Introduction
As a core piece of equipment in modern peanut oil production, the twin-screw oil press, with its unique twin-screw meshing design, high compression ratio, and powerful self-cleaning function, offers significant advantages in both cold and hot pressing of peanuts. Models like the SSYZ50 effectively address technical challenges, such as slippage and low conveying capacity, during the pressing of high-oil-content peanut kernels through an innovative structural design, achieving high oil yield and good cake quality. However, the equipment’s efficient and stable operation relies on scientific, standardized daily maintenance and timely, accurate fault handling.
This article systematically outlines the daily maintenance system for twin-screw peanut oil presses and provides detailed solutions to common production issues, offering comprehensive equipment management guidance for oil-pressing enterprises. By implementing scientific maintenance strategies, companies can reduce equipment failure rates by over 60% and extend equipment service life by 30%-50%, while maintaining stable oil yield and quality.
60%
Reduction in Failure Rate
30-50%
Extended Service Life
99%
Improved Operational Stability
Chapter 1: Daily Maintenance System for Twin-Screw Oil Press
1.1 Importance of Daily Maintenance
As a precision mechanical device, the twin-screw oil press’s operational status directly affects oil yield, oil quality, and equipment service life. Statistics show that oil presses that implement systematic maintenance can reduce failure rates by over 60%, extend equipment service life by 30%-50%, and maintain stable oil yield and quality. Daily maintenance not only prevents sudden failures and reduces downtime but also identifies potential issues early, preventing minor faults from escalating into major repairs and significantly lowering maintenance costs.
Core Objective of Maintenance: Ensure the equipment is always in optimal operating condition, maximize equipment efficiency, minimize downtime from faults, and guarantee stable product quality.
1.2 Daily Maintenance Items
1.2.1 Pre-Startup Inspection
- Equipment Cleaning Inspection: Clean oil stains, dust, and debris from the equipment surface and surrounding areas to maintain a clean working environment. Pay special attention to cleaning areas prone to buildup, such as the press chamber inlet/outlet and oil drainage channels.
- Lubrication System Check: Verify that the gearbox oil level is at the midpoint of the sight glass and that the lubricating grease level is sufficient. The sliding bearings of the twin-screw oil press use solid lubricants, requiring regular inspection of the lubrication status.
- Transmission System Check: Check if V-belt tension is appropriate, if pulleys are aligned, and if protective covers are secure. Overly tight belts increase bearing load, while overly loose belts affect power transmission efficiency.
- Electrical System Check: Check if all motor connections are secure, if the frequency control cabinet display is normal, and if the emergency stop switch functions effectively.
- Feeding System Check: Check for residual material in the horizontal and vertical augers, and if the hopper gate opens and closes smoothly.
1.2.2 Monitoring During Operation
- Sound Monitoring: Listen attentively to whether equipment operation sounds are smooth and uniform, and if there are any abnormal impacts, friction, or sharp noises.
- Vibration Monitoring: Touch the frame and bearing housings by hand to feel if vibration increases abnormally. Normal operation should have slight, uniform vibration.
- Temperature Monitoring: Check if temperatures at motors, reducers, bearing housings, etc., are normal, generally not exceeding 70°C.
- Current Monitoring: Observe if the main motor current fluctuates within the rated range. An abnormal increase may indicate excessive load or a mechanical fault.
- Oil Output Observation: Observe if oil output is continuous and uniform, if oil color is normal, and if there are obvious foam or impurities.
1.2.3 Post-Shutdown Maintenance
- Material Cleanup: Follow the “front to back” principle to stop each device sequentially, ensuring all materials on conveyors, such as scrapers and floor augers, are emptied. Pay special attention to emptying the steaming/wokting pan completely before shutting off the steam and stopping.
- System Cleaning: For cold-pressing processes, after shutdown, pass a small amount of cake or a specialized cleaning material through the press chamber to remove residual oil. For hot pressing processes, use steam or hot water for cleaning.
- Water Drainage: Open the condensate return valve of the steaming/wokting pan to drain all stored water, preventing internal corrosion.
- Oil Circuit Handling: Continue running the overflow oil tank for 2 hours, then wait for the oil layer to clarify before shutting down. Maintain the oil level so the overflow pipe does not discharge oil during shutdown.
- Safety Check: Comprehensively verify the closed status of all valves; inspect the area around the heating equipment for abnormalities; turn off all power switches; and close the main valve and the workshop electrical knife switch.
1.3 Weekly Maintenance Items
- Comprehensive Cleaning: Thoroughly clean the inside and outside of the equipment, including areas prone to dust accumulation, such as motor heat sinks and control cabinet ventilation openings.
- Lubrication Point Re-greasing: Supplement grease at all lubrication points, such as bearings and chains, and remove any old grease before adding new grease.
- Fastener Check: Inspect and tighten all bolts and nuts, especially at critical locations such as anchor bolts and bearing housing bolts.
- Drive Belt Check: Inspect the V-belt for wear; replace promptly if there are cracks or delamination.
- Electrical Connection Check: Verify that all electrical connection points are secure and free of heating or oxidation.
1.4 Monthly Maintenance Items
- Gearbox Oil Change: Replace gearbox lubricating oil after the first 500 hours of operation, then every 2000-3000 hours or every 6 months thereafter.
- Press Chamber Clearance Check: Use a feeler gauge to check the clearance between the press screw and the press cage. Standard clearance is typically 0.5-1.5mm; adjustment or replacement is needed if exceeding 2mm.
- Wear Part Inspection: Check the wear condition of easily worn parts such as press screws, press rings, and bar cages; record the wear amount; and predict replacement cycles.
- Feeding System Calibration: Check the conveying efficiency of horizontal and vertical augers, and calibrate inverter settings to ensure accurate feeding volume.
- Safety Device Testing: Test the functional effectiveness of all safety protection devices, emergency stop switches, and overload protection devices.
| Maintenance Cycle | Main Items | Key Indicators |
| Daily | Cleaning, lubrication check, operation monitoring | Temperature ≤70°C, normal current, no abnormal sounds |
| Weekly | Comprehensive cleaning, fastener check, lubrication re-greasing | Bolts tightened without loosening, lubrication adequate |
| Monthly | Gearbox check, press chamber clearance measurement, wear part inspection | Press chamber clearance 0.5-1.5mm, wear ≤30% |
| Quarterly | Reducer inspection, electrical system check, alignment adjustment | Alignment deviation ≤0.05mm, insulation resistance ≥5MΩ |
| Annually | Complete disassembly inspection, key component replacement, accuracy restoration | Restore factory accuracy standards, anti-corrosion treatment |
1.5 Quarterly Maintenance Items
- Reducer Disassembly Inspection: Check gear wear condition, replace severely worn gears and bearings.
- Electrical System In-depth Check: Check motor insulation resistance, clean electrical contacts, and calibrate instrument display accuracy.
- Hydraulic System Check (if equipped): Check hydraulic oil quality, clean or replace filter elements, and check seal condition.
- Foundation and Alignment Check: Check for settlement or cracking of the equipment foundation, and re-perform the alignment adjustment between the motor and the reducer.
- Performance Testing: Conduct no-load and load tests; record parameters such as current, temperature, and vibration; and establish equipment performance records.
1.6 Annual Overhaul Items
- Complete Disassembly Inspection: Fully disassemble the main components of the oil press to inspect wear and deformation of each part.
- Key Component Replacement: Replace parts that have reached service life, such as press screws, press rings, bearings, and seals.
- Accuracy Restoration: Repair or replace components affecting equipment accuracy to restore factory accuracy standards.
- Control System Upgrade: Check and update the electrical control system, upgrade aging components, and optimize control programs.
- Anti-corrosion Treatment: Perform derusting and anti-corrosion treatment on the inside and outside of the equipment to extend service life.
Chapter 2: Common Problem Diagnosis and Solutions for Twin-Screw Oil Press
Problem One: Reduced Oil Yield
Phenomenon: Oil yield after peanut kernel pressing is significantly lower than normal, and the residual oil rate in the cake increases.
Solutions:
- Temperature Control Optimization: For cold pressing, ensure the press chamber temperature does not exceed 80°C. For hot pressing, ensure steaming/wokting temperature reaches 110-120°C.
- Material Pretreatment Adjustment: Install online moisture detectors to monitor incoming material moisture in real-time and adjust drying parameters.
- Press Chamber Pressure Restoration: Check and adjust cake outlet gap (normal 0.3-0.8mm), replace severely worn press screws and rings.
- Pressing Time Adjustment: Reduce feeding auger speed via the inverter, and appropriately reduce the press screw shaft speed to extend pressing time.
- Oil Drainage System Cleaning: Regularly disassemble and clean bar cages, remove oil residue scale, and check the oil drainage channel slope to ensure smooth oil flow.
Problem Two: Cake Not Forming or Overly Powdery
Phenomenon: The output cake is loose and doesn’t form properly, or is overly crushed into powder.
Solutions:
- Precise Moisture Control: Install an automatic conditioning system. Control moisture at 5%-7% for cold pressing, 2%-3% for hot pressing.
- Fine Temperature Adjustment: Install temperature sensors at key positions on the press cage, and establish a temperature-cake quality correlation table.
- Cake Outlet Gap Optimization: Use specialized gap-measuring tools for regular inspections and maintain gap-adjustment records.
- Press Screw Condition Check: Inspect press screw wear monthly and repair local wear with a wear-resistant coating.
- Feeding System Modification: Install a feeding buffer bin to stabilize feed volume and optimize the inverter control program.
Problem Three: Abnormal Noise and Vibration
Phenomenon: Abnormal impact, friction sounds, or significantly increased vibration during equipment operation.
Solutions:
- Foreign Object Prevention and Handling: Strengthen raw material cleaning, install strong magnetic separators and stone removers, and stop the machine immediately for inspection upon detecting abnormality.
- Bearing Condition Monitoring: Measure bearing vibration value monthly, monitor bearing temperature with an infrared thermometer, and replace promptly if abnormal.
- Fastening System Management: Implement a bolt-fastening marking system and use a torque wrench to fasten bolts to the specified torque.
- Alignment Accuracy Assurance: Perform alignment checks and adjustments quarterly; use the laser alignment tool to improve accuracy.
- Gear System Maintenance: Regularly check gear oil quality and level, and use a borescope to inspect gear meshing condition.
Problem Four: Decreased Production Capacity
Phenomenon: Equipment processing capacity fails to meet design output, and production gradually declines.
Solutions:
- Feeding System Optimization: Check auger blade wear (replace if wear exceeds 30%), calibrate inverter output frequency.
- Press Chamber Flow Assurance: Regularly clean the press chamber to prevent material scaling, optimize bar cage design to improve oil drainage capacity.
- Power System Overhaul: Check motor three-phase current balance, replace worn V-belts, and install a voltage stabilizer.
- Process Parameter Optimization: Determine the optimal combination of feed volume, speed, and temperature through experiments, and establish a process parameter database.
- Equipment Efficiency Restoration: Conduct equipment performance evaluation test, formulate and implement efficiency restoration overhaul plan.
Problem Five: Oil Quality Issues
Phenomenon: Crude oil has a deep color, many impurities, a high acid value, or a burnt taste.
Solutions:
- Temperature System Modification: Add press-chamber temperature monitoring points, install a multi-point temperature-control system, and install cooling devices in high-temperature areas.
- Steaming/Wokting Process Optimization: Install an automatic steaming/wokting temperature-control system and develop optimal steaming curves for different peanut varieties.
- Cleaning Procedure Strengthening: Develop detailed equipment cleaning standard operating procedures, and use food-grade cleaning agents to ensure thorough cleaning.
- Oil Residue Separation Upgrade: Optimize crude oil filtration system, increase filtration stages, and install a centrifugal oil residue separator.
- Storage Management Standardization: Control crude oil storage temperature below 40°C, install a nitrogen protection system to prevent oxidation.
Chapter 3: Establishment and Implementation of Preventive Maintenance System
3.1 Maintenance Management Organizational Structure
Establish a three-tier organizational system for oil press maintenance management:
- Operator-Level Maintenance: Responsible for daily cleaning, lubrication, inspection, and simple adjustments.
- Maintenance Team-Level Maintenance: Responsible for weekly and monthly planned maintenance and general fault handling.
- Engineer-Level Maintenance: Responsible for quarterly and annual overhauls and complex fault diagnosis.
3.2 Maintenance Documentation System Development
- Equipment Files: Establish complete equipment technical files, including manuals, drawings, maintenance records, and related documentation.
- Maintenance Procedures: Prepare operation guides for all maintenance levels, specifying work content, standards, and cycles.
- Fault Database: Establish a shared fault case library to record phenomena, causes, and solutions.
