Working principle and structural composition of metal powder dryer


Importance of dryer on metal powder preparation technology

In metal injection molding technology, the injection feeding will be generated through the mixing and pelleting of metal powders and organic binders. However, in the mixing and pelleting process, it will use fine metal powders that have the particle size of less than 20 microns as well as are fully dry and have spherical shape. As metal powders that used in metal feed pelleting are usually produced by gas atomization or water atomization, they will contain a certain amount of moisture. Therefore, it is very necessary to dehumidify and dry metal powders.

metal powders feedingRegarding the dehumidification process of metal powders, some feeding manufacturers will finish it in the mixing process in the mixing mill, which means that before mixing and pelleting process, metal powders will be sent into mixing chamber for drying; when the metal powder moisture is almost completely evaporated, binders will be added; while other feeding manufacturers will install a special metal powder dryer in the upstream of pelleting production line so as to ensure that metal powders will be fully dehumidified as well as will have qualified dryness and can be directly used for metal pelleting before entering the mixing mill.

Categories, structural compositions and working principles of metal powder dryer

Although many types of metal powder dryers have emerged on the market, the basic working principles are almost similar. In this article, we can learn the working principles of metal powder dryer from by taking rotary dryer as an example.

Rotary metal powder dryer is composed by revolved body, raising plate, gearing and seal ring. When the metal powder is transferred to the furnace top, they will be pushed into backside by the rotating lifting board. In the slant replaced dryer, metal powders will not only slowly drop by the effect of gravity and turning force, but also will be repeatedly thrown up by the lifting board; after being thrown up, metal powders will continuously and evenly fall in the drying cylinder and will form a kind of even metal powder flow that is similar to the curtain. Therefore, it can be seen that the drying of metal powders will depend on the heat exchange between powders and the strong heat flow in the cylinder.

In fact, the working principle of metal powder dryer is very simple, but it still will encounter some problems in the operation process, such as the blockage of dryer. If metal powders contain large particles of powders and other mechanical impurities, it will cause crystallization in the transporting process of metal powders or the viscosity will be too high to be transported by the dryer, thus the metal powder dryer will be blocked.

Therefore, when using the metal powder dryer, appropriate filtration unit should also be used so as to filter the impurities that contained in metal powders and make sure that metal powder particle size will become even. If the conditions are permitted, metal powder manufacturers can also use metal powder dryers that are both equipped with air drying device and pressure drying device. When the pressure of high-pressure pump cannot reach drying stress, compressed air can be used for drying, however, it should be stopped using once the high-pressure pump works properly.