Characteristics of materials
We have manufactured many types of screw feeders for many types of materials.There are various characteristics of the powder in the world,for example
・Material that can flow smoothly like the sand in an hourglass
・Material that contains moisture and are moist like salt
・Material like potato starch, it hardens when you hold it
At Seiwa Giken, even materials with various characteristics as described above.We have developed the equipment and take measures to ensure quantitative transport.
What is powder bridging?
This is one of the phenomena that tends to occur with materials with poor fluidity. The material does not flow well from the hopper that stores the material into the gaps between the blades of the screw feeder, and the material is not discharged quantitatively or not at all. It clogs when it enters the entrance of the screw feeder from the hopper.
What kind of materials are likely to cause this phenomenon?
We check the shape, bulk density, angle of repose, and cohesiveness of materials.The most obvious is the angle of repose. It shows that the higher this height is, the more likely it is that it does not flow smoothly like sand ⇒ bridging may occur
Cohesiveness also has a large effect on bridging. Materials that tends to harden when gripped often does not crumble in the hopper, they does not flow to the entrance of the screw feeder.
Bridging may also occur in case of the materials has a low bulk density that does not fall off under its own weight, or if it has a unusual shape,like a fiber.
Each materials have its own characteristics. We do trial test to find out what is causing the bridging, and then take countermeasures.
We use preliminary tests to find out what is causing the bridging, and then take countermeasures.We will introduce concrete methods in the next column.