Title: Phase 5 Develop a Prototype
Course: ATEP - MMT: Module A: > Section: PHASE 5 DEVELOP A PROTOTYPE

5.1.1 Prototypes, Models and Simulations

In this phase, a model or prototype of the solution is created to identify possible modifications that might lead to changes or refinement of the design. Skilled craftspeople and technicians are often employed to make physical models before going to  full-scale mass production. Models can be physical models (full-size or scale), simulations (virtual models), mathematical models (graphs, charts, and formulas) and representational models (such as drawings or sketches). The all are designed to provide a simple and understandable portrayal of the actual system.

 A prototype is often used as part of the product design process to allow engineers and designers the ability to explore design alternatives, test theories and confirm performance before starting production of a new product. During the construction of a prototype, you may need to make adjustments to your original design.  As the product becomes a three-dimensional object, considerations to the fit of each part and serviceability will need to be addressed.

A prototype is used for experimentation and the goal is to obtain the maximum value from the prototype.  All changes and why you are making them should be entered into the engineering notebook.  If the changes are significant, you must verify and make certain that your design is still the best alternative.

The recent advances in computer modeling and simulation are now making it more practical to eliminate the physical model that has been used in the past, especially with the more complicated parts and assemblies. In some cases, animations of a human are placed into the CAD simulations to verify the ability to reach into difficult places (to shut off a valve or pull a lever). The height and weight of the human animation can be adjusted to match the person that might need to accomplish the task.

A CAD simulation showing how the parts of a desktop organizer are to be assembled is shown below.

5.1.2 Prototypes

Types or categories of prototypes:

  1. Proof-of-principle prototype/concept: Used to test some aspect of the intended design without attempting to exactly simulate the visual appearance, choice of materials or intended manufacturing process. Such prototypes are used to "prove" out a potential design approach such as range of motion, mechanics, sensors, architecture, etc. They are often used to identify which design options will not work, or where further development and testing is necessary.  The example of a cigar clip is shown at the right.
  2. Form study prototype: Allows designers to explore the basic size, look a nd feel of a product without simulating the actual function or exact visual appearance of the product. They can help assess ergonomic factors and provide insight into visual aspects of the product's final form. They are often hand-carved or machined models from easily sculpted, inexpensive materials (e.g., urethane foam), without representing the intended color, finish, or texture. Due to the materials used, these models are intended for internal decision making and are generally not durable enough or suitable for use by representative users or consumers.  A variety of spoon shapes are shown here as a typical form study.
  3. User experience prototype: Invites active human interaction and is primarily used to support user focused research. While intentionally not addressing possible aesthetic treatments, this type of model more accurately represents the overall size, proportions, interfaces, and articulation of a promising concept. This type of model allows early assessment of how a potential user interacts with various elements, motions, and actions of a concept which define the initial use scenario and overall user experience. As these models are fully intended to be used and handled, a more robust construction is required.  See the example of chairs to the right. Also see
http://www.ideo.com/images/uploads/news/pdfs/FultonSuriBuchenau-Experience_PrototypingACM_8-00.pdf
  4. Visual prototype: Shows the intended design aesthetic and simulates the appearance, color and surface textures of the product but is not a functional version of the final product. These models will be suitable for use in market research, executive reviews and approval, packaging mock-ups, and photo shoots for sales literature.
  5. Functional prototype/working prototype: Attempts to simulate the final design, aesthetics, materials and functionality of the intended design. The functional prototype may be reduced in size (scaled down) in order to reduce costs. Used as the engineers' final check for design flaws and allows last-minute improvements to be made before larger production runs are ordered.  A working prototype of an oil collection device is shown being tested in the video below.  Note that a video of the testing procedure is the best way to verify the effectiveness of the product.

5.1.3 Design Changes

During the construction of a prototype, is when you will need to make adjustments to your original design. The prototype allows you to "see" possible problems with the manufacture, fit of the parts and the serviceability of the components.  The additional information obtained may require that  changes be made to the original idea.  These revisions are known as Engineering Change Orders (ECO).  Each revision that improves the design and the testing to verify it, create a repetitive cycle of continuing improvement.  The revisions in the cycle are only limited by time and cost.

Again, all changes and why you are making them, should be entered into the engineering notebook. If the changes are significant, you must verify and make certain that your design is still the best alternative.

5.1.4 Risk Evaluation

Risk analysis is used to develop an estimate of the risks to human health and safety.  The Risk Evaluation Matrix, shown at the right, must be considered during the design and development stages for both the manufacturing processes and how the end user might use the product.

Models of the proposed solution are even more important if the solution is complex and costly, if a large quantity of the final products must be manufactured, or if the proposed solution presents risks to people and the environment. In all of these situations you would want to minimize the potential for costly errors which translates into injuries, liability suites and lost sales.

Risk Versus Hazard

Risk is a measure of the likelihood of a hazard occurring. Most production and handling processes involve some risk.  How you do specific tasks while being aware of the potential hazards in your plant affects the risk levels at the manufacturing facility.  Knowing how to eliminate or reduce safety hazards, with proper controls, will help to reduce the safety risks in the production process.

A safety hazard is a biological, chemical or physical problem that can possibly cause a health problem either during the manufacturing process (to the employees) or to the end user (customer). Many of the factors that can cause health problems are found specifically in the materials being used and the method of production.

Not all safety hazards are serious and not all of them create an immediate risk. Some hazards are higher risk, depending on the methods, equipment and levels or doses of unwanted substances in the manufacturing process or the product.  While some products may not be hazardous for the general population, they may be hazardous for more vulnerable consumers like the elderly, pregnant women or infants. An example here might be the paint or coatings used on a finished product or the type of material used for containers that might have a chemical that leaches out over a period of time.

Risk Analysis Components

Risk analysis has three components:

- Risk assessment is the scientific information that describes the likelihood and magnitude of specific hazards.
- Risk management applies to processes used to control the potential hazards.
- Risk communication is the exchange of information about the hazards between the people connected to the processes involved.