RAPID TOOLING & PROTOTYPING   

PROPOSAL FOR INTEGRATED IN-HOUSE PROTOTYPE TOOLING SOLUTIONS

RAPID TOOLING REPORT

PROPOSAL FOR IN-HOUSE PROTOTYPING SYSTEM

PROPOSAL FOR INTEGRATED IN-HOUSE PROTOTYPE TOOLING SOLUTIONS

DATE:  5/4/97
SUBMITTED BY:  Phil Orenstein
TITLE:  Proposal for Integrated In-house Prototyping Tooling Solutions

PROPOSAL:

This is an update to my previous proposal entitled "A Proposal for An In-House Prototyping System" submitted to the Manufacturing Engineering Department in February 1997. Since then I've done some research and discussed these ideas with Don Barnett and Vince Rosa at great length. This proposal outlines some very effective procedures to greatly cut tooling costs and reduce time to market utilizing P.O.P.'s CAD system and other equipment on hand with some new integrated approaches.


RAPID TOOLING:

The fastest growing segment of the rapid prototyping industry is in "Rapid Tooling": creating injection molding tooling directly from rapid prototyped models. This exciting new technology alone can save P.O.P. maybe $100,000's or more in tooling costs and cut mold making time from weeks and months to possibly days. Although its a very new and evolving process, I believe that it is definitely worth looking into and that I can perfect it here at P.O.P.
I will briefly outline the process. First we will draw on our computers a precise 3D solid model of the core and cavity side with draft and material shrinkage factored in. Then we will produce the model on the Stratasys RP system and properly finish it. Now that we are experts in Mechanical Desktop, we can create the kind of complex 3D solid geometries required for any injection molded part design. The next step is to spray the surface of the finished model with a thermal metal spray coating or a hard nickel plating to create an exact female of the surface. Then back it with cast metal-filled epoxy and insert it into the mold base. It may be necessary in production to adjust the cycle time and pressure in order to extend the mold life. I have read industry reports which made claims that rapid tooling molds were able to produce 100's to 10,000's of parts. It would also be cost effective to make multiple molds because the cost would be a fraction of our current tooling costs for machined aluminum molds. 
To create models for larger molds than the Stratasys can handle, I recommend acquiring a low cost intermediate size 3 axis VMC mill or CNC router, such as the Techno-Isel 3-axis CNC system (around $15,000). From my experience, this is a very good machine to do 3D cutting into machineable plastic block such as Ren-Shape. NC Polaris which directly reads and generates toolpaths from AutoCAD 3D solid models. 
Another very cost effective tooling process is to produce kirksite (a hard aluminum-zinc alloy) sand cast tooling from rapid prototyped or CNC machined models. Because of my familiarity with the process, Ted asked me to do some research to come up with less expensive tooling costs for the Ultima Wings project for a run of 5000 pieces. He had already received quotes of $35,000 - $45,000 for aluminum machined molds which would make the job too costly. I contacted Mack Industries who quoted $9000 for producing kirksite tooling from our model which can generate many more than 5000 pieces. Since Mack uses an outside source for kirksite casting, if we could find a local foundry that sand casts kirksite, we can drop the cost down even further. This tooling process is straightforward: First we create the 3D CAD solid model and run it on the Stratasys or CNC as described above. Then, finish, seal and lacquer it and send it out for sand casting. We would need to do some post machining to it and then insert it into the mold base.


RAPID VACUUM FORM TOOLING:

This is the typical aluminum sand casting or epoxy casting process which we are already familiar with. The major difference is that instead of using hand fabricated wood patterns, we would produce the patterns for casting on the Stratasys or the CNC as outlined above. Doing it this way would prove to be a definite time and cost savings. I have worked for a couple of years with vacuum form patterns and tooling, so I am familiar with some cost effective materials and methods for this process. 


LIQUID RESIN CASTING WITH RTV SILICONE RUBBER MOLDS:

What do we do if we need a low volume run, say 12 to 100 pieces, of a complex part such as a raised company logo in a molded clear plastic, or a display component made out of a flexible rubbery plastic? Projects such as these would be nearly impossible to fabricate by hand and too costly to build a metal mold. The best solution, besides out-sourcing, would be to utilize a liquid resin casting system with RTV silicone rubber molds. We can very easily and quickly produce low cost flexible silicone rubber molds (2 days for overnight curing time) from a CNC or Stratasys generated model then cast a low volume run with liquid plastic resin. We have a choice of innumerable resin systems from crystal clear epoxy to rubberized polyurethane. The silicone rubber molds capture every detail so you get perfect parts without sink marks or flow lines. I ran a long term job at Precision Prototypes for Dupont when their production plant burned down and many of their proprietary molds were destroyed. They needed continuous production of plastic molded components to maintain a steady flow of delivery in their medical instrumentation division. I was able to fill the gap for them by producing multiple silicone rubber molds from a single master allowing continuous casting of parts. Although this is a slow hand casting process, it is very effective for low volume runs. A faster version of this process, the rapid casting system, would require an investment in more expensive RIM processing equipment. This process could also be looked into. 


TOOLING DESIGN CONSIDERATIONS FOR POINT OF PURCHASE DISPLAYS:

Each of the processes I've described starts off with a 3D CAD solid model and then a CNC or rapid prototyped part being produced using P.O.P.'s resources at hand. Most display houses do not have this kind of technology. Low-tech companies' designs are driven by low-tech manufacturing processes. That is to say, rectilinear shapes and simple forms are much less expensive to produce by traditional machining operations than are curved free-form surfaces and complex geometries. Its very simple to machine a square block of aluminum and mill round holes for products. However the trend in industrial design today is tending towards organic free-form surfaces and flowing lines. This can be seen in Automobile design, packaging design, consumer electronics and a whole host of others. Once customers get used to flowing organic shapes and forms in display design they'll never want to go back to 'square' designs again. When the designing process is driven by a high-tech integrated operation, then these trendy designs will be forthcoming. The design considerations involved with integrating 3D CAD drawings with rapid prototyping, CNC and new tooling technologies, are that it really doesn't matter how complex the 
design is. The same tooling, prototyping and production costs are involved whether the design is simple and rectilinear or complex and organic. It can be seen that this integrated approach is very 
cost effective. This approach could be extended to other areas in the company as well. For instance, the same 3D CAD files could be used for 3D Studio renderings and isometric exploded drawings. These design considerations should be carefully thought about in order to fully utilize all of P.O.P.'s resources and technical capabilities and will certainly reduce costs and give us the edge over the competition.