In simple words, prototyping is the process of product design in a mockup form to precede the manufacture of the real product or process. We’ll look at this in more detail shortly, but how did we come to rapid prototyping?

Engineers have been making prototypes since time immemorial. In the past, they were using what we can call manual prototyping. The manual approach has since been replaced by advanced technologies. This transformation has enabled engineers get better results that are more cost-effective.

In this article, we are delving into the world of rapid prototyping, starting with how the process works. We will also outline the benefits and applications of rapid prototyping.

What is Rapid Prototyping?

Rapid prototyping is a method of making prototypes. It is a relatively old technique that emerged in the 1970s. Engineers manufacture prototypes to help them have a visual element of a product design.

There are varied ways of producing a prototype – CNC machining, 3D printing, and others. The specifics of the method depend on whether the technique is subtractive or additive.

Rapid prototyping is popular in many industries. Designers in automotive, aerospace, healthcare, and other industries widely use the method.

How Does Rapid Prototyping Work? (5 Steps)

There are different types or methods of rapid prototype. Whichever it is, there are usually five stages. These stages define how rapid prototyping works. The five steps of rapid prototyping are as follows:

Step 1: Vision Definition

In the first step of rapid prototyping, the goal is to understand exactly who the customer of the prototype is. At Aria Manufacturing Limited, we strive to understand the type of customer as much as possible before delving into rapid prototyping. User needs are the biggest driver of whatever design we will develop. That’s because a broad-based vision isn’t adequate for effective rapid prototyping.

At this point, it might be worthwhile to hold a sit-in or interview with the client. End-user requirements become clearer after the interaction. If a similar product exists, reviews from previous users can set the direction for a rapid prototyping project. It also prepares you for the next step of rapid prototyping.

Step 2: Identify the Main Features

Here is where the real product discovery happens. There are also several people or teams in the mix. A product manager will typically bring together a multi-faceted team. Team members could come from engineering design, manufacturing, data analytics, manufacturing, and other departments.

The goal at this stage is to define the product or prototype in terms of key features. The prototype doesn’t have to be identical to the final product. Single out one or two important features and focus on those. Those features are the biggest reason you are rapid prototyping.

Step 3: Produce or Build the Prototype

The third step entails creating the prototype. Your intention from the beginning was to solve a problem or problems for the customer. This is not the best time to incorporate fancy or visual features into the prototype. Of course, you should not lose the aspect of ease of use.

This step is usually the longest because there are various options to consider. Some popular production methods to use here are:

CNC machining
Casting
3D printing

Step 4: Share the prototype

After producing the prototype, it’s time to share it. Online connections, colleagues at work, or even family members can also get hold of the prototype. If you need more people to sample the prototype, you could post on LinkedIn or any other professional site and invite people. Get the demo to as many people as possible.

Step 5: Feedback and Iteration

Reach out to the people you shared the prototype with and ask for feedback in this last step. For the most valuable feedback, it is advisable to use open-ended questions.

At Aria Manufacturing, we have a structured way of getting feedback about our rapid prototypes. We focus on any patterns and iterate until we attain the best result. There are times when we are prompted to start the process from scratch. However, most cases are when we only need to make a few improvements.

Now that we have covered the five steps of rapid prototyping, let us look at the several types of rapid prototyping.

Different Types Of Rapid Prototyping

Choosing a rapid prototyping method is essential to the part-production process. There are several types of rapid prototyping. Each of these types is unique in terms of material compatibility, cost, and processing speed, among other elements. The options include CNC machining, vacuum casting, sheet metal prototyping, laser cutting & engraving, and 3D printing.

Remember that rapid prototyping doesn’t have to be restrained to one technique. You can create a prototype using two or more methods. Let’s now review several rapid prototyping types one by one.

CNC Machining

Parts that need to meet tight tolerances and accuracy are best manufactured using CNC machining. This subtractive process works excellently on different metals and engineering plastics. For starters, CNC machining refers to an engineering method of creating parts from rods or blocks of material (metal or engineering plastic).

CNC rapid prototyping is the ideal solution for precision prototypes. You would want to choose it if you want the prototype to feel and look closest to the real product. CNC machining for rapid prototyping is available in the form of different processes. The most popular ones are Electrical discharge machining (EDM), CNC turning, and CNC milling. The choice of either of these processes depends on the desired speed of material removal, the shape of the workpiece, and the complexity of the geometry, among others.

CNC machining may have geometry limitations and high cost, but there are reasons why it is worth the effort. The rapid prototyping method applies to a wide range of materials. It also has superior accuracy for the prototypes. The surface finish is also excellent. Advanced manufacturing processes from a top provider such as Aria Manufacturing can only make the rapid prototyping results even better.

Vacuum Casting

The other name for vacuum casting is urethane casting. It is a popular method for producing rubber and plastic parts. This process occurs in a pressurized environment. Vacuum casting occurs in three distinct steps namely master model creation, silicon tool creation, and part production.

CNC machining or 3D printing helps create the master model. To attain the desired look and texture, the part then undergoes sanding and painting. The vacuum-casted component will replicate the details of the master model. That’s why the master model must be of the highest quality.

In the second step, the master model hangs in the casting box. The machinist then pours liquid silicon around the model. After the liquid silicon has cured for up to 16 hours at 40°C, cut the mold and remove the master model. The remaining hollow space has the shape and dimensions of the master model.

The final step entails the formation of the parts. Use a funnel to pour polyurethane (PU) into the mold. Like in the previous step, leave this setup to cure. The temperature in this case is about 70°C. When the curing is done, remove the part. Put it through post-processing if necessary.

You may wonder what specific materials are suitable for vacuum casting. Depending on the characteristics you are looking for, the materials include ABS, PMMA, PP, and PC.

Vacuum casting has several benefits as listed below:

Reduced lead times
Creation of larger components
Relatively low upfront cost
Superior surface finish

Sheet Metal Prototyping

In line with the basic definition of prototyping, sheet metal prototyping entails manufacturing a sheet metal sample. It is a process that comes before one engages full-scale production of sheet metal parts.

Sheet metal prototyping is a relatively old method. The only thing that has changed is that the process is now more advanced. Users of this rapid prototyping method prefer it for several reasons.

Users can correct the design before producing the actual sheet metal parts. It is also the perfect opportunity to remove all assumptions taken during the design stage. Sheet metal prototyping goes further to promote quality control.

Laser Cutting and Engraving

Laser cutting and laser engraving are often mentioned together. Indeed, some people even use these terms interchangeably. However, it is worthwhile to reiterate that there are differences, however little.

Laser cutting is normally used for thick materials. It can cut through the material. Laser engraving works on much thinner materials and normally only removes a small depth of the material.

Now to the role of these materials in prototypes.

Advantages

Designers need to create prototypes with the finest details. Laser cutting and engraving are ideal in the product development process. They are some of the best methods to create functional prototypes. These prototypes are almost 100% similar to the real product.

Another plus for laser cutting and engraving for prototypes is the comprehensive range of materials it covers. The methods may not be as encompassing as the CNC machining method, but they are still impressive. Common materials for laser cutting and engraving are cardboard, stainless steel, and aluminum, among others.

Some rapid prototyping methods may only work with hard materials. Laser cutting and engraving work excellently even with soft materials. You can cut or engrave materials such as paper, fabrics, and leather. This versatility is not common with many other rapid prototyping methods.

Applicable Industries

Laser cutting and engraving for prototypes are applicable in various industries. These technologies support the creation of complex geometries and designs. Some industries that use these technologies are:

- Healthcare
- Automotive
- Electronics
- Aeronautics
- Defense

Laser cutting and engraving have transformed rapid prototyping greatly. These technologies have made the process cost-effective and fast and added versatility.

But there is one more technology for rapid prototyping worth discussing – 3D printing.

3D Printing/Additive Manufacturing:

You cannot discuss rapid prototyping and fail to mention 3D printing. That’s because the concept of rapid prototypes was inspired by the additive manufacturing method. 3D printing serves the main criteria of rapid prototyping: Speed, cost, and flexibility.

There are three types of 3D printing as discussed below:

Stereolithography (SLA)

SLA is a 3D printing method that entails hardening of a photopolymer layer after layer until the complete component is formed. A photopolymer is a type of liquid plastic that is sensitive to light. This process begins with the slicing of a 3D model into tiny layers.

When a layer comes into contact with a UV laser, it hardens. Subsequent exposures of layers to the light continue the formation of the model. When all the layers form, a 3D model emerges. After cleaning and further curing, the prototype is ready.

SLA is an effective method for creating tiny and intricate prototypes. An alternative method such as CNC machining may not be as effective in creating such prototypes for production parts. Check industries such as medical and jewelry. You will most likely find SLA as the prominent rapid prototyping method for prototypes.

Selective Laser Sintering (SLS)

Selective laser sintering is another additive manufacturing method that builds prototypes through fusion. Instead of plastic, this technique uses a special polymer powder. A laser fuses the layers until the 3D product is formed.

First, the system heats the build platform to near the melting point of the polymer powder. A blade spread the powder across the platform. A laser scans the area and selectively sinters. This fuses the layers. The process continues, each time the build platform is lowered and the blade spreads the powder for sintering.

When printing is complete, the operator lets the setup cool first. This could take hours. Then you can unpack the setup and clean the part.

With its high resolution and capability to produce functional prototypes, SLS is perfect for rapid prototyping. It outdoes SLA and FDM in terms of consistency of mechanical properties on the production grade parts.

Fused Deposition Modeling (FDM)

FDM is probably what comes to the minds of most people when they think about 3D printing. Like in the previous method, there is a build platform in FDM. The machine operator loads it with digital files carrying the 3D model design. The machine is capable of translating these files into physical prototypes.

The machine uses a thermoplastic spool to build the prototype. It feeds this spool to the build platform in an extrusion format. The machine carries a three-axis system that supports the movement of the extrusion head.

Layer after layer, the prototype slowly forms. The process is complete when the part has cooled. You may need to cool the setup to speed up the process if necessary.

Benefits of Rapid Prototyping

Here are several benefits of rapid prototyping:

Explore new concepts and ideas

Rapid prototyping is usually faster than conventional prototyping. It gives time to the designer to explore newer and better production ideas. Board members and other project stakeholders get the chance to see new ideas. They can give immediate feedback about the concept or idea.

Test Materials

Manufacturing partners and industrial engineers may use prototypes to evaluate the suitability of different materials. Identifying the most suitable material for a product using functional prototypes can aid in preventing product flaws and failures when it matters the most.

Rapid Prototyping Reduces Cost

The workflow in rapid prototyping is simple. The majority of the cost is related to equipment monitoring and maintenance. Some prototyping methods are cheaper than others. Note also that as you scale up, the cost tends to reduce.

Rapid Prototyping Saves Time

Rapid prototyping promotes speedy product design and development. Through this process, engineers can send digital designs for physical prototype production. For instance, for a 3D printing service, only design instructions and a sliced file are required. Within a few hours, the model is ready.

Eliminating the Risk of Product Failure

Another advantage of rapid prototyping is that it prevents costly product failure early in the development process. With this method, developers can dodge mistakes. It is a proactive measure that identifies and prevents possible manufacturing problems before full-scale manufacturing. This advantage can be particularly significant for large parts.

Minimize development costs on iterations

Rapid prototyping emphasizes prompt product testing and improvement of ideas. By identifying areas of improvement or refinement early in the product design process, you can make the necessary changes. This helps avoid last-minute adjustments that can be significantly costlier.

When should rapid prototyping be used?

As seen above, rapid prototyping has many benefits. However, it is important to know the best time to use the process. The following instances are when we consider this process most relevant:

After the Early Stages of the Design

During the initial stages of product design, you are defining the problem and understanding customer needs. It is a stage for getting a clear direction regarding the product. Once you are through this stage, you can introduce rapid prototypes. Prototypes will then help you get feedback and validate any assumptions you have.

Tight Schedules

Sometimes, a manufacturing company faces tight deadlines. Despite this, the product must be profitable and meet client expectations. With its swift iterative process and adaptation, rapid prototyping can help.

Stakeholder Engagement

Rapid prototypes provide a means to communicate with stakeholders. Functional prototypes are tangible and demonstrable. Different members of a company can therefore meet at this point and have a common understanding about a product.

Conclusion

Any engineering product design will almost always involve prototypes. Prototyping helps in testing different ideas and product functionality. But this can only be effective if you follow the right steps of product prototyping.

With the above coverage of the steps, benefits, and types of rapid prototyping, you can decide the approach to take with your manufacturing partners.

Aria Manufacturing can help you build a validated product following a proven product design process. We use the concept in projects involving tight tolerances, strict timelines, complex geometries, and difficult materials.

Rapid Prototyping: Process, Types And Benefits

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