When is vacuum casting more suitable than injection ...

3ERP offers a wide variety of prototyping processes, from industrial-grade CNC machining to FDM 3D printing. For small volumes of plastic parts, however, businesses are often torn between injection molding &#; a commonly used process in which molten material is injected into a metal mold &#; and vacuum casting, in which more affordable silicone molds are used to create smaller quantities of plastic parts.

Injection molding and vacuum casting are both very useful processes. Both are widely used in the prototyping world, and each offers a distinct set of advantages. However, because the processes share certain similarities (both are ideal for plastic components; both use a mold with a cavity to fabricate parts, etc.) it can sometimes be difficult to choose between the two.

While it is often best to consult an expert like 3ERP for tailored advice on which manufacturing process is most suitable for a given project, there are certain factors that one can consider when coming to a decision. Getting to know these factors is the best way to understand whether injection molding or vacuum casting is the best process for your project.

What is injection molding?

Injection molding is a widely used manufacturing process in which molten material is injected into a mold. It is used to create large volumes of parts, which can be used in industries like healthcare and consumer products. Chances are you&#;ll be sitting within arms reach of an injection molded part.

The injection molding process involves heating and mixing material &#; sometimes multiple materials &#; in a barrel. The material is melted and then forced into a mold, where it cools and takes the form of the inside of the mold. By repeating this process over and over, the mold can be used to make many identical parts.

While injection molding is generally thought of as a production process, it is also feasible for prototypes. This is largely thanks to rapid tooling, a means of cheaply and quickly creating prototype molds for the injection molding process. Injection molding is, however, not ideal for very small quantities of parts, since even rapid tooling is relatively expensive.

What is vacuum casting?

Although less widely used than injection molding, vacuum casting is an interesting alternative that can be used to make small quantities of a part at a low cost.

The vacuum casting process starts with a master model, which, in 3ERP&#;s case, is created using CNC machinery. (3D printing can also be used.) This master model is then immersed in liquid silicone, which is cured, cut and separated from the master model.

The cured silicone can then be used as a mold. Casting resin is poured into the silicone mold, while the vacuum removes bubbles and air pockets to ensure a smooth finish. The resin part is cured and removed from the silicone mold, which can be reused around 20 times.

When is vacuum casting more suitable than injection molding?

Since injection molding is more widely used than vacuum casting, many businesses may not even consider the vacuum casting process for their parts. But there are certain situations in which the silicone-based process represents better value for money and potentially higher quality.

Quantity

For very large quantities of parts, it is hard to look beyond injection molding. Although the setup costs for injection molding are high (even with the use of rapid tooling), the unit costs are very low. This means that, when a business needs hundreds or thousands of copies of a part, that initial outlay on the setup is easily recouped through savings on each unit.

On the flip side, not every business needs hundreds or thousands of copies of a part. When smaller number of parts are required &#; anywhere between a handful and a hundred &#; vacuum casting may be the better option, since the setup costs are much lower.

Detail

Since its tooling is generally made from high-quality metals, injection molding allows for the creation of more detailed parts than would be possible with vacuum casting. Injection molding can therefore be the better option for highly complex parts.

For simpler parts, particularly those that only need to be made in small numbers, vacuum casting can be preferable. It&#;s not simply a cheap option though: vacuum casting can offer an exceptionally smooth surface finish, which means simple parts may look better when made using vacuum casting.

Speed & iteration

The low setup costs associated with vacuum casting have positive knock-on effects. If a design needs to be amended at any stage during manufacture, it is much easier and cheaper to alter vacuum casting molds than it is to rework or remake tooling for injection molding.

In general, this means that vacuum casting is often the better choice during the earlier stages of development. In fact, businesses often make early prototypes using vacuum casting, before creating their end-use parts or latter-stage prototypes using injection molding.

Importantly, creating molds for vacuum casting is a faster process than creating tooling for injection molding, which means time-sensitive prototyping jobs for very small volumes can often be better suited to vacuum casting. (Injection molding will be faster for larger volumes.)

Material considerations

Even if all the signs point to vacuum casting, one should remember that some prototypes &#; particularly those that will be subject to physical testing &#; need to resemble the end-use part as closely as possible.

Because of this, if a functional part will ultimately be manufactured using injection molding, it may be beneficial to create the prototype using that same process, even if the outlay is greater.

Learn more

3ERP has years of experience in both injection molding and vacuum casting. Find out more about our injection molding services or our vacuum casting servicesvacuum casting services.

Contact us for more information about either process or to discuss a potential project.

Share this blog:

Selecting the proper manufacturing method is like solving a puzzle. When you solve that puzzle, you build better parts and save money producing them.

Two methods stand out among the many available options: injection molding and vacuum casting. These manufacturing techniques offer unique advantages you must carefully weigh to bring your creations to life.

The Injection Molding Process

1. Mold Design and Fabrication: Using precision machining techniques, create a mold with two halves &#; the cavity and the core.

2. Material Preparation and Injection: Melting thermoplastic material within an extruder and putting it into the mold under high pressure.

3. Cooling and Solidification: The molten material cools and solidifies within the mold through controlled cooling channels.

4. Mold Opening and Part Ejection: Opening the mold and ejecting the finished part using ejector pins or mechanisms.

The main advantages of injection molding are:

High Production Efficiency and Speed: Injection molding enables high-volume production with fast cycle times. Once the molds are created and set up, the injection molding process can quickly produce large quantities of parts.

Superior Strength and Durability of Parts: Injection molded parts exhibit excellent mechanical properties, including strength, durability, and dimensional stability. The high-pressure injection ensures uniform material distribution, resulting in parts with consistent and reliable performance.

Wide Range of Material Options: Injection molding offers a vast selection of materials, including engineering-grade plastics such as ABS, polypropylene, polycarbonate, and nylon. These materials provide properties such as high strength, heat resistance, chemical inertness, and electrical conductivity. Additionally, specialized materials like elastomers and thermosetting plastics are readily available for specific applications.

The Vacuum Casting Process

Vacuum casting involves the following steps: 

1. Master Pattern Creation: Creating a master pattern using 3D printing or CNC machining as a basis for the silicone mold.

2. Mold Preparation: Liquid silicone rubber is poured over the master pattern and cured to create a flexible and durable silicone mold.

3. Mold Assembly and Vacuum Chamber: Assembling the silicone mold and placing it inside a vacuum chamber to remove air bubbles.

4. Casting Material and Vacuum Casting: Mixing and pouring a two-component polyurethane resin into the mold cavity under vacuum for proper filling.

5. Curing and Demolding: The curing process solidifies the material so that it takes on the shape of the mold. Once cured, the mold is opened, and the finished part is carefully removed.

The main advantages of vacuum casting are:

Cost-Effectiveness for Low-Volume Production: Vacuum casting eliminates the need for expensive metal molds used in injection molding. Instead, it utilizes silicone molds, reducing initial tooling costs. This makes vacuum casting cost-effective for producing small to medium quantities of parts or prototypes without the high upfront investment. However, these molds are typically only usable for about 30 parts before a new one needs to be used.

Design Flexibility for Complex Geometries and Overmolding: Vacuum casting allows for intricate and complex part designs, including undercuts, internal features, or overmolding. Using silicone molds enables the replication of fine details and complex geometries, providing design freedom for creative and innovative projects.

Get access to vacuum casting now. Upload your part to get a quote.
Tooling Costs

Injection Molding &#; Higher Tooling Costs and Initial Investment: Injection molding requires the creation of molds, which can be costly, especially for complex geometries or multiple cavities. The initial investment includes mold design, engineering, and precision machining. However, once the molds are created, they can be used repeatedly, reducing the cost per part over time.

Vacuum Casting &#; Reduced Tooling Costs: Vacuum casting typically uses silicone molds, which are less expensive than the metal molds used in injection molding. This reduces the initial tooling costs, making it a cost-effective solution for low-volume production.

Production Costs

Injection Molding- Production Costs for Different Volume Requirements: Injection molding materials are often more cost-effective for high-volume production runs due to economies of scale. The cost per part decreases as the production quantities increase.

Vacuum Casting- Affordable Production for Small to Medium Quantities: Vacuum casting suits small to medium production quantities. It offers cost advantages when producing limited quantities, but the molds are only usable for about 30 parts before they need to be replaced.

Production Speed

Injection Molding &#; Cycle Times and Overall Production Times: Injection molding has shorter cycles due to the high-pressure injection process and efficient cooling systems. This results in faster production rates and shorter overall production times than vacuum casting. However, it may not be as time-efficient for low-volume production runs due to the initial setup and mold fabrication processes.

Vacuum Casting &#; Longer Production Times, Shorter Setup: Vacuum casting generally has longer production times than injection molding. However, the initial setup time is often quicker.

Strength and Material Options

Injection Molding &#; Strength and Material Suitability: Injection molded parts benefit from higher material density and uniformity, resulting in superior strength and structural integrity. The high-pressure injection ensures consistent material distribution, eliminating weak points or variations. Injection molding offers various material options, including engineering-grade plastics with specific properties suitable for multiple applications.

Vacuum Casting&#;Material Limitations and Reduced Strength: Vacuum casting materials often have lower strength properties than materials used in injection molding. The casting resins used in vacuum casting are typically weaker than engineering-grade plastics. However, advancements in materials are expanding the range of options available for vacuum casting, providing improved strength characteristics.

Getting Started

Injection molding is ideal for high-volume production, with its efficiency, strength, and extensive material options. It provides reliable solutions for automotive, consumer goods, and other industries.

On the other hand, vacuum casting shines in low-volume production, offering cost-effectiveness and design flexibility for intricate, tailored creations. It thrives in prototypes and small-batch production.

Want to get started with injection molding or vacuum casting? Need some expert consultation on what manufacturing technology is right for you? Try out the MakerVerse platform and start your project today. We&#;re ready to help.

Injection molding and vacuum casting are both very useful processes. Both are widely used in the prototyping world, and each offers a distinct set of advantages. However, because the processes share certain similarities (both are ideal for plastic components; both use a mold with a cavity to fabricate parts, etc.) it can sometimes be difficult to choose between the two.

While it is often best to consult an expert like 3ERP for tailored advice on which manufacturing process is most suitable for a given project, there are certain factors that one can consider when coming to a decision. Getting to know these factors is the best way to understand whether injection molding or vacuum casting is the best process for your project.

What is injection molding?

Injection molding is a widely used manufacturing process in which molten material is injected into a mold. It is used to create large volumes of parts, which can be used in industries like healthcare and consumer products. Chances are you&#;ll be sitting within arms reach of an injection molded part.

The injection molding process involves heating and mixing material &#; sometimes multiple materials &#; in a barrel. The material is melted and then forced into a mold, where it cools and takes the form of the inside of the mold. By repeating this process over and over, the mold can be used to make many identical parts.

While injection molding is generally thought of as a production process, it is also feasible for prototypes. This is largely thanks to rapid tooling, a means of cheaply and quickly creating prototype molds for the injection molding process. Injection molding is, however, not ideal for very small quantities of parts, since even rapid tooling is relatively expensive.

What is vacuum casting?

Although less widely used than injection molding, vacuum casting is an interesting alternative that can be used to make small quantities of a part at a low cost.

The vacuum casting process starts with a master model, which, in 3ERP&#;s case, is created using CNC machinery. (3D printing can also be used.) This master model is then immersed in liquid silicone, which is cured, cut and separated from the master model.

The cured silicone can then be used as a mold. Casting resin is poured into the silicone mold, while the vacuum removes bubbles and air pockets to ensure a smooth finish. The resin part is cured and removed from the silicone mold, which can be reused around 20 times.

When is vacuum casting more suitable than injection molding?

Since injection molding is more widely used than vacuum casting, many businesses may not even consider the vacuum casting process for their parts. But there are certain situations in which the silicone-based process represents better value for money and potentially higher quality.

Quantity

For very large quantities of parts, it is hard to look beyond injection molding. Although the setup costs for injection molding are high (even with the use of rapid tooling), the unit costs are very low. This means that, when a business needs hundreds or thousands of copies of a part, that initial outlay on the setup is easily recouped through savings on each unit.

On the flip side, not every business needs hundreds or thousands of copies of a part. When smaller number of parts are required &#; anywhere between a handful and a hundred &#; vacuum casting may be the better option, since the setup costs are much lower.

Detail

Since its tooling is generally made from high-quality metals, injection molding allows for the creation of more detailed parts than would be possible with vacuum casting. Injection molding can therefore be the better option for highly complex parts.

For simpler parts, particularly those that only need to be made in small numbers, vacuum casting can be preferable. It&#;s not simply a cheap option though: vacuum casting can offer an exceptionally smooth surface finish, which means simple parts may look better when made using vacuum casting.

Speed & iteration

The low setup costs associated with vacuum casting have positive knock-on effects. If a design needs to be amended at any stage during manufacture, it is much easier and cheaper to alter vacuum casting molds than it is to rework or remake tooling for injection molding.

In general, this means that vacuum casting is often the better choice during the earlier stages of development. In fact, businesses often make early prototypes using vacuum casting, before creating their end-use parts or latter-stage prototypes using injection molding.

Importantly, creating molds for vacuum casting is a faster process than creating tooling for injection molding, which means time-sensitive prototyping jobs for very small volumes can often be better suited to vacuum casting. (Injection molding will be faster for larger volumes.)

Material considerations

Even if all the signs point to vacuum casting, one should remember that some prototypes &#; particularly those that will be subject to physical testing &#; need to resemble the end-use part as closely as possible.

Because of this, if a functional part will ultimately be manufactured using injection molding, it may be beneficial to create the prototype using that same process, even if the outlay is greater.

Learn more

3ERP has years of experience in both injection molding and vacuum casting. Find out more about our injection molding services or our vacuum casting services.

Contact us for more information about either process or to discuss a potential project.

Share this blog:

Want more information on aluminum extrusion prototype design? Feel free to contact us.

Selecting the proper manufacturing method is like solving a puzzle. When you solve that puzzle, you build better parts and save money producing them.

Two methods stand out among the many available options: injection molding and vacuum casting. These manufacturing techniques offer unique advantages you must carefully weigh to bring your creations to life.

The Injection Molding Process

1. Mold Design and Fabrication: Using precision machining techniques, create a mold with two halves &#; the cavity and the core.

2. Material Preparation and Injection: Melting thermoplastic material within an extruder and putting it into the mold under high pressure.

3. Cooling and Solidification: The molten material cools and solidifies within the mold through controlled cooling channels.

4. Mold Opening and Part Ejection: Opening the mold and ejecting the finished part using ejector pins or mechanisms.

The main advantages of injection molding are:

High Production Efficiency and Speed: Injection molding enables high-volume production with fast cycle times. Once the molds are created and set up, the injection molding process can quickly produce large quantities of parts.

Superior Strength and Durability of Parts: Injection molded parts exhibit excellent mechanical properties, including strength, durability, and dimensional stability. The high-pressure injection ensures uniform material distribution, resulting in parts with consistent and reliable performance.

Wide Range of Material Options: Injection molding offers a vast selection of materials, including engineering-grade plastics such as ABS, polypropylene, polycarbonate, and nylon. These materials provide properties such as high strength, heat resistance, chemical inertness, and electrical conductivity. Additionally, specialized materials like elastomers and thermosetting plastics are readily available for specific applications.

The Vacuum Casting Process

Vacuum casting involves the following steps: 

1. Master Pattern Creation: Creating a master pattern using 3D printing or CNC machining as a basis for the silicone mold.

2. Mold Preparation: Liquid silicone rubber is poured over the master pattern and cured to create a flexible and durable silicone mold.

3. Mold Assembly and Vacuum Chamber: Assembling the silicone mold and placing it inside a vacuum chamber to remove air bubbles.

4. Casting Material and Vacuum Casting: Mixing and pouring a two-component polyurethane resin into the mold cavity under vacuum for proper filling.

5. Curing and Demolding: The curing process solidifies the material so that it takes on the shape of the mold. Once cured, the mold is opened, and the finished part is carefully removed.

The main advantages of vacuum casting are:

Cost-Effectiveness for Low-Volume Production: Vacuum casting eliminates the need for expensive metal molds used in injection molding. Instead, it utilizes silicone molds, reducing initial tooling costs. This makes vacuum casting cost-effective for producing small to medium quantities of parts or prototypes without the high upfront investment. However, these molds are typically only usable for about 30 parts before a new one needs to be used.

Design Flexibility for Complex Geometries and Overmolding: Vacuum casting allows for intricate and complex part designs, including undercuts, internal features, or overmolding. Using silicone molds enables the replication of fine details and complex geometries, providing design freedom for creative and innovative projects.

Get access to vacuum casting now. Upload your part to get a quote.
Tooling Costs

Injection Molding &#; Higher Tooling Costs and Initial Investment: Injection molding requires the creation of molds, which can be costly, especially for complex geometries or multiple cavities. The initial investment includes mold design, engineering, and precision machining. However, once the molds are created, they can be used repeatedly, reducing the cost per part over time.

Vacuum Casting &#; Reduced Tooling Costs: Vacuum casting typically uses silicone molds, which are less expensive than the metal molds used in injection molding. This reduces the initial tooling costs, making it a cost-effective solution for low-volume production.

Production Costs

Injection Molding- Production Costs for Different Volume Requirements: Injection molding materials are often more cost-effective for high-volume production runs due to economies of scale. The cost per part decreases as the production quantities increase.

Vacuum Casting- Affordable Production for Small to Medium Quantities: Vacuum casting suits small to medium production quantities. It offers cost advantages when producing limited quantities, but the molds are only usable for about 30 parts before they need to be replaced.

Production Speed

Injection Molding &#; Cycle Times and Overall Production Times: Injection molding has shorter cycles due to the high-pressure injection process and efficient cooling systems. This results in faster production rates and shorter overall production times than vacuum casting. However, it may not be as time-efficient for low-volume production runs due to the initial setup and mold fabrication processes.

Vacuum Casting &#; Longer Production Times, Shorter Setup: Vacuum casting generally has longer production times than injection molding. However, the initial setup time is often quicker.

Strength and Material Options

Injection Molding &#; Strength and Material Suitability: Injection molded parts benefit from higher material density and uniformity, resulting in superior strength and structural integrity. The high-pressure injection ensures consistent material distribution, eliminating weak points or variations. Injection molding offers various material options, including engineering-grade plastics with specific properties suitable for multiple applications.

Vacuum Casting&#;Material Limitations and Reduced Strength: Vacuum casting materials often have lower strength properties than materials used in injection molding. The casting resins used in vacuum casting are typically weaker than engineering-grade plastics. However, advancements in materials are expanding the range of options available for vacuum casting, providing improved strength characteristics.

Getting Started

Injection molding is ideal for high-volume production, with its efficiency, strength, and extensive material options. It provides reliable solutions for automotive, consumer goods, and other industries.

On the other hand, vacuum casting shines in low-volume production, offering cost-effectiveness and design flexibility for intricate, tailored creations. It thrives in prototypes and small-batch production.

Want to get started with injection molding or vacuum casting? Need some expert consultation on what manufacturing technology is right for you? Try out the MakerVerse platform and start your project today. We&#;re ready to help.

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