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A Comprehensive Comparison of Compression Molding and Injection Molding

A Comprehensive Comparison of Compression Molding and Injection Molding

silicone parts compression molding workshop
Silicone Parts Compression Molding

Injection Molding VS. Compression Molding

Injection molding excels at creating intricate components, while compression molding shines in producing straightforward shapes and sizable sheets. Injection molding is highly mechanized and doesn’t demand continuous oversight from humans, whereas compression molding frequently needs manual input for loading materials and taking out finished items. Additionally, the cost of equipment is more affordable for compression molding. This article will contrast injection molding with compression molding in the context of the definition, manufacturing method, the materials employed, and the rates at which they are produced.

What is Compression Molding?

Compression molding is the process of producing silicone parts which involves shaping materials by placing a preheated plastic into a mold that has been heated. The mold is sealed with a top plug and then compressed to ensure the material reaches every part of the mold.

This method can create components of various sizes, thicknesses, and intricacies. The items it yields are also known for their strength, which makes it appealing for many sectors.

What is Injection Molding?

Injection molding is a technique for producing large quantities of uniform plastic components. It involves injecting molten plastic into a mold to form a part that matches the mold’s shape, resulting in a tangible copy of the designed plastic components. This process has been in use since the late 1800s and remains a favored method. If you observe your surroundings, you’ll find injection molded components in various places, such as the keys of your computer, the dashboard of your vehicle, etc.

The injection molding process utilizes a specific hydraulic or electric device to heat, inject, and solidify plastic into the form of a metal mold, which is then inserted into the machine.

lsr workshop
Liquid Silicone Rubber Injection Molding

Process Comparison Between Compression Molding and Injection Molding

How Does Compression Molding Work?

The process of step-by-step compression molding is as follows:

  • Make molds – Molds can be created in various methods, such as machining, die casting, or 3D printing.
  • Prepare the machine – This step varies based on the specific equipment you’re using, which might involve cleaning the mold, activating the heat, and other initial setup tasks.
  • Prepare the material – Choose the material you wish to use and calculate the right amount needed. If the material amount is too large, it will overflow from the mold, creating flash that must be cut out by hand.
  • Place the material – Put the material in the middle of the lower mold.
  • Compress the part – Seal the upper mold, apply pressure, and let the piece take shape. Some manufacturers also heat the material during compression to make it more malleable and to accelerate the production process.
  • Release the part – Take out the completed piece.
  • Clean the part – Any resin flash around the mold’s edges needs to be cut off by hand, and the part might require cleaning before it’s ready for final assembly.

How Does Injection Molding Work?

The entire process of plastic injection moulding starts by collecting the raw plastic material, which comes in the form of granules or small pellets. This material is then taken through a hopper and heated at a high temperature to melt it. Once the plastic is sufficiently melted, it is injected under pressure into either a single or a multi-part mould, allowing it to take the shape or shapes needed. After this, the plastic pieces are allowed to cool down so that they can harden and become solid. Once cooled, the mould is opened, and the newly formed plastic component is freed using various methods such as moving rods,

Materials Comparison Between Compression Molding and Injection Molding

Frequently, compression molding employs stretchy materials such as rubber and silicone, but it is also capable of creating tough composite parts through the use of SPC and BPC. On the other hand, the injection molding technique can utilize hard plastics, as well as thermoplastic elastomers and thermoplastic urethanes.

Cycle Time Comparison Between Compression Molding and Injection Molding

Generally the compression molding has longer cycle times due to its heating and curing phases, the cycle time ranges from 1 to 10 minutes. While injection molded parts can be a few seconds.

Volume Comparison Between Compression Molding and Injection Molding

Injection molding stands out as a mass production technique that surpasses all other production technologies in terms of volume. The processes involved in injection molding can be completely automated, whereas compression molding typically necessitates manual intervention for loading the material into the mold, extracting it, and carrying out the post-processing steps.

What Are the Advantages of Compression Molding Compared to Injection Molding?

Listed below are some advantages of compression molding:
1. Reduced expenses for tooling in contrast to injection molding.
2. Suitable for parts requiring high strength and durability.
3. Effective for production levels ranging from low to medium.

Listed below are some advantages of injection molding:
1. Efficient in terms of production output and consistency.
2. Equipped to create intricate shapes.
3. Ideal for mass production with uniform standards.

custom silicone part
Customized Silicone Molded Parts

What Are the Disadvantages of Compression Molding Compared to Injection Molding?

Listed below are some disadvantages of compression molding:
1. Extended production periods in contrast to injection molding.
2. Restricted to parts with basic shapes.
3. Increased material loss due to the need for trimming.

Listed below are some disadvantages of injection molding:
1. Expensive upfront costs for molds.
2. Not cost-effective for small-scale manufacturing.
3. Bound by materials suitable for melting and injection.

In Conclusion

This piece outlined the contrast between compression molding and injection molding, detailing their definitions and exploring the various characteristics of each. To learn more about compression molding and injection molding, contact a JESilicone representative.

JESilicone offers a broad spectrum of production abilities, such as compression molding, LSR injection molding and additional services that enhance value, to meet all your prototyping and man

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