There are many different kinds of prototypes, or proof of concept models, terms of which oftentimes can run together and get a bit confusing.
Proof of Concept
This term refers to the earliest version of a new product. The new product concept could be an invention or a modification of a current product, or a fix for a product currently being manufactured. The key word here is functionality as opposed to visual appeal-proof of concept models generally will never be very pretty. Oftentimes, invention prototypes begin at this point.
As the name implies, it demonstrates the concept of the proposed product. It involves little or no investment in tooling, and is a great place for 3-D printing to be utilized.
Practically all design work is now conducted with 3-D software; advantages of this technology make design work so much easier to visualize.
Along with 3-D modeling, computerized analysis can be used to take a quick look at the concept. The boundary conditions-temperatures, pressures, thermal interactions, basically any physical condition that you can imagine-can be simulated. For the short amount of time it takes, investing a few hours in computerized analysis is very prudent at this stage of development.
In-depth, time-consuming and highly detailed analysis would be out of place at this level of development. As long as the 3-D electronic models exist, running a quick analysis can yield time and cost saving results for the small investment in time and money that is required.
Actual performance evaluation of the proof of concept model-that is, the actual model as constructed-should be performed at this point. Analysis is great, but it does not take the place of actual testing. Even if only a single model is constructed, much information can be gleaned by testing at this point.
Pre-production Prototype
This term is often used in place of proof of concept models. I see the pre-production prototype as the next design iteration following the proof of concept model. This design and build is a big step closer to the production version. It should be designed with manufacturing in mind. Questions such as expected sales volume, whether to mold, machine, cast, stamp, forge, extrude, build or buy, etc. need to be asked here. Expected quantities are a very important. With larger quantities, technologies such as molding and casting must be factored into the design.
Little, if any expenditure should be made in tooling of any kind at this point, whether it be temporary or permanent tooling-the design is way too soft at this point.
Testing of many types would be very useful. This could take the form of performance testing-what the product is expected to tolerate in the real world, approximate certification tests that may be able to be performed in-house without having to go through the trouble and expense of formal certification tests. HALT: testing-highly accelerated life tests-would be useful here. Briefly, this form of testing gradually cranks up the boundary conditions until something breaks, thereby demonstrating where design weak points might exist. FMEA analysis-failure modes effects analysis-should also be done at this point.
Production Prototype
At this point, some expenditure in non-permanent tooling should be made; any decisions regarding how components are manufactured or whether they are purchased from outside vendors or are off-the-shelf parts need to be made. The parts should be manufactured using expected production methods, with the idea that short production runs are going to be made. Formal certification tests are appropriate at this point. If there are any changes to be made, now is the time to make them before permanent tooling is in place and production is about to begin.
Full Production
At this point, the design should be frozen; permanent tooling in place, and a good bit of soul-searching needs to be done by all the players involved in this product. That is, every major department within the company needs to have an input before production runs are executed.
A plethora of tasks need to be completed at this point:
- Are all design changes complete, and are all these long-term or Band-Aid type fixes?
- Are all part to print-type changes completed? And have these been evaluated for form, fit, function?
- Is all documentation complete? Is packaging design complete, vendors in place, etc.?
- Are all bills of materials complete?
- Are all of your outsourced parts in stock?
- Have all assembly personnel and properly trained?
- Are all quality control and inspection documents, rejection criteria go no go tooling etc. ready?
- Vendors qualified? And are multiple vendors qualified? We all know the hazards of single sourcing! Tread very carefully when dealing with any sourcing from overseas, especially China.
- Are material sources qualified?
- Have the best possible prices been agreed to for off-the-shelf parts?
- Have all of the export legalities and controls been addressed?
The above list is far from complete. Obviously, there is a great deal of work-highly detailed work-that needs to be in place and everyone needs to be comfortable with it before you pull the trigger on production.
Norman T. Neher, P.E.
Analytical Engineering Services, Inc.
Elko New Market, MN
www.aesmn.org