The Correct Way to Switch Color and Materials
People who work with extrusion always want to keep the machine running for longer periods of time. But in reality, due to customer demand, we often have to keep switching between producing 80kg of product A, then 200kg of product B, etc.
1.The batch size of the product has to correspond to the size of the machine. This may seem self-evident, but many processors schedule production without a plan, producing 500lb orders on 75 machines, resulting in 300lb of scrap.
2.Write out a procedure for clearing or dismantling the machine for each product produced. This helps the operators to plan their time and eliminates their arguments about how much headstock will be produced.
3.Help the operator by placing clean operating tools around the extruder, and if there are frequent material changes, then get a workbench around the extruder and have everything you need ready.
4.Study the sequence of raw material and finished product flow in and out of the operation. Arrange it so that the operator spends less effort on moving the transport.
5.Be clear about the level of machine cleanliness required for the next product. If you know that the next product requires thorough manual machine cleaning, then don’t waste time and materials muddling through the machine.
6.If possible, schedule your production in a sequence that reduces the number of machines to be cleaned. This means going from light colours to dark colours. Instead, you will have to do multiple machine removals.
The Correct Way to Start and Stop An Extruder
1.Common operation practices:
The operator has a habit of leaving the extruder on when he arrives at the plant in the morning but then goes off to do other things. The extruder is allowed to heat up to full capacity and sit idle for several hours. This causes the polymer to adhere to the screw and barrel and subsequently, this polymer material will continue to degrade and char. Cleaning the machine will not remove this material and, worse still, once the machine is producing a product, black spots will periodically run out of the screw and barrel, contaminating the product and causing customer complaints.
2.The correct way of opening:
You should plan the really time you want to operate the extruder, then start heating it up just as soon as the temperature reaches a predetermined value and then proceed to barrel filling.
3.The correct way of power off:
Before power off, seal the machine gaps by filling the extruder to the maximum with an inert polymer (e.g. HDPE) which drives out oxygen and coats the metal surface, greatly reducing the formation of carbon oxides. After the extruder has been “sealed”, it is best to chill the extruder rather than leave it in the air for 18 hours. By rapid cooling, all temperatures are set to zero and all cooling water valves are opened. The cooling water pump is switched on and the cooling water is passed through all parts of the barrel to cool it down quickly. Rapid cooling will prevent polymer degradation and charring.
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