Early Prototyping
'Early prototyping' is a simple concept. You use cheap, quick-to-make models to test and prove solutions before committing to actual production hardware. A few hundred or a few thousand dollars invested in early prototyping can save many thousands of dollars later.
Any good technician, mechanic or programmer practices early prototyping. But like any other technique there are skills involved that can be mastered and there are special tools that can be used. With training and practice one can develop expertise in early prototyping, and use the technique effectively to quickly home in on solutions and reduce them to reliable production hardware.
On one job I designed and tested a chute in a computer simulation package one day, made a full-scale cardboard model that evening, put the model onto the actual packaging line the next day, and ran it. The prototype was successful, so we were able to immediately order six copies of the chute in production-quality hardware with full confidence that it would work as soon as we installed it.
In another case, a design concept for a semi-automatic tray-loading station was tested using a salvaged conveyor fitted with inexpensive pneumatic tooling fabricated and installed by a design/build shop. Testing in the shop not only showed that the design worked, but that it could be simplified. After the initial testing the prototype was packed and shipped to the client's plant where it was examined and tested by their Engineering and Maintenance departments. On their own initiative, the prototype was installed on one of the packaging legs and run in production. They evaluated the operator control layout and proved the packaging station would achieve all the design goals including, most importantly, long-term reliability in the actual production environment. By being able to show a working prototype to design/build shops, we were able to source better production hardware faster and at lower cost. Installation and startup was quick and clean. The investment in the prototyping effort was probably recovered several times over.
On many occasions I have used early prototyping to develop custom solutions for clients. The success stories are operating everyday in their factories, and are integral to their Competitive Advantage. As such, I'm not at liberty to share them here. However, I can illustrate how the technique is used with an example that never made it onto the factory floor. (Not to say that the effort was wasted. In this case we found out quickly we were developing hardware that was not going to solve the problem. It allowed us to redirect our efforts to a more productive approach, before we had wasted much time or money.)
The client had a station for filling bulk containers with soaps and cleaning fluids. The fluids were foaming during the filling operation. They had to reduce the speed of the filling operations to reduce the amount of foam created, otherwise the foam would spill out of the top of the containers, causing a number of problems. We thought design changes to the filling head might reduce the amount of foam made.
The first step was to design the prototype. Using 3D CAD software (Vectorworks) we were able to develop design concepts into fully-dimensioned drawings and realistic renderings. The 3D renderings made it easy for all of the project team members to understand what was being proposed. Once the design was approved, it could be transmitted to an outside machine shop as a computer file that could be automatically translated and loaded onto their CNC equipment.
Click to enlarge pictures and drawings.
The parts sketched above were machined into actual hardware, below, using design data automatically extracted from the 3D CAD drawing.
To save time and expense, some of the prototype parts were machined in UHMW polyethylene, instead of 316 stainless steel, and the valve was designed to be opened by a mechanical plunger, rather than an air cylinder. A few simple tricks like these can greatly reduce the cost and lead time to test a design.
To further simplify matters, the prototype filling head was tested off-line. A simple soap solution was used instead of the caustic cleaning solutions actually filled. The fluid was gravity-fed from a plastic barrel instead of from a storage tank. A clear glass jar was filled instead of an actual, translucent plastic jug, so the fill could be seen and videotaped.
What we discovered was the velocity of the fluid coming out of the filling head was far more important than any features of the filling head itself. As you can see in the sequence of photos below, the momentum of the fluid carries it well up the sides of the container. There is so much energy in the fluid that almost nothing can be done to prevent violent agitation, and the creation of foam. We did, however, see that once the filling head was completely immersed, the amount of turbulence in the jar decreased. As a result our efforts were redirected towards reducing the rate of flow during the first few seconds of the fill, when foam creation is greatest.
Edward A. Bianchi, PE
Consulting Engineer
Click to enlarge pictures and drawings.
Click to enlarge pictures and drawings.
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Edward Bianchi, PE
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www.EdwardBianchiPE.com/prototyping.html 2008/10/01