page 467
Roughness Height ( in.)
2000 |
1000 |
500 |
250 |
125 |
63 |
32 |
16 |
8 |
4 |
2 |
1 |
0.5 |
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700 |
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600 |
curve |
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by the |
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500 |
finish designed |
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400 |
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surface |
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300 |
in cost with |
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200 |
% increase |
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100 |
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66.3 DATABASE METHODS |
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•When process planning we may use historical data to select operation parameters.
•Metcapp basically does this, it uses sampled data, and then interpolates to find a suitable speed and feed for a cut.
•A sample of a table of roughness measurements is given below [Krar],
page 468
Tool |
Operation |
Material |
speed |
feed |
tool |
cutoff |
Range |
surface |
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RMS |
cutoff saw |
sawing |
2.5” dia. Al |
320’/min |
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10 pitch saw |
0.030” |
1000 |
300-400 |
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shaper |
shaping flat |
machine steel |
100’/min |
0.005” |
3/64” rad. |
0.030” |
300 |
225-250 |
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surf. |
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HSS |
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vertical mill |
fly cutting |
machine steel |
820 rpm |
0.015” |
1/16” rad. |
0.030” |
300 |
125-150 |
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stellite |
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horizontal |
slab milling |
cast Al |
225 rpm |
2.5 “/min |
4” dia HSS |
0.030” |
100 |
40-50 |
mill |
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slab cutter |
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lathe |
turning |
2.5” dia. Al. |
500 rpm |
0.010” |
R3/64” HSS |
0.030” |
300 |
100-200 |
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turning |
2.5” dia. Al. |
500 rpm |
0.007” |
R5/64” HSS |
0.030” |
100 |
50-60 |
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facing |
2” dia. Al. |
600 rpm |
0.010” |
R1/32” HSS |
0.030” |
300 |
200-225 |
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facing |
2” dia. Al. |
800 rpm |
0.005” |
R1/32” HSS |
0.030” |
100 |
30-40 |
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filing |
0.75” dia. steel |
1200 rpm |
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10” lathe file |
0.010” |
100 |
50-60 |
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polishing |
0.75” dia. steel |
1200 rpm |
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#120 cloth |
0.010” |
30 |
13-15 |
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reaming |
Al. |
500 rpm |
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3/4” dia HSS |
0.030” |
100 |
25-32 |
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surface |
flat grinding |
machine steel |
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0.030” |
60 grit |
0.003” |
10 |
7-9 |
grinder |
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cutter/tool |
cyl. grinding |
1” machine steel |
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manual |
46 grit |
0.010” |
30 |
12-15 |
grinder |
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lapping |
flat lapping |
.87”x5.” tool steel |
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manual |
600 grit |
0.010” |
10 |
1-2 |
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cyl. lapping |
0.5” dia. tool steel |
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manual |
600 grit |
0.010” |
10 |
1-2 |
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66.4 MANUFACTURING VOLUMES
•When we are planning operations we must consider the economy of scale.
•If we are producing large volumes, we may want to produce tooling (expensive), but amortize the costs over thousands of parts (less expensive). Examples of this include,
-injection molds for thermoplastics
-molds for wax, to make investment casting molds
-progressive dies