EDI Press Release

SIMULATION TECHNOLOGY PINPOINTS BEST SLOT DIE COATING SETUP FOR ANY PRODUCT, ENHANCING QUALITY AND INCREASING PRODUCTIVITY

Using the New Software to Determine the Ideal Die-Lip / Substrate Geometry for a Specific Application, EDI Can Help Converters to Shorten or Eliminate Costly Trial Runs

CHICAGO, October 29, 2006 - New coating simulation software developed with input from Extrusion Dies Industries, LLC (EDI) makes it easier for converters to exploit the advantages of slot die (proximity) coating over conventional roll coating, it was announced by EDI at CPP Expo 2006 (Booth 9520).
EDI is the only flat die manufacturer to employ the software, tradenamed TopCoat by developer RheoLogic Ltd., Leeds, UK. In a paper titled Using Simulations to Predict Coating Characteristics of a Slot Die System, EDI product manager Sam G. Iuliano notes that “in order to produce defect-free coatings, slot dies must be positioned so that an ideal geometry is formed between the die lips and the substrate.” Key variables in this geometry are the radius of the backing roll, the contour of the lip face, the die angle, the distance between die and the substrate, and the lip-face offset. The software determines the ideal geometry using rheological and surface-tension data for the coating material involved in a specific application. (The text and photos of Iuliano’s paper are on the CD accompanying this news release.)
“After years of working with RheoLogic, EDI now employs their software to improve die designs, speed troubleshooting, and help customers achieve greater quality assurance, reduce scrap, and economize on raw materials,” said Iuliano. “At the same time, by optimizing the configuration of a customer’s coating system, we can help that company reduce or even eliminate the cost and time of trial runs.”
The advent of this capability to simulate the proximity coating process will hasten converters’ shift from conventional roll coating to slot die coating, according to Iuliano. “While the advantages of slot die coating have never been in question, the process has involved a degree of trial and error in optimizing production,” he noted. “By replacing this guesswork with accurate modeling of the process, we have made slot die coating accessible to a wider range of converters.”
The key advantages of proximity coating over roll coating cited by Iuliano are:
• Control over material application. A slot die coating head is a “pre-metered” system that applies a coating fluid to the web at a constant rate and permits precise control over coat weight and cross-web distribution; this reduces waste, allows higher line speeds, and increases product quality and uniformity. By contrast, the amount of fluid applied in roll coating varies with factors such as viscosity and roll speed.
• Elimination of volatile organic compound emissions. While a slot die coating head is an enclosed system and applies to the substrate all of material fed into the die, a roll coater exposes the environment to emissions from excess coating fluid.
• Higher line speeds. Slot die application is less susceptible to “film-splitting” and “ribbing” defects that can develop at high throughputs. A sharp final edge on the wiping lip provides a clean break-away point for the coating fluid, so none remains on the applicator.

Customers Have Already Benefited from EDI’s Simulation Capability
Iuliano provided these examples of how EDI has used the coating simulation software to help customers:
1. For a producer of hot melt pressure-sensitive adhesives, coating simulation saved on investment cost by determining an optimum lip design that would make it unnecessary to employ a vacuum box.
2. Data generated by the simulation software enabled a manufacturer of aseptic packaging to solve problems with a new coating system during a single trial run at EDI’s headquarters facility in Wisconsin; the die was shipped overseas in ready-to-run condition.
3. In making his initial presentation to a customer, an EDI sales engineer drew on simulation data to determine whether the customer’s existing tooling—in this case a backing roll—was appropriate for the application.
4. In troubleshooting of a customer’s coating system, EDI quickly solved the problem once simulation technology pinpointed an awkward positioning of the die as the cause.
5. By incorporating calculations of rubber deformation in its prediction of coating characteristics, the simulation software has enabled customers to employ silicone rubber-surfaced backing rolls in applying hot melts.
Information on RheoLogic Ltd. and TopCoat™ software is available at www.rheologic.co.uk.