Home » News » Analysis and Solution of Common Faults in Extruder
Analysis and Solution of Common Faults in Extruder
Views: 569 Author: Site Editor Publish Time: 2024-04-09 Origin: Site
The host current is unstable
1. Cause of occurrence:
(1) Uneven feeding. (2) The main motor bearings are damaged or poorly lubricated. (3) A certain section of the heater is malfunctioning and not heating. (4) The screw adjustment pad is incorrect, or the phase is incorrect, resulting in component interference.
2. Handling method:
(1) Check the feeder and troubleshoot. (2) Repair the main motor and replace the bearings if necessary. (3) Check if each heater is working properly and replace it if necessary. (4) Check the adjustment pad and pull out the screw to check for any interference.
The main motor cannot start
1. Cause of occurrence:
(1) There is an error in the driving program. (2) There is an issue with the main motor thread, is the fuse burnt out. (3) The interlocking device related to the main motor works
2. Handling method:
(1) Check the program and restart in the correct driving sequence. (2) Check the main motor circuit. (3) Check if the lubricating oil pump is started and check the status of the interlocking device related to the main motor. The oil pump does not turn on, and the motor cannot be turned on. (4) Check if the emergency button is reset. (5) The induction power of the frequency converter is not fully discharged. Turn off the main power and wait for 5 minutes before starting.
Poor or blocked discharge of the machine head
1. Cause of occurrence:
(1) A certain section of the heater is not working, and the material has poor plasticization. (2) The operating temperature is set too low, or the molecular weight distribution of plastic is wide and unstable. (3) There may be foreign objects that are not easily melted.
2. Handling method:
(1) Check the heater and replace it if necessary. (2) Verify the set temperature for each section, and negotiate with the process engineer if necessary to increase the temperature setting value. (3) Clean and inspect the extrusion system and machine head.
Main power startup current too high
1. Cause of occurrence:
(1) Insufficient heating time and high torque. (2) A certain section of the heater is not working.
2. Handling method:
(1) When driving, use hand cranking. If it is not easy, extend the heating time or check if each section of the heater is working properly.
The main motor emits abnormal sound
1. Cause of occurrence:
(1) The main motor bearings are damaged. (2) One of the thyristors in the main motor's thyristor rectifier circuit is damaged.
2. Handling method:
(1) Replace the main motor bearings. (2) Check the thyristor rectifier circuit and replace the thyristor components if necessary.
The temperature rise of the main motor bearing is too high
1. Cause of occurrence:
(1) Poor lubrication of bearings. (2) The bearings are severely worn.
2. Cause of occurrence:
(1) Check and add lubricant. (2) Check the motor bearings and replace them if necessary.
Unstable head pressure
1. Cause of occurrence:
(1) The main motor speed is uneven. (2) The feeding motor speed is uneven, and the feeding amount fluctuates.
2. Handling method:
(1) Check the main motor control system and bearings. (2) Check the feeding system motor and control system.
Low lubricating oil pressure
1. Cause of occurrence:
(1) The pressure setting of the pressure regulating valve in the lubricating oil system is too low. (2) Oil pump malfunction or blocked suction pipe.
2. Handling method:
(1) Check and adjust the pressure regulating valve of the lubricating oil system. (2) Check the oil pump and suction pipe.
The automatic screen changing device is slow or ineffective
1. Cause of occurrence:
(1) Low air pressure or oil pressure. (2) Cylinder (or hydraulic station) leaks air (or oil)
2. Handling method:
(1) Check the power system of the screen changing device. (2) Check the sealing condition of the cylinder or hydraulic cylinder.
Safety pin or safety key cut off
1. Cause of occurrence:
(1) Excessive torque in the squeezing system. (2) The connection between the main motor and input bearing is not concentric
2. Handling method
(1) Check if any metal or other objects have entered the squeezing system and stuck the screw. At the beginning, check if the preheating heating time or heating value meets the requirements. (2) Adjust the main motor.
the wear-induced failure of screws and barrels, noting the limitations of chrome plating and nitriding. It investigates the feasibility of surface boriding treatment on 45 steel screws and barrels to enhance surface hardness and wear resistance, and validates the process through field testing.
This article introduces the working principle of ball screws, highlighting their high mechanical efficiency and load capacity, which have led to widespread adoption in all-electric servo-driven injection molding machines. It compares ball screw design philosophies for machine tools and injection molding machines, noting that injection units experience loads hundreds to thousands of times greater. Key design priorities for high-load ball screws—such as uniform ball contact pressure, optimized lubrication, and enhanced durability—are discussed, with reference to Ningbo Superior's specialized solutions.
The screw and barrel are the most critical components of injection molding machines, operating under high temperature and pressure. Wear enlarges the clearance between the screw flight and barrel, reducing melting and pumping capacity, causing product quality degradation, lower productivity, and higher energy consumption. The screw is more susceptible to damage than the barrel.
This section examines the key parameters of the venting section in vented extruder screws. Venting effectiveness depends primarily on venting section length L, melt residence time, shear rate, and the fill factor F (the ratio of melt cross-sectional area to channel area). To ensure good performance, the venting channel should be partially filled; experiments suggest L ≥ 3D, F ≤ 0.5, and a shear intensity K > 100 for optimal degassing. For screws with L/D ratios of 24–30, the venting section length is typically 4D, and its channel depth is 2.5–6 times that of the first metering section. Design verification must include fill factor, shear intensity, and screw strength.
On Labor Day, we pay sincere tribute to every hardworking professional around the world.Dedication creates value, and perseverance achieves dreams. May everyone enjoy a pleasant holiday, stay safe and healthy, and reap fruitful rewards from every effort.Wishing you all a happy and wonderful Labor Da
This section discusses the determination of channel depths H₁ and H₂ in venting screws, with emphasis on the pump ratio Ω (Ω = H₂/H₁). The pump ratio directly influences the risk of vent flooding and extrusion stability. A theoretical optimum Ω of 1.5 is derived for Newtonian fluids, while for non-Newtonian polymers like polyethylene an Ω of 1.75 yields maximum die pressure. In practice, most designs adopt Ω values between 1.5 and 2.0. The article also clarifies that the concept of a "second compression ratio" is invalid for venting screws, as the venting section is not fully filled.
This section outlines the functional characteristics of venting screws in extrusion. It identifies three main sources of gases in raw materials—entrained air, adsorbed moisture, and internal volatiles—and describes their detrimental effects on product quality and properties. While conventional methods rely on pre-drying or feed-throat venting, these approaches increase costs, risk contamination, and are often insufficient for high-speed extrusion. The text concludes that vented extruders offer superior performance in effectively removing these gases.
