September 23, 2020
rapid prototyping 3d printing guide cover

Rapid Prototyping – A Short Introduction

Originally rapid prototyping was used mainly in the car industry to test if new car parts were feasible back in the 1980s. Today, rapid prototyping is more accessible than ever before and is commonly used across sectors including the automotive, aerospace and medical industries.

Using 3D CAD software and a 3D printer, new prototypes can be printed, reviewed and improved on multiple times per day. 3D printing offers very flexible, accurate, fast and low-cost prototyping – allowing for more lean manufacturing and risk mitigation before any large manufacturing runs.

a 3d printer printing a prototype part
A 3D printer printing a plastic part prototype.

3D printers capable of high quality prototype 3D printing have become far more accessible and affordable in recent years, so now smaller businesses have easy access to these services.

Rapid prototyping can even be done with biomaterials to create 3D bioprinted tissues that imitate real organs and structures for drug testing and other important treatments.

What is Rapid Prototyping?

Rapid prototyping is the name that encompasses all the technologies and techniques involved in creating viable prototypes of products in record time, to review and refine. It usually involves additive manufacturing or 3D printing, though occasionally CNC machining is used.

Rapid prototyping means that you can quickly get a physical product in your hand, which is far better and easier to analyze than a CAD design on a computer screen. This is called a high fidelity prototype – one that is close in appearance and function to the final design – and with the additional testing you can conduct on a physical prototype you can find all flaws before investing in a full manufacturing run.

rapid prototyping 3d printed plastic and metal parts
A 3D printed plastic prototype for a metal part.

The Rapid Prototyping Process

Before you can 3D print your final prototype, you need a design. The 3D CAD design file of a scale model of your final product can then be imported into a 3D slicer to be sliced into layers before printing it. Sometimes 3D scanning is also used to create a model of the part to be iterated on, such as a 3D printed car part.

CNC milling is also occasionally used, but for individual, custom pieces, 3D printing holds several key advantages. 3D printing is an additive manufacturing technology, so only the materials needed for the design are used; whereas CNC milling is subtractive, removing excess material until you reach a final design. This uses up additional materials and requires more cleaning up afterwards.

The functionality of the part printed depends on your needs. If you only need to evaluate the design, you may not need the part to be able to perform any part of its functions – so may not need to print it in metal but in plastic instead.

Some high quality, industrial-standard filaments we recommend for FDM rapid prototyping:

Once the part has been printed, you can decide if the prototype is fit for purpose and whether it is good enough to go ahead and start manufacturing. If not, tweaks can be made based on the findings to create the next iteration, and the next prototype can be quickly 3D printed.

The process can be divided into three main phases: printing, reviewing and refining.

rapid prototyping 3D printing process

Rapid Prototyping Case Studies

Unilever Nozzles

As documented in Matthew Syed’s excellent book Black Box Thinking, Unilever had a laundry detergent production problem back in the 1970s in their factory near Liverpool. The process to create washing powder involved boiling hot chemicals and forcing them through a nozzle at high pressures before separating what was to become the detergent sold in stores.

But the nozzles often clogged, blocked, and were inefficient. Production was slower, and the resulting detergent grains were of different sizes. Unilever had both efficiency problems and quality issues.

A team of biologists were let loose on the problem after a prior team of mathematicians failed to come up with a solution. They created ten new nozzles, each iteration with small differences — slightly longer, shorter, with a smaller hole or with tiny grooves. One iteration improved slightly on the original, just by 1-2%.

The team then took this slightly improved iteration and created another 10 iterations of this nozzle, making another series of small changes and testing them for effectiveness. This continued and continued as more and more prototypes were created to find marginal gains, again and again, before an ‘outstanding’ nozzle was developed after 449 failures. Whereas evolution takes tens of thousands of years, the same principles could be augmented using cutting edge technologies and new iterations can be produced every hour now with 3D printing.

3D printing wasn’t commercially available in the 1970s when this occurred, but if it were to happen in the present day, 3D printing and rapid prototyping could create the ideal nozzle in record time. Rapid prototyping allows for extremely accurate prototypes and slightly different iterations to be quickly tested, reviewed and documented. With larger parts, 3D printing ten iterations could take several days, but with small parts such as a pen lid-sized object, ten iterations could easily be produced in one print run on an SLS 3D printer. This allows for extremely quick innovation.

An STL file re-design of the original and final Unilever nozzles. Credit: UniverseBecoming on Shapeways.

Rapid Prototyping Services

A number of rapid prototyping companies offer 3D printing services to meet the growing demand for 3D printed prototype parts. This offers businesses the opportunity to access 3D printing without having to pay the upfront cost of a 3D printer.

Though industrial 3D printers capable of rapid prototyping 3D printing have become far cheaper in the last few years, companies who only need to produce a few parts per year will save money by using these rapid prototyping services instead.

3D printer manufacturers such as Desktop Metal have tried to solve the issue of upfront costs with rapid prototyping machines by offering yearly rental fees. For example, their Fiber 3D printer can be rented for $3,495 per year, on a three-year contract. Some businesses may find that favorable to a large upfront cost or the continuous payments to services without ever owning a 3D printer.

Best 3D printers for rapid prototyping

There is no single best 3D printer, this all depends on the materials, size of prototype and a variety of other factors. If you need a metal 3D printed prototype, then you’ll need to choose between metal 3D printing technologies, whereas if you need a plastic part made, you have choices between FDM, SLA, SLS and others depending on the strength of part and other characteristics you are looking for.

If you want extremely smooth surface area, you may want a resin 3D printer or a part created using Multi Jet Fusion. For low cost parts and low cost 3D printers, you may prefer an FDM printer.

The Form 3 is a commonly used 3D printer for resin prototypes. You can view our full industrial printer recommendations by clicking the link in the bullet point below.

Some printers are more suited to industrial demands than others, and have become well known for their ability to create accurate parts that can be tested as functional prototypes, and do it quickly and consistently. The link below features a buyer’s guide to the best industrial printers that cost under $10,000 that provide excellent reliability, accuracy and are simple to operate.

Rapid Prototyping Software

To create a prototype to print you’ll first need to design it on a 3D CAD software modeling tool. Depending on how complex and intricate your part is, you may be able to design it on a consumer software tool, but usually in rapid prototyping a more complete software modeling tool is required. You’ll also need a 3D slicer to slice your model before you can print it.

Sometimes a 3D scanner is used to scan an existing part that can then be 3D printed and tested. Usually however a 3D CAD design is used instead.

We recommend reading the following guides for choosing a rapid prototyping 3D software tool:

Advantages and disadvantages of rapid prototyping

Rapid Prototyping Advantages

  • Very accurate: very intricate and precise models can be created that accurately reflect the final part. This makes it easy to evaluate the part’s shape and design.
  • Reduce time to market: can test multiple iterations very quickly, and even multiple iterations concurrently. You can test multiple iterations at the same time by printing multiple, slightly different parts and evaluating which performs the task best or looks best, and further iterate on the best one. Getting to the perfect design faster can save companies huge amounts of R&D investment.
  • Better design feedback: visual prototypes are better for examining than designs within a 3D software tool. You can gain a better idea of how a product will look and perform in use, and make changes based on any areas that need work. Additionally, real-life prototypes are easier to explain to upper management and to customers so they can provide their feedback.
  • Instantly incorporate changes: once problems have been identified, they can be instantly changed and improved on the 3D CAD file and reprinted.
  • Additive manufacturing uses less materials: especially valuable in metal part prototyping as these parts can cost hundreds of dollars each in materials alone.
  • Minimize risk: rapid prototyping means you can explore and test ever potential flaw, cheaply, before starting on a large production run. You can inexpensively minimize any risks leading to any product recalls by extensively testing these prototypes.

Rapid Prototyping Disadvantages

  • May require a skilled operator: metal 3D printers especially often require trained operators to ensure printing is safe and optimum. This is dependent on how complex the 3D printing technology is, as for example FDM 3D printers are far simpler and require far less skill to operate.
  • Time lags and costs if not done in-house: if you have a rapid prototyping service print the part for you, this may add 2-3 days to the process as the part needs to be mailed to you. The costs may also add up over time if you print many parts, so it is important to estimate how often you will be 3D printing parts to ascertain whether it is better value to outsource rapid prototyping or have it done in-house.