Foremost Machine Builders manufactures equipment and systems for the pneumatic conveying of plastic resins, polymers and other pellet or powered products commonly found in the plastics industry. While our systems and equipment can handle all sorts of materials, they serve what is only a part of what is the much broader industry of matieral handling.
For most of us material handling refers to everything from the movement of products on an assembly line to our luggage at the airport. Material handling is simply the physical movement of material from one location to another. While there is nothing really wrong with this definition, it is too broad and doesn't really tell us much about material handling in the manufacturing industry. To understand material handling, especially as we understand it here at Foremost, you have to look a little more carefully at what we mean by "handling" and "material".
For the plastics industry, material handling is the study of systems and equipment required for the movement of plastic resin, whether it be pellet, granule, powder or flakes. When it comes to the manufacturing process in general, the material being handled can come in any size, shape, weight or form. It can be everything from raw material, partially assembled components to finished goods. The material, in our case, is a plastic resin - a raw material that has certain properties and acts in a certain way.
For most industries, material handling is about the movement of something atomic that occupies space, has mass, and is used to make things. While raw material exists in either the form of a solid, liquid or gas, the plastics industry works primarily with a solid or a semi-solid polymer which is basically a long-chain of carbon-based molecules. As a solid or semi-solid, a plastic resin can exist in four possible forms: as pellets, granular, powdered or even flaked. Each form comes with its own set of properties that must be considered when it comes to their handling.
At Foremost we tend to restrict our expertise to the handling of material (powdered or in granule form) that is transported from machine to machine and finally delivered by truck or railcar. The handling of material can include everything from the physical movement of a finished product like a car to the alteration of an object's chemical composition. It can refer to everything from the movement, storage, control and protection of material throughout the process of its production, distribution, consumption, and disposal. We are concerned with the handling of the plastic resin from its delivery by truck or railcar, to its storage in storage silos, to its distribution to the processing equipment, i.e., an extruder hopper. Since we are always dealing with bulk quantities of resin, whether it be from a truck or a railcar, our methods of handling were designed specifically for bulk materials.
The handling, movement or conveying of plastic resins is typically divided into two categories: mechanical and pneumatic conveying equipment. In the pneumatic category, there are two competing methods for handling material that differ according to their air velocity and the kind of material that they can move.
The first method, known as dilute phase pneumatic conveying, is a method of handling that uses a vacuum pump to pull the plastic resin from the railcar through a pipe up to the vacuum receiver on the storage silo. The second method, called dense phase pneumatic conveying, uses a vacuum/pressure blower assembly to pull the plastic resin from the railcar through a pipe to a transfer station where the resin is blown into the storage silo by the pressure blower. In both cases, material is moved through a pipe at a velocity such that the material is moved in a stream-like state of suspension. The main difference is that the dilute phase method can produce a higher rate of air velocity than the dense phase method.
In order to know which method to use, the material handling expert has know what kind of material is to be moved and its saltation velocity, i.e., the velocity at which the material will fall from suspension in the pipe. The air velocity of the dilute phase method, for instance, is anywhere from 4000 to 8000 feet per minute (FPM). Since most plastic resins have a saltation velocity of 3500 FPM, it follows that most experts would recommend using the dilute phase method to move them. There are of course, certain drawbacks to the dilute method, that must be considered. Some plastic resins, for example, cannot be moved above a certain velocity or they begin to deteriorate. These issues are addressed in detail in our article How To Choose Between Dilute and Dense Phase Conveying. It is enough to know that by material handling we are talking about a certain kind of solid raw material and two competing methods of handling that material.
Pneumatic Conveying from our standpoint, is simply the study of the systems and equipment required for the movement of a solid raw material with a saltation velocity that is easily handled by the dilute or dense phase methods of pneumatic conveying. The critical question facing those in the manufacturing industry is whether or not their particular kind of material can be moved by these two methods of handling. These methods are not restricted to handling only plastic resins. If the material is a solid with the right kind of properties, i.e., the appropriate saltation velocity, there is no reason why these handling methods couldn't do the job.