EXTRUDER DEVELOPMENTS | MACHINERY
Recent extruder developments include new lines for blown and cast film, a single-screw installation for BOPET in China and a high-output, twin-screw extruder for polyolefin film
Upping output: latest extruder developments
Raising output is a critical measure for film and sheet extruders – and is a key focus for developers of extrusion lines. SML recently expanded its portfolio with a new
co-rotating twin-screw extruder – to meet increas- ing demand for high-output capacities for polyole- fins and polyesters.
“Our in-house-designed co-rotating twin-screw
extruder is tailor-made for the specific require- ments of our extrusion lines, contributing to an exceptional film quality,” said Hans-Jürgen Luger, head of research and development at SML. Compared to a large single-screw extruder of the same output capacity, it has a shorter process- ing unit – and smaller footprint. This means less heating power is needed to maintain barrel temperatures. Because of starve feeding, the extruder drive operates at high torque over the whole output range. In addition, melt temperature can be controlled by adjusting the degree of filling. Tests of the new extruder on a CPP line in SML’s
Technology Centre have shown that the specific energy input (SEI) is 10-15% lower than for a single-screw extruder. In terms of film quality, gel count detected by a web inspection system could
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be reduced by up to 20% for a standard CPP film. With throughputs in the range of 1,000 to 2,000
kg/h, SML says the extruder has potential applica- tion in its cast film lines with end film widths of up to 6.5 metres. A swivel-mounted barrel allows rear screw
extraction for fast, easy screw changes. The temperature of the barrel is controlled by ceramic heaters and air cooling – which SML says is a precise, cost-efficient, low-maintenance solution. The company offers pre-configured single-piece barrel designs of different lengths – with venting ports, depending on the application. For the extruder screws, single-piece solutions or shafts with segments are available. In combination with its vacuum unit, SML can offer a complete in-house extrusion solution for process- ing PET or PLA without pre-drying. In addition, the extruder enables high amounts of regrind or flakes to be processed – as well as in-line compounding.
New dimension BB Engineering has supplied two 360mm PET single-screw extruders to a customer in China. It says single screws extruders of this size – for
October 2026 | FILM & SHEET EXTRUSION 13
Main image: BB Engineering has supplied two 360mm PET single- screw extrud- ers to a
customer in China
IMAGE: BB ENGINEERING
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