Types of Screws in Screw Feeders and Their Applications
Screw feeders are devices used to stably supply powders and granules in fixed quantities. They are widely used across various industries. At the core of a screw feeder’s performance is the screw itself. While it may appear to be a simple component, its shape greatly influences feeding accuracy and the types of materials it can handle effectively.
What is the most commonly used type of screw?
The most versatile type used in our feeders is what we refer to as the standard screw or center-shaft screw. It features a simple structure with a central shaft and a single helical blade wrapped around it.
Materials are fed from the hopper into the screw feeder, where they are evenly captured in the space between the screw blade and the shaft as the screw rotates. This design enables consistent and reliable feeding.
The consistent feeding is achieved by the even distribution of material in the gap between the screw blade and the shaft.
This type is well-suited not only for free-flowing powders, but also for materials with low adhesion and low viscosity. It’s commonly used in industries such as chemicals, food, plastics, and ceramics, and it performs reliably in both batch dosing and continuous feeding operations.
[Key Features]
Highly versatile and capable of stable, consistent feeding. Supports a wide range of materials including powders, particles, and granules across various industries.
Is it suitable for all types of materials?
We receive inquiries about a wide range of powder materials, each with unique properties. For example, highly adhesive or viscous materials tend to gradually stick to the screw during repeated operation. Over time, this build-up can clog the space between the screw blade and shaft, significantly reducing or even completely blocking material discharge.
Based on our experience, materials like calcium carbonate and certain pigments, which are particularly adhesive, often lead to this issue.
To handle such materials effectively, we recommend using a coreless screw (also called a hollow-type screw).
What is a coreless screw?
A coreless screw is composed solely of the screw blade, with no central shaft.
This structure prevents material from clogging the pitch (the space between screw turns), and minimizes adhesion.
As a result, discharge volume and accuracy can be significantly improved.
After a few hours of testing with pigment in batch dosing mode.
[Key Features]
No central shaft, so there’s no risk of clogging between the shaft and blade. Highly effective for adhesive powders (e.g., moist powders or materials containing oil).
Note: Because there is no shaft, feeding precision may decrease depending on the material.
Want to prioritize accuracy?
If your priority is precision over volume, we recommend the twin-screw type. This type features two parallel screw blades wound together, which provides a more uniform material flow and higher feeding accuracy.
Since the material output per revolution is smaller than with a single-blade screw, it allows for finer control of the feed rate. The comparison below clearly illustrates the difference:
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Twin-screw: Two helical blades
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Standard screw: One helical blade
Twin screws are ideal for micro-dosing applications, such as reagent weighing or small-quantity measurement in lab settings. However, due to their lower throughput, they are not suitable for large-volume feeding.
[Key Features]
The two-blade structure offers stable material flow and enables high-precision feeding. Suitable for applications like testing equipment and small-batch processing.
Summary
When selecting a screw feeder, it’s essential to choose the right screw type based on the properties of your material and the required level of feeding accuracy.
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The standard screw offers the most versatility and handles a wide range of materials across industries.
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The coreless screw is best for sticky or highly viscous materials.
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The twin-screw excels in micro-dosing and high-precision feeding applications.
Selecting the appropriate screw type based on on-site needs and material characteristics ensures stable operation and minimizes problems. At our facility, we have all three screw types available for testing, so we can evaluate which screw best suits your material during the trial phase.
If you’re interested, please feel free to contact us.
