Investment casting of complex shapes

Click For Summary

Discussion Overview

The discussion revolves around the process of investment casting, specifically focusing on the creation of wax patterns for complex shapes such as impellers. Participants explore the methods of producing these patterns, including traditional and modern techniques, and the economic considerations involved.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant inquires about the economic feasibility of creating wax patterns for complex shapes like impellers using investment casting.
  • Another participant explains that complex wax patterns can be made from separate components that are melt welded together, utilizing metal or rubber molds depending on precision needs.
  • It is noted that the radial symmetry of impellers allows for identical components to be produced, reducing the number of molds required.
  • Modern techniques include 3D printing of wax patterns, although concerns are raised about the surface finish and the need for post-processing.
  • There is mention of wax filament being available for 3D printing, which can be used for creating high-quality patterns, though machining may still be necessary for critical dimensions.
  • One participant shares an anecdote about a foundry using robotics, highlighting the intersection of technology and traditional casting methods.
  • It is mentioned that 3D printers can produce small wax templates for jewelry with minimal post-processing required.
  • A participant notes that each casting requires the destruction of a wax model, which can be produced using injection molding in multi-part molds that cool quickly.

Areas of Agreement / Disagreement

Participants express a range of views on the methods and materials used for creating wax patterns, with some agreeing on the use of 3D printing while others raise concerns about surface finish and post-processing. The discussion remains unresolved regarding the best approach for economically producing complex wax patterns.

Contextual Notes

Participants mention various techniques and materials without reaching a consensus on the optimal method for creating wax patterns for investment casting. There are also references to the quality of 3D printing and its implications for the casting process, which may depend on specific applications.

GBA13
Messages
73
Reaction score
0
Hi guys,

I am learning about investment casting at the moment and have a question I would love someone to answer.

In investment casting a wax pattern needs to be created. How would that be made for a complex shape like an impeller? I've heard that lots of impellers are created using investment casting but can't work out how an impeller pattern could be economically (both time and money) in wax.

Could anyone shed some light on it?

Thanks!
 
Engineering news on Phys.org
Complex wax patterns were traditionally made from separate components melt welded together .

Individual components would be made in moulds . Usually metal moulds for precision engineering work and rubber moulds for lower precision and ornamental work .

In case of an impellor advantage would be taken of the radial symmetry of the design and the separate components would be made identical so only one or a small number of moulds would be needed .

In modern times complex patterns are often 3D printed in one piece .
 
Last edited:
Nidum said:
Complex wax patterns were traditionally made from separate components melt welded together .

Individual components would be made in moulds . Usually metal moulds for precision engineering work and rubber moulds for lower precision and ornamental work .

In case of an impellor advantage would be taken of the radial symmetry of the design and the separate components would be made identical so only one or a small number of moulds would be needed .

In modern times complex patterns are often 3D printed in one piece .
Hi Nidum,

Thanks for your reply! That's very helpful. For the 3D printing of patterns, would that not give a fairly poor surface finish which would need to be smoothed before casting? Also what sort of materials are used in printing? Do people print patterns in wax?

Thanks very much
 
There is a huge range of quality in 3D printing - and they do make wax filament for exactly this purpose. Still - for high quality finish the critical dimensions are probably machined. Impellers and also be sintered metal or forged - depending on the application.

Funny story - I had a client when I was in robotics that had a foundry. The owner could not use email, but his foundry was using robots - old ones that needed cool, clean air for the robot controllers. He had this foundry air conditioned to keep the robots runnng- cracked me up every time I went there,...
 
For each casting made, a wax model must be destroyed.
The wax models can be injection molded in a many-part mold that can be quickly cooled.
 

Similar threads

  • · Replies 2 ·
Replies
2
Views
4K
  • · Replies 6 ·
Replies
6
Views
2K
  • · Replies 18 ·
Replies
18
Views
2K
Replies
4
Views
2K
Replies
3
Views
4K
Replies
2
Views
2K
Replies
5
Views
17K
  • · Replies 8 ·
Replies
8
Views
3K
  • · Replies 4 ·
Replies
4
Views
2K
  • · Replies 13 ·
Replies
13
Views
2K