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Automatic strand feeding provides economic alternative for strand pelletizing
Pe l l e t i ze r s
Automatic strand feeding provides economic alternative for strand pelletizing Intelligent Pelletizing Solutions GmbH & Co. KG, now part of the Kreyenborg Group, has been developing automatic strand feeding technology to operate with a strand pelletizing system. A conventional strand pelletizing line can be considered to have a number of advantages. These include easy replacement or modification of individual components, as they are not firmly connected with one another. The cooling time before cutting can be changed simply through the length of the water bath, meaning that it can be suitable for all types of polymer. The manual threading of the strands results in a high occupancy density of up to 75 percent. In addition, the individual components are easy to set-up and understand the method of working and strand pelletizing has been established in the industry for many years. However, disadvantages include handling the strands during start-up. These require picking up while molten and feeding into the strand cooling trough and then into the feeding device of the pelletizer. This involves considerable risk of injury to the operators and their skills and motivation are a major factor in the operation of such a system. In addition, the duration of the starting process and the amount of waste produced (in molten mass and oversize pellets) are greatly dependent on the skill and motivation of the operator. Any strand tears that occur during operation have to be observed and then manually re-inserted as in the starting process. Intelligent Pelletizing Solutions has now developed a strand pelletizing system with automatic strand feed. The process involves a forming/cooling section, separating/tempering/cutting section and classifying section. The strand pelletizer with automatic strand feed includes a conveying belt that pro-
vides dry strand suction in the first section, followed by water suction. The dry and wet sections mean that the residence time can be varied. At the end of the dry and wet suction stages, the strands are moved by water up a water sluice to the pelletizer. Strand feed is effected by simple height adjustment of the strand cooling chute, which can be adapted to various installation heights of the strand die head and by varying the dropping height of the strands at the starting head. There are large cleaning/rinsing openings on the water box of the starting head for quick removal of contaminants and obstructions. Spray tubes to change the cooling effect can be added or switched off individually. The strand transport belts are made of temperature- and wear-proof materials, which can be easily replaced within five minutes. The company adds that the strand transport belt can be easily separated from the strand pelletizer for cleaning and maintenance. A pump is used to feed the process water from the strand transport trough into the process water circuit. According to Intelligent Pelletizing Systems, there are a number of advantages and disadvantages to take into consideration when contemplating whether a strand pelletizing system with automatic strand feed is appropriate for a particular application. The advantages include simple, precise repetition of the positioning of the components through the joint base frame. In addition, feeding of strands at start-up or after strand tears does not require operators. As a result, there are low amounts of waste due to the short duration of the starting process and the independence of skill/motivational issues regarding operating personnel. The company adds that the yield can be greater because production can begin earlier even if the strands are not yet
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running optimally, due to frequent strand tears for example. Finally, the cooling line is highly flexible due to the addition or switching off of individual spray tubes, or the switching on or off of the wet area of the strand transport trough. There are disadvantages associated with such a system, however. These include a low occupancy density of around 30 percent of the strand pelletizer due to the automatic threading of the strands. This is because strands sticking together on the water sluice must be avoided. There is also a higher screening quality requirement of the classifier due to the resulting oversized pellets resulting from automatic re-threading after strand tears. In addition, it is not economic to process plastics with high heat content. This is because the feeding speed has to be reduced due to the fixed overall length of the cooling line in order to achieve satisfactory cooling of the strands. This results in low throughput. Intelligent Pelletizing Solutions believes that a strand pelletizing system with automatic strand feed can provide the greatest flexibility in compounding for certain applications, depending on the polymer to be processed and the throughput. It is particularly suitable, says the company, for highly reinforced polymer compounding of up to 1500 kg/h. Glass-filled polyamide is one such example. Bottle grade PETP is another application cited as being particularly suitable for a strand pelletizing system with automatic strand feed. Contact: ips Intelligent Pelletizing Solutions GmbH & Co. KG Tel: +49 60 26 99 04 20 Fax: +49 60 26 99 04 23 E-mail: [email protected] Website: www.pelletizing.de
Automatic strand feeding provides economic alternative for strand pelletizing Intelligent Pelletizing Solutions GmbH & Co. KG, now part of the Kreyenborg Group, has been developing automatic strand feeding technology to operate with a strand pelletizing system. A conventional strand pelletizing line can be considered to have a number of advantages. These include easy replacement or modification of individual components, as they are not firmly connected with one another. The cooling time before cutting can be changed simply through the length of the water bath, meaning that it can be suitable for all types of polymer. The manual threading of the strands results in a high occupancy density of up to 75 percent. In addition, the individual components are easy to set-up and understand the method of working and strand pelletizing has been established in the industry for many years. However, disadvantages include handling the strands during start-up. These require picking up while molten and feeding into the strand cooling trough and then into the feeding device of the pelletizer. This involves considerable risk of injury to the operators and their skills and motivation are a major factor in the operation of such a system. In addition, the duration of the starting process and the amount of waste produced (in molten mass and oversize pellets) are greatly dependent on the skill and motivation of the operator. Any strand tears that occur during operation have to be observed and then manually re-inserted as in the starting process. Intelligent Pelletizing Solutions has now developed a strand pelletizing system with automatic strand feed. The process involves a forming/cooling section, separating/tempering/cutting section and classifying section. The strand pelletizer with automatic strand feed includes a conveying belt that pro-
vides dry strand suction in the first section, followed by water suction. The dry and wet sections mean that the residence time can be varied. At the end of the dry and wet suction stages, the strands are moved by water up a water sluice to the pelletizer. Strand feed is effected by simple height adjustment of the strand cooling chute, which can be adapted to various installation heights of the strand die head and by varying the dropping height of the strands at the starting head. There are large cleaning/rinsing openings on the water box of the starting head for quick removal of contaminants and obstructions. Spray tubes to change the cooling effect can be added or switched off individually. The strand transport belts are made of temperature- and wear-proof materials, which can be easily replaced within five minutes. The company adds that the strand transport belt can be easily separated from the strand pelletizer for cleaning and maintenance. A pump is used to feed the process water from the strand transport trough into the process water circuit. According to Intelligent Pelletizing Systems, there are a number of advantages and disadvantages to take into consideration when contemplating whether a strand pelletizing system with automatic strand feed is appropriate for a particular application. The advantages include simple, precise repetition of the positioning of the components through the joint base frame. In addition, feeding of strands at start-up or after strand tears does not require operators. As a result, there are low amounts of waste due to the short duration of the starting process and the independence of skill/motivational issues regarding operating personnel. The company adds that the yield can be greater because production can begin earlier even if the strands are not yet
Plastics Additives & Compounding November/December 2003
40
running optimally, due to frequent strand tears for example. Finally, the cooling line is highly flexible due to the addition or switching off of individual spray tubes, or the switching on or off of the wet area of the strand transport trough. There are disadvantages associated with such a system, however. These include a low occupancy density of around 30 percent of the strand pelletizer due to the automatic threading of the strands. This is because strands sticking together on the water sluice must be avoided. There is also a higher screening quality requirement of the classifier due to the resulting oversized pellets resulting from automatic re-threading after strand tears. In addition, it is not economic to process plastics with high heat content. This is because the feeding speed has to be reduced due to the fixed overall length of the cooling line in order to achieve satisfactory cooling of the strands. This results in low throughput. Intelligent Pelletizing Solutions believes that a strand pelletizing system with automatic strand feed can provide the greatest flexibility in compounding for certain applications, depending on the polymer to be processed and the throughput. It is particularly suitable, says the company, for highly reinforced polymer compounding of up to 1500 kg/h. Glass-filled polyamide is one such example. Bottle grade PETP is another application cited as being particularly suitable for a strand pelletizing system with automatic strand feed. Contact: ips Intelligent Pelletizing Solutions GmbH & Co. KG Tel: +49 60 26 99 04 20 Fax: +49 60 26 99 04 23 E-mail: [email protected] Website: www.pelletizing.de