MACHINERY | SCREWS & BARRELS
Right: Xaloy MPX incorpo- rates small spherical tungsten carbide particles to create a dense, abrasion resistant surface
University of Minho in Portugal. Minho University will carry out extrusion model-
ling of elements including the screw and barrel geometry. Antonio Gaspar-Cunha, of its Institute of Polymers and Composites, said that two potential challenges in the project would be: the difficulty in measuring the ‘real’ friction coefficients; and, modeling the real behaviour of the pellet flow in the grooves.
Diamond protection Finnish material specialist Carbodeon and German metal finishing specialist CCT Plating have developed an electroless nickel plating technology for wear protection, called NanoDiamond. Although it was developed for sliding wear
applications, Carbodeon says it considers the technology suitable for applications in extruder screw and barrel protection as it overcomes the traditional susceptibility of electroless nickel coatings to adhesive wear. Electroless nickel coatings provide good
Below: The NewEx project aims to
develop a new type of extruder, with a special focus on the screw and barrel
corrosion and abrasion resistance and allow an even coating thickness to be applied to complex geometries at relatively low cost, says the company. However, they do not perform well in tribological applications involving moving metal parts, where adhesive wear and galling tend to lead to rapid wear or failure. Carbodeon says that incorporating its NanoDiamond materials into the coating overcomes this problem. The spherical diamond nanoparticles are treated to carry a positive electrical charge to help disper- sion. This means that, during plating, the diamond particles behave similarly to the positively charged metal ions and co-deposit onto the component surface with them. The resulting metal-diamond composite surface treatments have already shown their value in abrasion resistant coatings, but optimising the process is said to have created a new generation of coatings that combat the
adhesive wear that occurs when plated parts are in sliding contact with other metals. The coatings can be used “as plated”, which does not affect the substrate’s heat treatment condition, or can be annealed for higher perfor- mance. Abrasive wear is said to be three times better than standard electroless nickel, while adhesive wear rate is cut by 30% in the “as plated” form and by 85% in the annealed state. Coating hardness is increased when annealed.
Abrasion award Meanwhile, Nordson’s Xaloy MPX wear coating technology, which increases the abrasion- and corrosion-resistance of single and twin plasticating screws, won an innovation award at last year’s Plastpol exhibition in Poland. “With the new Xaloy MPX technology, we continue our history of leading-edge innovations,” said Norbert Zając, Eastern Europe sales manager for Nordson’s polymer processing systems brands. The technology is recommended for resisting
abrasion from compounds with medium (15 to 35%) filler loadings and for resisting corrosion from halogenated materials, including flame retardants and PVC. It uses tiny tungsten carbide spheres to make a coating that resists wear better than standard coatings applied by high-velocity oxygen fuel (HVOF) thermal spray, said the company. Compared with standard HVOF tungsten carbide coatings, it has 61% less mass loss in ASTM G65 abrasion testing, 18% less mass loss in ASTM G77 sliding wear testing, and 8.5% greater bond strength in ASTM C633 bond testing, said Nordson.
CLICK ON THE LINKS FOR MORE INFORMATION: �
www.uml.edu �
http://newex.pollub.pl/ �
www.carbodeon.net �
www.cct-plating.com �
www.nordson.com
42 FILM & SHEET EXTRUSION | March 2018
www.filmandsheet.com
PHOTO: NORDSON CORPORATION
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
