Purging (manufacturing)

Purging is a cleaning process of injection molding to clean thermoplastics molding machines and extruders. This process is very important as a virgin resin cannot effectively remove previous resin residuals from the previous run.

Method
Below are the major steps for purging-
 * Turn off the material flow in the injection molding machine
 * Turn off the colorant flow which is added or applied in order to change the colour of a material
 * Maintain existing process settings and continue manufacturing plastics parts
 * When last part is completed, set the nozzle retraction mode
 * Clean hopper and colorant blender (whichever necessary)
 * Load any commercial purging material or new material to be used into hopper feed zone
 * Clean nozzle and sprue bushing by making few shots
 * Continue purging until most of the commercial purging material is out of the hopper
 * Feed at least one injection capacity of the next production resin to rinse out any residuals
 * Start the next production with new resin