P = value of recovered scrap in dollars per net ton of scrap. This price of scrap is item 3 on the average 
cost summary illustrated on page 18. 
Y = yield of good castings in percentage of metal charged into the furnace. This is calculated from the 
formula for yield given previously. 
The easiest and most convenient way to obtain the cost of steel for individual castings is to construct 
a table each month based on market prices of metals and showing the cost of steel for various yields. After 
calculating the yield for the casting whose cost is to be determined, reference to such a table will give the cost 
of steel per net ton of good castings. This table is constructed by using the formula given above. The follow- 
ing illustrates the use of the formula for constructing the table of steel costs: 
M in the formula, which is item 2 in the cost summary on page 18, is $28.14 
L, in the formula, which is item 40 in the cost summary on page 19, 1s 10.0% 
P in the formula, which is item 3 in the cost summary on page 18, is $13.00 
} 100 X 28.14) — [13 X (100 — 10)] 
Cost of steel per net ton of good castings = (106 —+ 13. 
1644 
Cost of steel per net ton of good castings == ——— 4 13. 
By substituting values for Y (yield) from 21 to 80, the following table is the result: 
COST OF STEEL PER NET TON OF GOOD CASTINGS FOR DIFFERENT YIELDS 
Yield 
21 
Cost of Steel 
ner Net Ton 
91.30 
*1.75 
24.50 
$0.50 
16.2. 
72.90 
75 
0 
iN 
1 
6. 
RO.6G0 
3 Cost of Steel ' 
Yield | per Net Ton 
26 
dj 
58.70 
57.50 
56.30 
85.50 
t 
r 
0.91) 
Yield 
1 
s 
Cost cf Steel 
per Net Ton 
15.30. 
14.60 
14.10 
£3.40 
12.90 
2.40 
90 
40 
0. 
€ 
$ 
i 
: i Cost of Steel 
Yield per Net Ton 
66 
F 
37.90 
37.60 
37.20 
36.80 
26.50 
56.20 
5.20 
5.50 
ER) 
34.90 
34.70 
34.40 BH 
34.10 
33.80 
23.60 
ae 
The above procedure is for the regular carbon steel. The cost of allov steel is obtained by adding to 
he cost of carbon steel. the additional cost of the allovs used. 
(b) Overhead Rates 
The method of establishing overhead rates and applying them when determining the costs of individ- 
ual castings, should be standardized throughout the steel foundry industry. Uniform methods to be used by 
all the members of the industry are very essential if vast differences in costs caused bv the use of different cost 
inding methods are to be prevented. 
There are five main overhead rates to be used for calculating the cost of an individual casting, in addi- 
don to the cost of steel mentioned in the foregoing. These are: molding overhead, core overhead. cleaning 
overhead. annealing cost. and general overhead.