Resin Sand Molding Line

Because no-bake 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 companies (or enterprises) in China are choosing no-bake resin sand casting means. Although no-bake resin sand casting technology has matured, but there are still many problems in the production process. In the no-bake resin sand casting production process, the following issues need to be noted.
1、to often pay attention to the operation of the equipment
The operation of the equipment 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 timely analysis and resolution, 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 The amount of liquid material added to the test every week to ensure that the amount of liquid material added to the accurate.

2、To pay attention to the correctness and reasonableness of the production process
Production process is reasonable or not, directly affects the casting yield, casting quality and casting costs, in the development of production processes, the main attention should be paid to the following.
2.1 Determine the appropriate LOI value of recycled sand
LOI value is the burn reduction is an important indicator to measure the rate of regenerated sand, but also with the amount of sand gassing and casting porosity defects closely related to the indicators, cast iron parts are generally produced using furan resin sand, 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 appropriate final strength
Generally, after no-bake resin sand is mixed, after about 24 hours of self-hardening, 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 modeling and pouring may not necessarily exceed 24 hours, so the final strength should be determined by the enterprise. Smaller scale, the implementation of a few days a furnace system of enterprises, can be used 24 hours final strength standards; casting curing time does not exceed the 24 hours of enterprises, the strength reached before pouring as the final strength standards. 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 to iron ratio
no-bake resin sand due to its high strength, curing after starting the mold, parting surface flat, so its sand content is smaller than that of clay sand, but its sand-iron ratio also has certain requirements. If the casting sand to iron ratio is too high, the production process will not only waste resin and curing agent but also produce larger waste sand blocks, which will increase the burden of regenerating machine, reduce the rate of release, increase the LOI value and increase the possibility of pores in the casting; if the sand to iron ratio is too low, it is easy to produce runner when pouring.
2.23 Determine the suitable pouring system
The thermal stability of furan resin sand is poor, there is information that the thermal stability of resin sand is best when the resin addition is 1.4%-1.6%, but in general, the resin addition is about 1.2%, so the design principle of the casting system is to ensure the metal liquid fills the casting cavity quickly and smoothly within the thermal stability time of resin, so, in determining the When pouring system, ceramic tube should be used as much as possible, and make the inner gate more and dispersed.

3、To pay attention to the choice of raw materials
The choice of raw materials 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 type sand, one should follow the principle of choosing nearby to reduce transportation cost, and the second should try to use the original sand with low angular coefficient.
3.2 The choice of resin
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.

4、in order to standardize the no-bake resin sand casting production process, the strict implementation of the operating process, reduce the scrap and reduce the production cost of castings due to violations of the process or improper operation, sanzhuji and many no-bake resin sand casting plant to develop this production operation process procedures. This procedure is applicable to the whole process of production of all resin sand castings in the company and all kinds of operators related to it. The following is an excerpt for your reference and reading.
4.1 Process regulations
4.11 Technical requirements or specifications of the main raw materials
Raw sand (natural quartz sand)
Grain size: 40/70 mesh (medium to large pieces) or 50/100 mesh (general pieces).
Chemical composition: SiO2 ＞90, mud content＜0.2%~0.3%, water content＜0.1~0.2%.
Micron content (below 140 mesh sieve) ≤0.5~1.0%, acid consumption value <5ml, scorch amount <5, particle shape: round or polygonal.
4.12 recycled sand scorch <3.0%; acid consumption value <2.0ml; PH value <5; 200 mesh sieve sump <1%; sump amount <0.2%; water content <0.2%.
Particle shape: round.
4.13 furan resin containing 2.0~5.0% nitrogen; 24h tensile strength>1.5MPa; free formaldehyde＜0.3%; viscosity＜60mPa.s; density 1.15~1.25 g/cm3; free phenol＜0.3%.
4.14 Curing agent using organosulfonic acid curing agent, its viscosity is generally controlled at &lt; 200mPa.s, the content of water insoluble matter &lt; 0.1%, while there should be reversibility between freezing and subsequent dissolution. In order to ensure the stability of the sand can be used time and hardening speed, can choose "a + b" curing agent or according to the different seasons choose different acidity model curing agent.
4.15 Coating adopts alcohol-based coating. The solid content of the coating is required to be high, the particle size of the powder is fine, the refractoriness of the powder and binder is high, and the resistance to heat explosion is strong. Specific process performance requirements are: density 1.25~1.35 g/cm3; viscosity 6~7s; suspension (2h) > 97%; brushability, leveling, permeability, crack resistance to be good, and high coating strength. For the surface spheroidization has the depth requirements of the casting, should use magnesium oxide coating.

4.2 Operation process protocol
4.21 Regenerated sand preparation according to the requirements of resin sand regeneration equipment and process flow for operation, to obtain the regenerated sand to meet the requirements of the process. Special attention should be paid to control the temperature of the regenerated sand when entering the sand mixer, preferably at 25-35℃.
4.22 Adjustment of the amount of sand, resin and curing agent added
4.23 Determination of the flow rate of the sand blender
According to the setting requirements of the sand blender, the flow rate is measured at least once every four days under normal production conditions. Weigh the flow rate of sand, resin and curing agent respectively in the same time to master the time flow rate. and first adjust the sand flow rate according to the nominal flow rate of the sand mixer.
4.24 Adjustment of resin amount
Adjust the amount of resin added according to the sand flow, the amount of resin added is generally controlled at 0.8~1.2% of the weight of the sand, with the upper limit for thick and large pieces and the lower limit for medium and small pieces.
4.25 Adjustment of the amount of curing agent
The amount of curing agent added under normal circumstances and sand temperature and workshop environment temperature, generally control the amount of resin added 30 ~ 50%, high temperature to take the lower limit, low temperature to take the upper limit. Put sand time long large pieces of curing agent added to take the lower limit, in order to ensure that the resin sand has sufficient useable time.
4.26 Adjustment and preparation of sand mixing machine
Strictly according to the "sand mixer operating procedures" for the daily maintenance of equipment, especially to clean up the blades and inner wall of the stirring cage in time. Every day before putting sand should be resin, curing agent pump separate cycle 1 ~ 2 minutes, and pay attention to check whether the curing agent to join the hole has crystallization blockage phenomenon.

4.3 Mold finishing and inspection
4.31 Understand the process requirements of the castings produced and be familiar with the process documents and process equipment.
4.32 Check whether the mold core box is complete and remove the excess residual accumulation existing on the surface of the mold core box.
4.33 Check whether the mold core box has missing corners and deformation, and whether the size is in accordance with the drawing requirements; check whether the live block and sprue are defective.
4.34 Check whether the positioning pins and holes are suitable; whether the installation of mold starting device and lifting device is suitable.
4.35 Check whether the bottom plate of the mold is straight and whether the size meets the requirements. The installation of metal plate must be flat, padded at all four corners, and guaranteed to be on a horizontal surface. Wooden base plate of the mold must be placed on the metal plate modeling, modeling should be checked before the base plate and the metal plate bond surface between the debris.
4.36 sand box size is appropriate, lifting lugs are securely available, large sand box for cracks and other defects.
4.37 Prepare the baking cold iron, core support (cold iron, core support must be cooled to room temperature after baking before use) lifting tools, ventilation rope, sand filling sand block. The surface of the cold iron used is best processed or the surface of the blank is free of defects, and the general use of cold iron for thick and large parts shall not exceed 3 times, and thin-walled parts shall not exceed 5 times.
4.38 All molds and core boxes are used after brushing with mold release agent.

4.4 Sanding and pounding
4.41 Cold iron, live block, pouring mold sample, and outgassing of mud core must be placed correctly according to the process requirements.
4.42 Start the sand mixer after starting the dust collector. The single stirrer cage sand mixer should pay attention to remove the head sand first before the sand release operation.
4.43 Small and medium-sized pieces can be put sand from the mold sample, when putting sand, attention should be paid to prevent the movement of cold iron and live blocks, and pay attention to the corners, groove parts with wooden sticks pounding, other parts also have to be evenly pounded with wooden sticks, especially to prevent the local loose sand near the mold sample parts.
4.44 Large castings should be placed from a corner of the sand box to start sand, and pay attention to the appropriate adjustment of the amount of hardener added to extend the use of resin sand time. To put sand while pounding, from the corner of the sand box gradually along the other direction of the mold continuous expansion, until put the entire sand box. For large space sand box, the resin sand can be placed with the shape of the mold to a certain thickness, generally controlled at 150~200mm (without filling sand block), must ensure that the resin sand of the gate, riser, air hole parts reach the height required by the process, the height of the gate and air hole parts can be used to meet the requirements of the process such as riser ring.
4.45 At the end of sand release, it should be noted that the tail sand should not be placed in the pouring mouth and vent area, but only in the unimportant place.
4.46 Since the fluidity of resin sand is very good, pounding only requires fast speed, but not excessive force. Corners, grooves and other parts must be pounded.
4.47 When the sand is put full, scrape the sand box and core box and air pin to tie the air hole. For thick large pieces, wall plate pieces, etc. in the cover box on the shape must be carefully tied ventilation holes, and control the distance from the mold sample 30 ~ 50 mm, can not be tied through.

4.5 Add sand block or other fillers due to the higher cost of resin sand, to further reduce costs available waste sand block or other fillers to fill the unimportant space of the sand box, but should pay attention to the following issues:
4.51 The surface of the mold sample should be pounded, and the sand filling thickness exceeds 100mm of the mold sample before adding sand blocks or other fillers.
4.52 No ceramic tube near the straight gate, near the cross sprue, near the air hole, the requirement of sand castings with high strength of the thick wall and other parts shall not be placed sand block.
4.53 filling sand block shall not have a gap between, should be pounded solid. The block of filling sand block shall not be too large or too small, and shall be controlled between 50~200mm according to the size of different products.

5、no-bake resin sand molding requirements for the mold process (no-bake resin sand production line):
Compared with green sand, the appearance quality of no-bake resin sand castings depends on the quality of the mold, thus no-bake resin sand has higher requirements for the quality of the mold. Mold process when making it better adapted to the needs of no-bake resin sand molding, mainly in the following areas.
5.1 machining allowance: the hardened resin sand casting has better stiffness and higher dimensional accuracy, and is not easy to deformation, so in the selection of process parameters, you can choose a smaller machining allowance, thus reducing the consumption of metal solution and the cost of machining, which can improve the dimensional accuracy of the casting.
5.2 mold pulling slope: no-bake resin sand in the starting mold already has a certain hardening strength, smaller retreat, larger friction, if the use of knocking methods to start the mold, easy to damage the mold, while the resin sand repairability is poor, starting mold, if damaged, more difficult to repair. When using no-bake resin sand modeling, according to the actual production and product structure should increase the mold slope, can smoothly start the mold, get quality With the market for castings product appearance quality requirements continue to improve, no-bake resin sand castings in the quality of the advantages, will be increasingly important, no-bake resin sand this casting production process, will also be rapidly developed and popularized.
5.3 mold surface roughness: mold surface roughness of no-bake resin sand casting surface roughness plays a decisive role, and therefore minimize the mold surface roughness, is an important measure to obtain high-quality castings.

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.