Vacuum casting is excellent way to make 10 to 50 of prototypes from wide range of polyurethanes, which can simulate ABS，PMMA，Rubber，PP，Nylon, etc.
RpProto provides a complete vacuum casting and urethane casting service. We have tens of vacuum casting machines, which can cast prototypes with the max dimension up to 2200mm*1200mm *1000mm.
We can accurately reproduce the prototypes with original color, over-mold, texture and geometries from the master model and components.
RpProto produces tens of thousands of high-quality prototypes by vacuum casting for customers all over the world every year. RpProto is the most competitive vacuum casting factory in China.
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What is Vacuum Casting
Urethane casting or vacuum Casting uses the original product to make a silicone mold in a vacuum, and then pours it with PU material to create a replica of the original.
Application of Vacuum Casting
Vacuum casting has a wide range of applications in various industrial fields, such as medical equipment, aviation, automotive industry, electronic products, etc. When you need a small quantity of production-quality plastic parts (from 10 to 50 sets), you should choose vacuum casting to avoid the long lead time and high cost of creating plastic injection mould tools.
These parts are used in prototypes and display models to verify the fit and function of a new design. In some instances, vacuum casting can also be used for end-use parts. Because the casting polyurethane can simulate the properties of ABS, Nylon, PP, PMMA, and soft TPE rubber.
Advantages Of Vacuum Casting
Fast turnaround
Molds can be made in a few days, depending on specification and volume.
Repeatability
Silicone molds are durable for 30 or more copies before they need replacing.
Superior surface
Cast copies are highly accurate with excellent surface texture
Lower Cost
Since silicone molds are cheaper than the tooling for injection molding
Color options
Coloring pigments can be added to the resin for a variety of color options.
Tolerances for Vacuum Casting
| Dimension | Tolerances |
|---|---|
| 0.5 – 6.00 mm | ± 0.10 mm |
| 6.00 – 30.00 mm | ± 0.20 mm |
| 30.00 – 120.00 mm | ± 0.30 mm |
| 120.00 – 400.00 mm | ± 0.50 mm |
| 400.00 – 1000.00 mm | ± 0.80 mm |
| Angular: ±0.5° | |
A shrinkage rate of 0.15 % is to be expected in general.
Example of application of tolerances:
Vacuum Casting Polyurethane
Materials used in Vacuum Casting include thermoplastics, rubbers and resins, all of which can emulate specific properties and characteristics including :Surface texture,Transparency,Rigidity,Strength,Hardness,Temperature resistance,Colour.
The materials used in Vacuum Casting can simulate the following production materials and properties:
- Rubber : high flexibility
- ABS : high rigidity and strength
- Polycarbonate and PMMA : shock resistance, translucence, high temperature resistance
- Polypropylene and HDPR : high elasticity
- Polyamide and glass filled nylon : high rigidity
- Filled ABS : fire resistance and retardance
| References | Description | Hardness (shore) | Strength （MPa） | Elongation (%) | Tg (°c) | Colour | |
|---|---|---|---|---|---|---|---|
| TRANSPARENT SYSTEM | |||||||
| Axson PX 522 HT | The same properties as PMMA, cristal PS, MABS. High transparency, Easy polishing, Good UV resistance. | 87D | 75MPa | 9% | 110°c | transparent | |
| Axson PX 521 HT | For crystal glass like parts. High transparency (water clear) , Easy polishing ,High reproduction accuracy . | 87D | 75MPa | 9% | 110°c | transparent | |
| AXSON UPX 5210 | For crystal glass like parts. High transparency, Easy polishing, High reproduction accuracy , Low shrinkage | 83D | 65 – 70 MPa | 15 – 20% | 80°c | transparent | |
| Axson PX 225 | Low viscosity for easy casting. Good impact and flexural resistance. Very easy coloring with all kind of pigments. | 80D | 70MPa | 15% | 80°c | transparent | |
| FLEXIBLE | |||||||
| Axson UPX 8400 | Rubber-Like, Easy to process and pigment, outstanding strength, low aggressiveness to silicone moulds | 20A-85A | 6-22MPa | 450-660% | 80°c | off white | |
| Hei-Cast T0387 | Cured material is transparent. Hardness in a range from Shore A 30 to 80. | 30A-80A | 1.5-40MPa | 260-300% | 60°c | Clear | |
| SPECIFIC, TECHNICAL PLASTICS | |||||||
| Hei-CAST PU8263 | Well-balanced physical properties, difficult-inflammability and excellent dimensional stability | 83D | 68MPa | 15% | 80°c | white | |
| Axson PX 330 | Conforms to FAR 25 (fire resistance) standard. Easy to use. Compliance ROHS. | 87D | 70MPa | 3% | 100°c | white | |
| HDPE – PP type | |||||||
| Axson UP5690 | High elongation, High impact resistance, no breakable, Easy processing, Good flexibility | 75-83D | 25-35MPa | 50-90% | 70°c | White/Black | |
| ABS – HIPS – FILLED PP TYPE | |||||||
| Hei-CAST PU8150 | Well-balanced physical properties, excellent cure properties and superior dimensional stability , high practical strength | 84D | 73MPa | 16% | 85°c | Amber,white and black | |
| Axson UP4280 | Easy processing, High mechanical properties, Good heat resistance up to 100°C | 81D | 84MPa | 13% | 93°c | Dark Amber | |
| Axson PX 100 | Low viscosity. Manual application possible. Long pot life. | 74D | 40MPa | 20% | 75°c | White/Black | |
| Axson PX 527 | Like ABS type or PC. Good impact and flexural resistance. Clear aspect. Can be easily coloured with CP pigments. | 80D | 73MPa | 13% | 80°c | White/Black | |
| Axson PX 223 HT | Low viscosity. Good impact resistance. High temperature resistance. Temperature stability up to 110°C. | 80D | 60MPa | 11% | >120°c | black | |
| Axson PX 245 / PX245L* | Filled.Very short demoulding time. Very rigid. Good abrasion resistance. | 85D | 85MPa | 3% | 95°c | off white | |
Transparent Materials
PX 522 HT
PMMA-LIKE
Dedicated to thin technical prototypes up to 10 mm, like lenses for headlights, traffic lights, light tubes, transparent covers, etc. Short demoulding time 4-5 minutes at 70°C. Good thermal resistance, easy to sand and polish. Withstand weather conditions. UV stable.
PX 521 HT
PMMA-LIKE
Dedicated for glass, art and decoration sectors. Could be cast with or without vacuum casting machine in 50 mm
thickness (but degas prior to cast in mould). Long working time, Easy to polish. Long term UV stability.
PX 225
ABS-LIKE
Technical transparent parts simulating polycarbonate. All parts simulating mass tinted ABS. Short demoulding time. High impact resistant. When long term ageing is required please use PX 521 HT as the best offer for UV stability.
Flexible Materials
PX 761
Rubber aspect prototype parts, seals.
The only soft PU able to withstand 100°C as a working temperature. Translucent amber colour; could be pigmented. Convenient pot life of 10 minutes.
UPX 8400
RUBBER-LIKE
Adjustable hardness Shore A 20 - 85, easy to process and pigment outstanding strength, low aggressiveness to silicone moulds. Dedicated to achieve rubber like prototype parts for all sectors of activities.
Technical Plastics
PX 234 HT
Similar to PPS or PEEK.
For all parts that have to withstand high temperatures, parts for engine compartments or household appliances. Really low viscosity, short demoulding time in 3 mm thickness. Even after final post curing it retains a nice flexibility.
PX 330
Technical parts for the aeronautical industry according to its FAR 25 certification. All parts requiring a fire-resistance rating in other markets. Rohs compliant for electrical casings.
ABS – HIPS – FILLED PP TYPE
PX 2017 HT
Used by casting for the production of prototype parts and mock-ups whose mechanical properties are close to ABS or filled PP. Thermoplastic-like resistance in temperature (TG > 180°C). Almost no change of mechanical properties after ageing under temperature. Good resistance to automotive fluids (except brake liquid). According to its exceptional compatibility with silicone moulds it’s possible to achieve easily 50 castings in a mould without deterioration.
PX 223 HT
ABS-like prototype parts for small production runs in vacuum casting machines. High chemical resistance against standard automotive fluids (except brakes fluid). Temperature stability up to 110°C after appropriate post curing.
PX 100
HIPS-aspect prototype parts. Large dimensions possible with or without vacuum casting machines. (Will be replaced by UR 845).
PX 220
Pure white resin similar to PS Choc. For all parts requiring good impact resistance even with thin sections. Easy to make resistant clips or all parts submitted to stress, as piece of working mechanisms.
ABS – HIPS – FILLED PP TYPE
PX 226
Off white resin similar to high flexural modulus ABS or ABS/PC blends. Suitable for low tension electrical equipments like casings for circuit breakers or switches as well as for House hold appliances parts; coffee machines, vacuum cleaner and casings for medical equipments. Also in long pot life version of 8 minutes for large parts.
PX 245 / PX 245 L
The only filled system of the PX range, similar to P.O.M. and filled thermoplastics as filled PA 6.6. For all parts requiring high stiffness in flexion. The right answer to mould parts for coping machines, printers and all electronic devices. Good abrasion resistance.
HDPE – PP TYPE
PX 212
PP-aspect prototype parts. Automobile interior trim, covers for household appliances. Translucent, can be pigmented in all colours.Good heat resistance.
PX 205
Similar to HDPE. For all parts with an integrated hinge, pinions, guide rails, rollers, limit stops. Long pot life, 80°C of working temperature. High abrasion and impact resistance. Low aggressiveness of silicone moulds.
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How does vacuum casting work?
1.Master Patterns
2. Positioning of the model in a box and casting of silicon
3. Mold cutting and RP model removal
4. Polyurethane or other material casting
5. Printed model with inlet to be removed
Before making the silicone mold, you need to make an master patterns, which can be made by cnc processing or 3D printing. Start making the silicone mold, and mix the silicone and curing agent evenly. The appearance of the silicone mold is a flowing liquid, and the component A is silicone. The B component is the curing agent.
Vacuum and bubble removal treatment:
After the silica gel and the curing agent are evenly stirred, perform the vacuuming to remove the bubbles. The vacuuming time should not be too long. Under normal circumstances, it should not exceed ten minutes. If the vacuuming time is too long, the silica gel will solidify immediately, resulting in a cross-linking reaction. The silica gel becomes piece by piece and cannot be painted or poured.
Painting or operation process:
The silica gel that has been evacuated and evacuated can be brushed or poured. Pour it on top of the product (Note: The product or model to be copied before pouring the silica gel must be coated with a release agent or release agent). Then apply the silica gel on the product. The application must be even. After 30 minutes, paste a layer of gauze and weft cloth to increase the strength and tensile force of the silica gel.
Production of outer mold:
The generally used method and material is to surround the mold with rubber sheets or wooden boards, and fill the mold cabinet with plaster. The other method is to use resin brushing. After applying a layer of resin, a layer of glass is pasted. Fiber cloth, brush and paste, repeat two or three layers to complete the outer mold of the mold.
The operation method of filling mold or pouring mold:
Pouring molds or perfusion molds are used for relatively smooth or simple products. There is no mold line to save labor and time, that is, to copy the product or model you want to copy, pour the vacuumed silica gel directly onto the product, and wait for the silica gel to dry and form After that, take out the product. (Note: The perfusion mold is usually made of soft silicone, so that it is easier to demold and will not damage the product in the silicone mold).
Vacuum Casting FAQs
Vacuum casting is also known as urethane casting or polyurethane casting. It is a process of producing plastic and rubber prototypes using silicone moulds.
The cost varies depending on the materials, complexity, and quantity. It consists of three parts. The cost of making master parten, the cost of making silicon mold, the cost of casting polyurethane.
Vacuum casting works in the same way that traditional injection moulding does. It needs the use of a mould tool with a part-shaped cavity, but soft silicone moulds are used.
Low cost for molds, Short lead time, A wide range of polyurethane resins available
When you need a small quantity of production-quality plastic parts (between 10 and 50 pieces), without the long lead time and hefty expense of building a plastic injection mould . Vacuum casting is suitable for making appearance prototypes, like non-mechanical end-use parts like cases and covers.
The materials used in Vacuum Casting can simulate the following production materials: Rubber, ABS, PMMA, glass filled Nylon
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