Too much downtime. (mainly about granulation)
 
 
In the part one I mention few things about sorting.
Here I'll be talking about granulation or, better the cutting of scraps to convert them into flakes.
What is available for cutting on the open market ?  Not much.
Shredders and granulators.
One, two, three and four shaft shredders, with or without grid, with or without pushers, running with or without water, and so on.
Granulators with three to seven rotating blades in one, two, three pieces and so on.
What all these machines have in common ?  Downtime when blades needs to be replaced.
And downtime is about all the system, not only the cutting machine itself.
If the machine is a single shaft shredder to downsize scraps as first step of the process, just be positive you have spare blades available because in this case it will be matter only to remove a single screw each blade and, after replacing it, put the screw back in place.
No big deal.
When talking about two or more shafts shredders the matter becomes thought.
These machine are working as a scissor and when the edges of blades become dull you are in real troubles from time and money point of view.
To replace the set of blades, doesn't matter the number, you have to open all the machine, sharpen all blades to exactly the same thickness and put a spacer at the end to compensate whicever thickness was ground, times the number of blades, and put everithing back together.
If this one has been your choice, good luck, you need a lot of it.
Now, let me talk a bit about granulators.
Granulators are spinning at a pretty high speed and wearing of blades is the issue.
Plastic, all kind of plastics, are wearing steel and the fact there is also dirt, paper, sand and other things like these is not helping much.
If grinder is working wet, life of blades is a little longer but running dirty scraps dry makes the time between two blades changes very short.
What to do ?
First one is a simple way; get two granulators on the same line and, while one is down for maintenance, run the other one.
You may say one more granulator cost money but, if you run your numbers well, the cost of another machine comes back in few month time, promise.
Unfortunately, this cannot be done in all situations but there are other ways to (almost) overcome the problem.
Will you be happy if life of your blades is three times more than what it is now ?
Answer is pretty easy:  Pre-washing of whatever it is before feeding scraps into granulator.
This operation removes a good 95% of surface dirt right before the granulator and blades will be lasting a lot longer.
The only limit is the fact that, after pre-washing, granulator must be running wet due to the fact after pre-washing material comes out, at least, humid, and granulators can only run completely dry or with a lot of water, nothing in between.
 
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