Description:TITLE
APPARATUS AND METHOD FOR PROTECTIVE MASKING JIG AND CONTROLLED ELECTROLESS NICKEL PLATING OF ALUMINIUM CYLINDER INTERIORS
FIELD OF INVENTION
[0001] The present invention relates to the field of selective plating and surface protection of metallic components. Specifically, it pertains to an apparatus and method for masking aluminium cylinders during electroless nickel plating, allowing controlled deposition of the plating material on the inner diameter while preventing exposure of the outer surfaces to plating chemicals. This invention is particularly useful in applications where aluminium cylinder components require wear-resistant coatings on specific internal surfaces while preserving the integrity of external cast and machined areas.

BACKGROUND
[0002] In various industrial applications, aluminium cylinders are used in environments requiring high wear resistance and durability, such as in automotive, aerospace, and mechanical systems. Electroless nickel plating is commonly employed to coat the internal surfaces of these cylinders, providing a hard, wear-resistant layer that enhances performance and longevity. However, applying this plating selectively to the inner diameter while protecting the outer surfaces from exposure is challenging.
[0003] Traditional masking techniques, such as applying peelable lacquers or masking tapes, are time-consuming and often fail to achieve effective protection for complex geometries, including cylinders with fins or intricate cast surfaces. Chemical seepage during plating can result in unintended coating, staining, or corrosion of non-targeted surfaces, compromising the component’s quality and requiring additional finishing steps.
[0004] To address these issues, there is a need for a reliable and reusable masking solution that enables precise plating of the cylinder's inner diameter while providing leakproof protection to the outer surfaces. Such a solution would streamline the plating process, improve quality, and reduce production costs. This invention proposes a novel jig and method for effectively masking aluminium cylinders, enabling controlled electroless nickel plating on designated internal surfaces only.

SUMMARY
[0005] The present invention provides an apparatus and method for selectively plating the inner diameter of aluminium cylinders using electroless nickel while effectively masking and protecting the outer surfaces from chemical exposure. The invention includes a specially designed, reusable jig with a box-type structure comprising a steel-reinforced frame surrounded by a molded silicon rubber lining that forms a leakproof seal. This jig securely encloses the cylinder, exposing only the inner diameter to the plating chemicals and safeguarding the external cast and machined surfaces from seepage and staining.
[0006] According to a preferred embodiment, the method involves placing the aluminium cylinder within the jig, sealing it with a top-closing lid, and immersing it into the plating bath. The jig's leakproof design ensures that the plating solution only contacts the inner bore, allowing for precise plating while preserving the quality of the exterior surfaces. The jig is reusable and can be re-molded to maintain its leakproof properties over time, offering a cost-effective, durable solution for selective plating applications.
[0007] Additionally, this invention streamlines the plating process, reduces the need for secondary finishing of unintended areas, and ensures high-quality, selective nickel plating of aluminium cylinders, making it ideal for use in industries requiring durable, wear-resistant coatings on internal surfaces.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] To further clarify the advantages and features of the present disclosure, a more particular description of the disclosure will be rendered by reference to specific embodiments thereof, which are illustrated in the appended drawings. It is appreciated that these drawings depict only typical embodiments of the disclosure and are therefore not to be considered limiting of its scope. The disclosure will be described and explained in additional specificity and detail in the accompanying drawings.
[0009] The subject matter that is regarded as the invention is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other aspects, features, and advantages of the invention are apparent from the following detailed description taken in conjunction with the accompanying drawings.
[0010] These drawings collectively demonstrate the configuration and functionality of the jig and method for selective plating, emphasizing the design features that ensure leakproof protection of non-targeted surfaces during the electroless nickel plating process.
[0011] FIG. 1 illustrates an aluminium cylinder requiring electroless nickel plating exclusively on the inner diameter, with the outer surfaces, including cast and machined areas, needing protection from chemical exposure during the plating process.
[0012] FIG. 2 shows a cross-sectional view of the leakproof jig, highlighting its steel-reinforced silicon rubber construction.
[0013] FIG. 3 illustrates an expanded view of the steel structure used within the jig to ensure mechanical strength and precision alignment.
[0014] FIG.4 illustrates the method flowchart, outlining the step-by-step process electroless nickel plating solely on the inner bore or diameter protecting the outer surfaces, including cast and machined areas from any chemical exposure, seepage, and stain marks.

DETAILED DESCRIPTION
[0015] For the purpose of promoting an understanding of the principles of the invention, reference will now be made to the embodiment illustrated in the drawings, and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended. Such alterations and further modifications in the illustrated system and such further applications of the principles of the invention as illustrated therein would be contemplated as would usually occur to one skilled in the art to which the invention relates. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. The system, methods, and examples provided herein are illustrative only and are not intended to be limiting.
[0016] FIG. 1 depicts an aluminium cylinder that requires electroless nickel plating (Ni-P-SiC) solely on the inner bore or diameter. The targeted inner diameter 102 is clearly indicated as the only area requiring plating. The outer surfaces 104, including both cast and machined areas of the cylinder, are designated to remain unplated and need protection against any chemical exposure, seepage, and stain marks. The drawing illustrates the complexity of the cylinder’s outer geometry, demonstrating why traditional masking techniques, such as peelable lacquers or tapes, are unsuitable for this application.
[0017] FIG. 2 presents a cross-sectional view of the protective jig developed to mask the aluminium cylinder during the plating process. The jig consists of a robust steel frame that provides structural stability and dimensional accuracy, over-molded with silicon rubber to create a leakproof seal.
[0018] According to an embodiment, 202 illustrates the Top Closing Lid; the top lid seals the jig, enclosing the aluminium cylinder securely and exposing only the inner diameter for plating. Silicon rubber 204 is molded around the steel frame and provides leakproof sealing around the cylinder’s complex outer geometry, protecting the non-targeted surfaces from chemical exposure during plating. Cylinder 206 is placed inside the jig, protecting the outer surface while the interior is plated with electroless nickel. Box-Type Structure 208 accommodates the cylinder. It ensures precise alignment, sealing all outer surfaces, including complex shapes such as fins and machined areas, while leaving the inner diameter exposed.
[0019] The illustrated figure emphasizes the jig’s unique construction, which includes a flexible but durable rubber lining over a steel framework to handle repeated plating cycles.
[0020] FIG. 3 illustrates an expanded view of the internal steel frame within the jig, showing how it is molded with silicon rubber to create a leakproof, reusable enclosure. This frame provides the necessary strength and dimensional stability to ensure proper alignment of the aluminium cylinder within the jig. The steel structure allows for consistent positioning of the cylinder and ensures that the silicon rubber forms a reliable seal around the outer surfaces, eliminating chemical seepage during immersion in the plating bath. This figure also illustrates how the jig can be re-molded to maintain the sealing integrity over time, extending its lifespan and reducing operational costs.
[0021] According to the embodiment illustrated in FIG. 3, the bottom steel body 302 is the skeleton of the steel-reinforced frame, which forms the core structure of the apparatus. Further, the cross-sectional view of the steel-reinforced frame 304 is constructed using robust steel to maintain its shape and withstand the stresses of repeated chemical immersions and high temperatures during the plating process. It is geometrically precise to ensure proper alignment of the aluminium cylinder within the jig. This steel frame provides the strength, stability, and dimensional accuracy required to ensure that the aluminium cylinder is securely held in place during the electroless nickel plating process.
[0022] Additionally, FIG. 3 further comprises a top lid steel body 306 and the cross-sectional view of a rubber moulded top lid 308 wherein the steel frame is over-molded with silicon rubber, which forms a flexible and leakproof seal around the cylinder. The rubber conforms to the outer geometry of the aluminium cylinder, including any fins or irregular surfaces, ensuring complete protection of non-plated areas. The moulding process provides a seamless integration of the rubber and steel, enhancing the durability and functionality of the jig.
[0023] FIG. 4 illustrates via a flowchart, the individual steps involved in the process of electroless nickel plating solely on the inner bore or diameter, protecting the outer surfaces, including cast and machined areas, from any chemical exposure, seepage, and stain marks.
[0024] Step 402 includes placing the aluminium cylinder within a jig having a box-type structure with a steel-reinforced, leak-proof silicon rubber lining.
[0025] Step 404 comprises sealing the jig with a top closing lid to secure the aluminium cylinder and form a protective enclosure around the non-plating surfaces. Proper sealing guarantees the selective plating of the inner diameter, preventing defects and ensuring the quality of the final product.
[0026] Step 406 comprises immersing the jigged cylinder into a chemical plating bath, whereby only the inner diameter of the cylinder is exposed to the plating chemicals, while the outer cast and machined surfaces remain protected. This ensures that the electroless nickel coating is deposited uniformly on the inner diameter of the cylinder while the jig’s leakproof design protects the outer surfaces from exposure to the plating chemicals.
[0027] Finally, step 408 comprises removing the jigged cylinder from the bath after plating. The post-plating removal step involves extracting the plated aluminium cylinder from the jig after the plating process is complete.
[0028] The illustrated figures collectively illustrate the construction, functionality, and effectiveness of the leakproof jig in selectively exposing only the cylinder’s inner diameter to plating chemicals. These diagrams underscore the jig’s innovative design, which simplifies the plating process while preserving the quality of non-plated surfaces on aluminium cylinders.
[0029] The present invention provides a novel apparatus and method for selectively plating the inner diameter of aluminium cylinders while protecting the outer surfaces from exposure to plating chemicals. The invention solves challenges associated with conventional masking techniques by introducing a reusable, leakproof jig that ensures precise plating control and robust protection of non-targeted areas.
[0030] Embodiments disclosed include a method for controlled electroless nickel plating of aluminium cylinder interiors comprising selectively plating the inner diameter of an aluminium cylinder. A preferred embodiment includes precise cylinder placement in a jig, and exposing only the inner diameter of the cylinder to plating chemicals. Further, the method comprises masking the outer surfaces and subsequently positioning the cylinder into an internal cavity comprised in the jig and aligning the cylinder such that its inner bore, i.e. the surface to be plated, faces the opening designed for exposure. Additionally, the jig further comprises a silicon rubber lining, preferably contoured to conform to the outer geometry of the cylinder, including fins, cast surfaces, and machined areas. As the cylinder is positioned, the rubber forms a snug seal around all non-targeted surfaces. Preferably, the jig further comprises a single or plurality of additional clamps or fixtures configured to secure the cylinder firmly in place and to prevent movement during immersion in the plating bath. According to an embodiment the jig includes a top closing lid comprising a gasket or other sealing mechanism that ensures a tight and leakproof closure. The lid is secured using locking mechanisms, such as clamps or screws, to maintain the seal and prevent any displacement of the cylinder during the plating process. This enables precise and selective electroless nickel plating of the inner diameter while protecting all non-targeted areas.
[0031] Embodiments of the disclosed method further include immersion of the jigged aluminium cylinder into the plating bath ensuring that the electroless nickel coating is deposited uniformly on the inner diameter of the cylinder even while the jig’s leakproof design protects the outer surfaces from exposure to the plating chemicals. The plating bath is prepared according to the required specifications for electroless nickel plating, including the concentration of nickel and any additives such as silicon carbide particles for enhanced wear resistance, as would be apparent to a person having ordinary skill in the art. Additionally, the bath temperature and pH are adjusted to the optimal levels recommended for the plating process. The jigged cylinder is submerged into the plating bath using a hoist, crane, or manual placement system, depending on the size and weight of the jig ensuring that the jig is fully immersed so the exposed inner bore of the cylinder is entirely covered by the plating solution. The jigged cylinder is allowed to remain in the plating bath for the required time (what is the required time?) based on the desired thickness of the nickel coating on the inner diameter. According to an embodiment, the bath is agitated gently if necessary to ensure uniform distribution of plating chemicals across the exposed surface. The temperature, pH, and chemical composition of the plating bath are preferably maintained throughout the immersion process to ensure consistent plating quality. After the plating is complete, the jigged cylinder is lifted out of the bath, and any excess plating solution is drained back into the bath before proceeding to the next step.
[0032] According to an embodiment, the next step, i.e., post-plating removal, comprises extracting the plated aluminium cylinder from the jig after the plating process is complete. The post-plating removal process is vital for maintaining the quality of selectively plated aluminium cylinders and preserving the jig for future use. It ensures the plated inner diameter remains defect-free while protecting the outer surfaces from chemical contamination or damage. According to an embodiment, the process starts with rinsing the jigged cylinder to remove residual chemicals, preventing exterior contamination during removal. The jig’s locking mechanism, such as clamps or latches, is released, and the lid is lifted without stressing the cylinder or the jig’s sealing components. The plated cylinder is then extracted, avoiding scratching or damaging the fresh nickel coating, especially if the plating is still curing or requires further processing.
[0033] According to an embodiment, once removed, the cylinder undergoes inspection to confirm the nickel coating is uniform and adherent, while the outer surfaces are checked for stains or chemical seepage. Any defects are addressed immediately by identifying the root cause and adjusting the process. The jig is thoroughly cleaned with water, and a mild solution to remove residual chemicals, and the silicon rubber lining is inspected for wear or damage. If required, it is re-moulded or replaced to maintain leakproof integrity. The jig is then reassembled and stored in a clean, dry environment, ensuring it is ready for the next cycle. This process ensures precision, efficiency, and reliability in selective plating operations.
[0034] The invention comprises a jig designed to securely hold an aluminium cylinder during the electroless nickel plating process, exposing only the inner diameter while safeguarding the outer surfaces. The key components of the jig are as follows:
[0035] Steel Frame: The core of the jig is a rigid steel structure that provides mechanical strength and ensures dimensional accuracy during the plating process. The steel frame serves as the foundation for the other components, maintaining the structural integrity of the jig even during repeated cycles of chemical immersion and high-temperature exposure.
[0036] Silicon Rubber Lining: The steel frame is over-molded with a silicon rubber lining to create a leakproof enclosure. The rubber conforms to the complex geometry of the aluminium cylinder, including fins, cast surfaces, and machined areas, forming a tight seal that prevents chemical seepage. This lining is durable, resistant to chemical degradation, and can be re-molded to extend the life of the jig.
[0037] Top Closing Lid: The jig includes a detachable top lid that securely seals the cylinder within the jig, exposing only the inner diameter for plating. The lid features a gasket or similar sealing mechanism to enhance its leakproof properties and ensure consistent protection during the plating process.
[0038] Box-Type Structure: The jig is designed in a box-type configuration to fully enclose the cylinder, leaving only the inner bore exposed. This design ensures complete protection of all non-plated areas, even in cylinders with complex outer geometries.
Embodiments disclosed enable selective plating; i.e., the jig ensures that only the inner diameter of the cylinder is plated, protecting the outer cast and machined surfaces from unintended chemical exposure and staining. Embodiments disclosed enable leakproof design wherein the silicon rubber lining and steel frame creates a robust and durable seal that prevents chemical seepage, even during prolonged immersion. Embodiments disclosed enable reusability wherein the jig is designed for repeated use, with a replaceable or re-mouldable silicon rubber lining, reducing waste and operational costs. Embodiments disclosed minimize the need for secondary finishing processes to remove unwanted plating from non-targeted areas, saving time and reducing costs. Embodiments disclosed are highly adaptable and reconfigurable wherein the jig can accommodate varying sizes and shapes of cylinders through adjustable sealing components and customizable rubber linings. Embodiments disclosed are highly durable; the steel-reinforced design ensures that the jig can withstand repeated cycles of chemical exposure and mechanical handling without losing performance.
[0039] The disclosed embodiment is particularly valuable in industries requiring selective plating of aluminium cylinders, offering specialized solutions for a range of applications. In the automotive sector, it is used to plate the internal surfaces of engine cylinders or hydraulic components, significantly enhancing wear resistance and improving durability. Similarly, in the aerospace industry, it provides protective coatings for critical components that operate under high stress, ensuring reliability and longevity. For mechanical systems, the invention is instrumental in protecting cylinders used in pumps, compressors, and other machinery, safeguarding against wear and corrosion.
[0040] Embodiments disclosed represent a major advancement in selective plating technology. Incorporating a robust steel-reinforced jig with a leakproof silicon rubber lining simplifies the plating process, ensures high-quality results, and reduces operational costs. The method precisely applies nickel coatings to the inner diameter of aluminium cylinders while effectively shielding the outer surfaces from chemical exposure. Reliable, efficient, and adaptable, this invention is a versatile solution for various industrial applications that demand high-performance coatings.
[0041] Since various possible embodiments might be made of the above invention, and since various changes might be made in the embodiments above set forth, it is to be understood that all matter herein described or shown in the accompanying drawings is to be interpreted as illustrative and not to be considered in a limiting sense. Thus, it will be understood by those skilled in the art of metallurgy and materials science, selective plating and surface protection of metallic components, and more particularly, for apparatus and method for masking cylinders during electroless nickel plating, allowing controlled deposition of the plating material on the inner diameter while preventing exposure of the outer surfaces that although the preferred and alternate embodiments have been shown and described in accordance with the Patent Statutes, the invention is not limited thereto or thereby.
[0042] The figures illustrate the architecture, functionality, and operation of possible implementations of systems according to various embodiments of the present invention. It should also be noted that, in some alternative implementations, the functions noted/illustrated may occur out of the order noted in the figures.
[0043] The terminology used herein is for the purpose of describing embodiments only and is not intended to be limiting to the invention. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.
[0044] The present invention and some of its advantages have been described in detail for some embodiments. It should be understood that although the system and process are described with reference to apparatus and method for protective masking jig and controlled electroless nickel plating of aluminium cylinder interiors, they are highly reconfigurable and may be used in other systems as well. It should also be understood that various changes, substitutions, and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims. An embodiment of the invention may achieve multiple objectives, but not every embodiment falling within the scope of the attached claims will achieve every objective. Moreover, the scope of the present application is not intended to be limited to the embodiments of the process, machine, manufacture, and composition of matter, means, methods, and steps described in the specification. A person having ordinary skill in the art will readily appreciate from the disclosure of the present invention that processes, machines, manufacture, compositions of matter, means, methods, or steps presently existing or later to be developed are equivalent to and fall within the scope of, what is claimed. Accordingly, the appended claims are intended to include processes, machines, manufacture, and compositions of matter, means, methods, or steps within their scope.
, Claims:CLAIMS
1. A method of masking an aluminium cylinder having fins to expose only the inner diameter of the cylinder for electroless nickel plating while protecting outer surfaces from chemical exposure, the method comprising:
placing the aluminium cylinder within a jig having a box-type structure with a steel-reinforced, leak-proof silicon rubber lining;
sealing the jig with a top closing lid to secure the aluminium cylinder and form a protective enclosure around the non-plating surfaces;
immersing the jigged cylinder into a chemical plating bath, whereby only the inner diameter of the cylinder is exposed to the plating chemicals, while the outer cast and machined surfaces remain protected;
removing the jigged cylinder from the bath after plating ensuring that only the inner diameter of the cylinder is coated with electroless nickel while the outer surfaces remain free from chemical seepage and stain marks.
2. The method of claim 1, wherein the jig further comprises a detachable lid that provides a secure and airtight seal to prevent any chemical leakage onto the non-plated surfaces of the cylinder.
3. The method of claim 1 further comprises the step of re-molding the silicon rubber lining of the jig after repeated uses to maintain the leak-proof integrity of the jig.
4. The method of claim 1, wherein the plating bath includes electroless nickel with embedded silicon carbide particles for enhanced plated inner diameter wear resistance.
5. The method of claim 1, wherein the jig is designed to accommodate cylinders of varying sizes through adjustable sealing components to ensure compatibility across different cylinder dimensions.
6. The method of claim 1, wherein the outer surface of the aluminium cylinder comprises both cast and machined sections, each protected by the leak-proof jig to prevent any chemical seepage.
7. An apparatus for masking an aluminium cylinder during electroless nickel plating, comprising:
a jig with a box-type structure adapted to house an aluminium cylinder, the jig comprising a steel frame for structural integrity;
a silicon rubber lining molded around the steel frame to provide a leak-proof seal for chemical immersion processes;
a top closing lid configured to seal the jig, such that only the inner diameter of the aluminium cylinder is exposed, while outer surfaces are shielded from plating chemicals;
wherein the jig is reusable and configured to protect the non-plated surfaces of the cylinder from chemical seepage and stains during plating, allowing selective plating of only the inner diameter.
8. The apparatus of claim 7, wherein the silicon rubber lining is reinforced with a steel frame to enhance structural integrity and ensure consistent alignment of the aluminium cylinder within the jig.
9. The apparatus of claim 7, wherein the top closing lid includes a gasket to enhance the sealing effect and prevent chemical seepage into the protected areas of the cylinder.
10. The apparatus of claim 7, wherein the jig further comprises adjustable clamps or fixtures to securely hold aluminium cylinders of various sizes and shapes during the plating process.
11. The apparatus of claim 7, wherein the silicon rubber lining is molded to match the contour of the cylinder fins precisely, ensuring complete sealing of all exposed areas except the inner diameter.
12. The apparatus of claim 7, wherein the jig is designed to withstand multiple cycles of chemical exposure and rinse processes without degradation, extending the jig’s operational life.
13. The apparatus of claim 7 further comprises a re-moldable silicon rubber material that allows the jig to be reconditioned periodically to maintain its leak-proof properties.