An abrasive article for precision grinding, a method of manufacturing the same and a method of precision grinding. There is a need for economic media because commercial media cost is too high (Rs2.5 lakhs/kg), available only in three standard forms and supplied by only one company (Extrude Hone Corporation). For this reason, amounts for inclusion of thermoplastic polymers or particulates or silicone rubber particulates are not specified herein, because the desired characteristics are easily determined and implemented: the invention inheres in knowing to combine the stated constituents in the first place. 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The elastomeric material tends to contribute extremely long relaxation times while the much more flowable viscoelastic material would contribute relaxation times that can be much shorter than the residence time of the media within the passageway during abrasive flow processing. Commercial elastomers which are too rigid for use in particular applications may be softened by the addition of plasticizers, such as phthalate esters. The letter S following the 2-digit number indicates that the lubricant in this media has been optimized for radiusing edges. By understanding the formulation code, a user can determine the characteristics of that media, and therefore intelligently select which media to use for a given operation. Copyright 2022 Elsevier B.V. or its licensors or contributors. With the invention of the Abrasive Flow Machining process, Extrude Hone Corporation developed an entirely new fi nish machining tool a plastic, abrasive laden polymer with very special properties that allow it to selectively and controllably abrade surfaces that it flows across. Moreover, the thermoplastic polymer based medium used alone can accomplish uniform abrasive work in otherwise difficult applications such as along the entire length of long tubes. Although media used for AFM are in widespread use at this writing, silicone media cannot be used in certain applications and/or is insufficient for use alone in certain applications. Typically, the sizes of abrasive used range from a coarse 20 mesh abrasive (average particle size ~0.9 mm) to a very fine 600 mesh abrasive (average particle size ~0.9 microns). A preferred method for ensuring a stable dispersion and avoiding segregation is to use elastic particles that have an affinity for the carrying base viscoelastic material. https://doi.org/10.1016/j.matpr.2019.07.173. Copyright 2012 Winbro Flow Grinding. When thermoplastic polymer is incorporated as a component in a silicone-containing medium, a particularly advantageous proportion in the base medium (exclusive of abrasive) is about 20-40%, more preferably 25-35%, most preferably 30% thermoplastic polymer additive, with the balance being silicone polymer. SECURITY INTEREST;ASSIGNOR:EXTRUDE HONE LLC;REEL/FRAME:052240/0667, Free format text: For example, in long, narrow tubes media having enhanced elastomeric character can maintain a more uniform radial pressure distribution throughout the length of the tube compared with the distribution realized when using media which does not contain a thermoplastic polymer. For example, there may be concerns about silicone polymers on surfaces which are later to be painted or plated, because the presence of trace amounts of silicone may prevent the adherence of paint products or plating. ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:MILLER, ROBERT A.;DELO, DAVID P.;SIGNING DATES FROM 19990706 TO 19990707;REEL/FRAME:034961/0833, Owner name: Commonly, the abrasive per pound of polymer base will weigh from about 0.2 pounds to about 15 pounds due to the high density of most abrasives. Various versions of the non-silicone formulations exhibit various degrees of elasticity, ability to flow, and flow rate. Interpenetrating second phase materials may include uniformly and intimately dispersed elastic polymers such as thermoplastic elastomers introduced during melt-blend processing. Basically, a thermoplastic is any material that softens when it is heated. For example: WB40S-24S (62). This application claims the benefit of U.S. We use cookies to help provide and enhance our service and tailor content and ads. In typical abrasive media applications, particulate or pelleted thermoplastic polymer starting material is obtained commercially and, prior to use, is liquified by elevating its temperature to between about 185 F.-375 F. The styrene-butadiene copolymers may be incorporated in the medium between 0.001-100%, more preferably 0.25-100% and most preferably between 0.5 and 100% by weight. Media of various descriptions have been used in a wide variety of applications, to polish, de-burr, radius, or otherwise to hone such diverse products as automobile intake manifolds, cylinder head intake ports, aircraft compressor and turbine section components, dies for striking currency, and prosthetic implants such as artificial knees and heart valves, without limitation. One typical articulation of relaxation time is to identify the time it takes for an imposed shear stress to be reduced by viscous flow to an arbitrary fraction 1/e of its initial value. However, this styrene block copolymer is exemplary only and virtually any other thermoplastic polymer having the same elastomeric and viscosity characteristics within the application temperature may be used. Other plasticizers are well known in the art. Each media formulation consists of a polymeric, flowable carrier into which one or more sizes of abrasive grain have been mixed. The use of the term thermoplastic herein is not intended to embrace materials which exhibit substantial fluidity or plasticity at ambient temperatures. This media is used to deburr relatively small diameter (2 3 mm) holes in fluid control components or in armatures. The selection of media depends on various testing as thermogravimetric analysis, flow capability, mechanical and rheological properties. In a particularly preferred embodiment, silicone- or polyorganosiloxane-based medium contains elastic silicone rubber particles dispersed therethrough to achieve increased relaxation times comparable to those attainable with the inclusion of a thermoplastic polymer. That is, this media provides a brighter more lustrous surface appearance, particularly on stainless steels components, with a slight loss in media aggressiveness. The study was executed by systematically abrasive flow machining approximately 100 identical castings using these various media formulations. PATENTED CASE, Owner name: The liquified thermoplastic polymer and silicone rubber may be combined and blended during the heating of the thermoplastic polymer: the two components do not chemically react. Free format text: 3,819,343 and No. The dispersed elastic particles should be of similar size scale or smaller in comparison to the abrasive particles included within the abrasive media (see below). SECURITY INTEREST (SEE DOCUMENT FOR DETAILS). Traditional media are unable to exhibit enhanced elastomeric (elasticity, compression resistance) properties even in high concentrations. 3,521,412. as a rate at which a viscous flow response relieves elastic stresses. For example, in long, narrow tubes media having enhanced elastomeric character can maintain a more uniform radial pressure distribution throughout the length of the tube compared with the distribution realized when using media which does not contain a thermoplastic polymer. One part by weight of the resulting admixture was combined with two parts by weight of aluminum oxide, 100 grain size. This would be a heavy and aggressive media, which would be suitable for polishing the internal passages in large cast industrial closed pump impellers. a quantity of abrasive particles dispersed in a base medium containing at least one thermoplastic polymer therein. 3,521,412 to McCarty, incorporated herein by reference. The performance of the media calculated by its finishing property on an AFM and various hybrid setup. The presence of thermoplastic polymer imparts a greater elastomer characteristic (elasticity, compression resistance, increased relaxation times) as contrasted with traditional media. The abrasive content is a blend: 30% by weight 20 mesh silicon carbide abrasive plus 35% by weight 36 mesh silicon carbide abrasive (for a total of 65% abrasive grain / 35% media base). Additional preferred thermoplastic polymers for the purpose of the invention are the styrene polymers and copolymers which are gel-like (and elastomeric) in consistency at ambient temperatures (24 C.5 C.). Preparations containing 20% or 25% of KRATON in mineral oil are both visually and characteristically distinguishable from the 0.75% preparation. Other prior art methods such as vaporblasting, sand blasting, and shot blasting presented their own disadvantages, particularly in that none was of any significant utility in polishing interior fabricated surfaces. The present invention incorporates at least one thermoplastic or elastic polymer in abrasive flow machining media either as the sole or as one of the polymeric constituents. In some extreme cases it could exceed the volumetric concentration of abrasive particles. With ONE WAY FLOW Abrasive Flow Machining, the abrasive media fl ows through the tooling and workpiece in only one direction. ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Disadvantages include the effect of turning a flowable, viscoelastic material (the base viscoelastic material) into a pseudo-flowable (or non-flowable), elastic solid, and the opportunity for behavior change in the event of a breakdown of the more solid-like components of the microstructure. In other words, the elastomeric constituents enhance the elastic component of the viscoelastic behavior of the media while preserving the beneficial presence of a viscous-flow behavioral component. 2019 Elsevier Ltd. All rights reserved. No. It should be borne in mind that the abrasive used will be varied to suit the individual application. The elasticity of traditional AFM materials is sufficient to cause some abrasion away from the ends of such a tube but the elasticity is not always sufficient to maintain a consistent degree of abrasion throughout the length of the tube. The present invention pertains to improved abrasive media for honing and/or polishing machined, cast and other surfaces. 60/584,590, filed Jul. Alternatively, at low percentage inclusion and with a significant percentage of mineral oil or other liquid carrier, the thermoplastic polymer abrasive flow medium can be formulated to achieve viscosities significantly lower than those of traditional media for honing applications where a more fluid carrier is preferred. So, the researchers developed alternate media at low cost, easy availability. The abrasive grain is a single size, a finer 80 mesh silicon carbide, and the abrasive content is 50% by weight. The finely divided particles may begin from the smallest sizes available up to about a 4/6 sieve size, with the median particle size not to exceed about 0.5 cm, with larger particles to be used only in exceptional and unusual circumstances. Enhanced elastomeric characteristics enable more uniform abrasive machining. Choice of particle size depends upon the application, and those skilled in the art of abrasive media honing can select the appropriate particle size for any given application. The present invention incorporates at least one thermoplastic or elastomeric polymer in abrasive flow machining media either as the sole or as one of the polymeric constituents. The carrier in this example is even more flowable having only 30% by weight polymer. In a particularly preferred embodiment, silicone- or polyorganosiloxane-based medium contains elastic silicone rubber particles dispersed therethrough to achieve increased relaxation times comparable to those attainable with the inclusion of a thermoplastic polymer. The particles must be uniformly dispersed and must remain so for successful abrasive flow processing as segregation of the elastic particles would create gradients in material properties and application effectiveness. When silicone rubber particles are used in place of the thermoplastic polymer particles discussed elsewhere in this specification, they generally meet the same size parameters. PAYMENT OF MAINTENANCE FEE, 8TH YEAR, LARGE ENTITY (ORIGINAL EVENT CODE: M1552); ENTITY STATUS OF PATENT OWNER: LARGE ENTITY. Although the invention has been described with particularity above, the invention is to be limited only insofar as is set forth in the accompanying claims. The formulation codes used for Winbro Flow Grinding Abrasive Media describe the polymer content of the base and the abrasive content of the media. No. The elastic nature of the media base supports the abrasive grain as it flows across surfaces or through internal passages to refine surfaces and edges with a pure grinding type action. A carrier with a high percentage of polymer will be stiff and can be used to polish or radius large features; a carrier with a high percentage of lubricant will be soft and flow easily through small or long passages. In any of the above approaches, the relative contributions of elastic and viscous behavior would be influenced by 1) the relative sizes of the elastic microdomains versus the abrasive particles and application geometry, and 2) the relative concentrations of the various viscoelastic, elastic, and abrasive constituents. When machined, cast, or other parts are complex, the challenges of polishing increase, because the presence of one or more intersecting bores, flats, slots; key ways or splines often produces a sharp corner or a raised burr at the point of conjunction. Moreover, in many applications traditional AFM media achieves an intensified abrasive action'in the vicinity of geometrical restrictions such as a change in cross-sectional area. A need remains, therefore, for an improved AFM medium useful in a wide range of viscosities and rheological (including elastomeric) properties and suitable for minimizing or eliminating silicone rubber and water-based gel from honing applications where silicone rubber and guar gum are contraindicated, and which is further able to maintain a consistent degree of abrasion throughout the length of the interior geometric surfaces. The letter A following the 2-digit number indicates that the lubricant in this media has been optimized for polishing. Other thermoplastic polymers include, without limitation, ethylene polymers and copolymers, polyurethane polymers and copolymers, polyvinyl polymer and copolymers, polyamide polymers and copolymers polycaprolactone polymers and copolymers, and polypropylene polymers and copolymers. Abrasive media will contain from a low of around 25% up to around 67% by weight abrasive grain. Generally, the characteristic relaxation time of the material is engineered to be comparable or large relative to the typical residence time of the material within the passage during abrasive flow processing. Abrasive particles may be incorporated in the present medium over a wide range of particle sizes and particle size distributions. Furthermore, the pure non-silicone media also proved effectively to machine, with abrasive flow, the tubular passageways of the work pieces. The present invention pertains to the use of non-silicone thermoplastic or elastic polymer as part or all of the polymer used to provide the medium for honing and polishing applications such as abrasive flow machining and orbital polishing. For these S media formulations, the amount of material removed through a bore or passage is significantly reduced compared to our standard media base, while the size of the edge radius is unaffected. A specific styrene polymer useful in the present invention is the styrene-ethylene/butylene-styrene block copolymer sold under the trade name KRATON. The results of the study confirm that the performance characteristics attributed to the non-silicone content of the test media contrasted and complimented that of the silicone-based media content. Although the prior art does not address the inclusion, in abrasive flow machining media, of non-silicone thermoplastic polymer, other aspects of abrasive flow machining media are known and are disclosed in U.S. Pat. 3,521,412, No. Ninety-five parts by weight of food grade white mineral oil were combined with 5 parts by weight of KRATON styrene-ethylene/butylene-styrene block copolymer at a temperature of approximately 225 F. The components were blended in a vessel provided with a manual stirring blade. Ninety parts by weight pelleted KRATON thermoplastic polymer was shredded, heated to 200 F. and combined with 10 parts by weight automotive-grade lubricating grease. This feature of the current composition and method enhances performance in various applications. Available with different size of media cylinders: 8 (200mm), and 10 (250mm), Gradnings- & Maskinteknik AB, Box 2180, S-750 02 Uppsala, Sverige, Tel: 018-15 83 16. A satisfactory abrasive for use in working on steel is silicon carbide which is readily available in standard grit sizes. Various grades of mineral oil or paraffin oil may also be used to plasticize and/or to dilute the thermoplastic polymer media. For example, long, narrow tubes can experience preferential abrasive work near the ends of the tube (i.e., where geometrical transitions exist) creating a condition described as bell-mouth. When thermoplastic polymer is present as the base medium in less than an amount of 100% by weight, the preferred diluents are mineral oil or paraffin oil, and the mineral oil grade may be anywhere from white food grade mineral oil on down to the lower mineral oil grades. CIBC BANK USA, ILLINOIS, Free format text: In comparative trials, the medium provided enhanced abrasion as compared with silicone medium containing the same type and amount of abrasive particles. EXTRUDE HONE CORPORATION, PENNSYLVANIA, Free format text: Alternatively, the cooled thermoplastic polymer-based material may be shredded and compounded into other abrasive machining media materials such as silicone-containing materials. Application Development / Turn-Key Systems, Part Processing / Contract Finishing Services. It has also been observed that the presence of thermoplastic polymers in abrasive media in many cases enhances lubricant retention in the medium as contrasted with the base medium alone. Traditional polishing methods originally involved manual filing or sanding or the use of rotary sanding and finishing tools.
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