Injection molding machine nozzle , runner —why get stuck ?
According to our experience, the stuck problem is made ​​by copper , aluminum , stainless steel, Magnetic Filter Bar can not attract all of metal impurities . Especially 1-2 mm diameter of the nozzle and runner is most prone to get stuck ! Manufacturers generally use only the Magnetic Filter Bar , but this bar couldnot attract all of copper and other metals with size of 0.5-2 mm, mixed in recycled plastic  ,the naked eye can not detect them.
Since the metal impurities can not be completely avoided, how can we do with it ?Users can adopt some key points in the process of installing metal separation device, usually a strong magnetic filter bar and metal separators .

      
lets take plastic granulator as an example: First, check the  powder before it is feed to extruder machine , then,check extruded and cut granules , in the end,check plastic particles after package .
To crush material for recycling , for example, considering the reasons of the higher raw material prices , more and more users tend to re-use  its own runner material , according to a certain proportion of new material mixed before use . Of course, such a mixture is based on the premise that this mixture does not affect the product quality ,which can indeed cut a lot of costs.
If  crushed material are not under operation of  detection and removal of metal impurities , this will certainly  lead to relatively large safe risk. That method might save raw material costs, but also  increase equipment repair and maintenance costs. Taking into account factors such  as downtime , the actual loss is often more than the cost of raw material savings .
Crushed material or recycled material typically contains  relatively large metal impurities , particularly copper , aluminum , solder, stainless steel and other metal particles. Therefore, the use of these materials would need use both strong magnetic filter bar and metal separators , this can be a good way to avoid the interference of metal impurities . Otherwise , plastic recycling and cost savings plan is basically impossible to achieve .

Even if the metal impurities does not cause any damage to the plastic machinery , these metal impurities in the molding products , such as plastic connectors ,will certainly result in product failure in terms of insulation ; Also, if press roller , when metal impurities come into the plastic sheet production line , it may lead to roller damage.

In short , due to the presence of metal impurities , risks always stay there , and it should be previously prevented.