Twin-screw extruders for plastic material
The design of innovative ZAMAK MERCATOR extruders for plastic materials is based on many years of experience gained in various sectors of the plastic material processing industry.
Plastics Green Twin - extruders for plastic materials intended for operation in harsh environments with high pressures (up to 400 bar) and high mechanical load.
Available cylinders diameters 16 - 20 - 24 - 90 - 120 mm
Zamak Mercator extruders for plastic materials are characterized by high capacity, durable construction, low power consumption and save space.
Important usable properties
• High torques
• High permissible pressure inside the cylinder
• Efficient and economical zone heating-cooling system
• Low power consumption
• Wedge closure with optional hydraulic drive
• Simple and ergonomic operation
• High performance
• High durability components
• Space savings
The main drive of extruders
Extruders are driven by modern AC motors in the 120 Hz technology, power range up to 22 kW, and 87Hz in the range of higher powers. These engines have an increased range of rotating speed control, especially at low rotating speeds and provide a constant maximum torque for the entire speed range. Furthermore, such engines are practically maintenance-free, and the costs of their use are low. An important element of the drive is a frequency converter (inverter). We use inverters produced by renowned manufacturers, tailored to customers' expectations. Our drives (motor + inverter) save up to 10% electric energy, e.g. in relation to the DC drives, which are still popular in extruders produced by a number of manufacturers. Optional module of consumed energy measurement and control of its quality, allows for controlling the costs and quality of the energy consumed.
Transmission of torque separation into two screws and thrust bearings
Torque splitting transmission to two screws is one of the key elements of twin-screw extruders design - it determines the maximum torque and the device reliability and durability. Gears for our extruders are supplied by renowned manufacturers with relevant experience. The structure of transmission allows for the transfer of maximum torque on two screws of the extruder and axial forces caused by the pressure in the cylinder through special thrust bearings. Our gears depending on configuration can work, as synchronous or asynchronous. All cooperating gear components are lubricated with oil through dedicated pump equipped with filter driven by an independent motor, which makes lubrication system independent of rotational speed and provides good lubrication of highly stressed parts in the entire range of rotational speeds, especially very low.
This is a key structure element of twin-screw extruders, which influences the maximum working pressure and reliability and durability of the device. For the extruder having a screw diameter of 120 mm operating at a pressure of 400 bar, the force acting on the thrust bearing is approximately 45 tons. The thrust bearing has to operate reliably at this load for many years. To achieve this, we use the gears from manufacturers who guarantee the reliable operation of this component. The bearings are lubricated with oil in a closed circuit, which is optionally equipped with an oil cooler. The thrust bearing directly cooperates with the cylindrical gear, which is also lubricated with oil in circulation equipped with a cooler. This ensures reliable operation.
Extremely important component of extruder, - which influences capacity, product quality, reliability and ergonomics of operation. The hopper module developed and designed in our company is adapted to work with granulate or powder. The module body of the hopper has an efficient system of channels through which coolant flows.
Cylinder and screw module
Extruder cylinders are designed to work at a pressure of 400 bar. The cylinder is divided into heating - cooling zones, which are placed every 4d. The configuration of the cylinder is adapted to customer’s expectations. The cylinder is equipped with a wedge closure allowing for easy attachment of the head or pump of plastic material. The cylinder is always equipped with a cover made of stainless steel, having a thermal insulation which reduces the possibility of touching the heated cylinder by the personnel and reduces heat loss.
The screws have monolithic or segmental structure. The segmental structure allows customizing the configuration to the specific works. The structure of the screw is suitably adapted to transfer high torques and axial forces on the thrust bearings and a mechanism for measuring the value of this force.
The connection of extruder with head is carried out by wedge closure closed either manually or hydraulically, particularly in extruders of large cylinder diameter. This solution is safe, convenient for operation and time-saving.
Cylinder zones thermoregulation
Ecological thermoregulators used in our extruders have excellent technical parameters and, at the same time, are easy to use. Each zone of the cylinder is equipped with a digital system regulating the temperature ranging up to 400° C. Each zone has heaters which allow obtaining the desired temperature in a short time and a radiator with a fan, which allows for quick temperature reduction.
Heaters and cooling system are simultaneously controlled by a digital PID controller. This solution allows maintaining the desired temperature with high accuracy of about 1°C (0.1°C temperature measurement accuracy) and avoid the so-called, overdrives, meaning uncontrolled increases or drops in temperature The digital temperature controller developed by our automation department supervises the work of all extruder zones at the same time taking into account all interactions so that the temperature is stable and in line with values set in the whole cylinder and the measurement is reliable. Each cylinder has its own thermal characteristics stored in the controller's memory.
The processor and the extruder program may perform pressure measurements of plastic material by means of appropriate transducers You can apply up to 4 pressure transducers This allows pressure adjustment and supply of plastic material using just the extruder After attachment of pump for plastic material, the extruder program takes control over pressure transducers on the inlet and outlet of the pump and its capacity - it gives the possibility of very precise pressure regulation and supply.
All the extruders are equipped with the ability to measure torque. Measurement of torque allows its adjustment by the user, which increases the production capacity. The extruder can be operated automatically in different modes:
o Stability of rotation and temperature
o Stability of pressure (also with the pump) and temperature
o Stability of torque and temperature
We can stabilize the selected parameter and on others impose limits of obtained values.
Vacuum degassing system
Zamak Mercator extruders may be equipped with a degassing system with one or two vacuum pumps. The degassing is carried out through the ports in the top of the cylinder.
Pump for plastic material
Extruders may be equipped with pumps of plastic material that provide precise pressure control and supply of the melted polymer. The pumps are properly selected to model of the extruder. They have precise temperature control and supply of the material, which is managed by a control computer of the extruder. The extruder can operate with the pump, using its own pressure control program, which allows for obtaining unique precision dosing of plastic material to the head.
Digital control system
As we cannot imagine testing processes and production without their automatics, our automation department, based on many years of experience, developed software allowing management of extruders and entire testing lines Our software allows for controlling, monitoring and managing the extrusion processes.
Continuous monitoring of extrusion parameters such as pressure, temperature, rotation, torque, force acting on the screw and cylinder, energy consumption, allow for controlling the process and the device. Additionally, saving parameters in the database for further analysis and archiving, displaying graphs on-line and work in the plant network or even global is also possible. The software designed by Zamak Mercator can carry out the production while the process, and a video image transmit via Ethernet to any place on computers, tablets, etc.
We can adapt our software to the expectations of our customers. The process can be controlled from the touch screen on the device console or Ethernet.
We use our own programs as well as Bernecker + Rainer Industrie Elektronik GmbH and Lenze Drives GmbH equipment to implement our solutions in the scope of automation and drives. We also cooperate with many other renowned companies. Our equipment can be integrated with device control systems produced by other manufacturers.
We manufacture efficient and durable extruders. The appearance and convenience of operation has meaning to us - extruders in accordance with the needs of our customers.