The Vacuum Casting Process
Vacuum Casting is typically used to produce small numbers (usually
up to 20) of highly accurate polyurethane prototype parts.
It is a slightly slower process than SLA alone because of the
additional steps involved in the process, some of which are
manually intensive. The time to manufacture depends on the desired
characteristics of the part, with size being a key factor as this
affects the curing time of the material.
Parts are made from a single master mould, which is itself made
using an SLA master model. The mould is made from silicone rubber,
and the casting made by pouring resin into the mould in a vacuum
The result is high quality bubble free casting with blemish free
When to use Vacuum Casting
Vacuum Casting is ideal when highly accurate, functional plastic
prototype parts in very fine detail are required.
The process can replicate patterns, dimensions, profiles and
textures, and as such is widely used for produce parts for:
- functional testing such as thermal and air flow testing
- assembly line trials
- marketing purposes e.g. presentations and trade shows.
Silicone tools have a limited production life. The number of parts
that can be produced from a single silicone tool depends on one or
two factors (and often both):
#1 – The polyurethane (PU) material used, and
#2 – The geometry of the part being produced
A silicone tool running a general PU material simulating ABS will
on average yield 20-25 parts; a flexible material in the lower
Shore A range will yield 25-30 parts; and a material with a filled
content will yield around 10 parts, but could be a low as 5.
The geometry aspect is down to the part detail, normally within the
“B” surface where clip features exist, which can cause the tool to
Some inserts may be required to hold certain features and will
affect price and lead time.
Plastic material simulation
- Elastomers (Range: 25 – 95 Shore A)
- Nylon including glass filled
Vacuum Casting Benefits
As well as being a highly effective method for producing small
numbers of good quality accurate polyurethane prototype parts,
Vacuum Casting can also deliver parts with varying degrees of
flexibility or rigidity, in a wide range of colours and materials –
as well clear parts. Used in conjunction with other prototyping
technologies, vacuum Casting obviates the requirement for expensive
purpose made production tooling.
- Ideal for functional testing and/or marketing
- Cost effective
- Low volume runs
- High quality
- Fine detail and accuracy
- Range of properties can be achieved to mimic the final product
- No requirement for expensive hard tooling.