Rapid Prototype For Injection Molding Services

Prototyping is essential for manufacturing custom parts or improving an existing product design. After 2D drawings and 3D modeling, the next step is rapid prototyping. There are many reasons to consider prototype injection molding and even bigger reasons to prefer it over 3D printing.

In this 5-minute read, you’ll find detailed instructions on prototype injection molding, considerations, and the product development cycle.

What is Prototypes Injection Molding?

Prototyping is a way to have a working model of a new design that is intended to be refined further before mass production. Prototype parts are assessed for their quality, design flaws, tolerance and fittings, and undergo functional testing. Prototyping phase has to be quick, accurate, and cost-efficient. 

Prototype injection molding is a production method that offers rapid prototyping before mass production begins. Rapid prototype injection molding creates tooling which in turn makes molded parts to test the design of the part. Strictly speaking, prototype injection molding makes molded parts and prototype tooling creates the negative mold that can produce multiple injection molded parts. It is an easier and more cost-effective way of pro

What Is Prototyping Tool For Injection Molding?

prototype injection molding

Before injection molded parts can be produced, a prototype mold needs to be made. Rapid injection molding requires injection molding tooling that can prototype the intended design. Prototype molding is different from standard steel tooling and costs less. 

Rapid prototype injection molding can be made by 3D printing or using aluminum. Aluminum mold is a better choice, as 3D printed mold limits the material, part complexity, and doesn’t offer a great level of dimensional accuracy. Injection molds for prototypes are fit for a few dozen to less than 1000 mold parts and have a minimum lead time of 2 weeks. 

Prototyping Tools Vs Production Tools For Injection Molding

Prototype tooling is often confused with production tooling. In injection molding industry production tooling refers to the actual injection mold designed for mass production with the desired surface finish. Whereas, prototype molding is not as durable. Prototype molds are often made of aluminum to reduce tooling costs. Mold production for prototypes accounts for significant costs when compared to the cost of injection molded prototypes. Prototype molding is only done to ensure quality and function of the part. However, production injection molding is done for high-volume production with high-strength steel mold. 

Here’s a breakdown of the different injection molding tooling

Rapid Injection Molding

Rapid injection molding can be classified as prototype molding. Rapid tooling for injection molds is cheaper than tooling for full-scale production molds. Rapid prototype tooling can be 3D printed for plastic injection molding or made from metal for producing many samples.

Since, the goal is to refine the design, prototype plastic parts are produced in dozens and tested for consumer feedback. This is one reason, metal injection molding for rapid prototyping is used. The tooling lead time is small and the intended use of the tooling is for low-volume injection molding. 

Soft Tooling

Aluminum molds are often called soft tooling. While it is a fast mold for a limited number of parts, it can be designed for plastic injection molding for high-volume production. The underlying difference between production tooling and prototype mold is more in the design than in the mold materials.

Generally, aluminum molds with a single cavity and limited tool life are prototype molds, and molds made from the same material for thousands of pieces and one or more cavities are production molds. For many designs, the cost of 3D printing injection molds is the same as soft tooling. Similar to rapid injection molds, soft tooling is used for design verification. 

Production Tooling

Cavity Mold

Experienced engineers and consumers are often unaware of prototype mold and opt for production mold. These molds are expensive because they are made from steel, have a long tool life, and in the real world are only made when the mold design is optimized to produce the highest production volume in the shortest time.

In other words, the fastest cycle times to reduce per unit cost as a production mold is significantly more expensive. Production injection mold has a multi-cavity design (one tool can produce more than 50 parts)  and the mold is made from production-grade materials that rapidly cools to allow the next production cycle. Production molding should not be considered as a prototype mold and only be used when the design is functional and no changes are expected to the mold. 

Production Tooling

Experienced engineers and consumers are often unaware of prototype mold and opt for production mold. These molds are expensive because they are made from steel, have a long tool life, and in the real world are only made when the mold design is optimized to produce the highest production volume in the shortest time.

In other words, the fastest cycle times to reduce per unit cost as a production mold is significantly more expensive. Production injection mold has a multi-cavity design (one tool can produce more than 50 parts)  and the mold is made from production-grade materials that rapidly cools to allow the next production cycle. Production molding should not be considered as a prototype mold and only be used when the design is functional and no changes are expected to the mold. 

Document
Rapid Tooling Soft Tooling Production Tooling
Tooling Material 3D Printing Plastic / Metal Aluminum Steel
Mold Cavities Single Single Multiple
Tool Life Low (a few dozen) Low ( 100 or more) Very High (thousands)
Mold Cost $$ $$ $$$$
Lead Time 1 week 1-2 weeks 5 - 7 Weeks
Tolerances 0.2 mm 0.0762 mm Up to 0.0254 mm

When Do You Need To Use A Prototyping Tool?

Prototype molds are crucial to product development. There are many reasons to use plastic injection molding for prototypes, from being able to iterate mold design to finding out the surface finish with the final material choice. 

Design Feedback

Process Of Injection Molding Snap Fit Joints
  • Prototype molds can give you design feedback for mass production process giving you ample time to make necessary adjustments. 

  • Optimize your final mold design for large runs.

Iterative Development

  • Injection molding project requires testing. Tens of prototypes can be released to customers for feedback and changes.

  • Produce molds that are as close as possible to the final product with identical mold material, production process, and mold parts before going into production. This allows you to tweak your design and assembly if needed.

  • Quicker and more confident end product

Design Validation

  • Quickly test your product for strength, and function.

  • Manufacture small quantities of mold parts with the same parts and material choice in a short period. 

  • Efficient design reduces overall costs and achieves a quicker final product. Resulting in turnaround time savings. 

Market Testing

  • Bridge tooling is your way into beta testing prototypes and assessing the demand for your product before launch. 

  • Save on expensive steel molds that produce the same quality plastic prototype as soft tooling reducing financial risk at the beta testing stage. 

How Prototyping Injection Molding Influences Design?

prototype tooling
  • 3D models are not indicative of the actual surface finish. Plastic parts often have surface defects that can only be seen after producing through molds. Some of these flaws are sink marks and flow lines which can only be fixed post-injection molding

  • It is possible to create thin geometries in models, but these parts fail in physical testing. Injection molding has its own tolerance and plastic parts should conform to these tolerances like wall thickness. This can only be done after prototype injection molding.

  • Often part design influences material flow inside the mold. This fact is overlooked during design and prototyping injection mold ensure the final manufacturing will be smooth and fill the entire mold. 

Summary

Prototype injection molding is a way to easily create viable injection molds with minimal lead times that offer the same end-quality product, material, and design functionality for testing, research, and having a physical product for the market. Plastic prototyping services take the lead in offering a single injection mold or multiple molds simultaneously.

These molds are an important step before mass production to keep costs low and minimize loss at launch. There are three main types of tooling, 2 of which are substitutable depending on the quantity and one is intended for complete manufacturing after no more design overhauls are needed.

Author

Gavin Leo is a technical writer at Aria with 8 years of experience in Engineering, He proficient in machining characteristics and surface finish process of various materials. and participated in the development of more than 100complex injection molding and CNC machining projects. He is passionate about sharing his knowledge and experience.

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