In the field of plastic processing, accurate batching is a key link in determining product quality and production efficiency. When companies face the choice of volumetric dosers and gravimetric dosers, they often need to consider multiple dimensions such as technical principles, cost-effectiveness and application scenarios. This article will deeply analyze the core differences between the two systems and provide professional reference for your decision-making.
Ⅰ. Working principle
1. Volumetric dosers
Volumetric dosers use “space occupation” as the measurement basis and control the volume output of materials through structures such as screws and turntables. For example, a four-color volumetric doser converts preset parameters into speed through a fully digital microcomputer control system to drive a precision screw to extrude raw materials with an error value of no more than ±1%. This system needs to be manually calibrated according to the material density. When the batch or type of raw materials changes, the parameters need to be readjusted to ensure the measurement accuracy.
2. Gravimetric dosers
Gravimetric dosers rely on load cells to monitor material weight in real time and use “loss-in-weight” technology to achieve closed-loop control. The system will continue to measure until the target weight is reached, and will not be affected by material density fluctuations. Just like a 250 ml cup of liquid cream, the volume expands to 1000 ml after whipping, but its weight always remains at 250 grams – this is the core advantage of gravity metering: mass is the only parameter, and frequent calibration is not required.
Ⅱ. Performance comparison: balance between accuracy, cost and flexibility
1. Measuring accuracy
The mixing accuracy of volumetric doserss is usually 95%-98%, which is suitable for scenarios with medium accuracy requirements (such as ordinary injection molding production); gravity systems rely on real-time weighing, with an accuracy of less than ±0.5%, which is more suitable for high-end modified plastics or medical-grade products.
2. Cost investment
The initial investment of volumetric dosers is low. For example, Kaifeng Machinery’s two-color volumetric dosers adopts modular design, with strong component interchangeability, and maintenance costs can be reduced by more than 30%; the gravity system is usually 30%-50% higher in procurement cost due to the integrated weighing sensor and complex control system, but in the long term, cost optimization can be achieved by reducing raw material waste (saving up to 50% of additives).
3. Production adaptability
The volumetric dosers supports 50 sets of formula storage and fast switching, which is suitable for multi-variety small batch production; the gravity system is more suitable for continuous large-scale production, especially in scenarios where strict record of material consumption (such as ISO quality certification) is required.
Ⅲ. Selection Guide: Adaptive scenario determines the optimal solution
1. Scenarios for giving priority to volumetric dosers
If your production needs are centered on “cost-effectiveness”, such as ordinary plastic products, recycled material recycling processing, or frequent switching of formulas (such as multi-color injection molding), the volumetric dosers is a more pragmatic choice. For example, Kaifeng Machinery’s four-color volumetric dosers uses 304 stainless steel contact parts and chrome-plated screws, which not only ensures corrosion resistance, but also enables rapid disassembly and cleaning through modular design, which is very suitable for small and medium-sized enterprises.
2. Scenarios for giving priority to gravimetric dosers
When products involve high-precision requirements (such as aerospace parts, medical catheters), or high raw material costs (such as nano-additives, special pigments), the “zero waste” characteristics of the gravity system are crucial. In addition, if the production process requires strict traceability of material usage (such as the food packaging industry), the real-time weighing data of the gravity system can be directly connected to the quality management system.
IV. Conclusión
Volumetric dosers and gravimetric dosers are not “either this or that” competitive relationships, but complementary solutions for different production needs. For plastic processing companies, understanding the technical boundaries and cost logic of the two can find a balance between efficiency and precision. Just like the solutions provided by volumetric dosers manufacturers Kaifeng Machinery – from basic volumetric dosers to high-end gravity systems, they always take “adaptation to scenarios” as the design core, helping companies to achieve quality upgrades while optimizing production costs.
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