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Developing a Prototype

NIC Document

Summary


Prototyping is the process of rapidly assembling a working model (a prototype) to test various aspects of a design, illustrate ideas or features, iterate the content of the design and gather early user feedback. This guide outlines the prototype cycle, the key questions to ask and the options you have when planning a prototype for your innovation.

In Brief


  1. The prototype cycle
  2. Developing design concepts
  3. Prototyping levels
  4. Prototyping methods

Introduction


Prototyping is a critical stage in product development. It is vital in determining the look, feel, functionality, operation and final design of a product.

The prototype cycle


The prototype cycle should include the following stages:

  • Understand your objectives – What are your expectations of the prototype and what do you hope to achieve through its creation?
  • Specify your requirements – What are the specifications of the prototype? Capture the requirements in a written form
  • Understand how you get there – What are the different approaches you can take to get to the required outcome? It is advisable to gain professional advice on prototype options at this point
  • Determine what resource to use – internal or external sources? What are the consequences of using different groups for timing, quality, cost, etc
  • Obtain quotes/proposals – Obtain several written quotations, understand and question the approaches and final products
  • Decide – Consider the complete picture and make a decision. If the decision is complicated, use a structured decision analysis process
  • Project Monitoring/Management – Who will manage the project? Document the process, if possible under an ISO 13485 quality management system. Project management methodologies such as PRINCE2 can help provide a robust management structure
  • Validate the prototype – Validate against original specifications, understand any variations, obtain third party validation and determine your future actions.

You may need to repeat the prototype cycle several times before you develop your finished product.

Developing design concepts


Before beginning the prototype process it is important to plan exactly what you want to achieve. In the first stage, you can identify exactly what you want to achieve by asking several questions that will help you decide on the specifications and prototype route:

  • Is the prototype to be used on people or animals in order to understand how it will work in a clinical setting?
  • Are you creating the prototype to test its mechanical properties?
  • Is the prototype to be used to impress potential investors or partners?
  • Are you designing for manufacture?
  • Are you designing for aesthetics or ergonomics?
  • Produce a specification: A written specification is vital as this will help to communicate what you need to others and will force you to consider what you require in detail
  • Don’t be afraid to learn from others: If you are operating in a competitive field it is important to examine the existing products on the market. It is also useful to talk to the users and find out about the good and bad points of the products they use and what they see as the key features they would require in a new product
  • Get advice from specialists when possible: The design and prototyping process is a minefield of technical and commercial risks, making it important to gain advice from a specialist at a critical point in the development process. Search for this expertise in your organisations, speak to scientists/engineers you know, and – if you have to – pay for a subcontractor to sit in your team and advise you. Many service providers (rapid prototype houses) will provide initial consultation and input for free which can be very valuable.

Prototyping levels


Your chosen prototype level reflects the progression of the project and your required objectives. The prototype levels are:

  • Virtual Prototype – This is software-based and can be used to develop the look and design of the prototype. There are several methods, such as finite element analysis, that can be used to examine the functionality before you make a physical product
  • 3D Models – These are used to provide a physical model of the design of the product, normally without functionality. They can be used to demonstrate the look and feel of the product, and can be very useful as an example to potential investors or partners, and to develop the design further with customers
  • Proof of Concept – These prototypes are developed to prove whether an idea will work and are not designed for manufacturing processes, easy-use, ergonomics, or aesthetics. This is often a cost-effective stage that will show whether the principle of your idea is sound
  • Experimental/ Developmental – This stage demonstrates that the prototype can reliably produce the desired results
  • Demonstrator – A demonstrator prototype shows experts or potential partners that the design works in a reliable and controlled way. You can also use it to decide on the features for the final product
  • Pre-production – This is the designed-for-manufacture product using manufacturing techniques for when the final design is produced

Prototyping Methods


There are many methods for producing prototypes, with virtual methods becoming more common.
Virtual Methods: Computer modelling systems are an extremely powerful method for product design. Some of the common tools are CAD (Computer Aided Design), CFD (Computational Fluid Dynamics), FEA (Finite Element Analysis) and various forms of mathematical and theoretical modelling of systems.

  • Rapid Prototyping: This is a relatively cheap method for producing a model of a device. The device will not have the same mechanical properties as the final product and it is unlikely that it would be useful in a testing environment. But it is very useful in demonstrating the device to external parties such as investors or potential commercial partners. Rapid prototyping methods include Stereolithography, Laser Sintering, and 3D printing
  • Fabrication: For one-off proof-of-concept prototypes, the most cost-effective approach is to use conventional fabrication methods such as machining or CNC (Computer Numerical Control) machining. Although these techniques are time-intensive, the machinery for making them is readily available and there should be few related equipment costs
  • Semi-Production Methods: As your innovation gets closer to going to market, you will need higher volumes of product for laboratory testing and clinical work. The set-up costs for some of these methods can be expensive, but are likely to be less than the final production set-up costs. Semi-production methods are vital for allowing you to see if the product works in a clinical setting. Semi-production methods include casting (lost wax), laser sintering, vacuum forming, injection moulding, and extrusion.