Precision Multilayer Coating and Manufacturing Partnerships

The research objective of this article is to demonstrate the key fields to successfully implement industrial-scale, computational fluid dynamics (CFD) and identify the mathematics that are the foundation of each of these three fields. CFD is a field where numerical methods, based on Finite Methods (FM), are applied to a discretization domain and a discretized form of the governing equations applicable for the fluid flow being modeled. The field of CFD is vast, including everything from fluid-solid interaction for micro-scale geometries to modeling the flow of gases in the atmosphere for climate modeling.

The article details the application of Computational Fluid Dynamics (CFD) to predict and optimize coating flow. The research offers an overview of different meshing techniques and advises on the use of mesh design and optimization to deliver solutions that are less taxing on the computer and more accurate for the process/product development engineer. The article also provides guidance on using simulation technologies such as CFD and other advanced numerical techniques to significantly reduce cost and shorten cycle times for the scale-up of new products.

Carestream R&D Manufacturing Technology Engineer Lee Runyon received an honorable mention in the AIMCAL John Matteucci Award for TechnicalExcellence in Web Coating for his technical paper entitled, “CFD Modeling: Key Fields and Numerical Methods to Understand Before Starting Hopper Modeling.”

This article details key mixing considerations for scaling up a coated product from small-scale laboratory to production.The mixing time is the minimum time required to obtain a desired level of homogeneity in the tank. It can be estimated for the most common mixing systems via empirical correlations. Assuming a desired homogeneity of 90%, as an example, at any time t greater than the mixing time, the difference between the concentration of the addition in any point of the tank and its final concentration will not be larger than 10%.

Carestream’s precision, multi-layer solution coating processes are ideally suited for the casting of a variety of polymers to create stand alone films such as polycarbonate, polyurethane and polyvinyl alcohol. Our latest casting advancements include the development of a new Carestream cast polycarbonate film, available in thicknesses from 6 to 40 micron. In addition to being well suited for medical and optical applications, the new cast polycarbonate film is an ideal replacement for films made by LOFO, which ceased production last year.

Accurate solution preparation and mixing processes are mandatory in high-precision, roll-to-roll coating operations. To ensure success, the liquid fed to an applicator must be homogeneous in composition, properties and temperature. Controlling these parameters batch to batch is also very important. Thus having a firm understanding of fluid dynamics and mixing parameters is critical to delivering a uniformly coated product with the expected performance characteristics.