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machinery feature | Lab compounders KraussMaffei

Berstorff’s new KMD 35-26/L can be used to

develop recipes for PVC pipe,

profile or sheet

standard screw that eliminate the requirement for a kneading block. The allows for processing of a wide variety of materials with one screw design. Compared to a classic kneading block based

configuration, there is much less shear with Feddem’s screw design and more mixing is used to heat up the material. “We use more heating energy than shear energy; there are more mixing elements in a given L/D versus a conventional twin-screw compounder,” explains Gross. He claims that the combination of lower shear and extended mixing zones delivers a better resultant mix, and can also help to retain longer glass fibre lengths in reinforced compounds. According to Gross, “more than 90% of the

formulations and recipes developed for compound extrusion can be processed without kneading blocks, and that includes masterbatch production from a premix.” He concedes that some recipes, such as calcium carbonate filled PP or PE, require kneading blocks and Feddem does supply equipment for such applications. ❙

KraussMaffei Berstorff recently launched a new counter-rotating twin-screw lab extruder for proces- sors looking to reformulate their PVC recipes for the production of pipe, profile or sheet products. Its new KMD 35-26/L is said to be the smallest extruder of its type on the market, and features 35 mm screws and machine lengths of 26 or 32D. “The model is ideal for processors looking to find out

Leistritz says that its Nano 16 has the lowest free volume available of any twin-screw extruder

how to save on stabilizer, or to adjust the amount of filler without compromising material strength,” says Martin Mack, vice president, research and development, in the extrusion division of KraussMaffei Berstorff in Florence, Kentucky, USA. Processors benefit from enormous cost savings when they can test the formula- tion on a small scale, and this machine provides a scale

down of the production process that creates premium quality end product without producing large numbers of rejects. “The behaviour and flow is similar to what occurs on a larger production machine,” Mack says. Different screw geometries are offered for pipe, profile and sheet extrusion, and it is suitable for all commercially available hard and soft PVC mixtures. The new model can produce profiles and sheets at 15-40 kg/h, and pipe at 30-70 kg/h. “Counter-rotating units are not modular like our co-rotating units; you cannot adjust screw geometry by pulling off an element then adding an extra mixing element. There is no splined shaft and everything is rigid for maximum strength,” Mack says. The unit is designed with internal screw tempering

and barrel air cooling, and features several transduc- ers mounted on the barrel. The unit is a low-speed, high-torque and high-pressure system, delivering screw speeds from 50- 80 rpm and pressure from 500 to 5000 psi. The unit uses KraussMaffei Berstorff’s C5 control system. ❙

Leistritz offers a range of lab-scale machines from the Nano-16 for processing tiny volumes of pharmaceutical materials, through to the ZSE 27 Maxx capable of delivering more than 300 kg/h. It also has a lab extruder that can be switched from co-rotating to counter-rotat- ing operation.

The Nano-16 was primarily developed for the

pharmaceutical industry, where a low volume machine is needed for early stage development. “Processors had grams of new material available to them, and with other conventional lab units, a feeder could not reach a steady state (for accurate testing) with less than 200 g,” says Charlie Martin, president and general manager at

40 COMPOUNDING WORLD | December 2012

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