What Is an Extruder?
An extruder is a processing machine that can process raw materials such as food, pharmaceuticals, plastics, rubber, and ceramics.
Extruders can simultaneously process and convey raw materials. Processing methods include heating, pressurizing, mixing, and extrusion. Extrusion, in particular, is used in the production of plastics and rubber because it heats the raw material, applies pressure, and extrudes it into a consistent shape. Extruders are available in a wide variety of nozzle shapes, which makes them viable for a wide range of shapes and applications. This allows the production line to be easily changed to meet demand, making them suitable for small-lot, multi-variety production.
Extruders are, however, subject to wear, overheating, and other problems that occur during processing. Therefore, use with certain materials requires a high level of skill and expertise. Furthermore, post-processing cleaning can require substantial additional equipment.
Uses of Extruders
Extruders have a wide range of applications, including processing food, pharmaceutical, and other raw materials by adjusting their shapes and other properties.
1. Food Processing
First, let’s look at the use of extruders in food processing. One way they are used is to process protein-based ingredients like soy, restructuring them to modify their texture, resulting in products like textured vegetable protein (TVP), also known as soy meat. They’re also used in the production of puffed food, candy, pet food, and grain products such as oatmeal.
2. Pharmaceutical Production
Extruders are widely used in the field of pharmaceutical production. They can be used to convert powdered pharmaceutical ingredients into tablets. The shape and size of the tablets can be adjusted based on the required dose.
3. Other Fields
Extruders are used in several industries, including cosmetic manufacturing and the production of fuel, paint, and resin. Facilities where they are used include laboratories, food factories, pharmaceutical plants, chemical plants, and resin factories.
Principle of Extruders
An extruder is a machine that processes a raw material while mixing it with a liquid.
The extruder consists of a feed section, a screw section, a barrel, and a die. The material enters through the feed section, is mixed by the screw, passes through the barrel under pressure, and is pushed out through the die. Since the material can be transported and processed at the same time, extruders operate very efficiently.
By changing the type of screw being used and adjusting the rotation speed, it is possible to calculate how long the material will remain inside the extruder and modify the extrusion pressure. The shape can be freely changed to produce thin sheets, squares, circles, and other shapes.
Types of Extruders
There are five types of extruders: single-screw extruders, twin-screw extruders, batch extruders, continuous extruders, and cold extruders.
1. Single-Screw Extruder
Single-screw extruders push out raw materials with a single screw. They are mainly used in small-scale processing plants and research institutes, and are characterized by their relatively low cost.
2. Twin Screw Extruder
Twin-screw extruders use two screws to extrude raw materials. They have a high processing capacity and, depending on the shape of the product, can produce more uniform products. As such, they are used in the production of foods and pet foods that require mass production.
3. Batch-Type Extruder
Being compact, batch-type extruders are sometimes used by small food manufacturers and research institutes. They are suitable for research and development because of their simple structure and the visibility of processing operations.
4. Continuous Extruder
Continuous extruders are suitable for mass production and have high processing capacities. In particular, large continuous extruders are characterized by their extremely high productivity.
5. Cold Extruder
Cold extruders with adjustable pressure and temperature are also available. Because they extrude at low temperatures, they can retain the nutrients in the ingredients, making them suitable for processing health foods, snacks, etc.