There are relatively few enterprises and scientific research institutions engaged in the production and research of wet clay sand railway steel castings in China. On the one hand, because the process is relatively difficult to control and has high requirements for the whole process, some important machinery and equipment still need to be imported, such as high-pressure molding machine and sand mixing equipment that meet the requirements; On the one hand, due to the raw sand commonly mined in China, the quality of bentonite is difficult to meet the requirements of wet molding clay sand steel casting process, and the mineral deposits of round (near round) sand and natural sodium bentonite are small. Nevertheless, in recent years, relevant enterprises and scientific research institutions have walked out of their own sky on the road of wet molding clay sand cast steel technology.
CSR group and CNR group, as the core enterprises of railway passenger and freight trains, have achieved satisfactory results in the production of railway steel castings by using wet molding clay sand process. On the basis of the successful introduction of the air impact molding automatic line of BMD company in Germany, Bai Wendi and others of Qiqihar rolling stock factory adopted the CO2 hardening process of sodium polyacrylate core sand, selected the flotation sand from Tongliao area as the raw sand, the natural sodium bentonite from Liufangzi coal mine as the binder, and all the surface sand was prepared with new sand, so that the total clay content in the molding sand was low, the fire resistance was good, and the sand sticking of railway steel castings was avoided, All the back sand shall be prepared with recycled sand. On the basis of having high-quality raw materials and selecting appropriate sand mixing and molding equipment, the coupler of C63 gondola truck was successfully produced in 1994. Zhang Tiejun and others of Tianjin locomotive and Rolling Stock Machinery Factory of the Ministry of railways have successfully produced railway steel castings of various materials, such as zg230-450 and zg270-500, by using the process of vertical parting, boxless injection molding and wet clay. The main raw materials are natural silica sand from yijiawan mine in Xiangtan, Hunan Province and bentonite from Heishan, Liaoning Province. Zhuzhou Siwei Railway Products Co., Ltd. has successively provided the market with more than 10 series of products, including K4, K5 (ZT), K6 type bolster, side frame, coupler, tailframe, 470A side frame, drawbar, Australian side frame, Thai coupler and non railway steel castings, using wet clay sand casting process and the introduction of American integral clay core technology. Nearly 60% of the products are exported to the United States, Australia, Thailand India and other countries. The products have passed and obtained ISO9001 and aarm-1003 quality system certification of North American Railway Association. In 2009, Zhuzhou Jiufang Foundry Co., Ltd. signed an agreement with American ASF company to cooperate in the production of integral traction beams for railway freight cars.
There are many successful examples of using wet molding clay sand to produce steel castings in China. For example, Liu Yumin, a state-run Chang’an machine manufacturing plant, added aluminum sulfate to the wet molding clay sand of steel castings, which can effectively prevent sand sticking of railway steel castings, make it easy to clean railway steel castings, and achieve good economic benefits. Quan Shangji and others of Mudanjiang valve general factory introduced the manufacturing technology of high and middle school die-casting steel valves from Japan and selected Haicheng sand as the raw sand, α Starch and dextrin were used as additives to successfully produce valve steel castings. Liu Yuman and others simplified the use of various additives by adding composite powdery additives to wet molding clay sand, which is conducive to desanding and smooth effect of steel castings. Harbin Weijian aircraft manufacturing company adopts Dalin water washing sand (55-100 mesh) α Starch and bentonite have successfully produced some parts of aircraft steel castings.