The right set up A bales breaker is almost compulsory if production rate is over 500/700 Kg/hour If you are in a country where operators cost is not high, you can choose to go with manual bales opening Just remember a machine never get sick, it works 24 hours a day without complains, doesn't ask for days off and so on. After bales is opened and bottles are "singularized" onto a conveyor belt, one operator should check for "strange" items, meaning a pair of shoes or a dead cat not to go to granulator, and this can be done with negative sorting. It is only a "just in case" precaution. The choice for the right granulator HDPE, like most of plastics, wears out steel pretty easily and together with paper and dirt things are not any easier; This is the very first consideration. A wet granulator is suggested, it is a good "pre-washing" machine, like any machine making friction in presence of water. Also, our "V" type rotors and ample gap between the rotors will put the bottles into the middle to reduce the wearing-out of knives and wall Second, we have to choose the size of the holes grid; This doesn't automatically means you should go with the size you need at the end to feed the extruder. The other choice is to run this granulator with a bigger screen, let's say twice as much than need, run this size flakes through the line and then go into a "refining" granulator to downsize flakes to where you want. With a bigger screen on first one, the production rate increases a good 70/80% (with holes double than whatever dimension it was decided to be) and this means the size of the machine it can be a lot smaller, less energy consumption, less number of cuts and therefore less wearing. Another advantage is the fact the bigger the flakes, the fewer amounts of fines will be lost in the washing line. And because this difference it can be as much as 2% it means, in a 1000 Kg/hour system, 20 Kg/hour, times 24 hours times 300 days, time the price you can sell your material, figure it out. Next step, washing Using a wet granulator the washing process is started already because out of this machine we receive flakes with a lot of surface dirt already loose and most of paper converted to pulp by the combination of water and friction. Washing plastic should be a combination of friction (the same way your wife brushes your T-shirt when very dirty), water, better if at least warm, and a certain amount of time under these conditions. And, if this machine can provide also for water change during this time, you got what you where looking for. To make this concept a little more clearly, it is the difference between taking a bath or a shower. In a bath you can wash yourself and then you need to get a rinse otherwise it doesn't work out while with the shower system you get washed and rinse at the same time Back to our washing line, we take our pre-washed flakes and fill them into this washing machine to "brush out" all sticking dirt that hasn't previously been removed, convert all paper into pulp, and take it out with the "shower" If material is heavily contaminated, or with some dirt very difficult to remove, time must be longer and this can be done with our machine just increasing one of the parameters Separation of HDPE flakes from other plastics. As we said before, all plastics other than olefins sink, so separation into fresh water does the job and because material has been washed already; Foamed materials are gone already because pulverized by the granulator, the centrifuge and the washing machine at the end. The very last step, drying, for bottle flakes, is not very hard to get. A powerful dryer that mechanically can remove all water and leave material with a mere 0.5% moisture content There is not a final answer to the problem yet because each situation is different and needs a "customized" approach and solution.
