AGS Machine Modifications to Process Regrind

June 11, 2022 | Featured, Newsletter, Tech Database

 Working with up to 100% regrind represents its own set of processing challenges.  Based on experience and continuous improvement AGS mitigates regrind related processing issues with specially modified injection molding machines:

  1. Material conveying challenges include coarse sized chunks and longs that can obstruct the flow of plastic in standard diameter hoses/pipes.   Fines generated during the size reduction process can also clog loader filters.  Using larger diameter hoses/pipes and heavy duty vacuum loaders from the bulk material handling industry, AGS easily conveys odd shaped regrind and powder.
  2. Virgin resin typically comes in a cylindrical pellet which is an optimal shape to help draw out moisture.  Regrind particles on the other hand are irregular shaped and much larger in size.  AGS specifies oversized hoppers to increase drying residence time for hygroscopic regrind.
  3. Hygroscopic regrind absorbs and retains water since it is not stored in sealed liners.  AGS uses high heat desiccant dryers with aftercoolers to maximize removal of moisture using low dewpoint at elevated temperatures.
  4. AGS specifies longer L/D barrels with custom mixing screws to optimize distributive mixing of recycled formulations.
  5. To screen unmelt and improve mixed colors dispersion, AGS uses proprietary nozzle filters installed on the injection units.
  6. Changes in regrind viscosity from lot to lot can result in short shots and flash.  Advanced processing technologies (eg. scientific molding, low constant pressure molding) help minimize the effects of these viscosity differences to help make high quality parts.