TECHNOLOGY | WIRE AND CABLE
Above: Flexibility is a prime feature of the latest Buss Compeo kneader extruder
There are other factors driving new cable and
wire technical developments, too. “Regulations are removing well known products, such as PVC, from certain applications,” Niklaus says. “There is also demand for higher voltages in XLPE insulation compounds, better electrical properties for data cables, and improved mechanical properties with thinner cable constructions. Economically, formula- tions are getting better adapted and specified for the required properties to get lower material costs. With higher volumes of compounds, this is an important factor. Replacing existing raw materials with cheaper ones is also a significant trend.” Buss Process Engineer Robert Hollosi says that
formulations are getting more specific to the required cable application. “Compounding and formulation know-how is increasingly being held by the cable producer, not shared with a toll compounder and other end users,” he says. “There is also always a need for better performing materi- als, driven by new regulations such as flame retardancy, or technological requirements includ- ing mechanical and electrical properties. The ban of some additives, such as organometallic stabilis- ers, is also a major technical issue at present.”
Flexible compounding The company’s technical team believe that more complex formulations call for more flexible compounding equipment. Maintaining good dispersion with new fillers requires more flexible screw geometries, as well as differently designed mixing elements, to obtain the best dispersion quality. This flexibility also means being able to change between XLPE-LV, HFFR (Halogen-Free Flame Retardant) and PVC compounds with ease. In addition, more abrasive materials are now being used in the cable compounding process, so higher wear resistant construction materials are required as well as gentler mixing. Other cable compound- ing requirements include more effective and flexible feeding of raw materials, such as liquids, pellets and powders, as well as better ventilation and degassing, they say. The latest Buss kneader extruder development is
the Compeo series, which can be equipped with 2, 3, 4 and 6-flighted kneading elements that can be combined to obtain the best mixing result for a specific requirement. Each element type is also available with different flight shapes to achieve the most suitable screw geometry. The Compeo design also includes an enlarged main feed port with patented venting arrangement and side feeders for improved feeding of powders. This is said to guarantee optimum filling in the intake section and allow further optimisation of the compounding line. And a new counter-rotating twin screw discharge helps to build up the pressure for pelletising gently and more flexibly for a wider variety of product viscosities. The company says this also opens up new opportunities where high discharge pressures are required, such as direct extrusion. According to Buss, a comparison of pure 3 and 4-flighted screw geometries against the combina- tion of 2, 3 and 4-flighted screw elements has shown reduced energy consumption and substan- tially improved dispersion of demanding fillers. Smart combinations of these elements create a
Lewa delivers precison in silane dosing
German metering pump manufacturer Lewa has supplied an undisclosed cable manufacturer with equipment to precisely dose silanes in its continu- ous production process. As the accuracy of dosing of the silane additive has a direct influence on the quality of the end product, the company says that fast response and
44 COMPOUNDING WORLD | May 2019
precise control of flow rate has to be guaranteed - even when different types of silane are being used for different products. The cable producer uses various
types of silane cross-linking and adhesion agents at its manufacturing sites around the world. Each metering system uses Lewa’s Ecoflow dia-
phragm metering pump – which provides flow rates of 0.5-10 l/h – in combination with the company’s Lewa Smart Control technology and a high precision mass-flow meter. Minor modifications were made to adapt the dosing systems to national regulations in each location. �
www.lewa.com
www.compoundingworld.com
PHOTO: BUSS
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72 |
Page 73 |
Page 74 |
Page 75 |
Page 76 |
Page 77 |
Page 78 |
Page 79 |
Page 80 |
Page 81 |
Page 82 |
Page 83 |
Page 84
