Where does machining center have quality problem to complain

Publish: 2021-05-04 21:11:19

1. Consult your local bureau of quality and technical supervision. They should be in charge
by the way, 218000 yuan machining center is too cheap.

2. Fifteen common faults and solutions of machining center: 1. Hand wheel fault cause: 1. Poor contact of hand wheel shaft selection switch 2. Poor contact of the hand wheel multiple selection switch 3. The hand wheel is damaged 4. The connecting line of hand wheel is broken solution: 1. Enter the system to diagnose and observe the contact condition of the axle selector switch (the connecting wire is in good condition). If it is damaged, replace the switch 2. Enter the system to diagnose and observe the contact condition of the multiplier switch (the connecting wire is in good condition). If it is damaged, replace the switch 3. Remove the pulse disk and measure whether the power supply is normal, and whether the resistance between + and a, + and B is normal. Replace if damaged 4. Enter the system to diagnose and observe the corresponding contact conditions of each switch, and then measure whether the contact points of the connecting line between the axis selector switch, rate switch and pulse disk are on or off with the corresponding points of the terminal entering the system, and replace them if they are broken< Second, XYZ axis and spindle box failure causes: 1. YZ axis shield deformation and damage< The YZ shaft drive bearing is damaged 3. The clothing parameters do not match the mechanical characteristics 4. The connection between the clothing motor and the screw head is deformed, with different axes 5. The upper and lower guide rails of the hammer in the column are loose and deviated 6. The chain and guide wheel of column weight hammer are worn and vibrated 7. The shaft pulley is not parallel to the motor end pulley< The spindle belt is damaged and deformed< solutions: 1. The sheet metal of the protective cover is not damaged 2. Check the main bearing and negative positioning bearing of the shaft, judge the bearing at that end is damaged, and replace it 3. Adjust the servo parameters to match the machine Servo gain, resonance suppression, load inertia) 4. Recalibrate the connector or replace the connector< The guide rail should be calibrated and lubricated with grease 6. Check the wear of the chain and guide wheel, correct the balance of the weight, and lubricate with grease 7. Correct the parallelism between the two pulleys and the dynamic balance instrument 8. Detect the belt deformation, replace it seriously, clean the belt and adjust the belt tightness< The oil level of the guide oil pump is insufficient< The oil pressure valve of guide oil pump is damaged< The oil circuit of the machine tool is damaged 4. The filter screen of guide oil pump core is blocked 5. The quality of guide oil purchased by customers exceeds the standard 6. The oil pumping time of the guide oil pump is set incorrectly 7. The circuit breaker in the overload electric box of the cutting oil pump jumps off 8. There is air leakage at the cutting oil pump joint< The cutting oil pump check valve is damaged 10. The motor coil of cutting oil pump is short circuited 11. The cutting oil pump motor is in the opposite direction solution: 1. Inject guide oil 2. Check whether the oil pressure valve is under pressure, and replace it if it is damaged 3. Check whether the oil circuit of each axis of the machine tool is unobstructed, broken, and whether the oil drain is damaged. Replace if damaged 4. Clean the oil pump filter screen 5. Replace the qualified guide oil that meets the requirements of oil pump 6. Reset the correct oiling time 7. After checking whether the guide oil pump is in good condition, reset the short circuit again 8. Look for the connector at the air leakage and connect it again< Check whether the check valve is blocked or damaged, and replace it if damaged< Check the motor coil and replace the cutting oil pump motor 11. Correct the direction of the cutting oil pump motor< Four, processing fault causes: 1, XYZ axis reverse clearance compensation is not correct 2. The XYZ direction is loose< The XYZ bearing is damaged 4. Fuselage mechanical geometric accuracy deviation 5. Axial and radial movement of spindle< The servo parameters and machining parameters of the system are not adjusted properly 7. The client programming program is wrong 8. XYZ axis screw rod and screw nut are worn< Solution: 1. Correct the reverse clearance of dial indicator 2. Adjust the tightness of the main inlay of each axis, and adjust the load of the observation system to the best state 3. Check the bearing condition and replace it if it is damaged 4. The geometric accuracy of each item, such as deviation correction, can be detected by marble angle ruler and ball bar instrument 5. Repair the precision of spindle inner hole and the clearance of spindle bearing. If it cannot be repaired, replace it< Adjust servo position loop, speed loop gain, load inertia ratio, machining accuracy coefficient, acceleration and deceleration time constant 7. Optimize and adjust the programming process 8. Screw clearance compensation with laser interferometer< 5. cause of tool release fault: 1. The tool release solenoid valve is damaged< The spindle cutter cylinder is damaged< The spindle shrapnel is damaged< The main shaft claw is damaged 5. The customer's air supply is insufficient 6. Poor contact of release button< The circuit is broken 8. The oil cup of the cutter cylinder is short of oil 9. The handle of the customer does not meet the requirements< Solution: 1. Check the action of the solenoid valve, and replace it if it is damaged 2. Check the action of the cutter cylinder and replace it if it is damaged 3. Detect the damage degree of shrapnel and replace shrapnel 4. Check whether the main shaft claw is in good condition, damaged or worn, and replace it 5. Check the damage degree of the button and replace it 6. Check whether the circuit is broken 7 8. The installation meets the standard< 6. The machine can not return to zero< Causes: 1. The contact of the origin switch is stuck and cannot operate 2. The origin stop cannot press the origin switch to the switch action position 3. Water in the origin switch leads to poor contact of the switch contacts 4. The origin switch circuit is disconnected or the input signal source is faulty< The PLC input point is burnt out< Methods: 1. Clean up the stuck part to make the moving part move smoothly, or replace the travel switch 2. Adjust the installation position of the travel switch, so that the zero switch contact can be smoothly pressed to the switch action position by the stop 3. Replace the travel switch and take waterproof measures 4. Check the switch circuit for open circuit, short circuit and signal source (+ 24 V DC power supply) 5. Change the input point on the I / O board, set the parameters and modify the PLC program< 7. The positive and negative hard limit alarm of the machine tool normally, this alarm will not appear, and it may appear when the machine tool is operated before returning to zero. Because the system has no fixed mechanical coordinate system before returning to zero, and the soft limit is invalid, it must return to zero before operating the machine tool< Causes: 1. The contact of travel switch is pressed and stuck (over travel)< The travel switch is damaged 3. There is open circuit, short circuit and no signal source in the travel switch circuit 4. The limit stop cannot press the switch contact to the action position< The PLC input point is burnt out< Methods: 1. Manually or manually shake the hand wheel away from the safe position, or clean the switch contact< Replace the travel switch 3. Check the travel switch circuit for short circuit. If there is a short circuit, deal with it again. Check the signal source (+ 24 V DC power supply) 4. Adjust the installation position of the travel switch so that it can be normally pressed on the switch contact to the action position 5. Change the input point on the I / O board, set the parameters and modify the PLC program< 8. Tool change fault causes: 1. Insufficient air pressure 2. Poor contact of knife release button or open circuit 3. The PLC input address of the tool release button is burnt out or there is no signal source (+ 24 V) 4. The knife release relay does not operate< The tool release solenoid valve is damaged 6 7. The oil cup of the cutter cylinder is short of oil 8. Cutter cylinder failure< Methods: 1. Check the air pressure until it reaches 6kg plus or minus 1kg< Replace the switch or check the circuit 3. Replace the PLC input port on the I / O board or check the PLC input signal source to modify the PLC program 4. Check whether the PLC output signal is present or not, whether the PLC output port is burnt out, and modify the PLC program 5. If the solenoid valve coil is burnt out, replace it, if the solenoid valve body leaks air and the piston doesn't work, replace the valve body 6. Adjust the cutting amount until the tool is released smoothly 7. Add the hydraulic oil in the oil cup of the cutter cylinder 8. If the screw in the cutter cylinder is loose or leaking, the screw should be re tightened and the sealing ring in the cylinder should be replaced. If it cannot be repaired, the cutter cylinder should be replaced< The reason is that the bearing is faulty 2. The lead screw bus and guide rail are unbalanced 3. Serious wear of wear-resistant plate leads to serious scratch of guide rail< The servo motor gain is not matched< Methods: 1. Replace the bearing 2. Correct the screw rod bus 3. Stick the wear-resistant plate again, and deal with it again when the rail scratch is too serious< Adjust the servo gain parameters to match the mechanical gain< 10. Causes of lubrication failure: 1. The oil tank of lubrication pump is short of oil 2. The pumping time of lubricating pump is too short 3. The pressure relief mechanism of lubricating pump is too fast< There is oil leakage in the oil pipeline 5. The check valve in the oil circuit does not work< The oil pump motor is damaged< The control circuit board of lubricating pump is damaged< Methods: 1. Add lubricating oil to the upper limit line 2. Adjust the oiling time to 32 minutes and 16 seconds< If the pressure relief speed can be adjusted, it should be replaced if it cannot be adjusted 4. Check and handle the oil pipe and oil line interface 5. Replace the check valve 6. Replace the lubricating pump 7. Replace the control circuit board 8. In case of emergency, the machine tool can work temporarily after forcing m64s to 1a and E60 to 32 in I / F diagnosis< The program can't be transmitted, and alarms of P460, p461 and p462 appear. methods: 1. Check the transmission line for open circuit, solder joint and plug< The parameters of computer transmission software side should be consistent with those of machine tool side 3. Replace the computer and try transmission< Whether the grounding is stable or not 12. Problems of tool magazine causes: 1. It stops suddenly in the process of tool change and cannot continue tool change 2. The hat type tool magazine can't come out 3. Do not loosen the tool ring tool change< The cutterhead can not be rotated 5. When the cutter head suddenly reverses, it will rotate half a tool position 6. When the tool is changed, the tool loosening and tightening error alarms appear 7. When returning the tool in the process of changing, the sound on the spindle side is very loud 8. After changing, the spindle can't be loaded (tool loosening is abnormal)< Methods: 1. Whether the air pressure is enough (6kg) 2. Check whether the tool magazine backward signal is in place, whether the tool magazine in and out solenoid valve circuit and PLC output are in place 3. Adjust the amount of knife, and check whether there is water in the cylinder 4. When the cutterhead comes out and rotates backward, check whether the power line of the cutterhead motor is open, whether the contact and relay are damaged 5. The brake mechanism of the magazine motor is loose and cannot brake normally 6. Check the air pressure, whether the cylinder is fully activated (whether there is water), whether the knife release switch is pressed in place, but not too much (if there is just a signal input) 7. Adjust the cutting amount< Modify the tool change program (macro program o9999) XIII. The machine tool can not be powered on reasons: 1. The three-phase contact of the main power switch is poor or the switch is damaged 2. The operation panel cannot be powered on< Methods: 1. Replace the main power switch 2 A. whether the switching power supply has voltage output (+ 24 V) B. the power on switch of the system is not in good contact, and the power off switch is open C. the power on relay of the system has poor contact and cannot self lock D. the circuit is open E. when the drive is powered on AC contact, the system power on relay is faulty F. whether the circuit breaker trips, G. whether the system works normally, whether the preparation is completed, or whether the z-axis driver is damaged, and whether the automatic power on signal is output< Check whether the water pump is burnt out 2. Whether the phase sequence of power supply is reversed 3、

3. Now the global manufacturing enterprises have done a wide range of practice in the application of proction process quality control software, but there are still a number of domestic quality managers who are very unfamiliar with it. They question what role the proction process quality control software can play

in order to ensure that the proction process is under control, the analysis, diagnosis and monitoring of the operation technology and proction process that directly or indirectly affect the proct quality in the proction, installation and service process are called proction process control. So, what role can the proction process quality control software play< The SPC proction process quality control software is an effective method to improve the quality management level of enterprises, and it is an instry standard methodology to measure, control and improve the quality of manufacturing process. It uses statistical methods to monitor the state of the process and determine that the proction process is under control, so as to rece the variation of proct quality. It draws the quality parameters obtained in the real-time proction process in the form of procts or other forms on the charts with the control limits determined in advance, so as to help enterprises manage and analyze the proction process in real time< The SPC proction process quality control software is a scientific and data-based quality analysis and improvement tool. It uses the principle of mathematical statistics, through the collection and analysis of testing data, can achieve the effect of "prevention in advance", so as to effectively control the proction process and constantly improve the quality< The SPC proction process quality control software can scientifically distinguish the normal fluctuation and abnormal fluctuation in the proction process for the enterprise, find the abnormal situation in time, so as to take measures to eliminate the abnormality, restore the stability of the process, rece the quality cost and improve the proct quality. It emphasizes the prevention of the whole process. First, it will tell users the fluctuation of the proction process and whether users should adjust the proction process; Secondly, it can compare the fluctuation with the pre-set control rules to provide accurate direction for quality improvement; Finally, it can evaluate the quality improvement measures taken by users, so that the quality can be continuously improved

as an improvement tool of proction process quality control trusted and adopted by manufacturing instry all over the world, SPC proction process quality control software can help users reach 6 Sigma quality level. Stable quality can bring greater customer satisfaction, rece abnormal fluctuations can greatly rece waste and downtime losses, save a lot of time and money, high quality can greatly enhance the competitive advantage of enterprises

if you want to know more information, please log on to the official website of soyingfei. You can learn more about various kinds of information about proction quality management.

4. Expose the program and let everyone see the program to help you find out the problem.

5. These problems reflect the non professional of equipment manufacturers as a whole
problem 1: there is a little noise in the rotation and speed increase of the spindle, which may be caused by the progress of the transmission part (belt type and gear type), bearing and machine head
questions 2 and 3: system configuration and parameter setting, accuracy of fuselage hardware and assembly process, etc
question 4: this should be e to the failure and quality problem of the pneumatic valve itself (the equipment and the car need regular maintenance)
now it's very difficult to achieve your desired effect ·····
these problems are not all the problems of the manufacturers. Your company didn't consider carefully when buying equipment and bought cheaper equipment. A cent price a cent goods You can explain the model and related configuration clearly so that we can analyze it

6. Call Tengzhou City Bureau of instry and Commerce telephone complaints, call Tengzhou 110 report. Early online more such information that he knows the consequences of deception! Brother, don't try to be cheap when you buy machines in Tengzhou. I believe you must have found the one with the lowest price. There is no free lunch in the world. This is always the truth. Don't pay for all the machines in the future, and pay after inspection

7. This can change the NC program, can also change the radius of the tool tip
it is suggested to change the tool tip radius
because the diameter of the inner hole is 0.1mm smaller, that is, the radius is 0.05mm smaller
the tool tip radius should be reced by 0.05mm
note: never change G41 and G42, otherwise the proct will be wasted.

9. Spindle cooling alarm, low oil pressure, check the oil cooler oil pressure, oil pump, cooling oil is not enough, etc.

10. According to the literature records and a large number of unearthed cultural relics, the origin of Chinese currency has a history of at least 4000 years. The development of Chinese currency culture has a long history, from the original shell coin to cloth coin, knife coin, round coin, ant nose coin and fangkong coin popular after the unification of China by the first emperor of Qin Dynasty. In the Northern Song Dynasty, jiaozi appeared in China
the emergence of paper money is a great progress in the history of money. Some people think that the origin of Chinese paper money can be traced back to the "white deer skin money" of Emperor Wu of Han Dynasty and the "flying money" of emperor Xianzong of Tang Dynasty. During the period of Emperor Wu of Han Dynasty, the National Treasury was empty because of the long-term war with Xiongnu. In order to solve the financial difficulties, the "three baht coins" and "white gold coins" (alloy coins made of silver and tin) were coined, and the "white deer skin coins" were issued at the same time. The so-called "white deer skin coin" uses the white deer skin of the palace as the coin material. Each piece is one square foot, and the surrounding color is painted. The value of each piece is 400000. Because its value is far away from its own value, the "white deer skin coin" is only used as a tribute between kings and princes, not used in the field of circulation, so it is not a real sense of paper money, only a pioneer of paper money“ "Feiqian" appeared in the middle of Tang Dynasty. At that time, when merchants went out to do business with a large amount of copper money, there were many inconveniences. They first went to the official to issue a certificate, which recorded the place and the number of coins, and then went to other places to withdraw money and buy goods with the certificate. This certificate is called "feiqian"“ In essence, "flying money" is only a kind of exchange business. It does not intervene in circulation and does not function as currency. Therefore, it is not paper money in the real sense. In the Northern Song Dynasty, "Jiaozi" in Cheng, Sichuan Province was the beginning of real paper money
for 900 years, the birthplace of Jiaozi has always been a mystery< According to the research of experts, "Jiaozi" first appeared in the form of private circulation, so it is also called "private Jiaozi". Liu Fangjian, a well-known expert in economic history and director of the currency and securities Museum of Southwest University of Finance and economics, said that in the early Northern Song Dynasty, business was very developed in Cheng, currency was tight, but the circulation of iron money was not smooth. As a result, 16 local rich families began to privately print a kind of voucher made of Broussonetia papyrifera bark, which could replace coins, and later was called "Jiaozi". At first, the local government wanted to ban this "new currency", but this "new currency" played an obvious role in economic circulation, so it decided to use official printing. But the birthplace of these two "Jiaozi" has not been found
based on historical research, "Jiaozi" was first printed in Cheng Wanfo temple
previous researchers believed that jiaozi street in the east gate of Cheng should be the place where jiaozi was officially printed at that time. Because "Cheng Chengfang historic sites research" has such an explanation of "Jiaozi Street" in the east gate of Cheng, "Yishuo street is called" Jiaozi ", and jiaozi was set up here in Song Dynasty."
however, local currency collectors have questioned this view, because according to the explanation in Cheng financial records: "jiaozipu in Yizhou of the Northern Song Dynasty was actually the earliest monetary and financial institution in Sichuan history, while jiaoziwu in Yizhou was the earliest banknote issuing institution approved by the state." Obviously, there is no basis to say that the issuing institution of paper money is the place of printing. In other words, there is no direct evidence that jiaozi street is the birthplace of Jiaozi. Because jiaozi has been born for more than 900 years, and there is no specific physical research, we have to find it from the literature. As early as three years ago, Zhan Xing of the currency museum began to search for the birthplace of Jiaozi from historical books. From the library, he found a passage in the book of Chu coins written by Fei of Yuan Dynasty: "in the first year of Yuanfeng (1078 AD), one member was added; There were 10 masters, 69 pasters, 81 printers, 6 sculptors, 2 casters and 12 handyman. Each had his own difference. In the beginning, the paper used was set up by oneself, and it was handed over to the son as an official. Later, considering the disadvantages of the paper, it was decided by other officials. In the first year of Longxing (1163 A.D.), a special official came and moved to Jingzhong temple in the west of the city. " This shows that the official "Jiaozi" is printed in Jingzhong temple in the west of the city. However, after more than 900 years, there is no Jingzhong temple in Cheng. How can I find it? Later, with the help of Ding zuchun, a scholar in Nanchong City of Sichuan Province, Zhan Xing's investigation went a step further. It turns out that Jingzhong temple was first built in the reign of Yanxi, Emperor Huan of the Eastern Han Dynasty. It was named Anpu temple in the Six Dynasties, Jingzhong temple in the Tang Dynasty, Jingyin temple in the Song Dynasty, Wanfo temple in the late Yuan Dynasty and early Ming Dynasty, and was destroyed in the war after Zhang Xianzhong entered Sichuan in the late Ming Dynasty. It was rebuilt in the early Kangxi of the Qing Dynasty, and still called Wanfo temple, The address is on the side of Jinhua bridge in the west gate of Cheng< Second, it is not accidental that paper money appeared in the Northern Song Dynasty, it is the inevitable proct of social, political and economic development. The commodity economy developed rapidly in Song Dynasty, and more money was needed in commodity circulation. However, the shortage of copper money at that time could not meet the demand in circulation. At that time, the iron coin was used in Sichuan area, which was of low value and heavy weight, and was extremely inconvenient to use. At that time, one copper coin was worth ten iron coins. The weight of one thousand iron coins was 25 Jin for a large coin and 13 Jin for a medium coin. It costs 20000 yuan to buy a piece of cloth. It weighs about 500 Jin. It takes a car. Cheng is an important economic area, and the road from Shuhan to the outside world is extremely rough and difficult, so it objectively needs light currency, which is also the main reason why paper money first appeared in Sichuan. Moreover, although the Northern Song Dynasty was a highly centralized feudal autocratic country, the national currency was not unified, and there were several currency areas, which were independent and not universal. At that time, there were 13 routes (administrative units in Song Dynasty) dedicated to copper coins, 4 routes dedicated to iron coins, and Shaanxi and Hedong used both copper and iron coins. The use of paper money can prevent the outflow of copper and iron money. In addition, the Song Dynasty government was often attacked by Liao, Xia and Jin Dynasties, and the military expenses and reparations were very large. It also needed to issue paper money to make up for the fiscal deficit. Various reasons contributed to the emergence of "Jiaozi"< Thirdly, the development process of Jiaozi was free issued by merchants. In the early years of the Northern Song Dynasty, "Jiaozi shop" appeared in Cheng, Sichuan Province, which specialized in keeping cash for merchants carrying huge sums of money. The depositor delivers the cash to the shop owner. The shop owner temporarily fills in the amount of cash deposited by the depositor on a roll made of paper, and then returns it to the depositor. When the depositor withdraws the cash, he pays the shop owner the interest of 30 Wen, that is, 3% of the deposit fee. This paper voucher which temporarily fills in the deposit amount is called "Jiaozi". At this time, "Jiaozi" is just a kind of certificate of deposit and withdrawal, not currency

with the development of commodity economy, "Jiaozi" is more and more widely used. Many merchants jointly set up jiaozi shops specializing in issuing and exchanging "Jiaozi", and set up jiaozi shops in various places. Due to the fact that jiaozi shop owners abide by the credit and take it as they come, the printed "Jiaozi" pattern is exquisite, it is hidden as a mark, there are mistakes between black and red, and it is difficult for others to forge their own words, so "Jiaozi" has won a high reputation. In order to avoid the trouble of carrying coins, there are more and more cases of large-scale transactions between merchants who directly use "Jiaozi" to pay for money at any time. It is in the repeated circulation process that jiaozi has graally acquired the character of credit currency. Later, jiaozi shop owners found that only using part of their deposits would not endanger the reputation of Jiaozi. So they began to print jiaozi with uniform denomination and format, which was issued to the market as a new means of circulation. This kind of "Jiaozi" has been the symbol of coins, and has really become paper money. However, jiaozi was not recognized by the government at this time, and it was still a private issue
however, not all jiaozi shops are law-abiding and trustworthy. There are some greedy shop owners who are greedy for profits, who cheat maliciously and shut down their business after they have made excessive payments; Or misappropriate deposits, run other business failure and bankruptcy, so that the "Jiaozi" can not be cashed. In this way, when depositors can't withdraw money, they often cause trouble and litigation. Therefore, ring the reign of Jingde (1004-1007), Zhang Yong, the governor of Yizhou, reorganized jiaozi shops, eliminated outlaws, and managed them exclusively by 16 wealthy merchants. So far, the issue of Jiaozi was approved by the government
in the first year of Tiansheng (1023), the government set up jiaozi business in Yizhou, and one or two officials of the Jing Dynasty acted as supervisors to preside over the distribution of Jiaozi, and "set up a papermaking house to eliminate the disadvantages of forgery" to strictly control the printing process. This is the earliest paper money officially issued by the government in China - "guanjiaozi". It issued paper money 600 or 700 years earlier than the United States (1692), France (1716) and other western countries, so it is also the earliest paper money in the world
in the early stage of the issuance of "guanjiaozi", its shape was modeled on the "private relationship" among the people, and stamped with the seal of the state, but the amount of money temporarily filled in was different, generally from consistent to ten, and the circulation scope was specified. In the reign of emperor Renzong of the Song Dynasty, it was changed into five Guan and ten Guan. By the time of emperor Shenzong of the Song Dynasty, it was changed to two kinds: Yiguan and wuwuwen. There are also restrictions on the amount of issue. It is stipulated that the issue shall be divided into three years (two years in full) for each sector, and the new one shall be exchanged for the old one. The first jiaozi issue was 1 256 340 units, with a reserve capital of 360 000 units (taking Sichuan tieqian as the note capital), and the reserve was equivalent to 28% of the issue“ The circulation scope of Jiaozi was basically limited in Sichuan. Later, although it was popular in Shaanxi and Hedong, it was soon abolished< In 1107, the Song government changed "Jiaozi" to "qianyin" and "jiaoziwu" to "qianyinwu". In addition to Sichuan, Fujian, Zhejiang, Huguang and other places still use "Jiaozi", other roads use "qianyin". Later, Sichuan changed jiaozi to qianyin in 1109“ The biggest difference between "Qian Yin" and "Jiao Zi" is that it takes "Luo" as the unit“ The paper, printing, picture and seal of "Qian Yin" are excellent. But "Qian Yin" did not buy notes, and was not allowed to exchange them, so the value of paper vouchers dropped sharply. In the Jiading period of the Southern Song Dynasty, each coin was only worth 100 Wen in cash< Fourthly, the emergence of Jiaozi has facilitated commercial exchanges and made up for the shortage of cash, which is a great achievement in the history of currency in China. In addition, "Jiaozi", as the earliest banknote issued in China and even in the world, also occupies an important position in the history of printing and printmaking, which is of great significance to the study of ancient banknote printing technology in China 
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Where does machining center have quality problem to complain

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