1. Raw materials
1.1 Raw sand
Silica sand is mostly used. There are both domestic silica sand and foreign silica sand. There is no report that the aeration performance of the two silica sands is different.
Silica sand with a size equivalent to No. 6 is often used. In the case where the quality of the castings is emphasized, the No. 7 silica sand is sometimes mixed.
1.2 Additives
1.21 Bentonite
Both Ca-based and Na-based are used in actual use. When selecting additives, in addition to considering the characteristics of the molding machine, the target product should also be considered.
Product (pouring weight and shape, etc.), sand box dismantling equipment capacity.
1.22 starch
In order to solve the defects of sand washing and sand inclusion, a-based starch has the best effect. B-based starch can also be used. However, dextrin will significantly reduce the sand
It is liquid, so it cannot be used.
1.23 pulverized coal
Use sea coal with an ash content of about 8%.
2. Recommended value of properties of mixed molding sand
2.1 Moisture:3~4%, To ensure the proper moisture value of the CB value, and give priority to the management of the CB value
2.2 CB value: 33~39%. In the stage of supplying sand to the molding machine, the CB value discharged by the sand mixer should be adjusted reasonably
2.3 Compressive strength (compression resistance): 10~14N/cm2 (1.0-14 kgf/ cm2)
2.4 Total clay content: 10-12%, this is to ensure water retention and reduce the change of CB value.
3. Reference value
3.1 Air permeability: >120
3.2le-Loss: 3~4%
3.3 Active clay composition: 6~8%
3.4 Surface stability: >85%
3.5 Compactness (CB value): 33-38
4. The reference value of the additive rate (the rate of addition to the sand mixer)
4.1 Bentonite: 0.3-0.6%
4.2 Starch: 0.03-0.1%
4.3 Coal powder: 0.05-0.15%
The basic idea of supplementary addition is to replenish the loss part caused by pouring, to keep the overall sand content at the most constant, and the addition rate is due to sand/gold
The attribute ratio (the ratio of the pouring weight of each flask to the weight of the mold) and the heat loss tendency of the additives used vary.
5. Moisture
5.1 Weight expressed in%
(Full weight-weight after drying)/full weight (moisture + sand)×100=moisture%
5.2 Compactness (CB value) is closely related to moisture content, the more the moisture content increases, the greater the CB value. The higher the CB value, the worse the filling degree of sand and the worse the flow of sand.
6. S/M ratio (sand/metal ratio)
6.1 The casting weight ratio corresponding to the weight of the casting mold (sand)
(S sand weight)/(M casting weight)=6-12 (general)
6.2 Resistance
6.21 For the endurance of the vertical load of the mold, it is generally used under 0.09-0.16MPa.
You can grasp the rough standard of the demolding process and the crushing load when carrying the weight.
6.22 Example
The approximate standard for the crushing load of a mold with a mold size of 400X500 and a compressive strength of 0.1MPa
0.4X0.5X0.1X1000000X0.4=8000N
(0.4=estimated% when contacting the mold pressing area)
7. Flat materials and precautions
The specifications of the rolled aluminum sheet comply with the regulations of jIS H 4000. There are various steel manufacturers on the market for sale. If you want to buy the thickness Materials below 100mm are easy to buy. Sanzhuji recommends the A50S2P material as the standard for the off-box molding machine. Raw materials with a thickness of 30mm The dimensional accuracy tolerance is +0.15mm, and the surface flatness is plus 0.4mm/1m. Therefore, only need to directly process the periphery and holes, it can be used as Tablet use.Regarding the precautions in manufacturing, when it is necessary to process large countersinks for assembling the model, the improper processing method may cause warpage, so requires attention. If possible, it is best to attach the obligation to check the flatness in the final state of the model after assembly.
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.
