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create quick plastic prototypes using CNC precision machining

Creating Plastic Prototypes: What Are My Options?

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Prototyping is an essential phase in the product development journey that allows you to determine whether or not the design (or modifications) work the way you intend them to—before they are in the hands of your users. The rise of rapid prototyping has made it both easy and affordable to quickly iterate a plastic prototype. Today, a variety of manufacturing technologies are at your disposal for crafting plastic prototypes. Discerning which one to use and when will help you optimise your product development process.

In this article, we will go through the advantages, disadvantages and scenarios of when to use different rapid prototyping techniques effectively.


Plastic Rapid Prototyping Techniques

In this section, we take a look at the top processes you can consider for making plastic prototypes quickly.


1. 3D Printing

Additive manufacturing, also known as 3D printing, is an umbrella term encompassing a diverse array of techniques that construct three-dimensional objects layer by layer using CAD designs. At HLH Rapid, we host 6 different types of industrial 3D printing technologies. The three most popular options for plastic prototypes are: Fused Deposition Modeling (FDM), Stereolithography (SLA), and Selective Laser Sintering (SLS).


create quick plastic prototypes using 3D printing


  • FDM 3D Printing: FDM is a low-cost process and one of the quickest 3D printing technologies. The process offers many material choices and is great for early-stage prototyping when you need a quick proof of concept.
  • SLA 3D Printing: stereolithography is one of the quickest and most reliable printing technologies, known for its high resolution prototypes. The process is favoured among the medical sector and many high tech industries for accurate and precise visual models and aesthetic plastic prototypes.
  • SLS 3D Printing: while there are many printing technologies available, selective laser sintering is the preferred option among engineers for functional plastic prototypes. Parts printed by SLS have excellent mechanical properties, the most common material being nylon which is excellent for producing stiff, durable and impact resistant parts for testing.  


2. CNC Machining

Inarguably, today 3D printing is considered the preferred option for rapid plastic prototyping. However when it comes to functional plastic prototypes, CNC machining is still the main choice. CNC machining is a fast-paced and reliable technology that uses a variety of precision tools to carve out a 3D object from a block of material. Compared to 3D Printing, CNC offers more potential for threads and undercuts, tight tolerances, reduced size limitations, material options and surface finishing options.


create quick plastic prototypes using CNC precision machining


Some limitations of CNC machining is that flexible and soft plastics can be tricky to machine due to the intense machining process. Certain geometries and designs that can be achieve with 3D printing may also be near impossible with CNC prototyping. Nevertheless, so long as the geometry is suitable, CNC is our preferred method of choice for functional prototyping.


3. Vacuum Casting

Vacuum casting, also known as urethane casting, is typically used to manufacture plastic prototypes in small batches of 5 to 25 pieces, especially for objects such as casings and housings. It is a quick and cost-effective alternative to 3D printing. 


building rapid plastic prototypes using vacuum casting process


It is a very versatile plastic prototyping process as polyurethanes of different types can be moulded to create specified hardness and desired surface textures, from matte to gloss. The process also allows for additional features like metal inserts and transparent parts to be comfortably worked into the casting, as long as they are compatible with the casting stage. 

This makes it excellent for visual models and aesthetic prototypes and also for assessing form, fit and function, although the process works with looser tolerances than CNC machining.


4. Rapid Prototype Injection Moulding

An injection moulded prototype is a production-equivalent plastic part made using the same plastic material and processes that will be used in production injection moulding.

In rapid injection moulding, ‘softer’ metals like aluminium that can be machined more quickly (and therefore less expensively) are used. The process allows for complex shapes and intricate designs to be produced with high accuracy that often can’t be achieved through 3D printing or CNC machining.


create rapid plastic prototypes using rapid injection moulding


It’s almost virtually superior in all other areas. The main two disadvantages is that it is not viable for 1-off components due to the high costs involved. It’s also not as flexible option for making big modifications or design changes. This makes it less ideal for the initial stages in plastic prototyping, and is therefore only used in later pre-production stages.


Plastic Prototyping: Which Technique Should I Use?

There are many different technologies available that each have their own strengths and limitations. When determining which plastic prototyping process to use, it’s important to establish these five points:


  • The purpose of your plastic part
  • Prototyping cost
  • Quantity needed
  • Prototype lead time
  • Complexity of the part


The table below provides a summary of the advantages, disadvantages and capabilities of the top four plastic rapid prototyping techniques to guide you with your decision.


3D PrintingCNC MachiningVacuum CastingRapid Injection Moulding
Tooling CostN/AN/ALowHigh
Lead TimeHours to days3-7 days1-2 weeks≥ 2 weeks
Unit CostModerateHighHighLow
Quantities1-501-505-100100 and over
Plastic Material OptionsModerateGoodGoodExcellent
Plastic Prototyping Application
Early Stage PrototypesExcellentGoodModeratePoor
Form and Fit PrototypesModerateGoodGoodExcellent
Functional PrototypesModerateExcellentGoodExcellent


Creating Plastic Prototypes With HLH Rapid

Are you deciding between which technologies and materials to use to create plastic parts and prototypes but are unsure where to start? A good place to start is by determining the purpose of your part and then use the information in the sheet above to see which matches your needs.

For more information, drop us an email at or upload your design using our Get in Touch form, and an expert from our team will provide you with advice.

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