Do you know this about plastic twin-screw extruder?

Do you know this about plastic twin-screw extruder?

What do you need to pay attention to when feeding?

According to the operation flow of plastic twin-screw extruder granulator, there are many things that should be paid attention to. The raw materials feeding of twin-screw equipment is added by quantitative feeder, which can be volume metering feeder, or weight-in-loss metering feeder; it can be one feeder or multiple feeders at the same time in proportion. When feeding, first of all, make sure to start the host twin screw extruder firstly, and then slowly start the feeder, pay attention to observe the current of the host at all times, to avoid excessive feeding, the host current surge and force the host to stop over current.

plastic twin-screw extruder-feed

In addition, the raw materials should be clean, and free of impurities such as metal or sand, and the moisture content should not be too high. For feeding some recycled raw materials, a magnetic frame (strong magnet) must be installed at the feeding buckle or in the hopper to absorb raw materials’ metal impurities. Prevent metal impurities from falling into the screw and damaging the equipment.

What do you need to pay attention to during the operation? 

  • The parameters of the temperature control instrument in each heating area must be set according to the technological requirements. After the heating temperature of each section reaches the set value, continue to hold heat. At the same time, further confirm whether the temperature control instrument and solenoid valve (or cooling air machine) of each section work normally. The oil pump must be started before starting the main motor.
  • In the case of no feeding, the idling speed can not be too high, so as to start feeding at the lowest speed as possible, and make the feeding machine and the host speed match.
  • Equipment operation must be carried out in strict accordance with the equipment instructions. Equipment operators should be trained and qualified before they can operate. Do not operate devices that are not in your charge or that you are not familiar with.
  • If you need to stop the device to rectify the fault when operating the device, stop the device; If the power supply needs to be cut off, the power supply should be disconnected, and the no-movement sign should be hung or supervised by special personnel to prevent accidental startup or closing, which may cause personnel injury.
  • When the device is running, field operators must periodically inspect the device. If an abnormal sound is found during the operation of the equipment, stop the machine immediately and remove the fault. Stop the machine should first stop feeding, and then stop the main host engine and other auxiliary machinery.

When plastic twin-screw extruder granulator feed slowly, how to do? 

There are many reasons for the low output of the twin screw extruders. In order to troubleshoot and increase output, Granuwel starts from the following main aspects as below:

  • The screw and barrel are severely worn, which mainly occurs in PE+ CaCO3 and other mineral fillers. In the production of glass fibre-reinforced modified materials, due to the high hardness of calcium powder and glass fibre, the damage to the screw and barrel is very large, leading to the gap between the screw and barrel becoming larger. The material in the Die head position, due to the effect of the perforated plate, the material cannot be extruded smoothly and flows back and forth in the barrel, thereby reducing the output.

Solution: Check and replace the worn cylinder and screw

  • Barrel heater failure: The plasticizing and melting of materials require heat. If the barrel heater is damaged or fails, the raw materials will not be completely melted and the die head will be blocked, thereby reducing the output. Check the instrumentation of the electric control cabinet Display status, if the set temperature in a certain area is much higher than the actual temperature, it can be concluded that the heater in this area is faulty.

Solution: Replace with a new heater.

  • The feeding volume of the feeder becomes smaller, which affects the output. Most of the time, our customers use the same equipment to make many kinds of materials, the material state is different, the proportion is different, the feeding volume will change. Some material than major, feed large, twin screw extruder’s output is large, and vice versa.

Solution: For this kind of multi-purpose machine, the customer should equip feeding screws with different structures, and record the production status of each material in time, including the speed of the main host machine, the speed of feeding, the current of the main host machine, the processing temperature, the melt temperature and Melt pressure and other parameters. Find the best combination of parameters.

What should I do if the engine is blocked? 

There are several reasons why the engine does not run:

  • The set processing temperature is low, the holding time before starting the machine is not enough, or the heater in one or two areas is faulty and the material is not melted.

Solution: increase the processing temperature and keep it warm for a period of time, half an hour in summer and one hour in winter. Check and replace faulty heater.

  • The feeding speed is too fast when starting up. Lead to overfeeding and screw lockup.

Solution: stop feeding, the main host engine, clean up the material accumulated in the feeding port, and slowly start the main host engine, also slowly push out the excess material in the screw. Properly increase the speed of the host machine and start feeding slowly. Wait until the current of the main host machine is stable and then slowly increase the feeding amount.

  • Metal or large material falls into the feeding port, resulting in instant over-current screw lockup.

Solution: Cut off the power supply and remove the metal or large material that falls into the feed. If you can’t take out, you must remove the barrel, screw and so on.

  • Motor failure: the motor bearing may be too high temperature or burnt out due to no regular maintenance of the motor.

Solution: add lubricating oil or replace bearing

  • The gear box is locked due to faults. There may be a lack of oil, or the lubricating oil becomes dirty, resulting in rising bearing temperature and rising gear temperature

Solution: Replace bearings, gears, and check the replacement gear box regularly.

What should I pay attention to when disassembling the extruder? 

Before disassembling the extruder, it is necessary to read carefully the “Equipment Instruction manual” of Granway Machinery carefully: It is necessary to use the specified special tools, and it is strictly prohibited to knock the equipment with hard objects such as hammers. To prevent damage to equipment parts. The machine must be heated before disassembly. Remove the die head, discharge the material in the barrel, and then pull out the screw.

The following must be paid attention to when removing the screw:

  • The positions of the two screws cannot be switched.
  • Clean the screw with wire brush, copper shovel will screw surface materials while hot quickly clean.
  • Remove the screw hanger ring (left screw thread) on the screw, and then remove the screw element while it is hot. The wood hammer, copper rod or aluminum rod can be used to gently knock around the screw element. If any material penetrates into the surface of the mandrel, making it difficult to disassemble, it can be heated, and the material in the gap can be removed while hot after softening.
  • It is not allowed to strike the screw element with sharp hardening tools.
  • The end face of the removed screw elements, inner hole and keyway should be cleaned in time.

For any further information,welcome to contact us—Nanjing Granuwel is here for serving you!

About us

Nanjing Granuwel Machinery CO., LTD is specializing in R&D design and manufacture of high polymer extruders, our team of top-level extrusion professionals provides the right extruder for your exact application.

plastic twin-screw extruder manufacturer

Nanjing Granuwel Machinery CO., LTD

We possess excellent capability of innovation and product development, and desire to provide best products for our customers through the improvement of equipment structure and reduction of equipment energy consumption through our practical experiences and technical innovation. 

For any question/inquiry,warmly welcome to contact us!!!

Tel: +86-25-86199956

Mobile: +86-13813371123

Emailinfo@granuwel.com

 

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