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Precision coating: thin and accurate R

oll-to-roll slot die coating has become the industry standard for extremely thin and

extremely accurate coating, according to Scott Zwierlein of Frontier. Just how thin can slot die go? With a

slot die, Zwierlein explains you can achieve an attainable wet coating thickness of <2 micron, but only slot die can achieve this level. Why? It is the nature of the equipment design. Other methods will flood a large amount of coating, and then wipe it away. Slot die does the opposite. It applies the exact amount to the substrate. Everything the pump delivers is applied to the substrate – there is no waste. Other methods, such as reverse roll, knife

over roll, and comma coating, use a device to wipe away excess coating leaving just the thickness desired. In this scenario you are requiring a blade or bar to be positioned 2 microns away from a substrate. According to Zwierlein that is almost impossible.

EXTREMELY ACCURATE Accuracy is based on the amount of material you want to put down, how close you are, and how uniform you want it to be. Zwierlein explains that you might be able to achieve 2 microns with other methods, but you cannot match the accuracy of slot die. With other coating methods the gap set for the blade, or the bar is fixed and the substrate and coating fluid pass through it. If the substrate thickness varies, the thickness will vary. “The substrate you coat on is never that flat,” he says.

4. Accurate and precise positioning of die to the substrate 5. Precision Die Vacuum System for coating bead stabilisation 6. Contamination free environment

STRIPE COATING In battery and capacitor applications, for example, stripe coating is the preferred method when you are producing a narrow strip with exposed foil along one or both edges. One requirement for good stripe coating is uniform coating thickness - proper cavity design is essential. You need proper die shim thickness for optimised die

pressure; that produces the right uniformity for cross web production. It is also essential to have accurate width control and good edge quality - accurate shim design and fabrication is important to maintain the proper alignment. A die vacuum is used to fine-tune the width and to ensure there is no saw tooth or waviness.


Slot die is becoming increasingly necessary in a number of industries. Here are just a few applications: Micro-electronics (flat panel displays, thin circuits), batteries

and capacitors (lithium-ion battery electrodes, multilayer ceramic capacitors), barrier films (food and medical packages), solar photovoltaic (solar cells require thin coatings), and medical diagnostics. Variations in thickness can lead to differing

results. The more accurate you coat the transdermal, the more accurate the dosage.

PROVE > DESIGN > BUILD Frontier is committed to helping you streamline the process of determining the right coating application for your company and your product. Contact Frontier today to learn how to improve your coating quality and production. Visit Frontier at the Battery Show Europe

Visit Frontier at The Battery Show Europe in Stuttgart, Germany, on May 7-9, 2019. Frontier will feature their DynaCoat in booth 1056. This completely self-contained coating and drying system sets the industry standard for coating process optimisation. The planned demonstration will feature slot die stripe coating to precise thicknesses, the material will be dried and wound with servomotor control. From lab scale to full production, Frontier can help you

THE IMPORTANT ATTRIBUTES OF SLOT DIE COATING A number of attributes need to be present

to help slot die deliver on its promise. These attributes result in significant benefits over traditional methods in terms of functionality and cost savings. 1. Precision pre-metered fluid delivery 2. Extremely flat and straight die surfaces 3. High-precision backing roll

8 April 2019

develop the best coating and drying equipment for your application. Coating technologies include slot die, patch and pattern coating, gravure, direct/offset coating, mayer rod, knife-over-roll, comma coating, screen printing and extrusion. Our drying ovens are engineered for the drying and curing of VOC solvent, aqueous, and thermally cured solvent-less coatings. We provide both air impingement flotation dryers and roll support dryers with various curing options including Infrared (IR), Ultra-violet (UV) and Electronic beam (Ebeam). Frontier representatives will be available to discuss your

product requirements and the capabilities of our equipment offerings. Delta ModTech and Frontier offer innovative solutions for manufacturing a variety of complex battery, electronic, medical/pharma, automotive, label, security, RFID, packaging and cosmetic products.

Slot die coating is the perfect solution for products that rely on precision

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