Twin screw extruders are the core precision processing equipment for modified plastics, polymer compounding, filler blending, plastic granulation, and special material extrusion production. With the advantages of strong shearing force, uniform plasticization, high output efficiency, and wide material adaptability, twin screw extrusion equipment has become essential in plastic manufacturing, new material research and development, and industrial material processing industries. In long-term continuous industrial production, high torque alarm is one of the most frequent and influential fault signals of twin screw extruders. Once the torque value exceeds the system preset threshold, the equipment will trigger an automatic alarm, accompanied by speed reduction, automatic shutdown, material jamming, and even mechanical failure downtime, seriously affecting production continuity and output stability.
High torque alarms are not simple single-point faults; they are early warning signals of abnormal matching of material fluidity, process parameters, mechanical operation status, and electrical control systems. Most production enterprises often simply restart the equipment to eliminate the alarm phenomenon without fundamentally solving the root causes, resulting in repeated faults, frequent production stops, increased material waste, and accelerated equipment wear. In severe cases, sustained high torque operation will cause screw twisting, gearbox damage, motor burnout, and other major mechanical failures, bringing huge maintenance costs and economic losses to the factory.
WANPLAS is a professional global manufacturer of high-performance twin screw extruders and complete plastic extrusion production lines, focusing on the R&D, manufacturing, and customized solution output of high-stability, low-fault, energy-saving extrusion equipment. WANPLAS twin screw extruders adopt optimized screw combination design, high-precision gearbox transmission system, and intelligent real-time monitoring system, which can effectively inhibit abnormal torque fluctuation and reduce alarm failure rate. This professional guide comprehensively sorts out all root causes of high torque alarms in twin screw extruders, provides step-by-step troubleshooting methods, targeted solution strategies, standardized daily maintenance specifications, and detailed equipment cost and operation benefit analysis, helping enterprises completely solve high torque fault problems and stabilize long-term high-efficiency production.
1. Basic Overview of Twin Screw Extruder Torque Operation Principle
1.1 Definition and Standard Working Range of Equipment Torque
The torque of a twin screw extruder refers to the rotational torque borne by the screw shaft during operation, which is the core parameter reflecting the load state of the equipment. It directly represents the resistance of material shearing, melting, and propulsion inside the barrel. The torque value of industrial twin screw extruders is usually displayed in percentage, with 60% to 80% defined as the standard stable operation range. In this interval, the equipment realizes balanced material plasticization and efficient extrusion, with uniform product quality, stable operation, and low failure rate.
When the torque continuously exceeds 85%, the equipment enters a high-load early warning state; when it breaks through 90% to 95%, the system will automatically trigger a high torque alarm. If the load continues to rise without intervention, the equipment will implement forced shutdown protection to avoid damage to the motor, gearbox, and screw components. Different from single screw extruders, twin screw equipment has stronger material conveying and shearing capacity, so its torque fluctuation is more sensitive to material changes and process adjustments, requiring more precise parameter control and daily operation management.
1.2 Core Functions of Torque Monitoring System
The built-in intelligent torque monitoring system of WANPLAS twin screw extruders runs in real time during the whole production process, synchronously collecting and analyzing motor load, screw rotation resistance, and internal material pressure data. The system undertakes three core functions: real-time load monitoring, abnormal fault early warning, and equipment safety protection. It can capture tiny torque fluctuations that cannot be manually identified, accurately judge abnormal load states, and provide early protection before equipment overload failure occurs.
For production enterprises, stable torque operation is not only the guarantee of equipment safety but also the key to consistent product quality. Stable torque means uniform material plasticization, consistent melt fluidity, and stable extrusion pressure, which effectively avoids product density deviation, particle unevenness, and surface defects caused by load fluctuation.
1.3 Hazards of Long-Term High Torque Operation and Frequent Alarms
Frequent high torque alarms will bring multi-dimensional losses to production lines. In terms of production efficiency, repeated alarm shutdowns interrupt continuous production, reduce effective operating time, and directly lead to reduced daily output. In terms of product quality, torque fluctuation causes unstable material shearing and melting degrees, resulting in unqualified plasticization of modified materials, inconsistent particle size, and poor batch consistency, increasing product rejection rate.
In terms of equipment loss, long-term high-load operation will accelerate the wear of screw elements, barrel inner wall, and gearbox gears, reduce equipment service life, and greatly increase the frequency of vulnerable parts replacement and overhaul costs. In serious cases, instantaneous overload torque will cause screw shaft deformation, gearbox tooth breakage, and motor winding burnout, requiring high-cost equipment maintenance and long-term production halt, bringing huge economic losses to enterprises.
2. Complete Classification of Root Causes for High Torque Alarms
The high torque alarm faults of twin screw extruders are systematically divided into four major categories: material factor abnormalities, process parameter mismatches, mechanical equipment failures, and electrical control system deviations. Each category contains multiple detailed inducements. Comprehensive fault sorting and targeted analysis are the premise of accurate troubleshooting and thorough solution.
2.1 Material Factor Abnormalities (Most Common Inducement)
Unreasonable material state and formula proportion are the primary causes of high torque alarms in daily production. First, excessive filling proportion of inorganic fillers such as calcium carbonate, talc, and glass fiber will significantly increase material hardness and internal friction resistance. These high-hardness fillers have poor fluidity and require greater screw shearing and propulsion force, resulting in rapid torque rise and triggering high-load alarms.
Second, uneven material mixing and inconsistent formula proportion will lead to local high-viscosity material accumulation inside the barrel. Some materials have excessive resin content while others have excessive filler content, resulting in unbalanced overall material fluidity and instantaneous load surge. Third, wet materials with high moisture content will cause material agglomeration in the barrel. The agglomerated materials cannot be evenly melted and conveyed, forming extrusion resistance and raising torque sharply.
Fourth, mixed impurities in raw materials such as metal particles, hard plastic blocks, and mechanical debris will form rigid resistance during screw operation, causing instantaneous torque overload and alarm. WANPLAS twin screw extruders are equipped with optimized screw shearing structure, which can adapt to high-filler formula production and effectively reduce torque fluctuation caused by material formula changes.
2.2 Unreasonable Process Parameter Setting
Mismatched temperature, feeding speed, and screw speed parameters will directly cause abnormal torque load. Temperature setting deviation is the most typical problem. If the barrel and die heating temperature is too low, the plastic resin cannot reach the optimal melting state, resulting in high melt viscosity, poor fluidity, and increased screw propulsion resistance. Low temperature is the main cause of sustained high torque in winter low-temperature production environments.
Excessively high feeding speed is another key factor. When the feeding volume exceeds the melting and conveying capacity of the twin screw, materials accumulate in the barrel cavity, forming material blockage, which sharply increases screw operation load and triggers high torque alarms. In addition, unreasonable matching of screw speed and feeding speed will also cause load abnormality. Excessively low screw speed cannot timely discharge the fed materials, leading to material accumulation and overload; excessively high speed will cause excessive shearing of materials, resulting in melt viscosity rise and torque surge.
2.3 Mechanical Equipment Operation Failures
Long-term operation wear and mechanical structural abnormalities will lead to increased equipment operation resistance and continuous high torque. First, severe wear of screw elements and barrel inner wall will increase the gap between the screw and the barrel, resulting in material backflow and unstable conveying. The repeated shearing of residual materials will increase load and cause torque fluctuation and overload alarm.
Second, unreasonable screw combination matching will affect material plasticization and conveying efficiency. Too many shearing elements and excessive dense tooth structure will cause excessive material shearing, melt overheating and viscosity change, and increased operation resistance. Third, gearbox failure and insufficient lubrication will increase transmission resistance. Wear of internal gears, bearings, and insufficient lubricating oil viscosity will cause unsmooth transmission, resulting in increased motor operating load and false high torque alarms.
Fourth, material jamming at the die outlet will cause unsmooth discharge. Long-term unsmooth discharge leads to material accumulation in the barrel, forming back pressure and increasing screw propulsion load, finally triggering high torque overload protection.
2.4 Electrical and Control System Abnormalities
Electrical system faults are easy to be ignored in daily troubleshooting. First, frequency converter parameter deviation and unstable speed regulation will cause inconsistent motor output power, resulting in fluctuating screw operation speed and instantaneous torque surge alarm. Second, motor aging, insufficient power output, and unstable voltage will lead to insufficient driving force, making the motor in high-load operation state for a long time and displaying continuous high torque.
Third, failure and calibration deviation of the torque sensor will cause inaccurate data feedback. The sensor cannot accurately identify the actual load, resulting in false high torque data and false alarms. Fourth, abnormal PLC program parameters and mismatched overload threshold settings will lead to sensitive alarm response, triggering frequent false alarms under normal load conditions.
3. Step-by-Step Standard Troubleshooting Process for High Torque Alarms
Facing twin screw extruder high torque alarms, blind restart and parameter adjustment cannot solve the fundamental problem. According to the fault priority and difficulty investigation sequence, the following standardized step-by-step troubleshooting process can quickly locate fault points, eliminate hidden dangers, and avoid repeated faults.
3.1 Emergency Shutdown and On-Site Status Confirmation
After the equipment triggers a high torque alarm and shutdown, first cut off the feeding system to stop raw material supply, and keep the screw running at low speed for 3 to 5 minutes to discharge the accumulated materials in the barrel and reduce internal residual pressure. Do not restart the equipment immediately after shutdown to avoid secondary overload damage caused by residual accumulated materials. Observe the equipment operation data panel, record the real-time torque value, alarm time, and current process parameters, and retain fault data for subsequent analysis and judgment.
Check whether there is material overflow, die blockage, and abnormal vibration and noise of the equipment on site, and initially judge whether the fault is caused by material blockage or mechanical abnormality.
3.2 Material Formula and Raw Material Status Inspection
First inspect the raw material status of the current batch of production. Check whether the material has excessive moisture, agglomeration, and mixed impurities, test the material fluidity index, and confirm whether the filler proportion exceeds the standard production range. If the material moisture is too high, dry the materials thoroughly before production; if there are impurities and agglomeration, screen and clean the raw materials to eliminate material quality hidden dangers.
Check the material mixing uniformity to ensure that the resin, filler, and auxiliary materials are fully and evenly mixed, avoiding torque fluctuation caused by uneven formula. For newly replaced material formulas, priority inspection is required, as formula changes are the main cause of sudden torque alarms.
3.3 Process Parameter Calibration and Optimization Inspection
Check the temperature parameters of each barrel zone and die zone one by one to confirm whether the heating temperature meets the melting requirements of the current material. Appropriately increase the temperature of the low-temperature zone to ensure full material melting and reduced viscosity resistance. Calibrate the matching relationship between feeding speed and screw speed, appropriately reduce the feeding amount for high-load production, and ensure that the material feeding volume matches the equipment melting and discharging capacity.
Check the temperature rise curve and heating stability of the equipment to eliminate torque abnormalities caused by heating pipe damage and uneven temperature in individual zones. After parameter adjustment, conduct low-speed trial operation to observe torque changes, and gradually restore normal production speed after the load is stable.
3.4 Mechanical Structure and Transmission System Inspection
After eliminating material and process problems, conduct comprehensive inspection of mechanical structures. Check the die outlet for blockage, clean residual carbonized materials and accumulated materials at the die to ensure smooth discharge. Disassemble and inspect the screw combination to check for serious wear, deformation, and material carbonization adhesion on the screw surface, clean residual materials, and replace severely worn screw elements in time.
Check the gearbox lubricating oil level and oil quality to ensure sufficient lubricating oil and no deterioration or impurities. Replace deteriorated lubricating oil regularly to reduce transmission resistance. Check the tightness of each transmission component and bearing operation status to eliminate equipment jitter and load increase caused by loose parts and abnormal bearing operation.
3.5 Electrical Control System Detection and Calibration
Detect the operating status of the frequency converter to confirm stable speed regulation and normal power output. Calibrate the torque sensor data to eliminate false alarms caused by sensor deviation. Detect the motor operating voltage and current to ensure stable power supply and no abnormal current surge. Check whether the PLC overload threshold parameters are set reasonably, restore the factory standard parameters for misadjusted thresholds, and ensure accurate alarm judgment.
4. Targeted Solutions for Different Types of High Torque Faults
4.1 Torque Overload Caused by Material Abnormality
For high torque alarms caused by high filler proportion and high material viscosity, the solution is to optimize the material formula appropriately, reduce the proportion of high-hardness inorganic fillers, increase the proportion of lubricating auxiliaries and dispersants, reduce material internal friction and melt viscosity, and improve fluidity. For wet and agglomerated materials, equip with professional drying equipment to control material moisture within the standard range before feeding production.
Install a feeding screening device to block impurity particles and hard blocks, avoid rigid resistance caused by foreign matters, and fundamentally eliminate torque overload faults caused by material problems. WANPLAS twin screw extruders support high-filler formula production and are equipped with matched auxiliary feeding and drying systems, which can effectively adapt to complex material production conditions.
4.2 Torque Abnormality Caused by Unreasonable Process Parameters
For low-temperature-induced high torque, formulate exclusive temperature parameter schemes according to different material characteristics, appropriately increase the temperature of the feeding section, melting section, and die section, and extend the constant-temperature heating time to ensure full material plasticization. For overload caused by excessive feeding speed, adopt the method of graded speed increase, start production with low feeding volume, adjust the feeding amount step by step after stable material melting, and avoid one-time full-load feeding.
Establish a dedicated process parameter database for different materials and specifications, record the optimal matching values of temperature, rotating speed, and feeding amount, and realize one-key parameter calling during production switching, avoiding torque fluctuation caused by artificial parameter misadjustment.
4.3 Mechanical Failure Type High Torque Solution
For screw and barrel wear causing increased load, regularly detect the wear degree of screw elements and barrel inner wall, replace worn parts in batches, and optimize the screw combination structure according to material characteristics, reduce excessive shearing elements, and adopt low-resistance conveying combination to reduce operation load. For gearbox transmission resistance abnormality, replace lubricating oil regularly, clean gearbox internal impurities, and repair or replace damaged gears and bearings in time.
For die blockage and unsmooth discharge, clean the die regularly during production, set fixed material cleaning and carbon removal cycles, avoid long-term accumulation of carbonized materials, and ensure smooth discharge channel and stable internal pressure of the barrel.
4.4 Electrical System False Alarm and Load Abnormality Solution
For sensor calibration deviation and false alarms, regularly calibrate the torque sensor and pressure sensor every three months to ensure accurate data feedback. For unstable frequency converter speed regulation, optimize frequency conversion parameters, update program data, and ensure stable motor output power. For unstable power supply causing load fluctuation, install voltage stabilization equipment to ensure stable operating voltage of the equipment and avoid instantaneous torque surge.
5. Standard Daily Maintenance Specifications to Prevent High Torque Alarms
Most high torque alarm faults are caused by irregular daily operation and inadequate maintenance. Formulating standardized daily, weekly, and monthly maintenance systems can effectively reduce fault frequency and maintain long-term stable torque operation of twin screw extruders.
5.1 Daily Maintenance Standards
Before daily startup, preheat the equipment according to the standard heating curve, strictly prohibit startup production without reaching the set temperature, and avoid unmelting material overload. Check the raw material status before feeding to ensure dry and impurity-free materials. Observe the real-time torque data during operation, record the load fluctuation range, and stop the machine for inspection immediately if abnormal surge occurs.
After daily shutdown, clean the residual materials in the screw and die thoroughly to avoid material carbonization and adhesion caused by high-temperature retention, which will affect the next startup load. Check the gearbox lubricating oil level every day to ensure sufficient lubrication.
5.2 Weekly Maintenance Standards
Every week, calibrate the temperature control parameters and sensor data of each equipment zone to ensure accurate temperature control and data monitoring. Clean the feeding system and screening equipment to remove residual materials and impurities and ensure stable and uniform feeding. Check the screw operation status and transmission system stability, fasten loose bolts and parts, and eliminate mechanical hidden dangers.
Optimize the operating parameters according to the weekly production material types, adjust the matching degree of rotating speed and feeding amount, and maintain the equipment in the optimal load operation state.
5.3 Monthly Maintenance Standards
Every month, conduct a comprehensive disassembly and inspection of the screw and barrel, detect the wear degree of components, replace severely worn parts, and clean carbonized materials thoroughly. Replace the gearbox circulating lubricating oil, clean the oil circuit system, and ensure smooth transmission and low resistance. Inspect the electrical control system, check the line aging status and sensor sensitivity, and calibrate the torque overload protection threshold.
5.4 Annual Overhaul Standards
Carry out full-line equipment overhaul every year, comprehensively detect the gearbox operation performance, motor power output, and screw assembly accuracy, repair and replace aging and failed components in batches, eliminate cumulative operation errors and wear losses, and restore the equipment's optimal operating performance. WANPLAS provides professional annual overhaul services for all twin screw extruder users, helping enterprises eliminate potential equipment faults in advance.
6. WANPLAS High-Stability Twin Screw Extruder Product Recommendations
To fundamentally reduce high torque alarm faults and improve production stability, WANPLAS has launched a full range of high-performance twin screw extruders with optimized torque control systems, covering small test models, medium conventional production models, and large high-output models, suitable for various plastic modification, granulation, and compounding production scenarios.
6.1 Small Twin Screw Extruder for Test and Small-Batch Production
This series of small twin screw extruders is suitable for laboratory material research and development, formula testing, and small-batch customized production. The equipment adopts optimized low-resistance screw design and high-precision intelligent torque monitoring system, with sensitive fault early warning and stable load operation. It can effectively avoid torque overload alarms caused by formula adjustment and material testing. The equipment has compact structure, low energy consumption, and simple maintenance, which is very suitable for new material enterprises and research institutions.
6.2 Medium-Sized Twin Screw Extruder for Conventional Mass Production
The medium-sized twin screw extruder is the mainstream model for industrial mass production, with stable output and wide material adaptability. The equipment is equipped with an upgraded reinforced gearbox and high-efficiency heat dissipation system, which can bear long-term high-load operation and effectively reduce torque fluctuation. The intelligent PLC system automatically matches process parameters according to different materials, realizing automatic load adjustment, greatly reducing manual debugging errors and high torque fault rate. This model is widely used in conventional plastic modification, filler blending, and waste plastic granulation production.
6.3 Large High-Output Twin Screw Extruder for Large-Scale Factories
The large high-output twin screw extruder is oriented to large-scale factory standardized mass production, with super strong shearing capacity and stable conveying performance. The equipment adopts dual intelligent torque monitoring and automatic protection system, which can realize real-time load fine-tuning, automatically adjust feeding speed and screw speed according to material changes, and maintain torque in the optimal stable range. The whole line has high automation, low failure rate, and can realize 24-hour continuous stable production, helping large enterprises maximize production efficiency and reduce comprehensive failure costs.
7. Equipment Price and Operation Cost Benefit Analysis
7.1 WANPLAS Twin Screw Extruder Price Estimation
The FOB price of WANPLAS small test twin screw extruder is 28,000 US dollars to 45,000 US dollars, which is suitable for enterprise laboratory research and development and small-batch production investment. The FOB price of conventional medium-sized industrial twin screw extruder is 65,000 US dollars to 98,000 US dollars, which is the mainstream cost-effective model for mass production. The FOB price of large high-output twin screw extruder is 135,000 US dollars to 185,000 US dollars, suitable for large-scale industrial intensive production.
All equipment prices include factory pre-commissioning, on-site installation guidance, professional technical training, and one-year full-machine warranty service, with transparent pricing and no hidden additional costs. Enterprises can select appropriate models according to production scale and budget.
7.2 Fault Loss Cost of Traditional Old Equipment
Traditional ordinary twin screw extruders have unstable torque control and frequent high torque alarms, bringing continuous invisible losses to enterprises. The frequent shutdown and restart caused by faults reduce the effective production time by 5% to 8% every month. The material waste and unqualified products caused by load fluctuation increase the raw material cost by 3% to 5% annually. In addition, frequent mechanical wear and vulnerable parts replacement increase the annual maintenance cost by 1,200 to 2,500 US dollars. The comprehensive annual loss caused by high torque faults of old equipment is very considerable.
7.3 Operation Cost Advantage of WANPLAS Optimized Equipment
WANPLAS optimized twin screw extruders can reduce the high torque alarm failure rate by more than 90%, almost eliminating production shutdown and product quality problems caused by torque abnormalities. The stable load operation reduces equipment wear and tear, extending the service life of screw, gearbox and other core components by more than 20%, and reducing annual maintenance costs by 60% to 70%. The stable production process improves product qualification rate and production efficiency, bringing stable output growth and quality improvement benefits to enterprises.
7.4 Investment Payback Analysis
Enterprises that replace or upgrade WANPLAS high-stability twin screw extruders can recover the equipment optimization investment through saved maintenance costs, reduced material waste, and increased output efficiency within 8 to 12 months. Long-term stable low-fault operation can continuously reduce comprehensive production costs and improve enterprise market competitiveness, with significant long-term economic benefits.
8. Common High Torque Alarm Fault Cases and Verification Solutions
8.1 High Torque Caused by Excessive Filler Proportion
In the production of high-calcium filled modified materials, many enterprises will blindly increase the filler proportion to reduce costs, resulting in excessive material hardness and fluidity deterioration, continuous torque rise and frequent alarms. The verified solution is to appropriately adjust the formula ratio, add high-efficiency lubricating dispersants, cooperate with low-resistance screw combination optimization, and match graded temperature rise parameters, which can effectively reduce torque load and realize stable production of high-filler materials.
8.2 Winter Low-Temperature Torque Overload Fault
In low-temperature winter environments, the ambient temperature is low, the equipment heating efficiency is reduced, and the material melting speed is slow, resulting in high melt viscosity and easy torque overload. The effective solution is to extend the preheating time before startup, appropriately increase the temperature of each barrel zone by 5℃ to 10℃, adopt low-speed and low-feeding startup, and restore normal parameters after stable material melting, which can completely eliminate low-temperature torque alarm faults.
8.3 Torque Fluctuation Caused by Screw Wear
After long-term operation of the equipment, the screw surface is worn and the shearing gap is increased, resulting in unstable material conveying and repeated torque fluctuation alarms. The solution is to replace the worn screw elements in time, recalibrate the screw assembly gap, and match the optimal process parameters, which can restore the equipment load stability and avoid repeated faults.
9. Conclusion
High torque alarm is a common and easily neglected key fault in the operation of twin screw extruders. Its root causes cover material formula, process parameters, mechanical wear, and electrical control systems. Blind restart and simple parameter adjustment can only solve superficial phenomena, while standardized troubleshooting, targeted optimization solutions, and scientific daily maintenance are the fundamental ways to eliminate repeated high torque faults.
WANPLAS series twin screw extruders adopt optimized mechanical structure and intelligent torque monitoring system, which have inherent advantages in resisting torque fluctuation and reducing overload faults. Equipped with professional process matching schemes and standardized maintenance specifications, the equipment can maintain long-term stable low-load operation, effectively reduce equipment failure rate and production loss, improve product batch consistency and production efficiency, and create stable and sustainable economic benefits for plastic processing and new material manufacturing enterprises.
