Furan resin self-hardening sand casting process knowledge summary
Since the self-hardening resin sand casting has the advantages of producing castings with good surface quality, high dimensional accuracy, low scrap rate, wide range of application, low requirements for workers'''''''' technical level, greatly reducing the labor intensity of workers and improving the working environment, more and more enterprises are choosing self-hardening resin sand casting means. Although the self-hardening resin sand casting technology has matured, but there are still many problems in the production process, sanzhuji combined with furan resin sand casting process characteristics to make the following summary.
In the process of self-hardening resin sand casting production, the following issues need to be noted.
1、to often pay attention to the operation of the equipment equipment operation is good or bad, directly affects the casting production costs and casting quality, therefore, in the casting production, to often pay attention to the operation of the equipment, found running abnormalities in time to analyze and solve, focusing on the following two aspects should be noted.
1.1 to pay attention to the operation of dust removal equipment. Dust removal equipment is good or bad, directly affects the regeneration of sand regeneration costs and casting quality, in the casting production, dust removal equipment running abnormalities are often not easy to find, but if the dust removal equipment is not good, not only affects the working environment, pollution of the air, more importantly, affects the recycled sand microfine content, the direct result is the increase in the amount of resin added when mixing sand and castings due to poor air permeability Scrap rate increases.
1.2 To pay attention to the operation of sand mixing equipment. Whether the sand mixer is able to run normally, directly affects the quality of sand mixing, of which the amount of liquid material (resin, curing agent) added is the most critical. In general, the amount of resin added by controlling the voltage of the gear pump motor, the amount of hardener added by controlling the voltage of the diaphragm pump motor to achieve, due to seasonal, weather changes, resulting in changes in the viscosity of the liquid material, in the case of the same voltage, the amount of liquid material added will produce fluctuations, and the hardener is easy to produce crystallization, resulting in valve and pipe blockage, therefore, should be cleaned every shift on the liquid material pipeline, weekly Therefore, the liquid material pipeline should be cleaned every shift and the amount of liquid material added should be tested every week to ensure that the amount of liquid material added is accurate.
2、to pay attention to the development of the correctness and rationality of the production process production process to develop a reasonable or not, directly affects the yield of the casting, casting quality and casting costs, in the development of the production process, the main attention should be paid to the following items.
2.1 determine the appropriate LOI value of recycled sand LOI value is an important indicator to measure the rate of regeneration of the sand, is also closely related to the amount of sand and castings produced porosity defects, cast iron parts are generally used furan resin sand production, practice has proved that LOI value control at about 3% can fully meet production requirements, and excessive reduction in LOI value is not significant.
2.2 Determine the appropriate casting process parameters
2.21 Determine the suitable final strength Generally, after the resin sand is mixed and hardened by itself for about 24 hours, it can reach the highest strength, that is, the final strength. Due to the different production conditions and production scale of each enterprise, the time interval between molding and pouring is not necessarily more than 24 hours, so the final strength should be determined depending on the enterprise. Smaller scale, the implementation of a few days a furnace system of enterprises, can use 24 hours final strength standard; casting curing time does not exceed the 24 hours of enterprises, the strength reached before pouring as the final strength standard. At the same time, in production to overcome the tendency of two aspects: on the one hand, to ensure the quality and blindly improve the strength, so that the casting cost increases, resulting in waste; on the other hand is to keep the cost and depress the strength, resulting in unstable quality, fluctuating range, so that the quality of castings by the raw materials and the operator''''''''s influence is greater.
2.22 Determine the appropriate sand-iron ratio of self-hardening resin sand due to its high strength, cured mold, flat parting surface, so its sand consumption than the clay sand to be small, but its sand-iron ratio also has certain requirements. If the casting sand-iron ratio is too high, the production process will waste resin and curing agent and produce a large block of waste sand, which will increase the burden on the regenerator, reduce the release rate, increase the LOI value, and increase the possibility of pores in the casting; if the sand-iron ratio is too low, it is easy to produce a runner when pouring, and the casting is easy to produce deformation. According to our experience, the sand-iron ratio should be chosen as 2.2~3:1.
2.23 Determine the appropriate pouring system; furan resin sand thermal stability is poor, there is information, resin sand resin addition in 1.4%-1.6%, its thermal stability is the best, but in general, the resin addition in 1.2% or so, therefore, the design principle of the pouring system for the thermal stability of the resin time to ensure that the metal liquid quickly and smoothly Therefore, when determining the pouring system, ceramic tubes should be used as much as possible, and the inner gate should be more and more dispersed.
3、pay attention to the choice of raw materials raw material selection has a greater impact on the casting production, because the quality of raw materials, on the one hand, affects the quality of the casting, on the other hand, affects the amount of various materials added and consumed. To this end, the following aspects should be considered.
3.1 the choice of raw sand raw sand is divided into ordinary sand, washed sand, scrub sand and other types, due to scrubbing sand in the mud content has been very little, so it can greatly reduce the waste of resin, should be preferred, followed by the choice of washed sand, but never use the raw sand without treatment. When choosing the type sand, one should follow the principle of choosing nearby to reduce the transportation cost, and the second should try to use the original sand with low angular coefficient.
3.2 The choice of resin directly affects the casting quality. If you choose a poor quality resin, not only increases the amount of resin added, but also affects the quality of the sand, resulting in more castings scrap, so the choice of raw materials, not only according to the technical data provided by the manufacturer to determine, but should have an understanding of the manufacturer''''''''s production equipment, production process and quality control means, and try to test the indicators of the resin or ask the relevant have a good reputation or draw on the experience of similar manufacturers, or choose the products of well-known large enterprises with good reputation.
3.3 Selection of other raw materials Other raw materials include curing agent, paint, binder, release agent, sealing clay bar, etc. The selection of these raw materials should consider not only their quality, but also their matching with the main materials, such as procurement, transportation and other issues. Because the impact of these raw materials on the quality of the casting is not the main, but the impact on the cost of casting can not be ignored, such as the amount of curing agent added to the different, not only due to the impact on the productivity of the molding process and affect production costs, but also affect the cost of materials.
Qingdao Sanzhuji Equipment Manufacturing Co., Ltd. specializes in the production of Green Sand Molding Line,Self-hardening sand molding line,foundry machines,Sand molding machine,Sand casting equipment,sand mixer,GS high efficiency rotary mixer,Resin sand mixer,no-bake resin sand mixer,Jolt squeeze molding machine/Jolt-squeezing moulding machines,Multi- Piston Moulding Machine/Hydraulic multi-piston moulding machine,sand casting molding machine,sand reclamation equipment，foundry molding machine,flaskless moulding machine,shot blasting machine,dust collector,according to the amount of old sand recovered Carry out plan customization, and provide sand reclamation equipment installation, commissioning, and training. Welcome guests to visit the factory.
