Choosing the Right Flexible Screw Conveyor: A Comprehensive Guide
Selecting the appropriate flexible screw conveyor for a specific application can be challenging, especially for those unfamiliar with its design and operation. This article will provide an overview of the basic mechanical structure of a flexible screw conveyor, highlight its advantages and limitations, and outline the critical information required to properly specify the right conveyor for your needs. Finally, it will explore how these considerations translate into physical hardware, ensuring a smooth and efficient deployment.
What is a Flexible Screw Conveyor & How Does it Work?
A flexible screw conveyor is designed to move and elevate bulk materials by rotating a helical-shaped auger within a casing. These conveyors are commonly used to elevate powders, granules, and other bulk materials into mixers, packaging machines, or storage bins. A typical flexible screw conveyor consists of an inlet hopper, a helical auger, a conveyor casing, couplings, and a drive/discharge head.
The flexibility in the screw and casing is what distinguishes these conveyors. The auger is shaftless, and the casing is usually made of Ultra High Molecular Weight Polyethylene (UHMW-PE). This design allows for the conveyor to be bent or flexed around fixed obstacles or to adjust the position of the discharge head, making it versatile for different layouts and configurations.
Advantages of Flexible Screw Conveyors
Flexible screw conveyors offer a range of benefits that make them an excellent choice for many bulk material handling applications:
- Cost-Effective
Flexible screw conveyors are relatively inexpensive compared to other traditional conveying systems, making them an attractive option for various industries. - Flexibility in Design
As the name suggests, the casing of smaller diameter flexible screw conveyors is flexible, enabling them to be routed around obstacles or easily adjusted to suit different installation configurations. - Ease of Cleaning
These conveyors are designed for quick cleaning, which reduces downtime and improves hygiene, particularly in industries where cleanliness is critical, such as food and pharmaceuticals. - Quick Disassembly and Reassembly
Flexible screw conveyors are easy to disassemble for cleaning and maintenance. Simply remove the clean-out cap, disconnect the auger, and slide it out. The casing can be easily removed, making maintenance quick and hassle-free. - Use in Food Applications
Flexible screw conveyors are made from food-grade materials, such as UHMW-PE and 300-series stainless steel, making them suitable for handling food products. - Adaptability
The auger profile can be easily changed to accommodate different materials, ensuring flexibility in handling varying product types and production requirements. - Minimal Moving Parts
With only the auger and drive shaft in motion within the product area, flexible screw conveyors have fewer moving parts, which reduces wear and maintenance costs. - Low Maintenance Requirements
Since the bearings are located outside the product flow area, flexible screw conveyors require less maintenance than other conveying systems with bearings in contact with the material. - Portability
Many flexible screw conveyors can be made portable by placing the hopper on a wheeled cart. This allows the system to be moved between different areas of a facility, improving flexibility and efficiency. - Easy Length Adjustment
Conveyors can be easily shortened or lengthened by adjusting the auger and casing, making them adaptable for future process changes or re-purposing.
Limitations of Flexible Screw Conveyors
While flexible screw conveyors have many advantages, they also come with limitations that must be considered for certain applications:
- Not Suitable for All Materials
Materials with high moisture content, dense textures, large solid particles, or slurries can reduce the effectiveness of flexible screw conveyors. Such materials may clog the system or not move efficiently. - Cannot Run Dry
These conveyors should not run dry for extended periods because of excessive wear caused by the rotating auger rubbing against the casing without material to lubricate the system. - Incomplete Emptying
Flexible screw conveyors typically cannot empty completely at the end of a cycle. Depending on the material, conveyor diameter, and auger style, residual material (ranging from ¼ to 1 ft³) can remain in the system, which may require additional cleaning when switching between incompatible products. - Limited Length
Flexible screw conveyors have a limitation on length. They can stretch over time, and typically lengths over 40 feet are not recommended, especially for heavy or dense materials.
How to Select the Right Flexible Screw Conveyor
To ensure you choose the right flexible screw conveyor, it’s essential to gather information about the material being conveyed and the operational requirements. Below are the critical details you need to consider:
Material Properties
- Product Density: What is the bulk density of the material (lbs/ft³ or kg/m³)?
- Particle Size: What is the average particle size, and how consistent is the size distribution?
- Flowability: Is the material free-flowing, or does it tend to pack, bridge, or smear?
- Abrasiveness: Does the material have abrasive characteristics that could wear down the UHMW-PE casing, requiring a metal casing?
- Aeration: Does the material create dust or easily become aerated?
Operational Requirements
- Discharge Rate: What is the desired flow rate (lbs/hr or kg/hr)?
- Discharge Height: How high does the material need to be conveyed from floor level?
- Layout: Does the conveyor need to navigate around obstacles or other fixed structures? What is the ideal angle for discharge (typically 45°)?
- Frequency: Will the conveyor run continuously or intermittently?
- Utilities: What power supply is available at the installation site? Is compressed air available, and at what pressure and flow rate?
- Controls: Do you need a simple on/off control, or will the system require variable speed and interlocks for starting and stopping?
Conclusion
Choosing the right flexible screw conveyor requires careful consideration of the material’s properties and the specific operational needs of your facility. Flexible screw conveyors are ideal for many applications, especially in industries that require easy handling, adaptability, and minimal maintenance. By understanding the advantages, limitations, and selection criteria, you can ensure that you select the best conveyor for your material handling needs.