A Basic Guide to Rapid Prototyping Process

The 4 Steps of Rapid Prototyping

Step 1: Make the 3D files

The first step is to make the 3D files for the product. For this step, you can work with design offices specializing in making 3D files. It is also recommended to create 2D designs, especially if the parts need critical tolerances. You should also clearly define the specs for the project. These specs will depend on how the parts will be used and any technical limitations. Once the 3D files and specs have been made, they can be sent to a company like LEADRP that does rapid prototyping.

Step 2: Figure out the Cost 

A specialist prototyping company considers the parts’ amount and technical features and figures out how much the rapid prototyping project will cost. The features mainly include the prototypes’ materials, process, finishes, and geometry. During this costing phase, it is also possible to ensure the parts will work. The 3D files can be changed if that’s what’s needed. To give an accurate quote for a rapid prototyping project, it must have a 3D part drawing.

Step 3: Production

Once all the parts of the project have been checked and approved, production starts. If the file is complicated, making parts or sample plates is best before starting the whole rapid prototyping production process.

Step 4: Test Phase 

Once production is done, a test step ensures that the parts meet the requirements set up front. 

In general, the following are the most critical aspects of the parts:

1. The prototypes’ geometries
2. Physical and mechanical properties
3. Visual features (including color: Pantone and RAL references)
4. Dimensions (including any diameters) 
5. Rendering of the finish

This step guarantees that the final parts can execute the anticipated function. If this last step doesn’t allow the parts’ functions to be checked, the project must be worked on more. 

How Does Rapid Prototyping Work?

Rapid prototyping encompasses many manufacturing technologies, most relying on layered additive manufacturing. Nonetheless, additional technologies used for rapid prototyping include high-speed machining, casting, molding, and extrusion.

While additive layer manufacturing is the most frequent rapid prototyping process, other, more traditional processes can also be utilized to build prototypes.

Among these processes are:

Subtractive – Using milling, grinding, or turning, a chunk of material is carved to achieve the required shape.

Compressive – the process of forcing a semi-solid or liquid material into the desired shape before solidifying it, just like casting, compressive sintering, or molding.

Why is Rapid Prototyping Important?

Companies must create and launch new products more quickly to compete in today’s fast-paced consumer market. Because speedier product development and technological innovation are critical to a company’s success, rapid prototyping has emerged as the most essential component of new product development. Rapid prototyping accomplishes the following goals:

• Because it accelerates the new product development process, rapid prototyping is critical in generating successful products.
• Early-stage design/concept validation of the design’s form, fit, and function.
• Product validation in the last phase against technical requirements and business objectives.
• It enables functionality testing to validate the concept’s objectives and finalize the product specification.
• The prototype lets the end-user, client, customer, and other users try it out for themselves so that feedback can be gathered.

What are the Different Types of Rapid Prototyping Processes? 

Rapid prototyping is a group of techniques for quickly creating prototypes and testing a wide range of solutions in a short time. Let’s look at the types of rapid prototyping along with their pros and cons so that you can pick the best fit for your next project.

3D Printing or Additive Manufacturing

3D Printing or additive manufacturing is constructing a three-dimensional object from a CAD or digital 3D model. 3D Printing is like having a particular machine that can turn a digital drawing into a real part! We use a computer to design what we want to make, and then the machine adds layer upon layer of material, like plastic or powder, until the object is complete. It’s like building a tower out of blocks but with more precision and complexity.

SLA – Stereolithography 

Stereolithography (SLA) builds parts from a pool of liquid resins using a laser to cure UV-curable resin. They are ideally suited for low-end functional prototypes, patterns, molds, and production tools. SLA enables product designers and engineers to rapidly prototype items with excellent surface finish and dimensional precision.

Pros of SLA:   

• Priced reasonably.
• The surface finish is excellent for AM products.
• Mature technology with a wide range of materials.

Cons of SLA:  

• Due to its low strength compared to other AM processes, some functional testing is limited.
• Over time, resin ages and becomes brittle.
• Support structures and a slower pace are required.

SLS – Selective Laser Sintering 

SLS sinters functional pieces from polymer powder using a laser. Because of the interior porosity of SLS pieces, they are brittle but have high tensile strength. SLS offers a greater build volume and can make objects with complicated geometry and long-lasting prototypes.

The technology’s cheap cost per component, high productivity, and proven materials fit many applications, from rapid prototyping to small-batch production.

Pros of SLS:

• Long-lasting and accurate.
• There is no need for a support structure.
• Dyeing and coloring are possible.

Cons of SLS:

• The surface finish is rough with a gritty feel.
• Resin material selection is limited.
• The structure is porous and brittle.

DMLS – Sintering of Direct Metal Lasers 

DMLS is an additive manufacturing process that uses a computer-controlled, high-power laser beam to melt and fuse layers of metallic powder. Because most alloys can be used in DMLS, causing prototypes to be full-strength. If developed with manufacturability in mind, it has the potential to shift into metal injection molding when higher production is required.

Pros of DMLS:

• It can use a wide range of metal alloys.
• With Outstanding material qualities.
• Shapes and features that are difficult to create with traditional CNC machining are produced.

Cons of DMLS:

• One of the slowest processes.
• It needs a specialized manufacturer.
• Expensive post-processing.

FDM – Fused Deposition Modelling 

FDM involves melting a thermoplastic material and depositing it layer-by-layer to create a 3D part. FDM is often more affordable than SLA and can use many materials, but parts may have a rough surface finish and limited accuracy.

Pros of FDM:

• Slightly less expensive than SLA and SLS.
• It is possible to create complicated form pieces.
• ABS, polycarbonate, or PC/ABS prototype parts are made with thermoplastic resin.

Cons of FDM:

• The surface finish is moderate, with a ripple effect caused by layering.
• Layering causes low Z-axis strength.
• Suitability for functional testing is limited.

MJF – Multi Jet Fusion 

Multi-jet fusion is a powder bed fusion 3D printing process. In this process, the fusing agent binds powdered materials and then warms them to fuse them to generate 3D parts. MJF can print precise, long-lasting, stiff parts from Nylon PA11, PA12, and PP. They can also print TPU parts that are flexible.

Pros of MJF:

• One of the quickest 3d Printing.
• Because of the powder bed, no support structure is required.
• Compared to methods like SLS, it has a better surface finish and mechanical and physical properties.

Cons of MJF:

• Material options are limited.
• The surface finish is rougher than that of SLA and Polyjet.
• Expensive equipment expenditures may raise the cost of the part.

DLP – Digital Light Processing  

DLP uses a projector to cure a liquid resin into a solid part. DLP can produce high-resolution parts with a good surface finish but is often slower than other rapid prototyping methods.

Pros of DLP: 

• High-resolution parts with a good surface finish. 
• Relatively low cost.

Cons of DLP: 

• Limited to smaller parts.
• It may be slower than other methods.
• Resin materials can be more expensive.

LOM – Laminated Object Manufacturing 

LOM is a rapid prototyping process that uses a laser or knife to cut paper or plastic sheets into the shape of the part, which are then stacked and bonded layer by layer. This process is capable of producing large parts quickly and cost-effectively.

Pros of LOM:

• Low cost and fast production times.
• Capable of producing large parts.
• Wide range of material options.

Cons of LOM:

• Limited accuracy and surface finish compared to other processes.
• Limited to simple geometries.
• Parts can be brittle and require additional post-processing.

SLM – Selective Laser Melting 

SLM uses a laser to melt the metal powder into a solid object layer by layer. This process can produce complex metal parts with high accuracy and strength.

Pros of SLM:

• High accuracy and surface finish.
• Capable of producing complex geometries.
• Wide range of metal material options.

Cons of SLM:

• It limits build volume.
• More expensive than other metal 3D printing processes.
• Parts can be porous and require additional post-processing.

Binder Jetting

Binder jetting is an additive manufacturing technology that produces metal and colored plastic parts. Compared to DMLS, the cost of making metal prototypes is low.   Binder jetting involves selectively depositing a binding agent into a powder bed, where it solidifies to make a 3d part.

Pros of Binder Jetting:

• Comparably less expensive.
• Faster method.
• Metal and plastic are both available.

Cons of Binder Jetting:

• Rough surface finish.
• Functional testing at low strength is not appropriate.
• Material options are limited.

Polyjet

Polyjet employs a print head to spray layers of photopolymer resin that ultraviolet light one after other cures. The layers are extremely thin, allowing for high resolution. A gel matrix holds the material together, which is removed once the product is finished. Polyjet can produce elastomeric parts.

Pros of Polyjet:

• Costs do not have too much to print.
• It is capable of printing thin walls as well as intricate shapes.
• Both rigid and flexible materials can be used on the same part.
• Parts produced have a variety of color choices.

Cons of Polyjet:

• Low strength.
• Not appropriate for functional parts or testing.
• Outdoor usage or testing is not permitted.
• When colors are exposed to light over time, they can be yellow.

CNC Machining

CNC machining is still the best prototype process available for parts whose operation is dependent on high precision and tolerance. CNC machining is a subtractive manufacturing process. It mills and turns blocks and rods of metal and engineered plastics to produce precise and complicated products. Many different kinds of materials can be used for any purpose.

When rapid prototyping CNC parts, consider the essential features that require machining and breaking down the parts. Therefore, only the critical part of the prototype is machined.

Pros of CNC Machining:

• Excellent precision and surface finish.
• A wide range of materials is available.
• Higher strength and more appropriate for all types of functional and environmental testing.

Cons of CNC Machining:

• Geometry constraints.
• Expensive owing to the cost of setup and tooling.
• Due to the cost of equipment, in-house capabilities are severely constrained.

Vacuum Casting/Urethane Casting

Vacuum casting, also known as urethane casting, utilizes silicone molds to produce plastic and rubber parts under a vacuum. They are one of the best methods for rapid prototyping injection molding plastic parts. As a result, they are appropriate for small to medium pre-production parts that will be functionally tested.

Pros of Urethane Casting:

• There is a large variety of vacuum-casting resins available.
• Aluminum and brass in-mold inserts. 
• Make small batches of high-quality injection-molded prototype parts.

Cons of Urethane Casting:

• The surface finish of the part is determined by its post-processing.
• Shrinkage can cause thin and thick features to depart from standard tolerance.
• It wears out fast and usually only works for 30–50 parts.

Injection Molding

Injection molding is a manufacturing process for producing parts by injecting molten material into a mold. The material is usually a thermoplastic polymer that is melted and injected under high pressure into a mold cavity. The molten material then solidifies, taking on the shape of the mold cavity. Injection molding is commonly used for the production of high-volume, mass-produced parts.

Pros of Injection Molding:

• High production speed, ideal for high-volume production runs.
• Produce parts with high dimensional accuracy and consistency from part to part.
• Process a wide range of thermoplastic materials, including commodity and engineering-grade plastics.
• Produce parts with complex shapes, including features.

Cons of Injection Molding:

• It requires expensive tooling.
• Complex and costly to make changes to the design of the part.
• For small production runs, the per-part cost can be prohibitively expensive.

Types of Prototype

Prototypes are used to test different facets of a proposed design. Generally speaking, the types of prototypes can be classified into a proof-of-principle prototype, working prototype, visual prototype, user experience prototype, functional prototype, and paper prototype.

Proof-of-principle Prototype: Proof-of-principle prototype validates certain essential functional features of the proposed design. However, it typically lacks all of the functionality of the final product.

Working Prototype: A working prototype represents all or almost all of the final product’s functionality.

Visual Prototype: Visual prototype shows the proposed design’s size and look, but it is not functioning. A form study prototype is a visual prototype that emphasizes the geometric elements of a design while being less concerned with color, texture or other aspects of the final look.

User Experience Prototype: A user experience prototype depicts enough of the product’s look and functionality to be utilized for user research.

Functional Prototype: A functional prototype captures the function and look of the intended design, even if it is built using different techniques and scales from the final design.

Paper Prototype: A paper prototype is a printed or hand-drawn depiction of a software product’s user interface. Such prototypes are widely used for early software design testing and may be utilized as a part of a software walkthrough to check design decisions before more costly design work is done.

Advantages and Disadvantages of Rapid Prototyping

When building a product, rapid prototyping may make a significant impact. While rapid prototyping is a wonderful product creation technique, it has flaws. Let us look at the advantages and disadvantages of rapid prototyping.

The Advantages of Rapid Prototyping

1. It is Both Economical and Quick. 

While other prototyping processes might be expensive or time-consuming, rapid prototyping involves low-cost materials and quick turnaround. Because rapid prototyping requires little work, time, or money, everything you learn from this testing process will be worthwhile.

2. It Enables You to Test Products Thoroughly. 

Any product needs prototyping. Each iteration must be tested to identify design faults and uncover solutions to make the final product look and work better. Rapid prototyping is a terrific technique to evaluate your product since it allows you to make changes without worrying about time or money.

3. It Supports Changes. 

Rapid prototyping aims to produce and test as many different versions of your product as possible. Rapid prototyping pushes you to make minor changes to your product to enhance it in every way possible. These little changes will assist you in producing the finest viable product.

4. It Aids in Forecasting Future Costs. 

During rapid prototyping, you’ll learn about potential production issues and your product’s shortcomings early on and be able to rectify them or plan around them. Without rapid prototyping, you may uncover a problem or issue too late in the mass manufacturing phase, forcing you to make costly corrections or recall the product and start over.

The Disadvantages of Rapid Prototyping

1. It is Less Useful for More Complicated Products. 

Rapid prototyping may not be the best method for testing if the prototypes do not resemble the final product in look and functionality. For instance, a functioning prototype is tough to create if you have a physical product with many moving components (such as a new engine type) or your website or video game focuses on a unique, difficult-to-code bespoke mechanism.

2. It is More Expensive in the Beginning Phase. 

The more prototypes you test before making your product, the higher the cost of the product development process. Thorough prototyping will almost certainly save you money in the long term. Still, it will demand more capital—especially if you use new rapid prototyping technologies, which are currently not cheap.

3. It Restricts the Materials Available to You. 

While rapid prototyping helps evaluate a proof of concept, it does not indicate the final product’s strength, color, or surface finish.

Applications of Rapid Prototyping

Rapid prototyping has a wide range of applications across various industries. Here are some of the most common applications of rapid prototyping:

Product Design and Development: Rapid prototyping is commonly used in product design and development to quickly and cost-effectively create physical product models. This helps designers and engineers test and refine their designs before final production.

Manufacturing: Rapid prototyping produces small batches of parts or products, tests and optimizes assembly processes, and creates custom tooling and fixtures.

Automotive: Rapid prototyping has been utilized to generate parts and scale models for the automotive industry since the late 1980s, and it remains a significant user of the technology today. Rapid prototyping is used to create concept cars, test parts and assemblies, and produce custom tooling and fixtures.

Aerospace: The aerospace industry uses rapid prototyping to create parts and components for aircraft and spacecraft and test and optimize designs for aerodynamics and performance.

Medical and Dental: Rapid prototyping is widely used in the medical and dental industries to produce custom prosthetics, implants, and surgical instruments. It can also create anatomical models for surgical planning and training.

Education: Rapid prototyping is used in the educational field to teach design and engineering concepts and to create educational models and prototypes.

Architecture and Construction: Rapid prototyping is used in architecture and construction to create scale models of buildings and structures and test and optimize construction processes.

Rapid prototyping is a valuable tool in many industries, enabling faster and more efficient product development and manufacturing processes, improving product quality, and reducing costs.

What are the Differences between Rapid Prototyping and 3D Printing?

Rapid prototyping is not the same as 3D Printing. Although the terms are used interchangeably, they are technically distinct. Rapid prototyping is a broad term for rapidly building prototypes using computer-aided software.

Many different types of 3D printing technologies are available, and each has its own set of materials that can be used. Some 3D printing technologies, such as fused deposition modeling (FDM) or stereolithography (SLA), are limited to plastics, resins, and similar materials, while others, such as direct metal laser sintering (DMLS) or electron beam melting (EBM), can be used with metals and metal alloys.

In contrast, rapid prototyping typically involves a broader range of materials, including plastics, metals, composites, ceramics, and more. This is because rapid prototyping encompasses a range of manufacturing techniques beyond just 3D Printing, including CNC machining, injection molding, urethane casting, and more. By using a more comprehensive range of prototyping materials and manufacturing techniques, rapid prototyping allows designers and engineers to create more realistic and functional prototypes that can better simulate the properties and performance of final products.

In General, 3D Printing is an essential tool in rapid prototyping, allowing for the creation of accurate, functional prototypes quickly and efficiently. 3D Printing is just one of several quick prototyping methods and processes.

What are the Differences between CNC machining and 3D Printing?

CNC milling and 3D Printing are two different manufacturing methods, each with benefits and drawbacks. The following are some essential distinctions between them:

Process: CNC machining is a subtractive process, which means the material is taken from a larger block to manufacture a finished item or product at the beginning. 3D Printing, on the other hand, is an additive process, meaning that material is added one layer upon layer at a time to build the finished product or component.

Materials: While CNC machining can work with a wider variety of materials, such as metals, plastics, and composites, 3D Printing typically works with a narrower array of materials, such as plastics, resins, and some metals.

Accuracy: CNC machining can produce parts with extremely high levels of accuracy and precision, often within a tolerance of 0.001 inches or even more stringent requirements. Conversely, 3D Printing may not be as exact as traditional manufacturing methods, with typical tolerances ranging from 0.005″ to 0.02″.

Surface finish: although CNC machining can generate components with very smooth and precise surface finishes, 3D Printing may produce parts with rougher surfaces that may require further post-processing. Surface finish: CNC machining can produce parts with very smooth and precise surface finishes.

Cost: CNC machining may be more expensive than 3D Printing when producing smaller batches or prototype components due to the higher setup costs and longer production durations associated with the former. On the other hand, for more extensive production runs or parts that demand tight tolerances, CNC machining can be the most cost-effective option in the long run.

In general, CNC machining and 3D Printing are good rapid prototyping processes. But many factors in your project can influence the selection between CNC milling or 3D Printing. These factors include the materials, tolerances, and surface finishes that are desired, as well as the manufacturing volumes.

In Summary

Rapid prototyping creates sample parts of your product to verify component fit, function, manufacturability, appearance, and strength. It enables you to detect design defects early in the product development process and remedy them. However, the success of your rapid prototyping project mainly depends on the machine shop with whom you collaborate.

LEADRP is a leading company that offers rapid prototyping services. We have 3D Printing, urethane casting, injection molding, CNC machining, sheet metal fabrication, and rapid tooling capabilities. Our highly trained engineers and quality control specialists work together to ensure your product is completed correctly. If you need rapid prototyping services, please contact us anytime.

References

Rapid prototyping – From Wikipedia

WHAT IS RAPID PROTOTYPING? – DEFINITION, METHODS, AND ADVANTAGES – TWI Ltd.

Rapid Prototyping Guide: Pros and Cons of Rapid Prototyping – From MasterClass