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I believe many people in this industry encounter an awkward problem: foreign equipment is of high quality, but it becomes quite troublesome to replace or repair it； Apart from spending a lot of money to hire technical engineers from the foreign manufacturer, hoping that they will come over sooner ； More importantly, the procurement and delivery time for original parts from abroad is absurdly long ； This causes significant losses to production! Is there any good solution then? This article introduces new approaches to the maintenance of gearboxes in imported extruders, through case studies of gearbox replacement and repair for blend-modified extruders used by companies such as Foxconn, Sabic, Water Group, Formosa Plastics Group, and Haier New Materials, as well as for reactive extruders used by CNOOC Tiannye Chemical, China National Blue Star Group, Idemitsu Kosan Corporation, and Guangdong Caiyan Group. Before that, let’s conduct a small survey: 1. The gearbox is the “heart” of the extruder; the heart is the source of power in the human body. The human body achieves blood circulation through the contraction and expansion of the heart, while oxygen and nutrients in the blood provide the necessary \"energy\" for various parts of the body. By the same logic, the gearbox is the “heart” of the extruder. The gearbox is able to transmit power to the screw, ensuring the proper operation of the extruder. Special gearboxes for reactive extrusion, supplied by Sichuan Zhongwang Technology Co., Ltd. Gearboxes, also known as transmission boxes, are mechanisms for transmitting power and serve as speed-reduction devices as well ； The gearbox converts the speed of the motor into the speed required by the working equipment through the meshing of gears with different numbers of teeth, while also increasing torque. For plastic extruders, the gearbox is a key component that directly affects the overall performance of the extruder. However, most of the extruder gearboxes in China are still at the level of the older generation, featuring relatively low load-bearing capacity or low torque ratings (such as gearboxes with a single-sided parallel drive structure), and are technologically far behind the high-torque gearboxes that are currently standard in the international market (such as gearboxes with bilateral symmetric gear drives). To meet certain high requirements, such as the production of polyoxymethylene, domestic plastic manufacturers must use foreign polyoxymethylene polymerization machines that offer greater power and better stability. II. What to do if the gear box of the imported extruder is damaged? What to do if the gearbox of an imported extruder is broken? This problem seems quite simple: if the gearbox is damaged, it should of course be repaired by the manufacturer; if that’s not possible, then a new gearbox needs to be installed. Indeed, in theory, it should be handled that way. However, the reality is not that simple: for most plastic manufacturers, production is a continuous and large-scale process ； They hope the gearbox can be repaired as soon as possible, with as little impact as possible on production. 1. The costs and time required for replacement and repair services provided by original manufacturers abroad are high. Moreover, since the headquarters and factories of large extruder suppliers are generally not located in China, they at most have offices in China’s first-tier cities ； When major issues such as broken gearboxes occur in plastic production or processing plants, the staff at the office are usually sales engineers and are unable to handle such problems ； This requires contacting relevant technical experts abroad to resolve the issue; as a result, something that could have been fixed in one day might take 4 or 5 days, severely affecting normal production. 2. Replacing and repairing them with well-known domestic manufacturers represents a new solution. A comparison before and after gearbox repair is provided by Sichuan Zhongwang Technology Co., Ltd. With the rapid development of machinery in China, although high-torque extruders (such as those used for polyoxymethylene production) may not yet be available domestically, key components like gearboxes can already replace those imported from abroad. This provides a better solution for problems that occur with imported extruder gearboxes and similar components! Reply “extruder” to see more. We illustrate this with some real cases: III. Examples of replacing imported extruder gearboxes domestically 1. Foxconn Group 1) In 2002, when Foxconn Group was repairing the gearboxes of KOBE Company, it replaced them with domestic gearboxes, using higher-quality domestic transmission boxes in place of those from KOBE Company’s KTX-73 extruders. Domestic transmission boxes were used to replace those of KTX-73 extruders. 2) In 2004, Foxconn Group repaired the transmission boxes of KTX-73 extruders manufactured by the Japanese company KOBE. 13 types of 27 bearings in this gearbox are severely worn; the output shaft has shifted due to wear and has seized, resulting in the entire shafting system becoming non-functional. The two output shafts are severely worn and cannot be used any longer. The roller of the needle bearing at the right end of the input shaft has suffered severe stripping, with the stripped area accounting for over 70%. By cleaning and derusting all gears, replacing the two output shafts, replacing all worn bearings, and repairing the output shaft bearing housings, it was possible to keep using this gearbox. 2. Sabic1) In 2011, replacement and repair of the TEM-73BS type extruder gears manufactured by Japanese Toshiba for the Guangzhou Nansha plant of Sabic Basic Innovative Plastics (China) Co., Ltd. 2) In 2012, the repair of one ZSK35 gearbox and two Toshiba75BS gearboxes at Sabic’s Nansha plant. Among them, the gearbox has been in use for over 10 years; the gear on the input shaft is severely damaged, and the bearings in other areas are also worn out. Domestic gearbox suppliers redesigned and remanufactured the gears, gear shafts, and all internal components of the gearbox based on the original one, and replaced all the severely worn bearings and oil seals inside the gearbox. In addition, the gearbox supplier redesigned a new replacement gearbox based on the installation dimensions of the original one, and corrected the unreasonable design in which the bearings caused direct wear on the output shaft; inner-ring bearings were used to prevent the output shaft from being worn directly ； The design was improved by changing the slight radial force on the output shaft in the original design to zero radial force. After installation, this gearbox restores the original installation dimensions of the previous gearbox; it operates smoothly, with minimal vibration, and its noise level meets the user’s requirements. It can handle full load loads equivalent to those handled by the original gearbox. 3) In 2012, Sabic’s factory in Thailand customized and installed a replacement Toshiba 75BS gearbox. The image on the left shows the old Toshiba 75BS gearbox, while the image on the right shows the gearbox after replacement. 4) In 2012, Sabic’s Nansha plant refurbished two extruder units of the original W&P model, namely the ZSK40 and ZSK58, including the repair of the gearbox for the ZSK58 extruder. Gears of the ZSK58 machine before repair (left image), gearbox of the ZSK40 machine (right image). Gears of the ZSK58 machine after repair (left image), gearbox of the ZSK40 machine (right image). The ZSK58 machine before repair. The ZSK58 machine after repair. The ZSK40 machine before repair. The ZSK40 machine after repair. 3. In 2013, Formosa Plastics Group carried out custom replacement of the TEM-136BS gearboxes at its Ningbo factory. 4. Haier New Materials: In 2013, Qingdao Haier New Materials replaced the gearboxes of 2 ZSK58 and 1 ZSK70 extruders. 5. In 2014, Water Group: Repair of the ZSK58 gearbox at Water Group’s Huizhou new materials factory. Not only the imported twin-screw gearboxes for modified plastics, but also the gearboxes of large reaction extrusion granulators can make use of this new solution: 6. In 2008, Guangdong Caiyan Group repaired the drive gearbox of a German Leitrize 80 extruder. Before repairs, the transmission box was disassembled; all its components were taken apart and its transmission structure was analyzed. Domestic gearbox suppliers determined that the transmission structure of this gearbox was of the parallel three-axis type, which has been phased out abroad. Moreover, the internal bearings, gears, and output shaft were severely damaged, making the repair costs extremely high and rendering the gearbox unsuitable for repair. Guangdong Caiyan Group accepted the recommendation to replace the gearbox, installing a new domestic gearbox in place of the transmission box of the 82 extruder manufactured by the German company Leistritz. The figure below shows the gearbox installed between the original frame and the barrel. The gearbox is installed between the original frame and the barrel. 7. In 2013, Nippon Shokubai Corporation carried out repairs on the Toshiba TEM-58SS gearboxes at its Nansha factory in Guangzhou. 8. Maintenance of the gearbox in the polyoxymethylene polymerization machine (reactive extruder) 1) In 2013, China National Blue Star Group successfully repaired two German-made ZSK 250 gearboxes (original manufacturer: FLENDER) capable of producing 140 T of polyoxymethylene per day each; by doing so, it saved nearly 2 million yuan in maintenance costs compared to the costs associated with repairs carried out by the original manufacturers abroad. Unboxing of the gearbox – Gearbox repair 2) In December 2014, CNOOC Tiannye Chemical successfully repaired a gearbox for an MRAISTM223 polyoxymethylene polymerization machine. MRAISTM223 polyoxymethylene polymerization machine gearbox – repair site 3) In March 2015, CNOOC Tianye Chemical repaired 3 MRAISTM223 polyoxymethylene polymerization machine gearboxes. Maintenance site. Acknowledgments: All the cases mentioned above were provided by Sichuan Zhongwang Technology Co., Ltd. Mr. Wang Duoyong, the chief engineer of Sichuan Zhongwang Technology Co., Ltd., offered valuable suggestions regarding the content of this article; we would like to express our gratitude to him as well! If you are interested in the repair and replacement of gearboxes for imported extruders, or in technical exchanges, you can contact Mr. Zhu via his mobile phone or WeChat: 18030608060. People experience joy and sorrow, partings and reunions; equipment also goes through periods of good performance and poor performance. Do you have an extruder at home? Scan the expert’s WeChat for future use!