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Investment Casting is a manufacturing
process capable of producing intricate shapes weighing from a small
fraction up to around forty pounds or more. Some examples would be:
parts of the aerospace, gas turbine, medical appliances, machinery
components and many others: The main advantages over other process
such as fabrication, forging or extrusion is that it offers superior
quality and economics. The converted ductile iron investment casting
would provide a better quality, near net shape, improved surface finish,
elimination of most costly machining, reduction in rejected parts
and significant cost savings.
Advantages
1. Elimination of Fabrication Welds
2. Weight Reduction
3. Machining Reduction due to Near Net Shape
4. Dimensional Repeatability and Consistency
5. Integration of Complex Design Features
6. Smooth Consistent Surface Finish
Besides INVESTMENT CASTING we also have " STACK
SHELL MOLD PROCESS". This process provides you better surface
and more consistent dimension comparing to the ancient process "GREEN
SAND PROCESS". Each curing resin sand mold is joined together
to form a stack mold, then proceed for metal pouring. Because this
resin sand is quite small size, thus make the castings with very
good surface. One stack shell mold could get many castings (depend
on casting size), then you can save production cost and lead time.
For more understanding, following tables are details of all casting
processes. From the tables you could see how many advantages you
can earn by our INVESTMENT CASTING AND STACK
SHELL MOLD PROCESS.
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| Requiremen |
Green Sand |
Permanent Mold |
Die Casting |
Sand Shell and CO2-Core |
Ceramic Mold & Investment |
| Cost, large quantities |
Low |
Low |
Lowest |
Medium high |
Medium high |
| Cost, small quantities |
Lowest |
High |
Highest |
Medium high |
Medium |
| Weight, maximum |
Unlimited
(up to 1 ton) |
100 lbs. |
30 lbs. |
250 lbs. |
Over 100 lbs. |
| Tolerances, mm. (in.) |
0.304 (0.012) |
0.76 (0.03) |
0.25 (0.01) |
0.25 (0.01) |
0.076 (0.003) |
| Thinnest section, mm. (in.) |
2.54 (0.1) |
3.18 (0.125) |
0.76 (0.03) |
2.54 (0.1) |
1.27 (0.05) |
| Surface finish |
Fair |
Good |
Best |
Shell good,
CO2 Fair
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Very Good |
| Mechanical properties |
Good |
Good |
Good |
Good |
Good |
| Soundness |
Fair |
Fair to good |
Fair to good |
Fair to good |
Good |
| Complex shapes |
Fair |
Fair |
Good |
Good |
Best |
| Ease of design Change |
Best |
Poor |
Poorest |
Fair |
Fair |
| Alloys |
Unlimited |
Copper-base and lower melting alloys preferred |
Zinc, Aluminum, and lower melting alloys preferred |
Unlimited |
Unlimited |
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| Casting Requirement |
Ceramic mold |
Investment |
| Surface smoothness |
2.03 to 3.15 mµm (80
to 124 mµin.) |
1.02 to 3.18 mµm (40
to 125 mµin.) |
| Intricacy |
Excellent, but not quite equaling
investment |
Excellent |
| Ability to cast thin sections |
Excellent, 1.27 mm (0.050 in.) |
Excellent, 1.27 mm (0.050 in.) |
| Tolerances |
Good to excellent |
Excellent |
| Machining costs |
Machining greatly reduced,
but not always eliminated; an excellent near-net-shape process |
Minimum machining required;
an excellent near-net-shape process |
| Lead time |
Short |
Long |
| Casting size |
Small-to-large castings over
100 lbs. and up to 152-cm (60-in.) diameter |
Small castings |
| Alloy |
No limitations |
No limitations |
| Pattern cost |
Low |
High |
| Prototype adaptability |
Low cost |
High cost |
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