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Frequently Asked Questions

Design and Engineering

QWhat is a Prototype?
AA prototype is a fully functional, working model of a new product invention or a new version of an existing product created to facilitate concept testing, or to explore market demand potential.

According to Barron’s Dictionary of Marketing Terms, a Prototype[1] is a Sample product innovation manufactured on a small scale in order to test product performance and market response. If a prototype is successful, the marketer must determine how to produce it in large quantities in a cost-effective manner. A small group of targeted buyers might be selected to use the prototype on a test basis and participate in fine-tuning the product characteristics.

Types of Prototypes[2]

The Encyclopedia of Small Business identifies three main types or stages of prototype creation:

  1. Breadboard — used in the early stages of product development to demonstrate functionality and communicate your idea to potential model makers or manufacturers so they can create a finished product for sale.
  2. Presentation Prototype — This type of prototype is a representation of the product as it will be manufactured. Often used for promotional purposes, it should be able to demonstrate what the product can do, but it is not necessarily an exact copy of the final product.
  3. Pre-Production Prototype — This type of prototype is for all practical purposes the final version of the product. It should be just like the finished product in every way, from how it is manufactured to its appearance, packaging, and instructions. It is most valuable because it enables inventors and producers to go over every aspect of the product in fine detail, which can head off potential trouble spots prior to product launch.

QWhy use Prototypes?
APrototypes allow developers and engineers to test the functions of the new design before starting the production process.

  • Produced in variable quantity from one piece to thousands
  • Design can be easily changed
  • Costs savings in long run brought by elimination of all technical glitches (non-conformities) before production

QWhat are the Prototype Building Techniques?
ADepending on the final product, a prototype can be manufactured in a variety of ways.

These processes are as follows:

  • Casting[3] – is a manufacturing process by which a molten material such as metal or plastic is introduced into a mold, allowed to solidify within the mold, and then ejected or broken out to make a fabricated part. Casting is used for making parts of complex shape that would be difficult or uneconomical to make by other methods (such as cutting from solid material).
  • Rapid prototyping[4] - can be defined as a group of techniques used to quickly fabricate a scale model of a part or assembly using three-dimensional computer aided design (CAD) data.
  • High Definition Stereo Lithography (SLA) – Stereo lithography is an additive fabrication process utilizing a vat of UV Sensitive polymer and a laser to build parts a layer at a time. Each part is traced by the laser beam on the surface of the UV-sensitive photopolymer, solidifying it.
  • Selective Laser Sintering(SLS)[5] – refers to the process where parts are produced using a high power Laser to fuse small particles of metal, plastic or ceramic powder. Parts made with this process can vary in size from very small (inches) to large parts (4 feet).
  • CNC – refers to the process used when parts are produced using a CNC Machine[6] (Computer Numerical Control) where a machine creates a part by selectively removing/carving unwanted material, resulting in the desired part.
  • Blow Molding[7] - A method of fabricating hollow plastic objects, such as bottles, by forcing a parison into a mold cavity and shaping by internal air pressure. Also known as blowing.
  • Injection Molding[8] - a method of producing parts with a heat-meltable plastics material. This is done by the use of an injection molding machine. The shape which is produced is controlled by what is called a "mold." This is a reverse image of the part desired and can be compared to the familiar "Jell-O®" mold. The injection molding machine has two basic parts; the injection unit, which melts the plastic and then injects or moves it into the mold, and the clamping unit, which holds the mold. The unit clamps the mold in a closed position during injection, opens the mold after cooling, and ejects the finished part.
  • Silicone mold – Parts made from this process are similar to injection molded parts in durability and accuracy. Epoxy or urethane materials are available for this operation. Up to 15 or 20 parts can be made from this process before the tool degrades.
  • Vacuum forming – This is a thermoforming process that heats a thin sheet of plastic (from 1/8” to 3/16” in thickness) to a moldable temperature. The sheet is then draped over a pattern and a vacuum is applied to form the sheet to the pattern. This process is frequently used in conjunction with Drader® welding to create boxes, tubes or other enclosed objects. This is an inexpensive method to simulate injection molded parts.
  • Metal Stamping – Brackets, baffles and shields can be produced using various metals and gauges. The parts are formed according to a pattern that satisfies the customer’s requirement. Weld-nuts can be added when the stamping is complete. Objects formed in this manner can be e-coated, powder coated or painted after the process is finished.

QWhat are the considerations regarding appropriate choices for prototype methods?
AConsider the following material product groups:

I. Plastic products:

There are essentially seven reasonable means of producing a plastic product. They would be rapid prototyping, machining from stock, injection mold, vacuum form, blow mold, the MagCoreTM process and silicone mold. Comparisons will be made between the suggested methods showing advantages and disadvantages.

The basic factors affecting the choice of the most appropriate method depend on the complexity of the design, the functional requirements, the material requirements and the volume of production.

  • Vacuum forming is a cost effective method to produce air cleaner boxes, for example, when the volume is fewer than 20 or 30 parts. Injection molding would be better when the volume is greater. When only one air box is needed for urgent design analysis then a rapid prototype, such as SLS or SLA, would be best.
  • Silicone molding is an effective alternative to injection molding in that it produces a part that is virtually indistinguishable from injection molding. This has the added advantage of a short lead time and lower tooling cost. The materials used in silicone molding are durable and can be used for functional testing purposes.
  • The blow mold operation can be duplicated, in some situations, with the vacuum form process. Lower volumes will usually be more inexpensively made by vacuum forming. The MagCoreTM process can simulate rubber or soft plastic parts and is a very quick and cost effective means to produce fully functional parts. Higher volumes, of course, should be made with blow mold tooling.
II. Metal products:

Metal parts that could be formed by a casting process may also be produced by machining from solid stock. One or two parts can usually be made more economically by machining from stock than from making a mold and casting the parts. Volumes above those mentioned should be produced from a casting operation. In certain cases an SLS can be used for fit and function, but this only applies when the requirement is one or two parts.

Magnum Manufacturing will assist in determining the most economical and satisfactory method for production. Our long experience in prototype development will be your best resource for an acceptable solution.

[1] "Prototype" Dictionary of Marketing Terms. Barron's Educational Series, Inc, 2000. 19 Apr. 2007.

[2] "Prototype" Encyclopedia of Small Business. The Gale Group, Inc, 2002. 19 Apr. 2007.

[3] "Casting" Wikipedia. Wikipedia, 2007. 19 Apr. 2007.

[4] "Rapid Prototyping" eFunda. eFunda 2007. 19 Apr. 2007.

[5] "Selective Laser Sintering" Wikipedia. Wikipedia, 2007. 19 Apr. 2007.

[6] "CNC" Wikipedia. Wikipedia, 2007. 19 Apr. 2007.

[7] "Blow Molding" McGraw-Hill Dictionary of Scientific and Technical Terms. McGraw-Hill Companies, Inc., 19 Apr. 2007.

[8] "Injection Molding" SPE. Society of Plastic Engineers, 2007. 19 Apr. 2007.