manufacturing process, such as long manufacturing cycle, large amount of material removal, low processing efficiency and serious processing deformation. In order to improve the machining efficiency and accuracy of aviation complex products, technologists have been seeking more efficient and precise machining methods. The appearance of turn milling compound machining equipment provides an effective solution for improving the machining accuracy and efficiency of aviation parts.

Meaning

Turning and milling is an advanced cutting method which uses the combined movement of milling cutter rotation and workpiece rotation to realize the cutting of workpiece and make the workpiece meet the requirements in many aspects such as shape accuracy, position accuracy, machined surface integrity, etc. Turning milling compound machining is not only a combination of turning and milling methods into a machine tool, but also a new cutting theory and technology under the condition of great development of CNC technology.

advantage

Compared with the conventional NC machining process, the outstanding advantages of turning milling composite machining mainly lie in the following aspects:

(1) Shorten product manufacturing process chain and improve production efficiency. A variety of special cutters can be installed, new cutter arrangement can reduce tool change time, improve processing efficiency, turn milling compound processing can achieve one-time clamping to complete all or most of the processing procedures, thus greatly shortening the product manufacturing process chain. On the one hand, it can reduce the auxiliary production time caused by the change of fixture, and reduce the manufacturing cycle and waiting time of fixture, which can significantly improve the production efficiency.

(2) Reduce clamping times and improve machining accuracy. The reduction of the loading times avoids the error accumulation caused by the transformation of the positioning datum. At the same time, most of the turning milling complex processing equipment has the function of on-line detection, which can realize the on-site detection and precision control of key data in the manufacturing process, so as to improve the processing accuracy of products; the high-strength integrated bed design improves the gravity processing power of difficult cutting materials; the machine is equipped with an automatic feeding device, which can realize the automatic feeding for continuous, basically realized Assembly line operation of single machine tool.

(3) Reduce floor space and production cost. Compact and beautiful appearance design improves the way of space utilization, Maintenance and repair are more convenient for customers to get great satisfaction; although the price of single turning milling compound processing equipment is relatively high, due to the shortening of manufacturing process chain and the reduction of equipment required for products, as well as the reduction of fixture quantity, workshop floor area and equipment maintenance cost, it can effectively reduce the investment, production operation and management cost of total fixed assets.

What is CNC boring?

What is CNC boring

What is CNC boring?

CNC boring refers to expanding or refining the original holes on the workpiece. The boring feature of CNC machining is to correct the eccentricity of the lower hole, to obtain the precise position of the hole, and to obtain high-precision roundness, cylindricity and surface finish. Therefore, boring is often used in the final process.

Compared with other machining, CNC boring is a kind of difficult machining. By adjusting only one blade (or blade holder), it processes micron sized holes like H7 and H6.

What are the characteristics of CNC boring?

1、 Tool rotation:

CNC machining is different from lathe machining. Due to tool rotation during machining in machining center, it is impossible to master the condition of tool tip in time during machining to adjust the feed amount, etc. It is also impossible to change the machining diameter just by adjusting the CNC button like the CNC lathe. This has become a big obstacle to automatic processing. Because the machining center does not have the function of automatic machining diameter adjustment (except for the one with U-axis function), the boring cutter is required to have the function of fine adjustment mechanism or automatic compensation, especially in the case of fine boring, it is sometimes adjusted at the micron level according to the tolerance requirements. In addition, the direction of chip flow out is constantly changing when boring in machining center, so the cooling of tool tip, workpiece and chip discharge are much more difficult than when machining in lathe. Especially when the vertical machining center is used for steel blind hole rough boring, the problem has not been solved up to now.

2、 Spring knife:

Spring knife is a common and headache problem in boring. The main reasons for the spring knife in the machining center are as follows:

1. Rigidity of tool system: including the rigidity of tool handle, boring bar, boring head and intermediate connecting part. Because it is cantilever machining, especially the machining of small holes, deep holes and hard workpieces, the rigidity of the tool is particularly important.

2. Dynamic balance of tool system: relative to the rotating axis of tool system, if the tool itself has an unbalanced mass, it will cause chatter due to the effect of unbalanced centrifugal force during rotation. Especially in high-speed machining, the dynamic balance of tools has a great influence.

3. Fixed rigidity of workpiece itself or workpiece: for example, some smaller and thinner parts cannot be fully fixed with reasonable jigs due to insufficient rigidity or workpiece shape.

4. Blade tip shape: the cutting resistance is also different due to the different front angle, escape angle, tip radius and chip breaking groove shape of the blade.

Teach you six steps to be proficient in CNC machining

In order to be a master in any industry, you must be able to stand the experience of time and improve your working ability. In the CNC processing industry, it will take at least 6 years to become a master in numerical control (metal cutting) since you graduate from university and enter the factory. He needs not only the theoretical level of engineers, but also the practical experience and hands-on ability of technicians. Kaicheng Precision Hardware Co., Ltd. will share with you: it is not difficult to learn CNC machining well. Dongguan Kaicheng Precision Hardware Co., Ltd. will teach you six steps to play with CNC machine programming!

Step 1: it must be an excellent craftsman without the support and trust of employees. It is impossible to become an excellent craftsman.

Step 2: proficient in NC programming and application of computer software.

Step 3: be proficient in CNC machine tools. It takes 1-2 years of study. The operation pays attention to hand feeling. Beginners, especially college students, understand how to do it in their hearts, but they just don’t listen to the instructions. In this process, we need to learn: the operation mode of the system, the installation of the fixture, the alignment of the part benchmark, the tool alignment, the setting of zero offset, the setting of the tool length compensation, the radius compensation, the loading and unloading of the tool and the tool handle, the cutting edge grinding of the tool, the measurement of the part (can skillfully use the vernier caliper, the micrometer card, the dial indicator, the dial indicator, the inner diameter lever gauge, etc.). Can reflect the level of operation is: horizontal processing, and large gantry (moving beam, top beam) processing. Operation practice needs savvy! Sometimes there is a kind of mood of “leisurely mind, wonderful place is difficult to say with you”. In the numerical control workshop, you can calm down and practice well! Generally speaking, the process of Kaicheng precision hardware from the processing of the first part to the processing accuracy is required to be completed by the numerical control programmer himself. You can’t operate the machine skillfully. This level can’t be passed.

Step four: have a good foundation of fixture and measurement technology. The difficulty of fixture analysis lies in the fact that it is only qualitative and difficult to quantify. If you have no experience in fixture design and parts clamping, it will be more difficult. In this respect, it is recommended to consult the precision coordinate boring machine and Kaicheng precision hardware technicians. When measuring the level accurately, one of the basic skills in machining is to be able to skillfully use vernier caliper, micrometer card, dial indicator, dial indicator, inner diameter lever gauge, caliper, etc. Sometimes when machining parts, CMM can’t be expected.

Step 5: be familiar with CNC machine tools. Proficient in the maintenance of CNC machine tools.

Step 6: CNC machining should cultivate good habits and adapt to the characteristics of CNC machining.

What problems should be considered in CNC machining to control dimensions?

What problems should be considered in CNC machining to control dimensions

In CNC machining, if we want to keep the dimension stable when machining aluminum parts, we need to consider the following two factors:

1、 Force Majeure:

1. Stability of machine tool itself.

If the machine tool is not brand-new or the machine tool has too many CNC machining and has not been debugged, the size deviation caused by the machine tool itself may occur. The deviation factors of machine tool itself are as follows:

Mechanical:

a. The servo motor and the lead screw are loose.

b. The ball screw bearing or nut is worn.

c. Insufficient lubrication between screw and nut.

Electrical:

a. Servo motor failure.

b. There is dirt inside the grating ruler.

c. Servo amplifier failure.

2. Thermal expansion and cold contraction deformation of workpiece.

The deformation of the workpiece after heat expansion and cold shrinkage is inevitable, so we should pay attention to the cooling effect, increase the frequency of in-process measurement, and pay attention to the deformation of the workpiece after cooling.

2、 Avoidable factors:

CNC processing technology

In order to control the machining error, it is necessary to have a reasonable machining process. In the process layout, in addition to the basic machining process (such as milling the basic machining process (such as “first rough and then fine, first face and then hole, first big face and then small face” or the basic machining process details such as “reduce the number of clamping, use the combined clamp as much as possible”) in the use of the fixture, it is also necessary to minimize the number of machining process details We all know that the aluminum parts are very soft due to the processing error caused by the aluminum scraps, and the waste scraps removed can easily cause the processing error of the aluminum parts.

2. Three cutting elements: cutting speed VC, feed F, cutting depth AP and tool compensation

In this respect, simply speaking, on the premise of ensuring the tool wear and machining quality, adjust the cutting parameters so that the cutting performance of the tool can be brought into full play, so as to achieve the highest cutting efficiency and the lowest machining cost.

In the numerical control lathe, there are other factors to be considered, such as cutter head wear compensation.

3. Numerical calculation of manual programming

In the manual programming, it is very common that there are errors in the calculation process. Although it is almost automatic programming now, we should pay more attention to it if we encounter the situation of manual programming.

4. Accurate knife setting.

If the tool setting is not accurate, it will also cause dimensional errors. Therefore, it is necessary to choose a better edge finder. If conditions permit, the machine tool should be equipped with a laser tool setting instrument to ensure the accuracy of the tool setting. If there is no edge finder and no condition, only a simple trial cutting method can be used!

The above is a summary of CNC machining, easy to make the accuracy error of several factors.

Yearly Archive March 18, 2020

What should be paid attention to in CNC machining?

What are the technical requirements in machining?

General principles of precision parts processing

1. Benchmark first

2. Division of processing stages

3. Face before hole

4. Finishing

Processing requirements for precision parts

How to inspect precision machining parts?

Knowledge of CNC turning and milling machining

Machining of CNC turning and milling composite parts

What is CNC boring?

What is CNC boring?

What are the characteristics of CNC boring?

1、 Tool rotation:

2、 Spring knife:

Teach you six steps to be proficient in CNC machining

Step 1: it must be an excellent craftsman without the support and trust of employees. It is impossible to become an excellent craftsman.

Step 2: proficient in NC programming and application of computer software.

Step 5: be familiar with CNC machine tools. Proficient in the maintenance of CNC machine tools.

Step 6: CNC machining should cultivate good habits and adapt to the characteristics of CNC machining.

What problems should be considered in CNC machining to control dimensions?

CNC Machining parts

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