Characteristics Comparison of 3 Types of Dispensing Pumps

Selecting the Appropriate Core Drive Unit in Precision Fluid Dispensing Applications

In precision fluid dispensing applications, selecting the appropriate core drive unit is crucial to the success of the process. Different types of dispensing pumps have distinct characteristics in terms of accuracy, applicability, cost, and maintenance requirements due to their differing working principles. This article will provide an in-depth comparison of the technical features and application scenarios of three mainstream dispensing pumps—Progressive Cavity Pumps, Piston Pumps, and Gear Pumps—to offer clear decision-making guidance for your equipment selection.

I. Progressive Cavity Pump: The Expert in Stable Transfer of Medium-to-High Viscosity Fluids

Progressive cavity pumps, particularly metering types, excel in handling complex fluids due to their unique rotary transfer principle.

l Core Principle & Features: Its core consists of a rotating precision screw and a fixed bushing (stator). The screw rotates eccentrically within the stator, forming continuous, sealed chambers that smoothly convey fluid from the inlet to the outlet. This design offers several key advantages: Firstly, the output is extremely stable and pulsation-free, making it highly suitable for applications requiring continuous, uniform coating (e.g., sealing, coating). Secondly, it has a wide adaptability to fluid viscosity, especially excelling at handling medium-to-high viscosity pastes containing fine fillers (e.g., thermal grease, silicone), with gentle shear action on the fluid, minimizing the risk of filler settling or property changes. Finally, by precisely controlling the screw speed via a servo motor, high linear metering accuracy and good repeatability can be achieved.

l Typical Application Scenarios: LED phosphor dispensing, photovoltaic module sealing, structural bonding in electronics (high-viscosity adhesives), automotive lamp sealing, and precision quantitative dispensing for most paste materials.

l Key Considerations: The internally moving screw-and-stator pair consists of contacting precision components prone to wear, especially when handling highly abrasive materials, necessitating the use of wear-resistant materials. Additionally, the pump structure is relatively complex, involving more steps for cleaning and disassembly, requiring a higher level of maintenance expertise.

II. Piston Pump: The Benchmark for Micro-volume, Ultra-Precision Dispensing

When application requirements demand ultra-high precision and repeatability at the microliter or even nanoliter level, piston pumps are often the preferred choice.

l Core Principle & Features: A piston pump achieves fluid intake and quantitative discharge through the reciprocating linear motion of a precision-machined piston within a cylindrical chamber. Its greatest advantage lies in its unparalleled metering accuracy and repeatability. Since the fluid volume discharged per stroke is directly determined by the piston displacement—which can be controlled at the nanometer level by a servo system—it enables extremely small and precise dot control. Secondly, it is relatively insensitive to fluid viscosity changes, effectively handling everything from low-viscosity solvents to high-viscosity epoxies, demonstrating strong adaptability. Furthermore, the piston pump’s mechanical structure is straightforward and its principle is easy to understand.

l Typical Application Scenarios: Semiconductor chip underfill, chip encapsulation (dam & fill), microelectronic component mounting (SMD dispensing), micro-volume reagent dispensing for medical devices, and any precision dispensing task requiring highly consistent single-point volume.

l Key Considerations: The precision seal between the piston and cylinder is a critical maintenance point, requiring regular seal replacement to prevent leakage and accuracy loss. For continuous, uninterrupted line coating, its reciprocating motion may introduce minor flow pulsation. Also, to achieve ultra-high precision, its single-cycle time might be slightly longer than that of continuous rotary pumps, necessitating a comprehensive trade-off in applications demanding extreme speed.

III. Gear Pump: The Economical Choice for Efficient, Continuous Output

Gear pumps hold a significant position in numerous industrial fields due to their robustness and continuous, stable flow output.

l Core Principle & Features: A gear pump relies on two meshing gears rotating within the pump cavity. The gear teeth and the pump housing form enclosed spaces that carry fluid from the inlet to the outlet. Its main characteristics are a compact structure, rugged durability, and the ability to provide nearly pulsation-free continuous flow. This makes it highly reliable for applications requiring long-duration, high-flow, stable output. Simultaneously, its purchase and operational costs are typically more economical, offering good cost-effectiveness. Gear pumps can also handle medium-viscosity fluids reasonably well.

l Typical Application Scenarios: Large-area panel adhesive application (e.g., automotive windshield primer coating), continuous bead coating for product sealing, grease lubrication, and batch production environments where absolute precision is not extremely critical but output stability and reliability are prioritized.

l Key Considerations: Metal contact exists between the meshing gears, making them unsuitable for fluids containing hard abrasive particles to avoid rapid wear. Their metering accuracy is generally lower than that of servo-driven progressive cavity and piston pumps, focusing more on flow control than volumetric metering. The clearance between the gears and pump housing affects its self-priming capability and efficiency in handling low-viscosity fluids.

Conclusion

In summary, selecting which type of dispensing pump is not a simple matter of determining which is better or worse, but rather a process of precise matching based on process requirements, fluid properties, budget, and production capacity targets. For the semiconductor and microelectronics fields pursuing ultra-micro precision and consistency, the piston pump reigns supreme. For applications requiring stable handling of high-viscosity paste adhesives in assembly and sealing, the progressive cavity pump performs exceptionally. For general industrial applications emphasizing continuous, reliable output and cost sensitivity, the gear pump provides a robust solution. A deep understanding of the fundamental differences between these three types is the first step toward a successful dispensing process.