Vacuum Casting vs Rapid Injection Molding
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For runs of 20 to 200 parts, vacuum casting usually suits the low end and rapid injection molding prototyping the high end, with the crossover set by part geometry
and material. Vacuum casting starts fast from a silicone mould. Injection
molding needs a tool but gives you production resin from the real process. |
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KEY FACTS ·
Vacuum casting, also called
urethane casting, makes parts from silicone moulds taken from a master
pattern. ·
Rapid injection molding makes
parts from a metal tool in production plastics. ·
HLH Prototypes Co LTD offers a
minimum order quantity of 1 for prototypes, typically rising to 100,000
parts. ·
Silicone moulds wear with use, so
vacuum casting suits short runs. |
When
does vacuum casting make sense?
Vacuum casting makes sense when you need a small batch of
good-looking parts quickly and the design may still change. A master pattern is
made first, often by 3D printing or CNC, and a silicone mould is cast around
it.
Resin is poured under vacuum, which draws out air bubbles and helps
it reach fine detail. The trade-off is mould life: silicone wears, and how many
parts one mould yields depends on geometry and resin.
When
is rapid injection molding the better choice?
Rapid injection molding is the better choice when you need
production plastics, tight repeatability or a count at the upper end of your
range. The tool is made faster than a full production tool, and parts come from
the real moulding process, so you test genuine material behaviour.
The cost is the up-front tool and a longer start. Late design
changes are harder once the cavity is cut.
How
do the two methods compare?
The table shows the main trade-offs. Exact figures vary by part, so
treat it as a guide, not a quote.
|
Factor |
Vacuum casting |
Rapid injection
molding |
|
Tooling |
Silicone
mould |
Metal
tool |
|
Best part count |
Lower
end of 20 to 200 |
Upper
end and beyond |
|
Material |
Urethane
resins |
Production
thermoplastics |
|
Design changes |
Cheap
and quick |
Costlier
once cut |
|
Repeatability |
Drifts
as mould wears |
Consistent
across the run |
How
should you decide for your project?
Start with the material. If the part must be tested in a specific
production thermoplastic, choose injection molding whatever the count.
Then look at design stability. A design still being refined suits
casting, and a frozen design suits a tool. Our team can look at your drawing
and say which route fits before you commit.
Frequently
asked questions
|
Q Can vacuum cast parts look
like production parts? Yes, with the right finishing. Cast parts can be painted or made in
clear resin to resemble moulded parts. |
|
Q How many parts does one
silicone mould make? It depends on the geometry and resin, so ask us about your design.
Silicone wears faster than metal tooling. |
|
Q What do you need to send for a
quote? A 3D CAD file, the material you want and the quantity. Our team then
reviews the project. |
|
Send your drawing for a free review through our
HLH
Prototypes Co LTD contact page
and we will advise on the right process. |
Source URL: https://www.hlhprototypes.com/vacuum-casting-vs-rapid-injection-molding/

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