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    Electroformed Nickel Screen Guide

    Ideal for Alkaline, Acidic, Neutral fluids and Solids filtration

    The greater quality Electroformed nickel is produced in the high precision with following attributes:

    1. Extremely tight tolerance
    2. Minimum surface tension
    3. Shape reliability and smooth aperture walls
    4. Outstanding edge acuity

    Our customers are successfully using nickel mesh screens for the demanding projects. It offers good ductility, corrosion resistance and heat and electric conductivities that lead to use of nickel mesh in the various applications. Our electroformed nickel screen is used in aerospace, mass spectrometry, sorting and separation. When you are looking for pure nickel mesh, we will assist you in manufacturing the best mesh for your project needs.

    Advanced applications of electroforming are extensive and nickel mesh is used in the vast range of diverse electroforming applications. It is because electrodeposited nickel is durable, hard and resistant to general corrosion, erosion and deformation. Its mechanical characteristics vary at the large limits by altering the plating conditions.

    Applications of electroformed nickel screen:

    1. Textile printing screens
    2. Parts for rocket thrust chambers, nozzles and motor cases
    3. Dies and molds for producing automobile arm rests and equipment panels
    4. Stampers for phonograph records
    5. Video discs and digital and audio compact discs
    6. Mesh products for creating porous battery electrodes
    7. Filters and razor screens
    8. Optical components
    9. Bellows, radar wave guides

    Electroforming Introduction

    Electroforming follows electroplating process for the production of components. The process includes the following steps:

    1. A mandrel is fabricated for electroplating
    2. Mandrel is kept in the suitable electroplating solution and metal is deposited on the mandrel through electrolysis
    3. After receiving the needed thickness of deposited metal, the mandrel covered by metal is eliminated from the solution
    4. The mandrel is separated from the electrodeposited metal

    Mandrels and materials

    Mandrels can be conductors or insulators of electricity which may be permanent, partially permanent or expendable. The conduction or insulation to current describes the procedures needed to prepare the mandrel for electroforming.

    Conductive mandrels are pure metals or alloys and made by common procedures and need application of a thin parting layer to offer separation of an electroform from the mandrel. Insulators are made conductive by spraying the surface with a thin metallic layer often silver. The thin layer of silver offers convenient separation of electroform from the mandrel.

    Permanent conductive mandrels

    Austenitic stainless steels, copper, brass, traditional steel, invar, kovar and pure nickel

    Expendable conductive mandrels

    Aluminum and its alloys and zinc based alloys

    Insulated mandrels

    Waxes, plastic materials, glass, wood and leather

    Electroforming Process

    The solutions used for Nickel electroplating are commonly used for electroforming such as concentrated nickel sulfamate with or without agents, called as watts. The benefit of using nickel sulfamate solutions is mild internal stress of deports and large accumulation rates particularly in the concentrated solution.

    Watts Solutions: The watts bath comprising of nickel sulfate, nickel chloride and boric acid, offers nickel accumulations that look like matte and have tension. The solution is economical and is widely used for conducting the electroforming process.

    Nickel sulfate is used as the major source of nickel ions in the Watts solution. The solution conductivity improves with nickel chloride and has a positive effect on the evenness of the metal distribution at cathode. Boric acid treats as buffer to monitor pH at the cathode-solution connection point. The wetting agents are significant for preventing the pitting corrosion due to air contact and hydrogen bubbles.

    With suitable care, the internal stress of the electroformed nickel can be limited through organic agents. The standard stress reducers are paratoulene, sulfonamide, meta-benzene disulfonate etc.

    Characteristics of Electroformed Nickel

    The mechanical characteristics of electroformed nickel are controlled by several factors such as pH, temperature and cathode current density. The solution elements, their concentration within the specific magnitudes and minor amount of metallic contaminants affect the mechanical characteristics of the electroformed mesh. The characteristics are interrelated and steps followed to improve the hardness of the electroformed product usually improve its strength and decrease ductility. The refined crystal structure is received by improving hardness and tensile strength and lowered ductility.

    The mechanical characteristics particularly the elongation% or ductility % are influenced by the thickness of electroformed mesh. An increase in ductility occurs with increase in mesh thickness up to 250 µm thereafter it becomes almost stable.

    The ultimate tensile strength changes with nickel thickness however it becomes constant for thickness above 250 µm. The strength of compressively compacted deposits is higher than tensively compacted deposits to almost equal values. High temperature annealing significantly decreases the tensile strength however the reduction is considerably more than in compressively compacted deposits. There is a significant difference observed in ductility with thickness as compare to that in ultimate tensile strength. Annealing at temperature 371oC improves the ductility of both kinds of accumulations however annealing at 760oC improves the ductility of the tensively stressed accumulations, but decreases the ductility of compressively stressed parts.

    Control on Electroforming

    A desired electroforming needs specific control of the purity of electrolyte and variables –pH, current density, temperature and agitation. It is equivalent to control of decorative nickel electroplating. The general problems occurred in electroforming include monitoring metal dispersion, internal stress, hardness and nodular production. Addition of elements may support in overcoming few of these complications but their contents should be strictly controlled.

    Metal dispersion

    The current distribution describes the variation in the accumulated metal thickness at the different locations. The current density and rate of accumulation of metal will be smaller in the recessed zones that on the zones that project from the surface which cause non-uniform metal accumulation in several cases. It can be controlled by decreasing the current density, increasing the separation space among anode and cathode, increasing pH, temperature and metal concentration of the bath.

    Internal Stress

    Internal stress control is imperative in the process of electroforming. It states the forces developed inside the electrodeposit is due to electro-crystallization and the codeposition of contaminants like hydrogen, sulfur and other agents. The forces may be of tensile or compressive type. Intense stress can result into damaging the electroform when it is removed from the mandrel, complications in removing the electroformed mesh from mandrel, early shedding or removal of electroform from mandrel and buckling and blistering of deposit that often is the sign of large compressive stress.

    Roughness

    A condition that causes roughness in decorative plating will cause more adverse effect on electroforming operation. Nuggets and trees will produce. These are the high current density regions and the larger the current they receive, quickly they develop and more they steal the surrounding areas of deposit. As a result, the filtration rates utilized in electroforming are very high in an effort to avoid roughness, the rates may magnitude to passing the complete solution through a filter one or more times per hour.

    Electroformed stampers for developing compact discs are created in clean rooms under specific cleanliness conditions. Anode particles may also develop irregularity and are controlled through anode bags and diaphragms, larger filtration rates and cathode agitation.

    After-Electroforming Procedures

    The procedures conducted after electroforming are machining, final finishing of electroform, removal of electroform from mandrel and backing the mesh.

    Uses of Electroformed mesh

    Electroformed nickel mesh products have extensive applications such as textile printings screens or rotary screens that are utilized to develop multi-color patterns on textiles, wallpaper and carpets. Many printing screens are seamless electroformed cylinders of nickel comprising mesh that has fine and precise holes. The designs are produced on the mesh screen through photoresist methods that close some openings whilst keep others free. The mesh is mounted on the rotary textile printing machines on color feed tubings that lie inside and are concentric with the larger mesh screens. Color is driven through the open mesh areas through magnetic roll kept against the screen. Every screen feeds single color, machines consist of around 12 different mesh screens to produce intricate and comprehensive designs.

    The advanced production includes continuous electroforming of porous materials for producing battery electrodes. It includes the accumulation of nickel onto a woven plastic fiber mesh that is produced by established plating on plastics, the mandrel is separated after plating by heating. However the details have not been stated, a porous mesh that can be impregnated with active nickel hydroxide is used in the production of nickel-cadmium batteries.

    The electroformed nickel mesh is also used as filters, sieves and electric razor screens.

    Electroformed Nickel Mesh Square Holes Specification

           Nominal Size Opening Size (W) Pitch (P) (ISO) Sheet Thickness
    principal sizes (opening) supplementary sizes Standard Size Tolerance Preferred Value Tolerance
    R40/3 series R20 series (±) Maximum Maximum Minimum
    500 mm 500 500 500 mm 6.5 18 620 710 530 50 mm
    500 mm 450 560 645 475 50 mm
    500 mm 425 425 mm 5.5 15 530 610 450 45 mm
    500 mm 400 490 555 425 45 mm
    355 mm 355 355 355 mm 4.6 13 450 510 380 30 mm
    355 mm 315 395 480 335 30 mm
    355 mm 300 300 mm 3.9 11 380 440 320 30 mm
    355 mm 280 355 420 300 30 mm
    250 mm 250 250 250 mm 3.3 9 320 385 270 30 mm
    250 mm 224 275 340 250 30 mm
    250 mm 212 212 2.8 8 270 320 240 25 mm
    250 mm 200 260 305 225 25 mm
    180 mm 180 180 180 mm 2.3 6 240 270 200 25 mm
    180 mm 160 210 255 180 20 to 25 mm
    180 mm 150 150 mm 2.0 5 200 230 170 20 to 25 mm
    180 mm 140 190 230 160 20 to 25 mm
    125 mm 125 125 125 mm 2.0 5 170 205 140 20 to 25 mm
    125 mm 112 155 205 135 15 to 25 mm
    125 mm 106 106 mm 2.0 5 150 205 130 15 to 25 mm
    125 mm 100 140 170 120 15 to 25 mm
    90 mm 90 90 90 mm 2.0 5 130 170 110 15 to 25 mm
    90 mm 80 115 170 100 15 to 25 mm
    90 mm 75 75 mm 2.0 5 110 140 95 12 to 25 mm
    90 mm 71 105 140 90 12 to 25 mm
    63 mm 63 63 63 mm 2.0 5 95 140 90 12 to 25 mm
    63 mm 56 90 140 75 12 to 25 mm
    63 mm 53 53 mm 2.0 5 85 100 70 12 to 25 mm
    63 mm 50 80 100 70 12 to 25 mm
    45 mm 45 45 45 mm 2.0 4 75 100 65 12 to 25 mm
    45 mm 40 70 90 60 12 to 25 mm
    45 mm 38 38 mm 2.0 4 65 85 55 12 to 25 mm
    45 mm 36 65 85 55 12 to 25 mm
    32 mm 32 mm 2.0 4 60 85 50 10 to 25 mm
    25 mm 25 mm 2.0 4 50 65 45 10 to 25 mm
    20 mm 20 mm 2.0 4 45 65 40 10 to 25 mm
    16 mm 16 mm 2.0 4 40 65 35 10 to 25 mm
    10 mm 10 2.0 4 30 50 25 10 to 25 mm
    5 mm 5 2.0 4 25 40 20 8 to 25 mm

     

    Relation between Mesh and Opening
    Mesh (LPI) Hole (square only) (μm) Open Area Void Fraction (approx. %) Mesh (LPI) Hole (square only) (μm) Open Area Void Fraction (%) Mesh (LPI) Hole (square only) (μm) Open Area Void Fraction (approx. %)
    1000 5 μm 3.9 % 200 63 μm 24.6 % 80 212 μm 44.6 %
    750 5 μm 2.2 % 200 65 μm 26.2 % 200 213 μm 45 %
    750 10 μm 8.7 % 200 75 μm 34.9 % 200 227 μm 51 %
    670 10 μm 7 % 200 85 μm 44.8 % 200 250 μm 62 %
    670 15 μm 15.6 % 150 85 μm 25.3 % 60 255 μm 36.3 %
    670 16 μm 17.8 % 150 90 μm 28.3 % 60 271 μm 41 %
    500 10 μm 3.9 % 150 97 μm 33 % 60 300 μm 50.3 %
    500 15 μm 8.7 % 150 106 μm 39 % 60 302 μm 51 %
    500 16 μm 9.9 % 150 125 μm 54.7 % 60 355 μm 70.4 %
    500 20 μm 15.5 % 125 107 μm 27.8 % 50 322 μm 40.2 %
    500 25 μm 24.2 % 125 125 μm 38 % 50 355 μm 48.8 %
    400 30 μm 22.3 % 125 150 μm 54.6 % 50 384 μm 57.1 %
    400 32 μm 25.4 % 120 116 μm 30 % 45 425 μm 56.8 %
    400 38 μm 35.8 % 120 125 μm 34.8 % 45 455 μm 65 %
    333 38 μm 24.8 % 120 127 μm 35.9 % 30 500 μm 34.8 %
    333 41 μm 28.9 % 110 139 μm 36 % 30 600 μm 50 %
    333 45 μm 34.8 % 110 150 μm 42 % 25 600 μm 35 %
    250 45 μm 19.6 % 110 151 μm 42.7 % 25 710 μm 48.8 %
    250 49 μm 23.2 % 100 165 μm 42.2 % 20 850 μm 44.8 %
    250 53 μm 27.2 % 100 180 μm 50 % 14.5 1000 μm 32.6 %
    250 57 μm 31.5 % 90 180 μm 40.7 %
    250 63 μm 38.4 % 90 181 μm 41.2 %
    250 65 μm 41 % 90 197 μm 48.8 %

    Meshes and openings are also available.

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