Rapid Prototyping vs Injection Molding in PLA Tensile Strength: How to Choose the Right Process for Your Project

In today's world of product design and manufacturing, there are various processes available for creating prototypes and functional parts quickly and accurately. Two of the most popular methods are rapid prototyping and injection molding. Depending on your project's specific requirements, one process may be more suitable than the other. In this blog post, we will compare and contrast these methods regarding PLA tensile strength, so you can choose the right manufacturing process for your project.

Rapid Prototyping and Its Advantages and Limitations

Rapid prototyping is an additive manufacturing method that uses 3D printers to create parts layer by layer. This process has gained immense popularity in recent years due to its speed, flexibility, and affordability compared to traditional machining methods. PLA is a popular material for rapid prototyping because it is readily available, easy to use, and produces parts with excellent surface finish and dimensional accuracy.

The most significant advantage of rapid prototyping is its ability to produce physical parts quickly, often in a matter of hours or days. This speed enables designers and engineers to iterate on designs rapidly, test their ideas, and make changes based on their results. Additionally, rapid prototyping does not require expensive tooling or molds, which significantly reduces manufacturing costs.

However, rapid prototyping also has some limitations. The main one is its relatively weak mechanical properties, making it unsuitable for functional parts that require high strength and durability. PLA, for instance, has a low tensile strength of around 50 MPa, meaning it can withstand only limited stress and strain before breaking. Moreover, rapid prototyping can be more expensive than injection molding when producing large quantities of parts.

Injection Molding and Its Advantages and Limitations

Injection molding is a subtractive manufacturing method that involves melting a thermoplastic material, such as PLA, and injecting it into a mold cavity under high pressure. Once the material cools and solidifies, the mold opens, and the part is ejected. Injection molding is renowned for its ability to create high-quality parts with excellent surface finish, precision, and consistency.

The primary advantages of injection molding are its ability to produce functional parts with high tensile strength, durability, and consistency. Injection molded parts made of PLA, for instance, have a tensile strength of around 70 MPa, making them suitable for applications that require stiffness, rigidity, and strength, including automotive, aerospace, and medical industries. Moreover, injection molding is highly scalable, making it ideal for producing large quantities of parts with tight tolerances and at low cost per unit.

The limitations of injection molding include the need for expensive tooling and lengthy lead times, particularly for new projects. Additionally, injection molding requires more setup time and expertise than rapid prototyping, making it less flexible for design changes and iterations.

Choosing the Right Manufacturing Process for Your Project

When deciding between rapid prototyping and injection molding for creating PLA parts with high tensile strength, you need to consider several factors, including:

The part's size, complexity, and geometry

The number of parts needed

The required mechanical properties (such as tensile and flexural strength)

The project's budget and timeline

The need for design flexibility and iterations

If you need to create a few complex parts quickly and with minimum setup costs, rapid prototyping may be the best option. However, if you need to produce functional parts with high mechanical properties, consistency, and scalability, injection molding may be the better choice.

In conclusion, rapid prototyping and injection molding are two excellent manufacturing processes for creating PLA parts of different shapes, sizes, and mechanical properties. Each process has its advantages and limitations, and choosing the right one depends on your project's specific requirements. By evaluating your needs and constraints carefully, you can determine the best process for your project and achieve optimal results.

rapid prototyping vs injection molding in pla tensile strength pdf

On-demand Rapid Injection Molding

Sigma’s rapid tooling service helps you to have the low volume to large volume plastic parts done, with no compromise on the material selection.

  • No MOQ required
  • Get the rapid tooling as fast as 2 weeks
  • Free DFM
  • 24/7 engineering support

Our rapid injection molding Application

Sigma Technik Limited's rapid injection molding service injects molten plastic materials into molds using injection molding machines and molds, and cools and solidifies them over a certain period of time, ultimately forming the required plastic parts. This manufacturing process is usually suitable for producing small and medium-sized plastic parts, which can obtain high-quality and precise parts in a short period of time.

Plastic Injection Molding

Injection molding is a common manufacturing process to produce low volume to large volumes of parts typically made out of plastic. The process involves injecting molten material into a mold and letting it cool to a solid-state.

Liquid Silicone Rubber Molding

Liquid Silicone Rubber is known as LSR, which is a process used to produce parts made from silicone rubber, widely used create products such as medical devices, automotive parts, baby care products, and many others.

2K Injection molding

2K injection molding is a manufacturing process in which two different types of plastic materials are molded together in a single operation to create a single homogeneous component. This process allows for efficient and cost-effective production of high-quality parts that can perform unique functions.

Overmolding and Insert Molding

Overmolding / Insert molding combines two or more materials into a single part, one of the material is usually soft and flexible, or metal. The purpose of overmolding/insert molding is to add functionality, improve grip, provide protection, or enhance aesthetics.

Mission And Vision

Rapid injection molding materials


ABS is a type of plastic with high strength, hardness, and toughness. It has good impact resistance and wear resistance, and is suitable for manufacturing shells, components, and models.


PC is a transparent, high-strength, high-temperature resistant, and excellent electrical insulation material. It is suitable for manufacturing transparent components, electronic components, and automotive components.


PP is a relatively flexible material with excellent corrosion resistance and high temperature resistance. It is suitable for manufacturing containers, pipelines, baby bottles, etc.


PA is a material with high strength, high rigidity, and wear resistance. It is suitable for manufacturing gears, bearings, brackets, etc.


POM is a material with excellent wear resistance, toughness, and rigidity. It is suitable for manufacturing gears, bearings, pulleys, etc.


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About Us

What can we do?

Sigma Technik Limited, as a prototype production company and rapid manufacturer focusing on rapid prototyping and low volume production of plastic and metal parts, has advanced manufacturing technology, one-stop service, diversified manufacturing methods, on-demand manufacturing services and efficient manufacturing processes, which can provide customers with high-quality, efficient and customized product manufacturing services and help customers improve product quality and market competitiveness.


Rapid Injection Molding Service Application

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Rapid Injection Molding FAQs

Burrs appear on the surface of the product, which affects its aesthetics and safety. The solution can be to adjust the parameters of the injection molding machine, such as temperature, pressure, speed, etc., or to perform post-processing, such as polishing, sandblasting, etc.

The warping deformation of the product is usually caused by unstable parameters such as temperature and pressure of the injection molding machine, or improper mold design. The solution can be to adjust parameters such as temperature and pressure, or to redesign the mold.

The occurrence of bubbles inside the product may be due to the high temperature of the injection molding machine and the high moisture content of the material. The solution can be to reduce the temperature of the injection molding machine, adjust the water content of the material, increase the pressure of the injection molding machine, etc.

The product size deviation is too large, which may be caused by material thermal expansion, mold deformation and other reasons. The solution can be to adjust parameters and optimize mold design based on material characteristics.