Drag Conveyors vs. Screw Conveyors: When Each Is the Better Solution
Selecting the right conveyor is a critical decision in any bulk material handling system. Two common options, drag conveyors and screw conveyors, are both widely used across industries such as cement, steel, mining, energy, and specialty chemicals. While they may appear similar in function, each conveyor type is better suited to certain materials, layouts, and operating conditions. Understanding their differences helps ensure reliable performance, reduced maintenance, and long-term efficiency.
What Is a Drag Conveyor?
Drag conveyors, sometimes referred to as drag chain conveyors, move material through an enclosed casing using a continuous chain with attached flights. The flights “drag” material along the bottom of the conveyor, making this design well suited for controlled, horizontal or inclined material movement.
Drag conveyors are commonly used for handling abrasive, heavy, or high-temperature materials. Because the system is fully enclosed, it helps contain dust and protect material from contamination. Drag conveyors can also be designed to handle multiple inlets and discharge points, making them flexible for complex material handling systems.
Advantages of Drag Conveyors
Drag conveyors are known for their durability and ability to handle challenging materials. They are well suited for ash, clinker, cement, slag, and other abrasive products. Their enclosed design reduces dust emissions and improves safety in industrial environments. Drag conveyors also tend to move material gently, minimizing degradation of friable products.
Another advantage is their ability to operate at relatively low speeds, which reduces wear and extends component life. With proper design, drag conveyors can handle high capacities over long distances.
What Is a Screw Conveyor?
Screw conveyors use a rotating helical screw inside a trough or tube to move material. As the screw rotates, it pushes material forward along the conveyor’s length. Screw conveyors are compact and commonly used for short-distance conveying, feeding, and metering applications.
They are often selected for handling fine, powdery, or semi-fluid materials. Screw conveyors are widely used in food processing, chemical handling, and light industrial applications due to their simple design and ease of integration into existing systems.
Advantages of Screw Conveyors
One of the main benefits of screw conveyors is their compact footprint. They can fit into tight spaces and are easily customized for various layouts. Screw conveyors also offer good control over material flow, making them useful for feeding or dosing applications.
Their relatively simple construction can result in lower upfront costs for certain applications, and they are available in many configurations, including horizontal, inclined, and vertical designs.
Key Differences and Limitations
While screw conveyors are versatile, they are not always the best choice for abrasive or heavy-duty materials. Continuous contact between the screw and material can lead to rapid wear, especially with abrasive products. Screw conveyors can also cause material degradation and increased power consumption when handling dense or sticky materials.
Drag conveyors, on the other hand, are typically more robust but may require more space and a higher initial investment. Their design is better suited for continuous-duty, heavy industrial environments where reliability is critical.
When Each Is the Better Solution
Drag conveyors are often the better solution for heavy-duty, abrasive, or high-temperature materials, especially in applications that require enclosed conveying and long service life. Screw conveyors are often preferred for shorter distances, lighter materials, and applications where precise material control is needed.
How MHE Can Help
Materials Handling Equipment (MHE) has been designing and manufacturing custom drag conveyors and screw conveyors since 1927. Our team works with customers throughout the country to evaluate material characteristics, operating conditions, and system requirements to determine the best conveyor solution.
Whether you need a heavy-duty drag conveyor for abrasive materials or a screw conveyor for controlled feeding, MHE delivers custom-engineered systems built for reliability and performance. Contact Materials Handling Equipment to learn how our expertise can help you choose the right conveyor for your application.