Material bridging, also known as material arching, in bins, hoppers, and storage vessels is an issue that many manufacturing facilities battle with. It halts production and, if not addressed, can be a drain on plant efficiency. NAVCO is the leader in applied vibration technology for dry bulk material processing and in this article will breakdown what exactly material bridging is, what causes it, and how NAVCO Bin Hopper Vibrators (BH Vibrators) address this issue and get material flowing.
What is material bridging?
Material bridging is a phenomenon in dry bulk material handing in which the material in a storage vessel forms a bridge, or arch-like structure over the outlet. When a bridge forms, it prevents any material above it from being able to flow out of the vessel, leading to a stop in the flow of material.
Material bridging is an issue that disrupts the manufacturing processes across every industry including:
Food & beverage
Plastics
Aggregates
Mining
Chemical
Petrochemical
Power
Trucking
Steel
Recycling
Construction
And many more
Blue lines highlight the material bridge that has formed over the outlet.
What causes material bridging?
The formation of a material bridge can be tied to two material characteristics – material strength and sliding friction.
Material Strength
Material strength is the ability of a material to retain shape after being consolidated. An easy way to think of material strength is to consider what happens when you squeeze a handful of dry sand versus clay. After squeezing dry sand in your hand and releasing it, the material will remain free flowing and fall from your hand. This simple experiment shows that dry sand exhibits low material strength. In contrast, when you squeeze clay in your hand and release it, the clay remains in the consolidated form in your hand. This ability to retain shape means the clay possesses a high material strength. When a material has a higher material strength, it is more likely to form a bridge than a material with a low material strength.
Sliding Friction
Sliding friction is the force between the material and the container wall surface. The higher the sliding friction, the greater the chances of a material bridge forming. In addition to the characteristics of the material, the geometry of the vessel will also influence the amount of sliding friction present. Vessel walls with shallower angles will increase the sliding friction, while steeper walls will decrease it. The geometry of the container’s wall is often influenced by the available space in the work envelope, and these constraints often lead to vessel designs that increase sliding friction and thus the chance for the formation of material bridges.
How NAVCO Bin Hopper Vibrators (BH Vibrators) Address Material Bridging
NAVCO Bin Hopper Vibrators (BH Vibrators) are pneumatic piston vibrators that utilize vibration to reduce material strength and sliding friction.
Vibration from NAVCO Bin Hopper Vibrator (BH Vibrator)
reduces material strength and sliding friction, promoting flow.
Addressing Material Strength – Transmission through the material
An easy way to visualize how vibration transmits directly into the material is to think of a “Newton’s Cradle”. The ball that’s lifted and released is the BH Vibrator – the source of energy. The middle balls are the vessel wall and the ball at the opposite end is the material. When the vibrator is operated, its vibration creates a force that travels through the wall and radiates out into the material. The mechanism through which this energy is transmitted is rooted in the Newton’s principle of conservation of momentum. As the vibration radiates through the material, it reduces the material strength. This reduction in strength results in the collapsing of the bridge, enabling flow.
Addressing Sliding Friction – Transmission through the wall
To easily visualize how the vibration from the BH Vibrator effects the vessel wall, think of ringing a bell. The vessel wall is the bell, and the BH Vibrator acts as the clapper, the metal shaft with the sphere on its end that moves back and forth. The vessel wall exhibits a resonance response to the vibrator’s impact, which results in a reduction of sliding friction between the material and vessel wall.
Material bridging can be a major obstacle to maintaining efficient and consistent material flow in industrial processes. NAVCO Bin Hopper Vibrators (BH Vibrators) offer a proven, reliable solution to directly address the root causes of bridging—material strength and sliding friction. By applying targeted vibration through the vessel wall and into the material, BH Vibrators restore flow, minimize downtime, and help facilities operate more smoothly. Whether you’re working in food processing, mining, chemical manufacturing, or any other industry handling dry bulk materials, NAVCO provides the vibration technology you need to keep your operations flowing.
