Sustainapack SDD Rev B

Last crawled date: 1 year, 10 months ago

This is basically a revision of my earlier entry “sustainapack entry SDD”. It has been modified to remove material from the injection molded parts tray. This change required the addition of a cardboard box, (see FIG 1) with outside dimensions of 512 x 537 x 389mm, and 2 foam pads. (see FIG 2) This packaging holds 200 low pressure switches. They are arranged in a 5 x 5 (100 sq. mm) matrix and located into pockets formed into an injection molded tray. The trays have been extended on one end by 25 mm and are stacked 8 layers high, rotating alternating flats by 180 degrees. (see FIG 3) The extension and rotation of the flats allows for an interface of the trays making a 43 mm tray height posable. Note the part height is 63.4 high. This is a savings of 20.6mm per layer. The interface also assists in securing the switch inside the package. The parts positioned to the 3 nest pads. (see FIG 4) Located in the bottom of each pocket is pressure pad that works much the same as a snap. It applies pressure to the top of the switches plastic case in the layer below. (see FIG 5) There is no pressure applied to the sheet metal brackets, avoiding damaging. The weight or vertical pressure placed on the container is not applied to the switches. When the box is closed the 6.5mm thick foam sheet are compressed by 2/3 in the contact areas. This will apply constant pressure to the stack. The vertical pressure passes through the box and legs of the trays. The only place the vertical pressure passes though the part is the vertical flanges (variable brackets) on the top layer and passes directly to the tray.
The tray could have more material removed from it and still work. But I think this present design shows the concept. And that further refinement, by me, would only be a guess and a waste of time. I think this tray could easily have mold flow problems and needs mold flow analysis. The same would be true for FEA. I do not know how much force can be exerted if the package would be placed at the bottom of a shipping container? Another item not known is what is the ratio of scrape material generated and material used in the product? I estimate the two plastic parts use 17 cu. cm. of material each. Multiplying this by 25 gives us 425 cu. cm. The (rev B) tray design uses 451.5 cu. cm. of material. This gives a 51.5 % ratio scrape to product. This is probably is not so good. I have seen a 25% regrind used in most drawing that I have done. I assume this is an average lose dew to gates and runners? This would give us a target of 106.25 cu. cm. per tray. Could the regrind material be mixed with filler at 50% to70%? This project offers a big challenge?