machinery feature | Twin-screw extruders
Maffei Berstorff’s ZE A UTX series. Tooth profiles of the screw shaft and screw ele- ments, the screw preloading system and the geometry of the connecting sleeves have all been improved to make sure that the extra available torque is fully exploited. Substantially higher output rates are achieved at considerably lower energy consumption, the company claims. KraussMaffei Berstorff says that, to achieve effective
Magnetized sleeve couplings measure torque levels on the Leistritz ZSE 50 XX concept extruder
New elliptical collar liners
increase wear protection on KraussMaffei Berstorff’s ZE BluePower
larger mixing chambers than the company’s V class and HT class extruders, providing a free volume (screw OD/ ID ratio) of 1.65 vs. 1.55. As a result, an HP model with screws turning at 1,000 rpm will have an output of more than 550 kg/h of 30% glass-reinforced polyamide, compared to less than 400 kg/h for an HT model. Giorgio Colombo, managing director at ICMA San
Giorgio, says that the new models have been conceived to save as much energy as possible, with such features as water-cooled AC motors and new barrel insulation. The company has also put considerable effort into the development of special steels with improved wear properties. ICMA San Giorgio has its own foundry, it collaborates with the nearby Milan Polytech- nic, and is also located in an area with an important industrial cluster connected with the aerospace industry from which it is able to “borrow” expertise. “Metallurgy is part of the ICMA DNA,” says Colombo. Increased free volume and higher torque density are
ICMA San
Giorgio’s new HP models combine increased
torque with higher free volume
also features of KraussMaffei Berstorff’s ZE BluePow- er, which the company says received a positive welcome on its introduction at K 2013. It also cites “unparalleled wear protection and maximum process flexibility,” as well as innovations in energy efficiency and process engineering. The machine features a water-cooled motor, a high-efficiency gear unit, plus a completely redesigned processing section. Just like ICMA’s HT, the ZE BluePower
features an increased OD/ID diameter ratio of 1.65, providing torque density of up to 16 Nm/ cm³, which is 30% more than on Krauss-
30 COMPOUNDING WORLD | March 2014
www.compoundingworld.com
wear protection for all applications, it has complement- ed the range of patented induction hardened or powder- coated barrel sections by new wear liners. Elliptical collar liners provide optimum heat transfer and “perfect” tightness of the processing chamber. The ZE BluePower series also features a new base
frame concept, which ensures easy and rapid access to the different machine components. Peripheral equip- ment and control systems can either be integrated into the base frame or mounted separately. Maris has extensive experience in building com- pounding extruders for masterbatch. It provides this rule of thumb on shear rates and free volumes (OD/ID) related to the materials to be processed (the lower the free volume, the higher the shear): l OD/ID 1.55 when the formulation or the type of pigment requires a high shear-rate or when it is difficult to obtain a good dispersion due to the low quality of the pigments.
l OD/ID 1.65 for high quality pigments or when a low dispersion level is acceptable.
l OD/ID 1.78 when the formulation or the type of pigment requires a delicate processing. It is also possible to use these machines when the concentration of the dispersed phase is high or when it has a low bulk density (see table on the next page). Century Extrusion has been increasing the
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