Prototype Plastic Parts

preliminary injection molds

The rapid prototyping of new products makes it possible to produce durable, economical, and aesthetically-pleasing plastic molded goods. Including rapid prototype injection molding in product development can also help evaluate and eliminate unanticipated geometric or appearance issues.

Additionally, creating custom-designed prototype plastic parts can help express marketing ideas to stakeholders in a concrete manner.

Read on to learn more about prototype plastic parts and their many benefits.

What Are Prototype Plastic Parts?

Prototype plastic parts function as a representation of a final product, both in functionality and appearance.

plastic molded parts manufacturer

You can prototype plastic parts both at the preliminary and at the final design stage. The product is quickly manufactured using a traditional injection molding process. However, the molds for rapid prototype injection molding can be quite different from the tooling used for final production. It is important for the buyer to understand how the prototype mold will be made as compared to the final production mold.

The manufacture of prototype plastic parts is a big part of the product research and development phase that will help clarify the following manufacturing challenges:

Design of Tooling

You can test many of the design features of a prototype injection mold. In fact, it’s important to test a prototype’s design features, as they can help designers and engineers discover manufacturing challenges.

The prototype injection mold should:

  1. Incorporate the intended gate type and location on the part.
  2. Be made from mold materials that can test the intended mold temperatures during processing.
  3. Have the ability to keep up with the production-intended cycle times.

Remember—be cautious of prototype injection molds that are constructed using 3D printer technologies. 3D printed prototype molds are not representative of true production injection molding conditions.

Selection of Component Material


During rapid prototype injection molding, you should always use the exact type of plastic material that you will use in the final product. The purpose of prototyping is to finalize part geometries and test the function of the part, and uncover any problems that may occur during full production.

After you select the plastic material to be used, you should complete a final run of the prototype plastic parts. This final run is needed for engineering reviews, production mold making, and the formation of a production quality control plan.

Analysis of Production Costs

One of the greatest benefits of rapid injection molding is that it offers stakeholders the benefit of product analysis and helps with discovery of final production costs. For example, if your prototype plastic parts needed costly tooling, had slow production runs, or incurred long lead times, you can then make changes to fix these issues. 

The Basics of Rapid Prototype Injection Molding

Rapid prototype injection molding has become a crucial part of the engineering and design phase for components and products that need more market evaluation. The purpose of rapid injection molding is to produce a true plastic injection molded prototype part for quality reasons, yet do it with low-cost tooling methods and compressed lead times. 

Unlike 3D printed prototypes that may lack full functionality and are typically used only for visual representation, an injection molded prototype is of a much higher quality and is as functional as the final product. As a part of the final design stage, rapid prototype injection molding produces a part that can be tested for structural problems, functional deficiencies, or ergonomic issues.

When you turn to MSI Mold for rapid injection molding, our engineering team starts by creating a mold design. Our team then takes the approved mold design and loads it to our production floor. We then machine the final mold shape (typically from aircraft-grade aluminum) with our CNC machine. 

Once the mold is complete, MSI Mold starts the prototype manufacturing process by installing it into our injection molding machinery. Then, we inject hot plastic into the mold cavity under high pressure. Once filled, the plasticized resin material in the mold cools for a specific length of time to obtain proper hardness.

After the part is solidified, the mold will open and the part will be ejected from the mold. The injection molding machine cycle times can range from around 20 seconds to several minutes depending on the product’s design.

Benefits of Rapid Prototyping Plastic Parts

plastic molded parts manufacturer

Rapid prototype injection molding is a preferred method that not only helps engineers and designers confirm part quality, but also delivers real-world parts that can be market-tested before designs are considered finalized. In addition to design verification and structural validation, you can use rapid prototype injection molding to help finalize tooling designs for your long term production runs. Other benefits of making prototype plastic parts before full scale manufacturing begins include:

  • Faster & More Reliable Product Launch: Many products fail to succeed for many reasons, including costs and price miscalculations, lack of market testing, and worst of all—product failures. Rapid prototyping and market testing can reduce these challenges before a product launch.
  • Better Product Functionality & Appearance: When products are judged aesthetically based on engineering drawings and visualizations, they often fail to impress in real-world production scenarios. You can also field-test a prototype sample for functionality and aesthetics.
  • More Efficient Design Process: A prototype can actually help shorten the overall engineering and design review phases of a new product. And, when you have a prototype plastic part in hand, you can easily convince its market viability to stakeholders.
  • Reduced Tooling Costs: When manufacturers don’t prototype, they often have to rework their production tooling. If you opt for rapid prototype injection molding, you’ll find and address any challenges before you make expensive production molds. 

Rapid injection molding greatly benefits buyers of products with strict appearance requirements and functionality early in product launch phases. Before you spend extra on production tooling, contact MSI Mold for a quote rapid prototype injection molding. 

What Options Are There for Plastic Prototyping?

Rapid prototype injection molding, CNC machining, and industrial 3D printing are the most common options for plastic prototyping. Each method has its own set of advantages and disadvantages. Read on to learn more about these methods.

Rapid Prototype Injection Molding

Rapid prototype injection molding is the preferred method for products that require confirmation of geometry, functionality, and appearance. In this method, the prototype is 100% representative of the final product that will later go into production, unlike other plastic prototyping methods like CNC machining and 3D printing.

CNC Machining

There are two reasons you would use CNC machining for prototyping:

  1. When the final component has unachievable tolerances for injection molding on form and fit.
  2. If production quantities are very low.

Manufacturing companies in the medical and aerospace sectors will often CNC machine plastic components. This is because CNC machining can help meet some of their critical standards for functionality. Additionally, CNC machining can accelerate the production process for these quality-stringent industries.

Industrial 3D Printing

Industrial 3D printing, or additive manufacturing, is growing as a complementary method for product development phases. The main objective of 3D printing is to build a product replica of a 3D model. In 3D printing, you would fuse, cure, and extrude plastic filament into its final form.

While 3D printing a prototype avoids the need for making tooling, you can only use a limited range of materials, and large-scale production is not feasible. Rapid injection molding can use an endless number of plastic resin materials, color options, and surface finishes. And, when aluminum molds are used instead of steel, the cost of injection molded prototyping of even complex components is comparatively low.

Learn More From MSI Mold Today

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To learn more about the benefits and applications for rapid prototype injection molding, contact MSI Mold, an industry leader in plastic prototyping. We’ve provided top-rated engineering consultation, mold manufacturing, and production injection molding to clients in Michigan and around the United States since 2005. From product development to manufacturing, we continue to expand in talent, technology, and capacity.

When you need high-quality plastic parts, contact MSI Mold. We serve the automotive, agricultural, consumer, industrial, medical, transportation, oil and gas industries, and more.