Conveying System for Plastics Compounding
Introduction:
During the process of plastics compounding, the auxiliary equipment utilized in the material conveying system mainly include those for unloading, conveying, weighing or scaling and compounding. As part of the upstream process in plastics production, the right auxiliary equipment and system solutions ensure reliability and convenience for highly automated production.
With decades of experience in material conveying and advanced technology from our parent company, we provide customized conveying & weighing system solutions for all kinds of plastics manufacturing needs.
Example:
Wuhan Sunwill Santech Engineering Plastics Co., Ltd is one of the main customers of Colormax Systems. Five complete material conveying systems help Sunwill reach its maximum productivity and quality requirements with highly accurate material conveying and feeding equipment.
The raw material for engineering plastics includes pellets such as PP, PET; powders such as talc, calcium carbonate, and addictives such as titanium dioxide, flame retardants, etc.
Main process:
Raw material in bags is unloaded into bag dump stations, and then delivered into material hoppers through vacuum or pressure conveying systems. Then loss-in-weight feeders deliver respective ingredients into the extruder with accurate ratio and speed.
Advantages:
The complete conveying system helps Santec realize a high level of automation in engineered plastics production.
Pneumatic conveying simplifies the process, decreases the labor force so as to save the labor costs; vacuum blowers can reduce the leakage of dust, hence ensure a sanitary working environment; highly accurate feeding process provides stability in controlling the ingredient ratio, minimizes the mistakes, and therefore enhances the final quality and decreases material waste.
Main steps:
Vacuum receiving (negative pressure)
Roots blower creates the negative pressure in conveying system. For pellets, the Colormax Systems SW2415 provides max conveying rate over 2700kg/hr; for powders, the SW2423 reaches the conveying rate at over 1400kg/hr. The polyester cartridge filter is equipped with automatic reverse jet pulsing for thorough cleaning. It separates the material from the conveying air, eliminating product carryover and maintaining a clean process area.
In this case, one blower operates with 3 receivers, controlled by a single IPC. All ingredients enter the mixing hopper in sequence after an initial batch sizing based on their general ratio. There are high and low level indicators on every hopper to control the filling of the storage tanks.
The system is initiated when a signal is received from the low level indicator on hopper. The blower package starts producing the negative pressure and pulls the material from the bag dump station through the convey piping and into the receiver. When the vacuum decreases inside the receiver, the material weight triggers the discharge gate to open, and material falls into the hoppers below. The pulse cleaning mechanism separates the materials from filter as 1 cycle. The cycle repeats until the high level indicator sends the signal to stop the conveying.
One of the advantages of vacuum systems is the inward suction created by the vacuum blower, which reduces any outward leakage of dust. This is one of the reasons why vacuum systems are often used in higher sanitary or dust containment applications.
Loss-in-weight feeding
Loss-in-weight feeding is applicable for those situations where every ingredient needs an accurate weight control.
In this case, S60 and T38 and liquid feeders are integrated for 1 extruder. The single screw S60 is more suitable for pellets and free flowing powders, while the twin screw T38 suits powders and fibers or flakes.
In operation, the material and the feeder is continuously weighed together. With the material delivered, the true rate of weight loss is compared with the set weight loss rate (required value). Loss-in-weight feeders automatically correct the deviation from the set point by adjusting the feeder speed, so as to achieve an even and accurate continuous feeding rate. For Colormax Systems feeders, weighing accuracies of +/- 0.5% of the full scale capacity can be expected.
Colormax Systems provides proven strain gauge load cells from a famous international manufacturer of weighing technology With the unique control software and hardware, the feeder controls represent a major advance over older PLC-based control systems and completely eliminate the hysteresis experienced with less robust control technology. Unsurpassed stability in feed accuracy through the use of load cell & control card is critical for controlling costs and quality.
The on-line controller provides a combined and simple interface, and provides great operational flexibility on recipe storage and recall.
Properly weighing and accurately delivering the ingredients to the mixing process without manual intervention can result in a number of process advantages, including fewer mistakes, better accuracy, lower bulk material costs, improved product quality and savings in manufacturing costs.
Colormax Systems provides customized pneumatic conveying and systems solutions, designs and installations, complemented by over 50 years of application experience from our parent company. Moreover, the test reports provided by our new test lab on actual bulk material tests, field service support and customer training ensure successful operation and a maximum return on investment for every conveying system.
