The easiest way to get mass production of CooKits started in many countries is to follow the procedure Solar Cookers International (SCI) followed in both Kenya and Zimbabwe. In those cases, we simply approached local manufacturers of cardboard (cartonboard) boxes, showed them a sample CooKit, and asked them if they could duplicate it with good quality at a reasonable cost.
Since the CooKit can be made simply from reflective aluminum foil glued to cardboard, this mass production process is quite simple. Box-making companies obtain large shipments of pre-foiled cardboard and then run it through their cutting and scoring machinery.
Tips learned from production in Kenya
We do not have a blueprint for a factory. The company we sub-contract to normally makes cardboard boxes, paper containers, aseptic packaging and the like. They make our CooKits on the same production equipment. The machinery is roller fed, and relatively automated. I do not know equipment brands or models, but presume that any population center sufficient to require packaging manufacturers will have the right equipment.
Starting with brown craft paper, they make corrugations and then corrugated cardboard with a water soluble glue. A layer of thin aluminum foil is bonded to one side. DO NOT USE SILVERED MYLAR - it will not last long in the sun's Ultra-Violet rays. This is also bonded with a water-soluble glue. Eventually, for durability reasons, we had them do a wax spray coating on the back side of the cooker. We tried plastics and other materials; I'm not sure what the current water protection method is. You do need some way to keep the material from spills and long-term exposure to humidity.
The material is then passed through a press which uses a board with knives and scores embedded per our design. The material is fed in, the press closes over the board and material, and then opens. The waste material is removed and the Cookits are bundled into packages of 25 or 50 for shipping.
The board of knives and scores is often called a “die” and a “die-maker” should be able to make the die by working from an existing sample CooKit. The box company you deal with probably has a ready source for making new dies. The above procedure has worked in Kenya, Zimbabwe, Turkey and India to provide easy mass production of cardboard CooKits in those countries.
Experiments have also been done with using corrugated plastic instead of corrugated cardboard as the basic structural material for CooKits. The basic concepts are the same—covering the plastic with a thin sheet of reflective foil, then using a “die” to cut and score the plastic CooKits. The intention behind using plastic is to increase durability and resistance to humidity of the CooKit while keeping costs within reason. Gluing aluminum foil to plastic may require more specialize types of glues than needed to affix foil to cardboard. As of September 2003, there has been little field experience with plastic CooKits, so we are unable to yet report on their durability or affordability. Some early reports have been discouraging. Some testers of plastic cookits have found that they don’t fold well, that the edges can scratch one’s fingers, and that the plastic sags after long exposure to sunlight.
CooKits can certainly be made of other materials. Wood or pressboard are likely materials. However, such rigid materials would require hinges in the places where cardboard CooKits fold along score lines in the cardboard. The need for hinges--and for a simple method for adjusting the angles of the CooKit’s panels--does make mass production of such CooKits much more complicated and presumably much more expensive. SCI has not pursued CooKit mass production in materials other than cardboard and therefore cannot offer seasoned advice.