1 2 . H O W T O D E T E R M I N E T H E LOWEST
COST PER CUT
changed to:
If cost per square inch is desired, figure total
To determine this you must have the following
Curve A .75 per hour
run 200 x 12.56 area equals 2,512 square
information
B .00 per hour
inches cut.
1. Overhead cost per hour.
C .00 per hour
Example `A' (continued)
2. Blade cost.
D $Blade cost only
Find 2,512 on column 7 and move horizontally
3. Hours of run time
Also the number of blades used to cut the
left to column 6.
same number of pieces increased as the
4. Number of pieces cut, or square inches
Select 159.37 on column 4, read 6.5 on
cutting rate Increased, as the blades were fed
cut
column 5, move decimal two places to the left
harder and therefore broke down sooner and
for cost of
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.065 per square inch.The following is a typical example with a sim
this also changed the total cost used.
Example `B' (continued)
plified overhead figure:
By connecting the minimum cost points on
Select column 7 as above use total cost
1. Overhead cost per hour.
each curve (Line E) a general cost trend
235.50 for column 4.
appears. That is, as overhead rates increase,
Cost of machine 00.00
Read 9.3 on column 5. move deceimal two
more economical sawing is acheived by
Cost per year for 10 year life $ 500.00
places to left for cost per square inch of
Increasing the cutting rate even though blade
7000.00
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.093.Cost per year for operator
life IS shortened.
Total 00.00
Graph 1
The only way to find the minimum costs for
Total hours worked 1 shift per yr. 2000.00
Graph 1 has been constructed by computing
your applications is to compute a chart as
more examples as above with the high speed
Simplified overhead cost per hr. $ 3.75
shown, or use this one as an average until your
steel blade, except the overhead rate has been
own shop history accumulates.
2. Blade cost (approximate for this example)
High speed steel blade .00 Example `A'
Example `B'
Carbon steel blade .00
Cost of cutting 200 pieces of 4" 4140
Example `A'
High speed steel blade
Cutting rate 4 in.2 minute*
Running time 10.5 hours
Blade cost 3 blades
.00 each 0.00 total
Example `B'
Carbon steel blade
Cutting rate .84 in.2 minute*
Running time 50 hours
Blade cost 6 blades
.00 each .00 total
Referring to the nomograph 1 select cost per
hour overhead on column 1 (3.75). Select
hours per run on column 3. Find total run
overhead on column 2.
Example `A' (continued)
$ 39.37
Total overhead
120.00
Add blade cost
9.37
Total cost
Example `B' (continued)
$ 187.50
Total overhead
48.00
Add blade cost
5.50
Total cost
NOW select total cost on column 4 and num-
ber of pieces cut on column 6. Now read cost
per cut from column 5
Example `A' (continued)
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.79Cost per cut
Example `B' (continued)
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.18
Cost per cut
*Square inches per minute
12
