PETpla.net Insider 03 / 2017

CONVEYING PET planet Insider Vol. 18 No. 03/17 www.petpla.net 36 The concept is based on a machine-specific conveyor system, which means that every processing machine has its own material supply line. This principle is particularly suited for production processes that involve a high number of materials, frequent material changes and a large number of machines. Machine-specific systems are very suitable for supplying dried materials when used with a dry air supply system and discharge valves for the supply lines. When long distances are involved, dry air supply systems with discharge valves have the advan- tage of preventing the material in the supply lines from being re-moisturised. The drying hoppers and several separate service tanks are connected to the material lines leading to the machines through a coupling station through which several machines can be supplied at the same time. The coupling station is equipped with suc- tion lances that can be connected to an additional back-up dryer or a service tank as required when processing small quantities of materials. One of the drying hoppers and two supply lines are reserved for transparent and white material. This drying hopper is also fitted with a high efficiency particulate air (HEPA) filter between the heater and hopper. The coupling station is operated, i.e. the lines are connected and dis- connected, by personnel. For safety, the system also features a material path selection system (target-source assignments), where personnel have to enter the address of the source (drying hopper) and target (machine) at the control. Provided the lines have been correctly connected, the material will subsequently flow accordingly. If one of the two addresses is incorrect, the material will not flow, because only the material slide gate of the correct drying hopper will be opened. This principle ensures that materials are not mixed up. Starting from the coupling sta- tion, a near 1,000m of pipes were laid throughout the rest of the production hall. The pipes leading to the machines are made of wear-resistant stainless steel, while the pipe bends are made of borosilicate glass. The flexible connec- tions between the material lines and machines were realised using high- quality PUR ducting. Higher productivity – higher energy efficiency The vacuum is generated by two frequency-controlled blowers inside the system that are coupled to one another. One of these supplies the drying system and the other is for the mate- rial supply to the machines. In order to safeguard production, both of the blow- ers’ performance has been selected such that each one of them could take over all of the supply processes in the system in the event the other fails or has to be serviced. In that case, the switch will happen automatically. To make sure that the material is transported in a careful way, the blow- ers can be operated at variable speeds, which is a way to affect the speed at which the material is transported. This means that every machine and its con- veyor – as well as every material – can be assigned an optimum conveying speed. This solution is designed both to protect the system components from wear and to protect the material itself. Thanks to the throughput-depend- ent drying process and associated use of frequency-controlled pumps, the production system has become sig- nificantly more energy efficient. Even though actual electricity consumption has not yet been determined in detail, initial rough estimates indicate signifi- cant energy savings. The automated material supply system also means that production processes are more reliable and less material is being used. The system’s operation is supported by a database stored in the dryer control that contains the drying parameters for more than 70 standard materials. This means that the only action required by personnel is to select the correct material. The corresponding informa- tion is also displayed on a terminal in the production hall. If necessary, the system can also be protected by setting up password protection for different operating levels. www.spritzguss-bergmann.de www.motan-colortronic.com www.flinkundwortmann.de A central material supply system with a decentralised colour dosing system ensures that processes are reliable and low energy and material consumption.