Raw Material Ratio Control for Geogrid Production Line Equipment

The tensile strength, creep performance and aging resistance of finished geogrid are directly related to the raw material ratio. Ratio fluctuation will lead to differences in mechanical indicators among batches, and even defects such as tensile fracture and excessive elongation. For raw material ratio control, geogrid production line equipment shall implement closed-loop management including formula confirmation, feeding metering, mixing, on-line monitoring, abnormality handling and record keeping according to product types, so as to stabilize the composition of each batch of mixture and meet the requirements of stretching, extrusion and net forming processes.

Preliminary formula confirmation is the foundation of ratio control for geogrid production line equipment. Before production, classify products such as plastic uniaxial geogrid, biaxial geogrid and fiberglass geogrid, and determine the types and proportions of base resin, masterbatch and additives. Common raw materials include polyethylene and polypropylene resin, matched with anti-aging masterbatch, carbon black masterbatch, compatibilizer and processing additives. Different specifications adopt different formulas; geogrid used for roadbeds and slopes requires a higher dosage of anti-aging additives. After the formula is determined, carry out small-scale tests to verify material fluidity and tensile indicators. Only qualified formulas can be entered into the production process documents without arbitrary modification. If the raw material grade is changed, re-test samples to confirm adaptability.

Accurate feeding by automatic metering system is the core method to stabilize the ratio for geogrid production line equipment. Most large-scale production lines are equipped with loss-in-weight feeders, with an independent feeding unit for each raw material and set target flow rate respectively. After the geogrid production line equipment starts, the control system weighs in real time, compares the actual feeding amount with the set value, and automatically adjusts the screw speed to compensate feeding deviation. Pellet raw materials and masterbatch shall be stored separately with marked silos to avoid material mixing. Arch-breaking devices are installed at silo outlets to prevent bridging and material breakage of powder and masterbatch which cause ratio imbalance. Manual feeding is only applicable to a small amount of additives and recheck is required after feeding; automatic metering is preferred.

Mixing process control ensures uniform mixture for geogrid production line equipment. Metered raw materials are sent into a high-speed mixer, with stirring speed, mixing temperature and mixing duration controlled to fully blend resin pellets and masterbatch. Excessively high mixing temperature will cause premature decomposition of additives, while low temperature leads to poor dispersion of masterbatch and local component concentration. After mixing, materials are transferred to a cooling stirring bin to reduce temperature and prevent caking. Sampling inspection after mixing: uniform color without obvious color difference particles means qualified dispersion. Insufficient mixing time will cause uneven dispersion of carbon black and anti-aging additives, resulting in local insufficient strength of finished geogrid.

Conveying and silo isolation prevent secondary ratio deviation. Conveying pipelines and intermediate silos of geogrid production line equipment shall be thoroughly cleaned. When switching between different formulas, completely clean silos, because residual old materials mixed into new materials will change component proportion. Silos shall be sealed and dustproof to prevent dust and moisture from entering. Moisture not only affects extrusion molding, but also interferes with readings of weighing sensors. Independent feeding pipelines are adopted without shared pipelines to reduce cross contamination. Intermediate silos are equipped with material level monitoring and alarms for material shortage, so as to avoid long-time production with missing components which produces unqualified semi-finished products.

On-line monitoring at the front of extrusion detects ratio abnormalities timely. On-line inspection points are arranged at the feeding section of the extruder main machine of geogrid production line equipment. Material status is judged by changes of melt pressure, melt temperature and main motor current. Abnormal ratio changes material fluidity, leading to obvious fluctuation of main machine current and die head pressure. Operators take samples regularly to test melt flow rate and compare with standard values. Stop production immediately if melt indicators are out of range, check the feeding system and troubleshoot feeder jamming, sensor drift and silo bridging. Carbon black content and additive content can be sent for inspection periodically to verify whether the ratio meets design requirements.

Abnormality handling and production record management form a closed loop of ratio control for geogrid production line equipment. Once feeding fluctuation or missing components are found, pause extrusion first, isolate abnormal mixed materials with marks and evaluate reusability. Calibrate sensors regularly. Long-term operation of loss-in-weight scales may cause zero drift, so the weighing system shall be calibrated periodically to ensure metering accuracy. Record formula number, set ratio of each raw material, actual feeding data, mixing parameters and melt test results for each batch, and reserve samples. Parameters can be directly called for re-production of the same specification to reduce trial time.

With confirmed formulas, loss-in-weight feeding metering, standardized mixing and dispersion, thorough silo cleaning during material switching, on-line monitoring and regular calibration, geogrid production line equipment can stabilize raw material ratio, guarantee stable mechanical performance and aging resistance of geogrid, and reduce the output of nonconforming products.