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Urethane Casting (Vacuum Casting) Service
What is Urethane Casting (Vacuum Casting)
Urethane casting, also known as vacuum casting, is a manufacturing process that involves creating a mold of a desired part or product and then pouring a liquid material into the mold to create a solid, three-dimensional object. The process is used to create small to medium-sized quantities of parts that have a high level of detail, accuracy, and durability.
How Does Urethane Casting (Vacuum Casting) Work?

The process of urethane casting typically involves the following steps:

1.Design and create a master pattern: This is a prototype of the desired part or product that is used to create the mold.

2.Create a mold: A mold is created from the master pattern using materials such as silicone or urethane rubber. The mold is created in two or more parts to allow for easy removal of the finished product.

3.Prepare the mold: The mold is then prepared by applying a release agent to prevent the plastic material from sticking to the mold.

4.Pour the liquid material: The liquid material is poured into the mold and allowed to cure or harden. The material can be tinted or colored to match the desired color of the finished product.

5.Remove the finished product: Once the material has cured, the mold is opened and the finished product is removed.

Vacuum Casting
Features of Overmolding
Rapid Turnaround
After the molding is finished, the fastest turnaround can reach 2 days, supports mass production.
Product Quality
Urethane casting is a cost-effective and efficient way to create small to medium-sized quantities of parts or products with a high level of detail and accuracy.
Cost Saving
Urethane casting requires less labor because the process is automated in most steps, and requires no assembly work or other post-production processes, significantly increasing production efficiency.
Custom Materials
It supports the use of multiple materials in different colors, ABS, PC, PMMA, Nylon, etc.
Material Restrictions
Compared with metal products, its heat resistance is far inferior, and it will deform at a slightly higher temperature, and it is easy to burn.
Maximum and minimum part size for Urethane Casting (Vacuum Casting)
Size Metric units Imperial units
Maximum size 800*500*200mm 32*20*8inch
Min thickness 1mm 0.04inch
Minimum part volume 50mm³ 0.03inch³
Available materials for urethane casting (vacuum casting)
Here is a list of our standard urethane casting (vacuum casting) materials available through our online platform.
Urethane Casting (Vacuum Casting) Plastics
ABS POM Nylon Polycarbonate (PC)
PC/ABS PVC Polyethylene (PE) Polypropylene (PP)
Polystyrene (PS) TPU Rubber
Custom Material
The materials available on the online system may not be exhaustive of all materials available on the market. If the materials you need are not listed on the order page, please select "custom" under the material menu, and our engineers will review and purchase.
Urethane Casting (Vacuum Casting) Design Guidelines
We have summarized recommended and technically feasible values for the most common features encountered in Urethane Casting parts.
1. Wall thickness
The wall thickness of plastic parts is generally in the range of 1-5mm. Urethane Casting parts should have a uniform wall thickness throughout the part, too much variation in wall thickness can cause the material to cool at different rates, leading to sink marks, voids and warpage.
2. Draft angles
Draft angle refers to the gentle taper added to the surface of an Urethane Casting part, aligned with the direction of pull, so that the part can be removed from the mold without damage due to friction or suction. A draft of 1.5-2 degrees is usually a safe minimum for most parts.
3. Avoid sharp edges and inner corners
Sharp edges and inner corners can easily lead to deformation, defects and cracks in Urethane Casting parts. Therefore, sharp edges and inner corners need to be avoided as much as possible in the design.
4. Support ribs
Ribs are used to increase the structural integrity of a part and increase its load carrying capacity. Ribs are often used to reinforce a section wall where two section walls meet at a 90 degree angle, or where the length of a particular section is weakened by the section wall thickness. Ribs that are too thick usually cause sink marks. The bottom thickness of the ribs shall be a maximum of two-thirds the thickness of the adjacent wall.
What is injection molding?

Injection molding is a manufacturing process used to create plastic parts in large quantities. Molten plastic material is injected into a mold or cavity, which is then cooled and solidifies into the desired shape. The process involves feeding plastic pellets into a hopper, which are then heated to a molten state and injected into the mold under high pressure. This pressure ensures that the material fills the mold completely and uniformly, resulting in a high-quality finished product. Injection molding is commonly used to create products such as toys, automobile parts, packaging materials, and medical devices.

What materials can be used in injection molding?

A variety of materials can be used in injection molding, including thermoplastics, thermosets, and elastomers.

Thermoplastics: These are the most commonly used materials in injection molding, including polyethylene (PE), polypropylene (PP), polystyrene (PS), acrylonitrile-butadiene-styrene (ABS), and polyvinyl chloride (PVC).

1. Thermosets: These materials are harder, more rigid, and more heat-resistant than thermoplastics. Examples include epoxy resins and phenolic resins.

2. Elastomers: These are rubber-like materials with high elasticity and flexibility. Examples include silicone, natural rubber, and styrene-butadiene rubber (SBR).

The choice of material depends on the specific application and requirements for the finished product. Properties such as strength, durability, flexibility, heat resistance, chemical resistance, and color can be tailored by using different materials and additives in the plastic pellets. In addition, recyclable and biodegradable materials are becoming increasingly popular in injection molding as part of a sustainable production process.

What are the different types of injection molding machines?

Single-shot injection molding and multi-shot injection molding are both methods used for producing plastic parts, but they differ in the way that the plastic material is injected into the mold.

Single-shot injection molding: This is the most common method of injection molding. It involves injecting a single material into the mold, which solidifies to form the final part. The mold is typically designed to have a single cavity or multiple cavities, enabling multiple identical parts to be produced simultaneously.

Multi-shot injection molding: This method uses multiple materials to create a single part. It is also known as overmolding. Depending on the design of the mold, two or more materials can be injected into the mold in a single operation. Multi-shot injection molding allows for the creation of parts with multiple colors or materials, or for the creation of parts with rigid and flexible sections.

There are two main types of multi-shot injection molding:

1. Sequential injection molding: This involves injecting one material into the mold cavity and allowing it to partially solidify before injecting the second material. The process can be repeated with additional mold cavities to create more complex parts.

2. Co-injection molding: This involves injecting two materials simultaneously into the mold cavity. This method is typically used for creating parts with a core and skin structure, for example, plastic cups with foam insulation.

The choice of single-shot or multi-shot injection molding largely depends on the specific requirements of the part and the manufacturing process. Multi-shot injection molding is more complex and can be more expensive, but it allows for greater design flexibility and the creation of parts with multiple materials or colors.

What is the maximum injection molding capacity of a machine?

The maximum injection molding capacity of a machine depends on several factors, including the volume of the mold cavity, the shot size, and the material being used. The machine's clamping force and injection pressure also play a role in determining the maximum injection molding capacity.

Injection molding machines can range in size from small benchtop machines with a maximum injection capacity of a few grams to large machines capable of producing parts that weigh several kilograms. High-capacity, industrial-grade machines can have a maximum injection capacity of up to 60,000 grams (or 60 kilograms), depending on the manufacturer and model.

The maximum injection molding capacity of a machine is typically specified in terms of the shot size, which is the maximum volume of material that the machine can inject into the mold with a single injection stroke. The shot size can range from a few grams to several kilograms, depending on the machine's size and capacity.

It's important to note that while a machine may have a high maximum injection molding capacity, the actual production rate will depend on the complexity of the part being produced, the cycle time, and the number of cavities in the mold.