The present invention relates generally to methods and systems of removing a coating or masking layer or an aluminum oxide layer from an area of a part, for the purpose of being able to combine individually desirable material properties on the same part.
Aluminum is well established in many industries as a base metal with a wide range of favorable material properties: It is light-weight, readily available, can easily be recycled, and can be deformed into nearly any shape without great effort in tooling and machinery. Typical aluminum alloys used for these applications include the materials covered in industry standards designated in 1000, 3000, 5000 and 6000 series aluminum alloys of varying grades of tempering (base hardness), but other alloys could also be considered for the application of the proposed process. These materials are commonly used in manufacturing applications in the form of coils in varying widths and thicknesses, where the efficiencies of continuous processing are advantageous, or sheets of various shapes and sizes, where smaller production volume and simplicity of handling are preferred.
For esthetical and other reasons, aluminum can also be covered with a coating which can be colored in various ways. One commonly applied process is the practice of anodizing the raw aluminum, to create a thin layer of very small pores of Aluminum Oxide. These pores will readily absorb certain dyes to provide a full spectrum of colors, while, at the same time, forming a protective, wear-resistant surface due to the very high hardness of the Aluminum Oxide. Commercial anodizing processes are designated as Type II or III anodizing defined in industry and military standards like MIL-A-8625 or MIL-STD-171. In other applications, conventional coatings with paints, lacquers or other coatings with special formulations have also been applied to achieve sufficient levels of hardness, wear resistance and color.
There are certain applications, where the goal is to combine the wear-resistance and color-carrying properties of the coating layer, with the high degree of pliability of the base aluminum. The above mentioned layers of hard coatings tend to peel, chip or crack once exerted to certain high levels of strain induced stress.
For example, there have been attempts to change some of the parameters of the anodizing process to reduce the thickness of the anodizing layer and/or its hardness and increase the degree of deformability of the anodized aluminum, but it has been found that these variations can change the properties of the aluminum oxide layer only to a very small degree, which does not nearly reach the ratios of deformation of raw aluminum, which can easily exceed strains of 20% and more, while typical strain levels achievable with aluminum oxide without severe structural damage to the anodizing layer are limited to 1-2% or less. These desirable high degrees of strain of 20% or more are typically encountered in forming operations like the forming of small radii, effecting diameter increases or reductions and other deformations for purposes of aesthetic effects or increased structural strength, or dimensional or shape changes e.g. accomplished in operations like deep-drawing, in transfer presses or progressive die-sets, crimping or other manufacturing or assembly operations requiring large degrees of deformation.
Attempts have also been made to “mask” those areas of the aluminum material that are required to maintain their high level of deformability with certain compounds that prevent the formation of the oxide layer in the anodizing process. However, these compounds are difficult to apply, are difficult to remove after anodizing, and generally can interfere with the anodizing operation: In addition to the obvious surface and process contamination issues from the removed masking compounds, there are challenges in the cross-reaction of these masking compounds with the electrical and chemical parameters of the anodizing process.
In a first preferred embodiment, the present invention relates generally to a method of at least partially removing a coating or masking layer from an area of each of a plurality of parts, the method comprising the steps of:
In a second preferred embodiment, the present invention relates generally to a method of at least partially removing an aluminum oxide layer from an area of each of a plurality of anodized aluminum parts, the method comprising the steps of:
In a third preferred embodiment, the present invention relates generally to a method of at least partially removing a coating or masking layer from an area of a part, the method comprising the steps of:
In a fourth preferred embodiment, the present invention relates generally to a method of at least partially removing an aluminum oxide layer from an area of an anodized aluminum part, the method comprising the steps of:
The present invention also relates generally to systems for removing a coating or masking layer or an aluminum oxide layer from an area of a part.
In a first preferred embodiment, the present invention relates generally to a system for at least partially removing a coating or masking layer from an area of each of a plurality of parts, the system comprising:
In a second preferred embodiment, the present invention relates generally to a system for at least partially removing an aluminum oxide layer from an area of each of a plurality of anodized aluminum parts, the system comprising:
In a third embodiment, the present invention relates generally to a system for at least partially removing a coating or masking layer from an area of a part, the system comprising:
In a fourth embodiment, the present invention relates generally to a system for at least partially removing an aluminum oxide layer from an area of an anodized aluminum part, the system comprising:
In yet another preferred embodiment, the present invention relates to a method of at least partially removing at least one of a coating and a masking layer from an area of at least one part, the method comprising the steps of:
In still a further preferred embodiment, the present invention relates to a system for at least partially removing at least one of a coating and masking layer from an area of at least one part, the system comprising:
The novel features of believed characteristic of the invention are set forth in the claims. The invention itself, however, as well as other features and advantages thereof, will be best understood by reference to the descriptions which follow, read in conjunction with the accompanying drawings, wherein:
For a fuller understanding of the invention, reference is had to the following descriptions, taken in connection with the accompanying
It is a purpose of this disclosure to establish that a novel way to achieve the combination of the above described favorable material properties of aluminum and aluminum oxide on the same part is, to anodize the part in the conventional way, including the process steps of dyeing and sealing the aluminum oxide pores, and then partially or entirely removing the entire aluminum oxide layer in those areas where high degrees of deformation on the finished part are required. This is accomplished by combining technologies of first creating special layers with the desired properties on a suitable base material, and then partially removing these layers in those areas where these properties are undesired, to create parts that exhibit a combination of these individually desirable specific properties on the same part, to facilitate the use of these parts for their intended purposes.
One particularly favorable process to remove the aluminum oxide layer is by means of a laser device, for example used in engraving operations to apply graphics and patterns to suitable surfaces, including raw or anodized aluminum. These engraving lasers are commercially available, with modern controls that allow adjustments for the size and shape of the part, the size and depth of the area in which all or a portion (certain depth) of the aluminum oxide layer is to be removed, processing speeds, etc. Depending on the size, shape and location of the area of removal, a manipulation of the parts themselves, the laser beam, or a combination of both may have to be employed.
One particularly beneficial implementation of this process is achieved in so-called rack- or belt-anodizing, where the parts, typically small sizes and/or large quantities, are oriented and aligned on fixtures to maximize process efficiency and provide the proper electrical contact during anodizing. This process implementation is typically found in industries and applications like cosmetics, medical or pharmaceutical packaging, where large volumes, high quality standards and cost efficiencies are required. The required parts handling volume in these applications can reach several hundred million parts per year. Since the parts are already aligned in a defined orientation, it is advantageous to implement the process step of removing controlled areas of the aluminum oxide after the completion of the anodizing process. This can be accomplished by using the anodizing racks or belts directly, or by automatically transferring the parts from their attachments to the racks or belts into secondary fixtures while maintaining their orientation, for proper alignment in the removal process. In many cases, these parts are fairly thin, with thicknesses ranging from a few micrometers to one millimeter or more, which makes it desirable to minimize the need to handle the parts with the risk of damage to the shapes and surfaces.
The following is a list of required operational steps and parameters for one successful implementation of the above outlined process, incorporated within a combined Anodizing and Finishing Line, see
It will be obvious to those skilled in the art of metal finishing that the above exemplifies only one suitable range and set of parameters in a process with a wide range of interdependencies between the parts (size, shape, color, etc.; see table 1 below), the application requirements (size, shape, depth, etc. of the areas to be removed; see table 2 below) and the specifics of the selected removal system and the design of the automated handling system as outlined above, including their interface with the anodizing line and its own process parameters, as indicated before. It is therefore understood that other combinations of overall process parameters exist that lead to equally acceptable process results. It is understood that the matrices in the tables below are meant to indicate that any parameter in a row or column can be combined with any other parameter in another row or column of the same table.
It is furthermore understood, that the means to provide the required energy to remove the anodizing layer are not limited to employing the highly focused energy of laser systems, which generally have the advantage of being commercially available and very precise in the controls of their operating parameters. Alternatively suitable, with little concern for less quality in the result of the layer removal, are removal systems based on the mechanical energy of water-jets (with or without the addition of abrasive media) or abrasive blasting (e.g. employing silica sand or aluminum oxide as abrasive medium in a controlled stream of high-pressure air or other gases), provided the stability in part position and orientation can be maintained against the impact of the media, or the chemical energy of certain material removal processes, as long as the residue of the process can be adequately captured and disposed of.
It is also understood, that the above removal process is not limited to the removal of the hard aluminum oxide layer obtained after the anodizing process. The removal process can also be successfully employed to solve the above described challenge of removing a masking layer, which may have been introduced and applied onto the raw metal prior to the anodizing process, to protect certain areas from, being anodized in the first place. If the masking is detrimental to the final use of the parts and must be removed in a controlled manner, the above described methods can be applied to remove such a layer of masking material in very much the same fashion as described above to remove the anodizing layer in those exact same areas.
Naturally, the above described processes can be equally successful when implemented at smaller scales of volume and productivity, e.g. at a lab level down to processing only a single part, or volumes of only a few hundred or thousand parts per run cycle, if the cost of the implementation can be justified.
It is equally implied that the removal of layers of insufficient ductility is not limited to layers of aluminum oxide created in an anodizing process. Other layers of coatings, like paints, lacquers and specially formulated coatings based on various chemical substrates and compounds can equally be removed taking advantage of the benefits of the above described processes, provided the process and operational parameters are adequately adjusted to match the properties of such materials. One example of such applications include pre-lacquered or pre-anodized sheet or coil materials, with anodized layers on one or both sides, to achieve a match in the desired color for the application. Another example is the anodizing in a bulk process, where parts of sufficient stiffness to withstand the mechanical stresses encountered in bulk applications are anodized in large batches, with a trade-off in color consistency and anodizing quality. Finally, the above described processes can be applied on parts of any shape or size, small or large, thin walls or thicker parts made from bar stock. Castings or otherwise machined parts, in quantities down to single prototypes, can be successfully processed, where localized, defined areas of an applied coating need to be removed, for purposes of improved ductility or other reasons.
It is also contemplated that the removal processes and systems described herein can be used for removing coating or masking layers and/or oxide layers from other materials, including for example, various metal alloys, including aluminum alloys, steel, including stainless steel, brass, and other similar materials.
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/US2011/041352 | 6/22/2011 | WO | 00 | 12/21/2012 |
Number | Date | Country | |
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61357762 | Jun 2010 | US |