Top Rapid Prototyping Process | How to Choose? Comparison Guide

jiga rapid prototype part

Rapid prototyping process is one way that you can test out new ideas without making any long-term commitments or spending too much money upfront. With this process, you get an idea off the ground within weeks instead of months or years!

Additive and subtractive manufacturing has increased the usefulness of rapid prototyping technology. This has further lowered the cost and time it takes to make a prototype.

In this article, we listed the different manufacturing processes best suited to rapid prototyping. We also defined their advantages and disadvantages. Furthermore, we highlighted how to choose the best rapid prototyping method for each product development process.

The Rapid Prototyping Processes

At its most basic, rapid prototyping is an iterative and incremental design process that takes advantage of the ability to quickly prototype and test products. It uses CAD (computer aided design) models and data to create the physical product.

That test information is rolled over into the next iteration of the design until all of the important features are in place and any identified issues are resolved.

Rapid Prototyping in the Product Development Process
Prototyping in the Product Development Process

One of the rapid prototyping advantages is that it can be used to bring products quickly through the design and testing phase while still accurately identifying and resolving problems.

However, in order to work effectively, it relies, as you might expect, on the ability to rapidly create prototypes. Computer aided design and manufacturing (CAD/CAM) tools allow new products to be designed, built quickly, tested, and repair if needed.

To achieve that, there are a number of processes that are used in modern rapid prototyping, each with their own pros and cons.

There are a range of metal and plastic prototyping processes and we’ll be breaking down some of the most common and what their benefits and potential drawbacks are:

Stereolithography

Stereolithography, is also known as SLA or resin 3D printing. This additive manufacturing process that uses UV-curable photopolymer resin suspended in a vat above a LED screen or laser projector. 

The 3D design of the prototypes is projected onto the screen, or traced out by the laser, in layers. The UV light emitted by the screen or laser hardens the UV-curable photopolymer resin. 

Depending on the type of printer, the hardened layer is then lowered or raised so more resin is between the hardened layer and the UV source and the process is repeated, creating the object in thousands of individual layers adhered to each other.

Pros

SLA 3d printing can be used to create resin prototypes with intricate internal and external geometries as long as the part is properly internally and externally supported.

The finished product produced by an SLA printer has a far finer finish than other forms of 3D printing; it takes very little to get a newly printed and cured resin prototype to a commercial finish.

Modern SLA 3D printing is hugely economical.

Cutting edge SLA printing methods, such as Azul’s HARP, can produce large volume prints in a very short amount of time.

Cons

While flexible and damage resistant resins are on the market, resin SLA prints are normally relatively fragile and prone to breakage. 

This makes the process better suited to creation proof of concept or display models, rather than testing or engineering prototypes.

Certain UV-curable photopolymer resins will degrade if exposed to large amounts of UV light or high levels of humidity.

Selective Laser Sintering

Selective Laser Sintering (SLS) is another additive manufacturing method. It uses the sintering process, which means “to become a coherent mass by heating without melting” to fuse together layers of a powdered material using a computer-controlled CO2 laser.

Once a layer has been fused together, a roller then deposits a layer of powdered material over the sintering bed and the process begins again. 

Using the SLS 3d printing process, manufacturers can produce both large build volumes and objects with complex geometries.

Pros

The sintering process and the rigid nylon or elastomeric TPU powders commonly used in SLS printing create parts that are far more durable than SLA printing.

Parts printed by Selective Laser Sintering SLS can have the same complex internal and external geometries as SLA prints.

Cons

Because they are formed of fused powder, prototypes produced by SLS printing often have a grainy sandy finish.

Because the powdered material needs to be heated before the sintering process begins, and heated powder can’t be reused, the process is comparatively wasteful.

Direct Metal Laser Sintering

Direct Metal Laser Sintering (DMLS) uses a very similar process to SLS in which a laser is used to draw out a layered pattern onto atomized metal powder. 

The powder fuses into a layer, then more powder is placed layer by layer to fused to the first. 

DMLS process can be used with most metals and alloys and is some of the few additive manufacturing technology that can be used to create full-strength, functional testing prototypes that are constructed from the same material as the final product. 

Pros

DMLS can produce 97 percent dense, engineering-grade prototypes which can be tested as if they were the end product.

The process works with a wide range of metals and allows.

Unlike SLS, the headed metal powder can be reused, making it less wasteful.

Cons

Out of all the AM processes, DMLS is comparatively expensive and slow.

Selective Laser Melting

Selective Laser Melting (SLM), also known as Powder Bed Fusion (PBF) is similar to DMLS, but rather than sintering the powdered material together, SLM suses a electron beam or high-powder laser to actually melt the layers into the powder.

This results in a faster process, because it can be done at far higher temperatures than low temperature sintering, and more robust parts.

Pros

SLM can be used on almost any powdered material that can be melted. These include aluminum, stainless steel, copper, titanium, and cobalt chrome alloys.

The SLM process produces high-strength multifaceted prototypes. These are commonly used in the automotive, medical, defense, and aerospace industries. 

Cons

SLM is an energy-intensive process in which parts can become stressed and dislocated, jeopardizing their structural integrity.

SLM also requires the use of inert gas for its source materials which must have good flow characteristics but not be single-component metals or any specified material with poor flow qualities such as polymers, ceramics, glasses etc..

Fused Deposition Modeling

Fused Deposition Modeling (FDM) is one of the most common types of additive manufacturing technology. 

FDM printers use a heated print head that extrudes filaments of thermoplastic resin, commonly ABS or PLA or some combination of the two.

Because the process uses heat to melt together thermoplastic resins, the parts tend to be a good mix of durable. Therefore, parts produced are testable and cost-effective

Pros

Fused Deposition Modelling printing can make use of a range of thermoplastic resins.

Modern FDM printers can use multiple print heads to make prototypes from combinations of thermoplastics.

With proper support, the FDM process can make objects with complex geometries. 

Cons

The primary issue with FDM printing is that the finished product has a rough finish with visible deposition lines. Additional post processing needs to be used to get these prototypes to an acceptable finish.

Polyjet

The Polyjet process uses fine sprays of photopolymer resin that are hardened into distinct layers using a UV light. 

Because of the very fine sprayed layer by layer, this printing process can produce results with high levels of resolution.

During the printing process, the part is supported in a gel matrix which is removed after the process is complete. 

Pros

The Polyjet process can be used to create elastomeric parts with rubber-like properties.

Prototypes can be printed in multiple colors. 

Over molded parts can be printed with complex geometries.

The Polyjet printing process is moderately cost-effective.

Cons

Parts have limited strength, around as durable as SLA, and are not useful for functional testing.

Because of its specificity, Polyjet manufacturing isn’t able to offer any insight into the end product manufacturing stage.

Laminated Object Manufacturing

Laminated Object Manufacturing technology is a 3D printing method that originally developed by Helisys Inc. There are many materials that can be laminated, but paper is the most common. Paper gets glued together layer by layer using adhesive-coated sheets to create a finished product.

Pros

LOM machines are useful for rapid prototyping.

Can be used to make prototypes that you might not use in the end.

Have a low price and quick production time which makes them perfect for making models quickly!

Cons

You won’t get as much detail or accuracy with Laminated Object Manufacturing. It is incapable of printing intricate geometries like lasers sintering or stereolithography.

Computer Numerically Controlled Machining

Computer Numerically Controlled Machining (CNC) is a subtractive process that uses milling tools or a lathe to cut a design from a block of material, known as a workpiece. 

CNC machining is generally used to create plastic or metal prototypes that need to be significantly stress tested and constructed of the same materials used in the final product. 

This process is most commonly used in the automotive and aerospace industries where small machine parts need to be developed and rigorously tested to make sure they can survive under working tolerances.

Because it is not an additive manufacturing method, CNC machining can be used to make prototypes from a huge range of objects, from plastics to metals, that cannot be 3D printed.

Pros

CNC machining can be used to produce prototypes from a huge range of materials, some of which cannot be used in other manufacturing processes.

The parts produced by CNC machining are of a high quality finish.

This process can produce prototypes from the material to be used in the end product. Furthermore, the end product can be thoroughly tested under working conditions.

The process is relatively fast.

Cons

While CNC machining shops do use four and five-axis machining rigs, there are some geometry limitations to what can be constructed and undercuts can be difficult to mill.

The machinery used in CNC milling is often cost prohibitive to own in-house.

Rapid Injection Molding

Rapid Injection Molding (RIM) uses exactly the same process as traditional injection molding, injecting pressurized liquid thermoplastic resins into a specific mold. 

What sets this process apart from traditional injection molding is that the mold is often made from aluminum instead of steel.

The aluminum molds are faster to make than the steel molds used in end-product production, but wear out faster.  

Almost any liquid silicone rubber (LSR) or engineering-grade plastic can be used in injection molding. It is considered to be the industry standard for the manufacturing of plastic parts.

Injection molding is also the primary way of producing living hinges, because of the specific alignment of the molecules caused by liquid polypropylene being injected into a low thickness mold. 

Pros

RIM can be used to make prototypes from engineering-grade materials. This makes it an ideal process for making prototypes to be tested.

The finish on injection molded products is almost the same as the commercial end product will be.

Prototypes produced by RIM can be used as predictors of potential manufacturability.

Cons

Requires the tooling of molds, which is both an initial cost not found in 3D printing or CNC machining.

This adds to the length of lead in time.

How Do You Choose Which Rapid Prototyping Process to Use?

There are a number of different types of prototypes based on fidelity and the stage of development.

To make this clearer, we’ve listed the five most common types of custom prototypes. Also, we added their required primary attributes and which rapid prototype processes can be matched up with it.

TYPEDEFINITIONPRIMARY ATTRIBUTESBEST RP PROCESS
Concept prototypePrimarily used to demonstrate a particular product, either internal or as part of sales pitch. Handy for design teams to actually hold a physical version of their design and gain insights that aren’t available from a 3D design. Ideally needs to have an end-product finish and the same geometries as the 3D design, all these don’t need to be 100% accurate. If large numbers of prototypes are needed, then cost-effectiveness and speed are also important.SLA, Polyjet, and SLS printing are ideal for concept prototyping as they are low-cost processes with good resolution and objects can be printed rapidly.
Assembly prototypeIf the prototype is made from multiple parts or needs to fit into other complex components, then this type of prototype will be used to check for precise fitting and highlight any design errors. Because of this, the assembly prototype needs to be exact in its geometries.Needs to be made to exacting geometric tolerances and ideally out of the same material as the final product.Depending on the end production material, CNC machining, SLA printing, and rapid injection molding can be used to create assembly prototypes.
Testing prototypeUsed to make sure that a certain part can stand up to the working tolerances and resist the stresses it is expected to take during its working. Most testing prototypes are made from metals, engineering-grade plastics, and other durable materials.Needs to be made from the same material as the end product and need to be durable enough to withstand working stresses. CNC machining, DMLS, SLM, and injection molding are the primary rapid prototyping manufacturing processes used to create prototypes durable enough to work as testing prototypes.
Life test prototypeDesigned to test how the properties of a given material change over time the potential lifetime of a given product. These tests often include subjecting a prototype to extreme versions of expected conditions. Needs to have exactly the same dimensions and be constructed from the same materials as the proposed end product to make life testing useful.Because the geometries and materials are more important than the finish in a life test prototype, nearly all of the rapid prototyping manufacturing processes can be used to create one. However, there may be some geometric considerations that will make some processes, such as CNC machining and injection molding less suited to making certain prototypes.
Compliance prototypeUsed to test a design for its compliance with the rules set out by certain regulatory bodies, such as the U.S. Food and Drug Agency (FDA), International Standard Organization (ISO), Canadian Standards Association (CSA), and European Commission (EC).Needs to be as close to the finished product as possible to demonstrate that the proposed end product meets compliance requirements.Almost any rapid prototyping manufacturing processes can be used to create compliance prototypes.

However, since they need to mirror the finished product, processes like SLS and Polyjet are less suited than others.

Let Jiga Help You Make the Right Rapid Prototyping Choice 

The Jiga Marketplace puts you in touch with experienced manufacturing and rapid prototyping experts who can help you pick the right manufacturing process for your prototype. 

You’ll receive expert feedback on your order, without needing to place one first.

We’ll hold your money in escrow to make sure that you only pay for the parts you receive. 

With Jiga, you can quickly and efficiently nail down your rapid prototyping manufacturing needs. We can help you get back on with bringing a game changing product to market.

Book a demo with us today to find out how!

Sheet Metal Roll

Sheet Metal Gauge Chart

Sheet metal gauge (or gage) size numbers refer to the thickness of sheet metal. The higher the gauge, the thinner the sheet metal.

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Top Rapid Prototyping Process | How to Choose? Comparison Guide

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