Photochemical Machining Process for Heatric Printed Circuit Heat Exchangers | Filtration Technology

Photochemical Machining to manufacture Heatric Printed Circuit Heat Exchangers Parker Heatric has a worldwide reputation for designing and manufacturing printed circuit heat exchangers or PCHEs. These are robust, corrosion-free, high-integrity plate-type heat exchanges mainly used in the oil and gas industries. A PCHE is manufactured from several corrosion resistant plates that are joined together using a diffusion bonded construction. Each individual corrosion-resistant plate is nominally a two-millimeter stainless sheet of steel into which fluid flow channels are chemically etched. These fluid flow channels are typically two-millimeter wide and one-millimeter deep semicircles. Sheet sizes can range from 600 by 900 millimeters to 600 by 1,500 millimeters. Batch sizes can range from one singular plate to an infinite number of identical plates. The fluid flow patterns are bespoke for each exchanger and designed to suit customer requirements. The process that turns a two-millimeter sheet of metal into a corrosion-resistant plate is called Photochemical Machining and is one of the key manufacturing technologies at Heatric. Photochemical Machining is a burr and stress-free manufacturing process. Unlike conventional metal removal processes such as milling or laser cutting, photochemical machining does not affect the original properties of the metal sheets. By inducing stresses or heat-affected zones, the photochemical machining process can be broken down into six steps: • Cleaning • Coating with Photo Resist Lamination • Exposing to Film Work • Developing • Etching • Photo Resist Removal Step 1. To begin, the raw two-millimeter metal sheets are thoroughly chemically cleaned to remove all contaminants and prepare the surface for lamination. Step 2. Once cleaned, the two-millimeter sheets are coated with a photo-sensitive polymer. During this lamination process, contact between the metal and the photoresist layer must be uninterrupted. So, an impeccably clean environment is essential. Step 3. The CAD-designed film work, or photo tool, which bears the design pattern to be edged, is then placed on top of the sheet and exposed to a burst of ultraviolet light under a vacuum. The ultraviolet light cross-links the areas of the pattern that are not shielded by the black portions of the photo tool. This cross-linking with the photoresist makes that are resistant to acid. Step 4. The sheet is then developed, and any unexposed photoresist is washed away, leaving bare metal for the acid to attack. Step 5. The metal sheet is then sprayed with ferric chloride. Ferric chloride (FECL3) is a fairly strong Lewis acid. This process dissolves the exposed areas of the metal, ultimately revealing the etch design. During this process, one to 1.4 millimeters of metal is etched away from the two-millimeter sheets. Double-sided etching would occur if filmwork were applied to both sides of the sheet. This can create holes through the sheet, which form ports when the sheets are bonded into a block. The design of the artwork controls the ridge width and depth of the etch channels. Step 6. The remaining photoresist is then stripped away to reveal the finished plate. The ferric chloride, now converted to ferris chloride, having changed state during the etching process, is then regenerated by adding chlorine gas. The Ferris chloride FECL2 is regenerated to ferric chloride, FECL3, and ready to be reused in the etching process. Each plate takes an hour to produce, and neither quality nor speed is affected by the complexity of the etched design. The finished plates will be rigorously quality checked and are then ready to form part of a PCHE core. Heatric photochemical machining plants near Birmingham, UK, is the largest etching plant in the world and etches three tons of metal each day, making it a world leader in photochemical machining. Learn more about Parker Heatric - https://www.parker.com/gb/en/division... Video Chapters 0:00 Intro 1:41 Photochemical Machining Process Description 1:53 Step 1 cleaning 2:03 Step 2 Photo Sensitive Polymer Coating 2:21 Step 3 Photo tool Exposure 2:46 Step 4 Metal Sheet is Developed 2:57 Acid wash and rinse 3:35 Photo resist removed and recycled #PrintedCircuitHeatExchanger #PCHE #PhotoChemicalMachining