Reducing plastic waste at sheet extrusion company

[akondida]

We are sheet extruder and we generate about 10% waste through edge trim and floor sweeps and purgings. we do recover about 5% by grinding the edge trims and putting back in the blends. But it still adds grinding time, reprocessing costs and machine hr cost. I want to know how some have overcome these? also how to avoid lot of floor spills and die purgings which account for almost $400 a week.

Thanks

 

[mjh368]

well if you are purgin for color changes or your materials are expensive you could use a purging compound. as far as floor spills what exzactly are you talking about, guys dumping materil on the floor or what. you could get a material handling system. more info

 

[patprimmer]

Your question is very general.

The very general answer is optimise your process and improve your materials handling and housekeeping.

I guess you control the width before trimming by extruder output and roller speed and pressure or clearance settings. If so reducing extruder output and roller pressure will reduce edge waste. If the rollers are set gap rather than pressure, leave the gap but reduce output.

If you overdo this, you will end up with 100% waste rather than less than 5%.

re purgings, careful attention to production scheduling and correct technique are possibilities. Also, the screw and barrel clearance should not be excessive and the die and die plate should have no hang ups. A sheet or so called Coat Hanger die should be pretty straight forward and if in good condition should not be a problem.

You may need to remove the die face for major colour change purgings. If you remove the dieface, use a gas torch to burn out any material on it.



Regards

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[boora]

You might try to control the width by using a restrictor bar in the outside lip of the extruder and turn off the heats to the restricted zones to run a narrow sheet if the full width isn't required.
The time involved and the readjustment of the puddle can take some time, so it would only be feasable on a lengthy run.