Using several different types of patterns, Texcast can produce investment castings for prototype or production. At Texcast it is very common to use different methods to produce patterns depending on delivery and design maturity. New designs are often prototyped to allow testing of an actual investment casting. Once this has been done, hard tooling is normally built — but not always. We produce many parts using methods other than hard tooling once parts go into production.
There is not really any difference between rapid prototyping, rapid production, direct manufacturing, and rapid manufacturing of investment castings other than which type of pattern is most appropriate to meet delivery, quality, quantity, and cost constraints. Each part configuration is unique and must be reviewed by the foundry to determine the most appropriate path.
Tooling Options
Hard Tooling
- First article samples: 4–12+ weeks depending on complexity
- Production: 2–12 weeks after first article approval
- Highest tooling expense
- Lowest per-pattern cost
- Longest tool life — hundreds of thousands of parts for simple tooling
- Best surface finish and most consistent dimensional control
Soft Tooling
- First article samples: 3–6 weeks
- Production: 2–12 weeks after first article approval
- Less costly than hard tooling
- Higher per-pattern cost due to slower cycling
- Limited tool life — depends on part complexity
- Surface finish and dimensional control not as good as hard tooling
- Typically uses a single SLA or Objet pattern to make the tooling
Individually Produced Patterns
Each casting produced requires one pattern. This method is generally used for small quantities of prototypes or rapid production. It is becoming increasingly popular as the fastest way to produce investment castings where design changes or unknown future requirements allow for higher per-piece pricing, since no tooling expense is incurred.
To produce investment castings, it is necessary to shell the pattern by coating it with a ceramic material. After shelling, the pattern must be removed completely without damaging the shell, creating a void that receives the molten metal. Wax is a foundry-friendly pattern material — it is removed by heating in an autoclave. Some RP patterns do not melt and must be burned out of the shell. Some also expand and can severely crack the shell if not hollow. The foundry's expertise helps choose the most appropriate pattern for your application.
Pattern Methods
3D Printers / Multi-Jet Modeling (MJM)
ThermoJet RP patterns are the best choice for certain part configurations where thin sections would be a problem for other pattern types. Surface finish and dimensional stability depend on part configuration.
SLA / QuickCast Stereolithography
Highest quality RP patterns from both dimensional accuracy and surface finish standpoints.
SLS / CastForm Selective Laser Sintering
Surface finish is rough (approximately 250 RMS). Dimensionally lower quality than SLA patterns.
Objet
Highest quality RP patterns from dimensional and surface finish perspective. Patterns must be hollowed out.
Z-Corp Investment Casting Pattern Material
Roughest surface finish of all RP patterns. Least consistent dimensional stability, but also the least costly of all RP pattern methods.
The most important thing to remember: get the foundry involved in your design early to allow us to advise on how to make the part friendlier for investment casting.