Vacuum casting service

What is Vacuum casting?

Vacuum casting, sometimes referred to as Urethane Casting or Polyurethane Casting,using silicone moulds to make plastic and rubber components under vacuum. It is an extremely adaptable manufacturing process capable of mimicking the injection moulding to produce complex parts in polyurethane resins and cast nylon.

Due to the process being under vacuum, it produces high-quality bubble-free casting with smooth surface texture similar to painting effect.Vacuum casting can be extremely useful and worth considering when selecting rapid prototyping processes for plastic or rubber parts.

Advantages of Vacuum Casting

Low cost for silicone molds

Cast urethane parts are made of cheap molds, eliminating the need to invest in expensive and time-consuming metal tooling. It is a cost effective method for making high quality prototypes and low volumes of parts.
Fast delivery

Up to 50 functional cast urethane parts can be produced in 10 to 15 days when you choose vacuum casting.
A wide selection of materials

Casting resins materials range from soft and flexible to rigid and impact-resistant, as well as colored and clear.
High precision and fine details

Vacuum casting provides end-use parts of high precision and fine details with production-level quality.
Excellent surface finish

Urethane casting can provide better surface textures compared with CNC prototyping or 3D printing.

Vacuum Casting Process

There are three steps to making polyurethane vacuum cast parts: making the master pattern, making molds and casting the parts.

01 Master Patterns

Patterns are 3D solids of your CAD designs. They are usually made by CNC machining or with 3D plastic printing such as SLA/SLS. You can supply your own patterns or we can make them for you. Patterns need to be able to withstand heating to 40°C.

A master pattern can be any physical solid of your design. They are often made either by CNC machining or some form of 3D printing such as SLA. Note, however, that a pattern made from 3D printing will not be quite the same as the CNC counterpart, since the later process uses round cutting tools that cannot make very tight radius corners.

02 Making the Molds

Casting molds are made from liquid silicone. This silicone is poured around the master pattern inside of a casting box, and then allowed to cure in an oven for 16 hours. Once dried, the mold is cut open and the master removed, leaving behind an empty cavity in the exact negative shape of the original.

First the pattern must be carefully prepared, and that means sanding and sealing the surface with primer. Once it’s ready, it’s placed into a casting box and liquid silicone is poured around it. Depending on the size of the part, it can take 12~24 hours to fully cure inside of an oven. Once dried, the mold is cut open and the master removed, leaving behind an empty cavity in the exact negative shape of the original.

03 Vacuum Casting Tolerances

The finished dimensions of vacuum cast parts are dependent on the accuracy of the master pattern, the part’s geometry and the type of casting material used.

Generally a shrinkage rate of 0.15% is to be expected.

Typical technical specification

Time frame Within 24 hr – 5 working days for up to 30-50 parts

Material choice Wide variety of materials available

Accuracy ±0.3% (with a lower limit of ± 0.3 mm on dimensions smaller than 100 mm)

Minimum wall thickness To ensure that the mould is filled properly, a wall thickness of at least 0.75 mm is necessary. But best results are achieved with a recommended wall thickness of 1.5 mm

Maximum part dimensions The size of the mould is limited by the dimensions of the vacuum chamber

Typical quantities Up to 50 parts per mould

Surface structure Gloss to Matt surface finish can be obtained

Materials of vacuum casting

ABS TYPE
Vacuum casting polyurethanes resins (Transparent PU, Soft plastic PU, ABS PU, PP/PE PU, Polycarbonate PU)
Material	Supplier (Country)	Material Simulation	Strength Shore	Flexion(MPA)	TC Max	Product color description	Advantage/Disadvantage	Shrinkage
PU8150	Hei-CAST (Japan)	ABS	83 shD	1790	85	Amber,white and black	Good resistance	1
UP4280	Axson (France)	ABS	81 shD	2200	93	Dark Amber	Good resistance	1
POLYPRO TYPE
UP5690	Axson (France)	PP	75-83 shD	600--1300	70	White/Black	Good resistance	1
COLORABLE ELASTOMERS
PU8400	Hei-CAST (Japan)	Elastomer	20-90shA	/	/	Milky white/Black	Good Bend	1
T0387	Hei-CAST (Japan)	Elastomer	30-90shA	/	/	Clear	Good Bend	1
HIGH TEMPERATURE
PX 527	Hei-CAST (Japan)	PC	85 shD	2254	105	White/Black	High T℃ 105°	1
PX223HT	Hei-CAST (Japan)	PS/ABS	80 shD	2300	120	Black	IdealTG 120°	1
UL-VO
PU8263	Hei-CAST (Japan)	ABS	83 shD	1800	85	White	94V0 flame retarding	1
PX330	Axson (France)	Loaded ABS	87 shD	3300	100	Off White	V 0 far 25	1
CLEAR
PX522HT	Axson (France)	PMMA	87 shD	2100	100	Clear	Coloration TG100°	0.996
PX521HT	Axson (France)	PMMA	87 shD	2200	100	Clear	Coloration TG100°	0.996

FAQ

1.Why Use Vacuum Casting Services

Vacuum Casting is a vital element of professional rapid prototyping services and low volume production. It is a very cost-effective and efficient manufacturing process, small batches high quality similar injection molding parts are made within several days.
2.What Are Vacuum Casting Applications

Doing test of the products before starting new products development.
Attending Exhibition & Market research.
Rapid prototyping.
Low Volume Production.
Conduct propaganda new products to user.
3.What Materials Are Used In Vacuum Casting?

Vacuum Casting resins are available in various hardness and colors, depending on customer's product's requirement. In vacuum casting services, Polyurethanes(PU) is probably the most widely used type of casting resins
4.The Advantages Of Our Vacuum Casting Services

Our vacuum casting prototyping manufacturing cost is low and production time is short.
Cost effective for Low volume production. After making a master pattern and the silicone mold, it can be duplicated according to the master pattern.
Flexible de-mould operation. After the mold is dry and solidified, the mold is soft and flexible, conductive to cutting and de-mould.
Diverse material and colors for your choosing.
High quality. The defect rate is small. As long as there is no defect on the master pattern, the vacuum casting parts will not be wrong. Most of the time we have avoided it.
Good repeatability, ensure same quality and consistency.