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Technical Information
1 General FAQs
2 Melting Furnaces
3 Environmental Aspects
4 Financial Support Schemes


Q1. How is gray iron graded?

Gray Iron is classified into different grades, depending upon the desired tensile strength. The IS standards for gray iron are tabulated below:

IS : 210 " 1970
(CGS UNIT)
IS : 210 " 1978
(SI UNIT)
Grade Tensile Strength
Kgf/mm²(min.)
Grade Tensile Strength
N/mm²(min.)
B H N
15 15 FG 150 150 130 " 180
20 20 FG 200 200 160 " 220
25 25 FG 220 220 180 " 220
30 30 FG 260 260 180 " 230
35 35 FG 300 300 180 " 230
40 40 FG 350 350 207 " 241


FG 400 400 207 " 270

Q2. How do I select the moulding process for my foundry?

Various factors such as castings quality, complexity of the shape, tooling costs, quantity required and capital costs need to be considered during selection of moulding process. A comparative chart of various molding processes is given in the following table.


Green Sand Precision Molding Chemically Bond Mold
Sand Casting Perm Mold Die casting Ceramic & Invest. Shell, CO2 Nobake
Typ. dimen. tol. ±.010" ±.030" ±.010" ±.050" ±.001" ±.015" ±.010" ±.020" ±.005" ±.015"
Rel. cost in qty. Low Low Lowest Highest Med. High
Rel. cost for small qty. Lowest High Highest Medium Med. High
Permiss. cast wt. Unlimit. 100 lb 75 lb oz-100 lb Shell (oz.-250 lb.)CO2 & Nobake(.5 lb-tons)
Thinnest cast sect. 1/10" 1/8" 1/32" 1/16" 1/10"
Rel. surface fin. Fair-Good Good Best V-good Shell-goodCO2-fair
Ease of casting complex design Fair-good Fair Good Best Good
Ease of designchange in production Best Poor Poorest Fair Fair
Range of alloys thatcan be cast Unlimit. Al-base & Cu-base preferr. Al-base preferr. Unlimit. Unlimit.
(Characteristics are approximate and depend upon the metal.)
*This article has been excerpted from the publication, "Casting Buyers' Guide," American Foundrymen's Society, Des Plaines, Illinois.

Q3. Which type of nobake moulding system is preferable " furan based or phenol based?

Phenol based nobake moulding system is commonly used in Indian foundries. However moulds made using phenolic binders tend to crack easily. Furan resins are easier to use especially for preparing larger moulds. Due to its advantages, furan based nobake moulding system is preferred internationally by foundry units over phenol system.

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