Cast Iron, Sand Casting, Metal Foundry - FAQs

1. What is the most suitable ductile iron grade for hardening heat treatment? - on Jul. 26, 2012
   Ductile iron ASTM A536 80-60-03 could be quenching and tampering heat treated to hardness HRC 50. However, the heat treatment requirements are very high, only very professional and experienced heat treatment workshops could do it. The treatment costs are very high.

2. What is pure iron ? - on Jul. 25, 2012
   If the content of iron exceeds 99.6%, then it will be pure iron. Pure iron is very soft, but has good magnetism. Its density is 7.87 g/cm3. They could be used as a raw material to reduce the carbon content for iron castings, but they could not be produced by casting methods.

3. Is pig iron a type of cast iron ? - on Jul. 16, 2012
   Yes, pig iron is also produced by casting process, so theoretically, it is a type of cast iron. However, you can not require a foundry to produce your casting parts only by pig iron. Pig iron has too many impurities, and very bad mechanical properties. So, pig iron is only a main material of cast iron products.

4. What is the min. wall thickness of sand castings ? - on Jul. 12, 2012
   Answer: For most of sand castings, the min. wall thickness should be kept larger than 5mm. However, for some positions, and with small areas, the 3mm wall thickness is also possible.

5. Are exothermic riser, heat insulating feeder sleeve useful for sand castings ? - on Jul. 05, 2012
   Answer: Yes, they could reduce inside shrinkage effectively, especially useful for medium and large iron and steel castings with complex structures. Although they could increase some production costs, they could improve castings quality, decrease defective rate and hot metal consumption.

6. Is cast aluminum pan better than cast iron pan ? - on Jul. 04, 2012
   Cast aluminum pan is lighter and better heat conduction, but cast iron pan is more healthy. Because aluminum pan can cause chemical reaction with acid, salt and base materials.

7. What is the price for 18% Manganese Steel Casting ? - on Jul. 03, 2012
   High Mn cast steel is much more expensive than normal carbon steel. The price also depends on the carbon content. The required carbon content is lower, then the price will be higher, because lower carbon content will require to add more pure Manganese alloy. Normally 18% Mn Steel will be 0.8 USD/kg higher than carbon steel.

8. The hardness range of gray cast iron GG20, ASTM A48 Class 30 ? - on Jul. 02, 2012
   Answer: The normal hardness range is 170 to 220 BHN (Brinell Hardness) according to Chinese standard GB/T 9439.

9. Is gray iron class 35 (GG25) better than class 30 (GG20) ? - on Jul. 01, 2012
   Answer: The gray cast iron class 35 has higher tensile strength and hardness than class 30. However, class 30 has slightly better vibration absorbance, easier to be manufactured and lower production costs.

10. What are the differences between green sand, resin sand and shell molding processes ? - on Jul. 01, 2012
    Answer: Shell molding can get the best surface quality, dimensional tolerance and less casting defects, however, its price is also the highest.
    Resin sand can also get comparatively good surface quality and dimensions, but normally this sand was used to produce large iron castings with unit weight from dozens of kilograms to 2 tons. If we use this sand to produce small castings, then the production costs will be very high.
    Green sand just can get normal surface quality and dimensions, but its price is also the lowest comparatively, and this sand is suitable to produce from small castings to middle size castings.

• Cast Iron, Sand Casting, Metal Foundry