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When designing a casting, active participation should take place between the Design Engineer, the casting producer and the machining source. Meloon Foundries does this through direct contact with the casting buyer or with the Sales Representative.
Meloon Foundries Size Capabilities
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Tolerances and Wall Section Considerations
The chart establishes general guidelines, the type of metal and other variables that will affect the casting cost directly linked to the process.
| |
Green
Sand |
Precision
Molding |
Chemically
Bonded Molding |
| |
Sand
Casting |
Permanent
Mold Cast |
Die
Casting |
Ceramic
& Investment Casting |
Shell,
CO2 Nobake |
| Typical
Dimesional Tolerances, inches |
+/-
.010 in.
+/- .030 in. |
+/-
.010 in.
+/- .050 in. |
+/-
.010 in.
+/- .015 in. |
+/-
.010 in.
+/- .020 in. |
+/-
.005 in.
+/- .015 in. |
| Relative
Cost in Quantity |
Low |
Low |
Lowest |
Highest |
Medium
High |
| Relative
Cost for Small Number |
Lowest |
High |
Highest |
Medium |
Medium
High |
| Permissible
Weight of Casting |
Unlimited |
100
lbs. |
75
lbs. |
Oz
- 100 lbs. |
Shell:
0z-250 lbs. |
CO2
& Nobake:
0.5lbs to Tons |
| Thinnest
Section Castable, Inches |
1/10
in. |
1/8
in. |
1/32
in. |
1/16
in. |
1/10
in. |
| Relative
Surface Finish |
Fair
to Good |
Good |
Best |
Very
Good |
Shell-Good
CO2 |
| Relative
Ease of Casting Complex Design |
Fair
to Good |
Fair |
Good |
Best |
Good |
| Relative
ease of Changing Design in Production |
Best |
Poor |
Poorest |
Fair |
Fair |
| Range
of Alloys that can be Cast |
Unlimited |
Aluminum-base
and Copper-base preferable |
Aluminum-base
preferable |
Unlimited |
Unlimited |
Pattern or Tooling
A significant variable in the construction of a pattern is the determination of the shrink factor. The shrink factors vary for different metals and also the configuration of the part. The number of impressions, the gating system, the process or methodology will affect the casting cost. This is better left to the foundry and pattern maker to determine.
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Alloys
The chart provides typical mechanical properties for aluminum alloys and copper base alloys commonly cast by Meloon Foundries.
Aluminum
Alloys
| Alloy |
Temper |
Tensile
Strength (ksi) |
Elongation |
Typical
Brinell Hardness |
| Ultimate |
Yield
0.2% offset |
| 319 |
F |
27 |
18 |
2 |
70 |
| SR319 |
F |
31 |
27 |
1 |
70-80 |
| 355 |
F |
23 |
12 |
3 |
65 |
| 355 |
T-6 |
35 |
25 |
3 |
80 |
| 355 |
T-51 |
28 |
23 |
1.5 |
65 |
| 356 |
F |
24 |
18 |
6 |
40-70 |
| 356 |
T-6 |
33 |
24 |
3.5 |
70 |
| 356 |
T-51 |
25 |
20 |
2 |
60 |
| 443 |
F |
19 |
8 |
8 |
40 |
| 535 |
F |
35 |
18 |
9 |
60-90 |
| 713 |
F |
32 |
22 |
3 |
60-90 |
1. Mechanical properties are dependent on the casting process
2. Other and special alloys are available on request
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Copper
Base Alloys
Alloy
(UNS No.) |
Tensile
Strength (ksi) |
Yield
Strength with 0.5% Extension (ksi) |
Elongation
in 2 in. (%) |
Hardness
(BHN) |
| C83600 |
37 |
17 |
30 |
50-65 |
| C86300 |
119 |
83 |
18 |
225 |
| C86500 |
71 |
28 |
30 |
130 |
| C87200 |
55 |
25 |
30 |
85 |
| C87500 |
67 |
30 |
21 |
120 |
| C90300 |
45 |
21 |
30 |
60-75 |
| C90500 |
45 |
22 |
25 |
75 |
| C90700 |
44 |
22 |
20 |
80 |
| C92200 |
40 |
20 |
30 |
60-72 |
| C92600 |
44 |
20 |
30 |
65-80 |
| C92700 |
42 |
21 |
20 |
77 |
| C93200 |
35 |
18 |
20 |
60-70 |
| C93400 |
32 |
16 |
20 |
55-65 |
| C93700 |
35 |
18 |
20 |
55-70 |
| C95400 |
85 |
35 |
18 |
140 |
| C95800 |
95 |
38 |
25 |
150 |
| C97600 |
40 |
24 |
20 |
75-90 |
1. Mechanical properties are dependent on casting process
2. Other and special alloys are available on request
3. Bismuth is substituted for lead in above alloys - Alloys are lead free.
Additional information may be obtained by contacting Meloon Foundries or The Non-Ferrous Founders Society.
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Casting Design
|
| A
Between two points in same part of mold not
affected by parting plane or core |
| Specified
Dimension, in. |
Tolerances,
in |
| Up
through 6 |
+/-
0.030 |
| Over
6 |
0.0300
+/- 0.003 in/in. over 6 in. |
|
| B
Across parting
plane. A-type dimension plus following: |
| Projected
area of casting A1xA3 sq
in. |
Additional
tolerance for parting plane, in. |
| Up
through 10 |
+/-
0.020 |
| Over
10 to 49 |
+/-
0.035 |
| Over
50 to 99 |
+/-
0.045 |
| Over
100 to 249 |
+/-
0.060 |
| Over
250 to 500 |
+/-
0.090 |
|
| C
Affected by
core. A-type dimension plus following: |
| Projected
area of casting affected by core, A3 x
G sq in |
Additional
tolerance for core, in.
|
| Up
through 10 |
+/-
0.020 |
| Over
10 to 49 |
+/-
0.035 |
| Over
50 to 99 |
+/-
0.045 |
| Over
100 to 499 |
+/-
0.060 |
| Over
500 to 1000 |
+/-
0.090 |
| Over
1,000 |
consult
foundry |
|
| D
Dimension:
Draft |
| Normally,
a drawing does not show draft.
Standard foundry practice is to
"add" draft to the part. For
the amount of draft required depends
on design and type pattern. |
|
| E
Allowance for
finish |
| Maximum
dimension, in. |
Nominal
allowance, in. |
| Up
through 6 |
0.060 |
| Over
6 to 12 |
0.090 |
| Over
12 to 18 |
0.120 |
| Over
18 to 24 |
0.150 |
| Over
24 |
consult
foundry |
|
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Process Development
Producing a casting for the first time creates a certain amount of trial and error. It is a development phase and experimental. The expertise and past experience with similar casting configurations provide a guideline for the initial production. Usually the more intricate the casting design and the more drastic the change in section thickness the less predictable the casting soundness. This is why it is important to consider location of isolated heavy sections, uniform wall thicknesses and correct placement or ribs and junction design. Visual casting soundness many times is not sufficient to verify acceptability and machining the sample casting prior to production release is important.
A further classification of Non-Ferrous Alloys cast by Meloon Foundries, Inc. are shown in the following
chart:
| Aluminum
Alloys |
Copper
Base |
| Aluminum-Copper |
High
Copper |
| Aluminum-Silicon |
Brasses |
| Aluminum-Magnesium |
Bronzes |
| Aluminum-Zinc |
Copper
Nickel |
| Aluminum-Tin |
Special
Alloys |
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Rapid Prototyping
Rapid Prototyping is the developing of a temporary pattern or tooling from a 3-D computer design. This temporary tooling reduces casting time from months to days. The computer model is used as the blue-print and its dimensions to produce a model. Any rapid prototype pattern that is durable enough to withstand green sand or no bake molding can be used. There are several rapid prototyping processes and the selection depends on the application.
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