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Mass flow rate: Ring shear testing in industry

What is a Ring Shear Tester?

A ring shear tester is a specialised instrument designed to analyse powder flow behaviour, offering precise measurement and characterisation of parameters essential for understanding bulk solid materials. The device employs the principle of shear testing, where it applies controlled forces to a specimen of bulk solid material, inducing flow and allowing for the assessment of its flow properties under different stress conditions. 

The ring shear tester evaluates the flow properties of bulk solids, including compressive strength, internal friction, bulk density and compressibility. By subjecting the powder specimen to controlled shear forces, it generates quantitative data crucial for understanding powder behaviour in industrial processes.

Ring shear testers are widely used across various industries including pharmaceuticals, food processing, chemical manufacturing and material handling. Here, it plays a role in quality control processes, product development and process optimisation. Additionally, it contributes to the design of storage systems like silos and hoppers by providing insights into powder flow characteristics.

The Shear Test method is often defined as the “gold plated Standard” for testing powders as it is the only non empirical method for measuring powder flowability.

Equipped with load beams containing strain gauges for measuring normal and shear forces, as well as an inductive displacement transducer for monitoring sample height, ring shear testers offer advanced functionalities. Moreover, its computer-controlled systems enable automated testing and data analysis, enhancing efficiency and precision.

Understanding the flow properties of bulk solids is paramount for ensuring efficient handling and processing in industrial settings. By providing precise data on powder flow behaviour, ring shear testers can empower engineers, researchers and manufacturers to opti-mise processes, mitigate flow-related issues and enhance product quality.

What is the best way to measure powder flow?

In industries where precise powder flow information is needed, such as in pharmaceutical and chemical manufacturing industries, the ring shear testing method is one of the more reliable solutions. This technique offers insights into powder flow behaviour by sub-jecting powder specimens to controlled shear forces.

SciMed offers a variety of ring shear testers, including the RST-XS.s and the RST-0.1pc. Both can automatically analyse the com-pressive strength, internal friction, bulk density and compressibility of the samples. 

This provides data necessary for optimising pro-duction processes and ensuring product consistency. This info can also aid in the design of storage systems, streamline material han-dling and address flow-related issues.

Ring Shear Tester

How can I predict the flow behaviour of my powder in the process?

Predicting the flow behaviour of powders in industrial processes is essential for optimising production efficiency and ensuring product quality. Ring shear testing offers valuable insights into powder flow properties, aiding in the prediction of behaviour during processing.

Ring shear testing provides crucial data for understanding powder flow behaviour. By assessing flowability and cohesive strength, manufacturers can predict how powders will behave in various pro-cess conditions.

Flowability, characterised by the unconfined yield strength (rhoc) and flow function coefficient (ffc), determines a powder’s ability to flow. Different ffc values categorise materials into various flowability levels:

Non-flowing (ffc <1)

Highly cohesive materials such as certain clays or heavily packed, fine-grained substances with low flowability.

High cohesive to non-flowing (1 < ffc < 2)

Substances with slightly improved flowability but still prone to sticking or clumping, like cosmetic powders or certain types of cement.

Cohesive (2 < ffc < 4)

Powders with fair flow but moderate cohesion, like metal powders or fine-ground spices.

Easy flowing (4 < ffc < 10)

Powders with fair flow but moderate cohesion, like metal powders or fine-ground spices.

Free flowing (ffc > 10)

Granular materials that flow freely without sticking or clumping.

How can I optimise the design of my silo and hopper?

Optimising the design of silos and hoppers is crucial for efficient material handling and preventing flow issues during discharge. By leveraging insights from flow property measurements, such as the ffc obtained through ring shear testing, manufacturers can design silos and hoppers that promote smooth material flow and minimise flow-related challenges.

The ffc derived from ring shear testing quantifies a powder’s flowability, providing valuable information for designing silos and hoppers. Understanding the materials’ flow behaviour allows for tailored design approaches to address specific flow characteristics.

Powders with moderate cohesion (1<ffc<4) require careful design considerations to prevent material buildup and flow obstructions. Adjustments to hopper geometry, such as smoother wall surfaces and appropriate outlet sizes, can enhance flow performance.

Materials exhibiting high flowability, such as certain types of flour, may require minimal design modifications. However, ensuring proper hopper geometry and outlet configurations can further opti-mise flow efficiency and prevent issues such as segregation or un-even discharge.

By optimising the design of silos and hoppers to accommodate the flow behaviour of the stored powders, manufacturers can enhance process efficiency, reduce downtime and minimise material waste. Investing in design optimisation based on flow property measure-ments ensures smooth material handling and contributes to overall operational excellence.

Industries ranging from pharmaceuticals to high-value industrial powders benefit from optimised silo and hopper designs tailored to their specific powder characteristics. By leveraging flow property data obtained through ring shear testing, manufacturers can achieve superior process performance and product quality.

What to do next?

Interpreting ring shear tester results opens doors to optimising material handling, production processes, and structural design. Understanding these outcomes to gauge flowability, caking tendencies, and bulk density, is essential for enhancing manufacturing efficiency or resolving flow-related issues.

To use these insights for improved operations, explore our ring shear tester options, and discover how these findings can improve handling in your industry. Visit each product page for detailed specifications or reach out to us on our enquiry page to speak to an expert about which ring shear tester is most appropriate for your specific requirements.

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