Strictly-Extrusion

Initially published by Carl Hanser Verlag to bridge the gap between theory and practice in extrusion, this 4th edition of Chris Rauwendaal´s “Polymer Extrusion” continues to serve the practicing polymer engineer and chemist, providing the theoretical and the practical tools for successful extrusion operations. In its completely revised form, it also incorporates the many new developments in extrusion theory and machinery over the last 15 years. Contents: Different types of extruders – extruder hardware – instrumentation and control – fundamental principles – important polymer properties – functional process analysis – extruder screw design – die design – twin screw extruders – troubleshooting extruders – modeling and simulation of the extrusion process.

Hostaglas acquired by Arla Plast Privately owned Swedish company Arla Plast AB, a leading European supplier of extruded thermoplastic sheet, has acquired all assets of Dublin, Ireland-based Hostaglas Ltd. from the German Hagedorn group. Hagedorn acquired the business in December 1998 from the now defunct Hoechst group. Hostaglas has annual production capacity of 4,000 t/y for PC and PET sheet. Its two extrusion lines are to be transferred to Borenberg. The acquisition will give Arla Plast 10 extruders, including seven for PC/PET and three for ABS/PO.

As an alternative to plated dies, Cloeren is using two standard materials of construction; hot-work alloy H13 (DIN 1.2344) and 15-5PH (DIN 1.4540) stainless steel, both through-hardened to 40 Rockwell C (Rc). While these materials cost substantially more than typical alloy mould steel, Cloeren will offer these constructions at the same price as a plated die. Customers will benefit from shorter delivery times and an extended warranty of two years on dies made with these materials. Extrusion dies are typically constructed from variations of mould steels such as P-20 (DIN 1.2311/1.2330), and are most commonly plated with nickel or chrome. Initially, such steels were mildly hardened to about 30 Rc. Plating was added for three primary purposes, to increase surface hardness, to enhance corrosion resistance, and in some cases, to improve wear resistance. “Plating is the weakest link of an extrusion die, both in the manufacturing process and in field performance and reliability,” said Cloeren President, Peter Cloeren, Jr. “It is the single largest variable in the manufacturing process and the most unpredictable variable in the field. Causes of plating failure vary.” Employing higher alloy materials eliminates the potential of plating failure and enhances the overall robustness and dependability of a die.

Kuhne, Germany, developed a new multi-layer bolt adapter, which offers flexibility, a high degree of production safety and the possibility to reduce production cost. Currently there are a number of three, five, seven and nine layer flat film lines with melt bolt adapter technology installed worldwide. One of the highlights at the Kuhne booth during last year’s K Show was a seven layer flat film line with a new patented bolt adapter, which included an edge encapsulation. The line was laid out for the production of barrier films which are used for thermoformed articles. The line produced a combination with EVOH as the barrier material and a bonding material on both sides. Onto this combination two layers of reground PP were added with a further layer of virgin PP. The film combination included an edge trim encapsulation, which meant that the film edges which were cut off consisted of one raw material and the expensive barrier materials were positioned in the film where they were actually needed. According to the company, the bolt adapter provides cost savings and pays for itself within approximately six months.

Edge Building Products Inc.,USA, is gearing up for growth with what officials say is the industry’s first vinyl composite trim board. The Newport manufacturer of cellular PVC trim boards is searching for a new building to accommodate its growth and will add a twin-strand extrusion line in the next 60 days.

Two years after it sold an extruder factory in Austria, Milacron Inc. has purchased a small German company, Compounding Processing Machinery GmbH, that makes parallel twin-screw extruders and designs screws and barrels. CPM brings the ability to design screws for any brand of machine, not just Milacron extruders.

Plastic Extruders has introduced a new electronic 4-head winder, into its standard range of extrusion machinery. It is now available for supply to manufacturers for the winding of extruded products such as flat strip. Different types of winder and coiler are also available for the extrusion of cables, tubes, gaskets and flexible profiles. With 35 years experience of making single-screw extruders and associated equipment for their own in-house production lines, the horizontal in-line winder was originally purpose-designed for use on Plastex polpropylene and polyester strapping lines. The machine gives a positive and geometrically correct lay-on of strap that produces reels which have even faces and straight lines. The new winder replaces older designs which relied on a gearbox and mechanical drive. The machine can be programmed to give every reel optimum pitch and width. Changeover from one head to another takes less than 20 seconds even when the line speed is in excess of 200m a minute. To prevent costly over running of the extruder product, an electronic counter measures the product as it is wound.

Guill Tool and Engineering, USA, has developed a solution to industry problems that have plagued extrusion wood and polymer manufacturers over the past several years. Guill Tool’s new Equaflow has been designed to help eliminate problems such as warping, twisting, voids, sagging at the products centre, unnecessary tolerance variations, having to run at reduced production speeds and uneven material distribution. The Equaflow Series is engineered for solid core, hollow core, single-layered and multi-layered wood composite and polymer applications. The product is available in two different models, one for single straight product throughput that produces thin product strips or trim type moulding. The co-extrusion model enables two different types of material to be extruded simultaneously, such as wood fibre core in combination with a PVC skin. The unique Equaflow material distribution is accomplished by a specially designed patent-pending reservoir system.

The Competence Centre for Wood Extrusion established by Cincinnati Extrusion, Vienna in co-operation with Cincinnati’s partners Fasalex, JRS, TechWood and PPT as a forum for all questions concerning wood processing, enjoyed unrivalled popularity at the K 2001 exhibition. Even the participating companies were surprised by the overwhelming feedback. Due to the successful presentation at the exhibition, wood extrusion experienced a breakthrough with plans for large-scale production of fibre profiles, and as a result first orders have been placed. The Dutch company TechWood International, participating in the SMS Technology’s joint exhibition stand, finalised a large-scale order during the exhibition. Over the next five years, Industrias Vassallo Inc. of Puerto Rico, the largest plastics processor in the Caribbean, will be producing wood profiles for 50,000 hurricane-proof houses. Vasallo has acquired a licence for the production of wood profiles from the Dutch company TechWood. Moreover, both business partners agreed that TechWood will produce the initial 1,000 houses at its own production site in the Netherlands pending completion and start-up of the new Vassallo facility in Puerto Rico. TechWood, Vassallo’s license and business partner, works with renowned machine suppliers. The company uses extruders of Cincinnati’s Titan F series for its extrusion processes. These extruders are already successfully operating at TechWood’s Dutch headquarters. Conical twin-screw extruders of the Titan F series are perfectly suitable for processing materials with low apparent density which are characteristically used in wood processing. These extruders’ feed throats have specifically-designed wide openings to accommodate bulky material. They offer the additional advantage of providing a wide diameter in the screw’s feed section combined with continuous compression brought about by the conical shape. Metering zones with a low volume and small surface area reduce the friction to a minimum and thus guarantee high-quality products. Moreover, the short residence time in the Titan F extruder ensures the protection of thermally unstable natural materials. In conical extruders, residence time is halved in comparison with parallel extruders.

The French company E.H.P. (Environnement Handicap Plasturgie), a subsidiary of Maine Plastiques S.A., which specialises in the production of small industrial profiles such as cable conduits, has recently started up a new profile extrusion line for processing HDPE reclaim at its production site in Sotteville Les Rouen. Maine-Plastiques chose a complete extrusion line from Battenfeld Extrusionstechnik, a leading manufacturer of pipe and profile extrusion machinery. This particular line is specially designed for reclaim processing, and has been successfully operating in France for some months. The single-screw extruder type BEX 1-60-30 B/4 is equipped with a water-cooled positive conveying feed bush and a special barrier screw. The extruder has a minimum output rate of 150 kg/h and a maximum output rate of 350 kg/h. The line is also equipped with a screen changer, an indispensable component for reclaim processing. The reclaim material is derived from shredded HDPE bottles collected in the Rouen area. Around Rouen, 300 tonnes of HDPE bottles are disposed of annually, mainly for fruit juices and liquid detergents. E.H.P. uses the Battenfeld extrusion line to turn this material into twin-wall sheet which, in France, is used for applications such as separating compartments in animal sheds. With the operation of this new profile line, the French processor is taking part in a project called EHP (Environnement, Handicap, Plasturgie) which aims at providing employment opportunities for the handicapped. Hence, Battenfeld has designed this line with a lower height to accommodate workers operating from a wheelchair.