Medical rubber tubing process and die optimization: Die redesign and fine tuning

Part 1 of this contribution, published in the May 2021 edition of Rubber World, investigated a real manufacturer’s process that was set to produce medical tubing. It was found (through trials at the extruder, then through simulations) that the equipment available to the manufacturer was too large for the relatively low output that was required for this project, and consequently the polymer was degrading on the screw surface. It was ultimately determined through simulation that a smaller extruder, with a screw optimized for the low rate, would work better.

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CPE: A unique polymer for rubber and plastics extrusion

Chlorinated polyethylene (CPE) polymers were developed by DuPont in the late 1950s by a simple chlorination of polyethylene (PE) in a solution process using a solvent. In 1971, Dow Chemical Company introduced Tyrin CPE using a more efficient and cost-effective aqueous suspension chlorination known as the slurry process. The polyethylene feedstock is in a powder form and the final CPE product remains in powder form. The chlorination process can be modified to produce amorphous (non-crystalline) products or products that contain residual crystallinity

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Medical tubing process and die optimization, part 1: Troubleshooting and fine tuning

An extrusion die is a purpose built tool designed by cutting shapes in plates to reflect an intended extruded rubber product. In advance of an extrusion project, a process engineer designs the die according to specifications of the project and those of the customer, and installs it on an extruder. Often, an extrusion die is made from hard metal, like steel, polished and with sharp edges. Once all plates of the mold or die are created, rubber is forced through them under high pressure in a high temperature zone

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New developments in polymer science lead to ultra low density closed cell EPDM sponge extrusion

It has long been established that unvulcanized solid elastomer compounds can be expanded to sponge forms by the incorporation into the formulation of thermally activated gas releasing chemicals known as blowing agents. During controlled heating of the compound, there is molecular dissociation of these blowing agents, and this is often designed to occur in conjunction with the onset of vulcanization of the compound, enabling the production of a range of sponge structures.

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Development of an enabling EPDM polymer to improve performance and processability of EPDM compounds

Royalene EPDM, a terpolymer of ethylene, propylene and a
non-conjugated diene, is one of the most versatile specialty
elastomers in commercial use today. The main attributes of
EPDM are its outstanding resistance to oxidation, ozone and
the effects of weathering. It is also highly extendable, allowing
high levels of fillers and plasticizers to be added, while still
maintaining good physical properties

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Guill announces 800 series hybrid extrusion tooling

Guill announces the introduction of a new version of its popular 800 series, known as the 800 Series Hybrid. In some extrusion applications that utilize crossheads and inlines, layers of the exact same material are applied multiple times, using a single die. This method is used to reduce the propensity for errors caused by gels breaking through a thin wall, weld lines, inconsistent wall thickness, plus material and process variations. Additional errors include difficult-to-process materials and demanding applications where there is zero fault tolerance.

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KraussMaffei bundles all extrusion technologies under one roof

KraussMaffei Group has bundled its technological know-how and decades of experience in extrusion by merging its corporate extrusion operations at a single location. This strategic approach results in substantial product benefits for customers, valuable synergy effects for the company, and new opportunities and fields of research for the future. The highlight will be the world’s most modern extrusion research and development center currently built at the company’s new site in Laatzen on the outskirts of Hannover. The new plant is part of the largest investment program in KraussMaffei’s history. The relocation of the entire extrusion division is scheduled for the second half of 2022.

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Dimensional Change Resulting From Swell And Drawdown Of Extruded Polymers

Understanding and predicting how extruded profile dimensions change along an extrusion line contribute significantly to the design of shaping dies and the effectiveness of dimensional control. Upon exiting the extrusion die, the dimensions of nonsymmetric profiles change non-uniformly along the line due to swell and drawdown.

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Functionalization Of Hydrogenated Styrene Block Copolymers By Reactive Extrusion

Reactive extrusion is an attractive route for polymer processing to carry out various reactions, including polymerization, grafting, branching and functionalization. The extruder is like an ideal reactor for polymer chemical modification. Reactive extrusion is an economically attractive process, since the extrusion and processing are done in a single stage.

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