Dies need less space, provide precision
Based on its success with film dies, Dual Spiral Systems has designed new coextrusion dies for manufacturing pipe and tubing.
The company’s recent release of the DSS Compact Coex pipe and tubing dies followed its launch of compact extrusion dies for film, President Rafael Castillo said.
“The DSS Compact Coex dies’ main inception was for the purpose of achieving very tight film thickness deviations and having accomplished this by producing films of under 2 percent thickness deviation, without a thickness correction device, the concept was adapted to the coex pipe and tubing sector,” Castillo said.
Pipe and tubing manufacturers want the same accuracy as film manufacturers, he said.
The compact dies have been reduced in height and weight by 50 percent compared to the company’s traditional multilayer DSS modular die system.
The DSS Compact Coex dies have the following advantages over traditional dies:
• Faster heat-up time due to their lower mass.
• Lower residence time due to shorter flow passages.
• Faster purge and material changeover times.
• 60 percent less energy consumption.
• More streamlined melt port entries.
In addition to their other benefits, the compact dies are easier to handle and move. The pipe dies take up less floor space.
As an example of potential benefits, Castillo pointed to the company’s 22-layer DSS Compact Coex die, which is capable of processing 22 different resin layers from five extruders. Dies with the capability are available for both film and pipe and tubing production.
With a traditional 22-layer DSS die, the weight of the die would be more than 8.1 tons with a length of nearly 5.3 feet. By comparison, the 22-layer DSS compact die has a weight of a little more than 4.2 tons with a length of a little less than 2.7 feet. Also, by comparison, the total heater wattage for the traditional 22-layer DSS die would have been 173,000 watts, while the 22-layer compact DSS die heater wattage is 68,000 watts.
While smaller and requiring less energy, the compact dies maintain the company’s patented “layer-splitting technology,” which divides polymer flow from the extruder into two layers, which doubles the number of layers in the die.
“Our research has shown that layer division substantially reduces film thickness deviation, increases output rates and makes film twice as strong compared to dies with single-film layers,” Castillo said. “When we applied the DSS concept to pipe extrusion, pipe wall thickness was equally uniform, to the point where any nonuniformity could no longer be measured by traditional methods.”
DSS Compact dies can produce tubing and pipes ranging from 0.25 inch to 60 inches in diameter, Castillo said.
Dual Spiral Systems specializes in manufacturing extrusion dies for applications ranging from one to 42 layers. While the company sells the products to plastics manufacturers looking to upgrade their technology, the company also manufactures its own line of extruders and sells the dies to other machinery manufacturers that incorporate them into their lines.
Bruce Geiselman, senior staff reporter
Dual Spiral Systems Inc.
Burlington, Ontario, 905-524-2438, www.dualspiralsystems.com