In order to standardize the production process of no-bake resin sand casting, strictly implement the operating process, reduce the waste caused by violation of the process or improper operation and reduce the production cost of castings, sanzhuji and many no-bake resin sand foundries specially formulated this production process Procedures. This process specification is applicable to the entire production process of all resin sand castings in the company and various operators related to it. The following excerpts are for your reference.
1 Process regulations
1.1 Technical requirements or specifications of main raw materials
1.11 Raw sand (natural quartz sand)
Granularity: 40/70 mesh (medium and large pieces) or 50/100 mesh (general pieces);
Chemical composition: SiO2 ＞90, mud content＜0.2%~0.3%, water content＜0.1~0.2%;
Micropowder content (below 140 mesh sieve) ≤0.5~1.0%, acid consumption value <5ml, ignition loss <5, particle shape: round or polygonal.
1.12 Burning loss of regenerated sand<3.0%; acid consumption value<2.0ml; PH value<5; 200 mesh sieve bottom plate＜1%; bottom plate volume＜0.2%; water content＜0.2%;
Grain shape: round.
1.13 Furan resin nitrogen content 2.0~5.0%; 24h tensile strength> 1.5MPa; free formaldehyde <0.3%; viscosity <60mPa.s; density 1.15~1.25 g/cm3; free phenol <0.3%.
1.14 The curing agent adopts organic sulfonic acid curing agent, its viscosity is generally controlled at <200mPa.s, the content of water-insoluble matter is <0.1%, and there must be reversibility between freezing and subsequent dissolution. In order to ensure the usable time and hardening speed of stable molding sand, "a+b" curing agent can be selected or different acidity types of curing agents can be selected according to different seasons.
1.15 The coating adopts alcohol-based coating. It is required that the solid content of the coating is high, the particle size of the powder is fine, the powder and the binder have high refractoriness, and the ability to resist explosion heat is strong. The specific process performance requirements are: density 1.25~1.35 g/cm3; viscosity 6~7s; suspension (2h)>97%; good brushing, leveling, permeability, crack resistance, and high coating strength. Magnesium oxide coatings should be used for castings with deep requirements for surface spheroidization.

2 Operating process regulations
2.1 The reclaimed sand is prepared to operate according to the requirements of the resin sand reclaiming equipment and the process flow to obtain reclaimed sand that meets the process requirements. Special attention should be paid to controlling the temperature of the reclaimed sand when it enters the sand mixer, preferably at 25-35°C.
2.2 Adjustment of adding amount of sand, resin and curing agent
2.21 Flow measurement of sand mixer
According to the setting requirements of the sand mixer, under normal production conditions, the flow rate should be measured at least every four days. Weigh the flow of sand, resin, and curing agent in the same time, and grasp the time flow. and first adjust the sand flow rate according to the nominal flow rate of the sand mixer.
2.22 Adjustment of resin amount
Adjust the amount of resin added according to the sand flow rate. The amount of resin added is generally controlled at 0.8~1.2% of the weight of the molding sand.
2.23 Adjustment of curing dose
Under normal circumstances, the amount of curing agent added is related to the temperature of the sand and the ambient temperature of the workshop. Generally, it is controlled at 30-50% of the amount of resin added. The lower limit is taken at high temperature and the upper limit is taken at low temperature. Take the lower limit of the amount of curing agent for large pieces with long sanding time to ensure that the resin sand has enough usable time.
2.24 Adjustment and preparation of sand mixer
Strictly follow the "Sand Mixer Operating Regulations" for daily maintenance of the equipment, especially to clean the blades and inner walls of the mixing cage in time. Before putting sand every day, the resin and curing agent pump should be circulated separately for 1-2 minutes, and pay attention to check whether the curing agent is added to the hole for crystal blockage.

3 Mold finishing and inspection
3.1 Understand the process requirements of the castings produced, and be familiar with process documents and process equipment.
3.2 Check whether the mold core box is complete, and remove the excess residual accumulation on the surface of the mold core box.
3.3 Check whether the mold core box has missing corners, deformation, and whether the size meets the requirements of the drawing; check whether the live block and the pouring riser are incomplete.
3.4 Check whether the positioning pins and holes fit properly; whether the mold ejection device and lifting device are properly installed.
3.5 Check whether the mold bottom plate is straight and whether the size meets the requirements. The installation of the metal plate must be flat, the four corners should be leveled, and ensured on a level surface. The mold of the wooden base plate must be placed on the metal plate for modeling. Before modeling, check whether there is debris between the base plate and the metal plate.
3.6 Whether the sand box is of appropriate size, whether the lifting lugs are reliable and usable, and whether the large sand box has defects such as cracks.
3.7 Prepare the cold iron that needs to be baked, the core support (the cold iron, the core support must be cooled to room temperature after baking) to lift the mold, the air rope, and the sand block for sand filling. The surface of the cold iron used is best processed or the surface of the blank is free of defects. Generally, the cold iron should not be used more than 3 times for thick and large parts and 5 times for thin-walled parts.
3.8 All molds and core boxes are brushed with release agent before use.

4Add sand and pound
4.1 The cold iron, live block, pouring riser appearance, and the outflow of mud core must be placed correctly according to the process requirements.
4.12 After starting the dust collector, start the sand mixer, and the single-cage sand mixer should pay attention to removing the sand before starting the sand discharge operation.
4.13 Small and medium parts can be put sand from the pattern. When putting sand, you should pay attention to prevent the movement of cold iron and live pieces, and pay attention to the corners and grooves with wooden sticks. Other parts must also be tamped with wooden sticks, especially Prevent local loosening of molding sand near the pattern.
4.14 For large castings, sand should be placed from a corner of the sand box, and the amount of curing agent should be adjusted appropriately to extend the usable time of resin sand. Tamping while putting the sand, gradually expand from the corner of the sand box along the other directions of the mold until the entire sand box is filled. For large-space sand boxes, the resin sand can be placed with a certain thickness according to the shape of the pattern, generally controlled at 150~200mm (without sand block), and the resin sand at gates, risers, and vents must reach the height required by the process , The height of the pouring riser and vent hole can be used with riser rings to meet the technological requirements.
4.15 At the end of sand release, it should be noted that the tailings should not be placed in the pouring riser and vent hole, but only in unimportant places.
4.16 Since resin sand has very good fluidity, pounding only requires fast speed, but no excessive force is required. Corners, grooves and other parts must be pounded.
4.17 After the sand is filled, flatten the sand box and core box and prick the air holes with the air needle. For thick and large parts, wall panels, etc., when modeling on the cover box, the vent holes must be carefully pierced, and the distance from the shape of 30~50mm must be controlled so that it cannot be penetrated.
4.2 Adding sand blocks or other fillers Due to the high cost of resin sand, in order to further reduce costs, waste sand blocks or other fillers can be used to fill the unimportant space of the sand box, but the following issues should be noted:
4.21 The surface of the pattern should be pounded, and only when the thickness of the sand filling exceeds 100mm of the pattern, sand blocks or other fillings can be added.
4.22 Sand blocks shall not be placed near the straight gate without ceramic pipe, near the runner, near the vent hole, and thick-walled castings requiring high sand mold strength.
4.23 There should be no gaps between the filled sand blocks and should be compacted. The size of the filled sand block should not be too large or too small, and should be controlled between 50 and 200 mm according to the size of different products.

5 No-bake resin sand molding requirements for mold technology (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, so no-bake resin sand has higher requirements on the quality of the mold. The mold technology makes it better to adapt to the needs of no-bake resin sand modeling, mainly in the following aspects:
5.1 Machining allowance: The hardened resin sand casting mold has better rigidity and higher dimensional accuracy, and is not easy to deform. Therefore, when selecting process parameters, a smaller machining allowance can be selected to reduce the metal solution Consumption and machining costs, which can improve the dimensional accuracy of castings.
5.2 Draft angle: no-bake resin sand has a certain degree of hardening strength, less retreatability, and greater friction when the mold is drawn. If the punch is used to start the mold, it is easy to damage the mold, and the resin sand The repairability is poor, and it is difficult to repair if it is damaged when the mold is drawn. When no-bake resin sand is used for modeling, the draft angle of the mold should be increased according to the actual production and product structure, so that the mold can be smoothly removed and the quality obtained. With the continuous improvement of the market’s requirements for the appearance of casting products, no-bake resin The quality advantages of sand castings will definitely be paid more and more attention, and the casting production process of no-bake resin sand will also be rapidly developed and popularized.
5.3 Mold surface roughness: The surface roughness of the mold plays a decisive role in the surface roughness of no-bake resin sand castings. Therefore, minimizing the surface roughness of the mold is an important measure to obtain high-quality castings.

The above is the process specification for the safe production process of no-bake resin sand casting. By controlling each process, the entire no-bake resin sand casting is perfected, and then high-quality castings can be obtained. Sanzhuji can provide no-bake resin sand mixer. ,Sand Reclamation Systems,dust collector,Flip molding equipment, welcome guests to visit the factory.

Qingdao Sanzhuji Equipment Manufacturing Co., Ltd. specializes in the production of sand reclamation equipment,foundry machines,Sand casting equipment,GS high efficiency rotary mixer,no-bake resin sand mixer,Jolt squeeze molding machine/Jolt-squeezing moulding machines,Multi- Piston Moulding Machine/Hydraulic multi-piston moulding machine,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.