CN115052714A

CN115052714A - Loose abrasive aggregate and method of abrading workpiece using the same

Info

Publication number: CN115052714A
Application number: CN202180012880.2A
Authority: CN
Inventors: 波莉·H·R·基恩; 海伦·E·皮尔逊
Original assignee: 3M Innovative Properties Co
Current assignee: 3M Innovative Properties Co
Priority date: 2020-02-06
Filing date: 2021-02-01
Publication date: 2022-09-13
Also published as: WO2021156730A1; US20230085096A1

Abstract

A method of abrading a surface of a workpiece includes agitating a container including loose abrasive granules and the workpiece. At least a majority of the loose abrasive agglomerates have a largest dimension of 0.25 cm to 3 cm. On an individual basis, each loose-abrasive granule comprises abrasive particles secured to an organic substrate by a binder material. The container is agitated with sufficient energy that at least some of the loose abrasive granules contact and abrade at least a portion of the surface of the workpiece. Further, a plurality of chopped loose abrasive granules are disclosed, wherein the chopped loose abrasive granules each comprise abrasive particles fixed to a backing on an individual basis and have a largest dimension of 0.25 cm to 1.5 cm.

Description

Loose abrasive agglomerates and method of abrading a workpiece using same

Technical Field

The present disclosure relates broadly to abrasives and methods of abrading the same.

Background

Additive manufacturing of metals, polymers, composites and ceramics for prototyping and manufacturing has become increasingly important in recent years. Components produced by additive manufacturing methods such as Direct Metal Laser Sintering (DMLS) often have unacceptable surface roughness and do not perform their intended function. Most users require post-processing techniques to reduce the roughness of the component surface prior to use. Examples of such post-processing steps include vibratory tumbling and abrasive flow processing. In vibratory tumbling, abrasive media are rolled with the component to burnish the surface of the component.

The manufacture of various abrasive articles (e.g., coated abrasive articles and nonwoven abrasive articles) can generate a significant amount of waste during the conversion of forms (e.g., abrasive discs). The waste material is typically disposed of by incineration or landfill.

Disclosure of Invention

In accordance with the present disclosure, the inventors have discovered that the waste material produced during the conversion of various abrasive articles in form already has a desired size (e.g., the punched out form produced by the perforating operation) or can be chopped into a desired size range and used as an abrasive media for vibratory finishing. This not only provides an opportunity to recycle the waste material, but it has also been unexpectedly found that the recycled grinding media actually functions in a better manner than an equivalent amount of loose abrasive particles.

Accordingly, in one aspect, the present disclosure provides a method of abrading a surface of a workpiece, the method comprising:

providing a container comprising:

loose abrasive bodies, wherein at least a majority of the loose abrasive bodies have a largest dimension of from 0.25 cm to 3cm, and wherein each loose abrasive body comprises, on a respective basis, abrasive particles secured to an organic substrate by a binder material; and

a workpiece; and

the vessel is agitated with sufficient energy so that at least some of the loose abrasive granules contact and abrade at least a portion of the surface of the workpiece.

In another aspect, the present disclosure provides a plurality of chopped loose abrasive granules, wherein the chopped loose abrasive granules each comprise abrasive particles fixed to a substrate on a respective basis and have a largest dimension of 0.25 centimeters to 1.5 centimeters. Chopped loose abrasive granules may be used, for example, to practice the methods disclosed in this disclosure.

As used herein:

the verb "chopping" means cutting into pieces, for example by striking with a sharp instrument, slicing or cutting with scissors, die-cutting, perforating, cutting with a laser, characterized by a shredding operation that cuts cleanly and specifically excludes tearing or tearing;

the adjective "chopped" means cut into pieces, for example by knocking, slicing, perforating or cutting with a sharp instrument or laser, characterized by clean cuts and definite exclusion of torn or torn pieces;

the term "loose-fill" refers to compaction using only agitation and gravity; and

the term "container" refers to a hollow or concave container for holding a liquid or other contents.

The features and advantages of the present disclosure will be further understood upon consideration of the detailed description and appended claims.

Drawings

Fig. 1 is a schematic process flow diagram of an exemplary method 100 according to the present disclosure.

Fig. 2 is a schematic cross-sectional side view of an exemplary coated abrasive article 200.

Fig. 3 is a schematic cross-sectional side view of an exemplary coated abrasive article 300.

Fig. 4A is a schematic perspective view of an exemplary nonwoven abrasive article 400.

Fig. 4B is an enlarged view of the region 4B in fig. 4A.

Fig. 5 is a schematic perspective view of an exemplary wound grinding wheel 500.

Fig. 6 is a schematic perspective view of an exemplary stacked grinding wheel 600.

Repeat use of reference characters in the present specification and drawings is intended to represent same or analogous features or elements of the disclosure. It should be understood that numerous other modifications and embodiments can be devised by those skilled in the art that will fall within the scope and spirit of the principles of this disclosure. The figures may not be drawn to scale.

Detailed Description

Referring now to fig. 1, an exemplary method 100 of abrading a surface 112 of a workpiece 110 includes the steps of: providing a container 120 containing loose abrasive granules 130 and at least a portion of workpiece 110, and then agitating container 120 with sufficient energy such that at least some of loose abrasive granules 130 contact and abrade at least a portion of surface 112 of workpiece 110. At least a majority (and preferably all) of loose abrasive granules 130 have a largest dimension of 0.25 cm to 3 cm; for example as shown in figures 2 to 6. Each loose abrasive body 130 comprises abrasive particles secured to a backing by a binder material. In some embodiments, the loose abrasive granules may be composed of the same or different materials, but they need not be the same size and/or shape. For example, they may be recycled waste from common abrasive articles.

The container can contain any volume of material and may be partially or completely filled with loose abrasive granules, preferably completely filled if compressible loose abrasive granules are used. In either case, there should be sufficient mobility between the loose-packed abrasive granules or the workpiece such that there is relative motion between the granules and the workpiece during agitation. In some embodiments, the loose-fill abrasive granules fill at least 10 vol%, at least 20 vol%, at least 30 vol%, at least 40 vol%, or even at least 50 vol% of the maximum holding capacity (i.e., excluding overflow) of the container. In some embodiments, including any of the preceding sentences, the loose-packed abrasive granules fill less than 90 volume percent, less than 80 volume percent, or less than 70 volume percent of the maximum holding capacity of the container. Fewer and greater amounts of loose-abrasive agglomerates may also be used. Typically, the greater the mass of each loose abrasive particle, the less the container fill percentage, but this is not required.

In some embodiments, the container may further comprise additional optional items, such as loose abrasive particles, if desired, in addition to the workpiece and the loose abrasive granules. In other embodiments, the container may be free of such additional optional items.

Any suitable method may be used to agitate the container and, thus, the loose abrasive agglomerates, including, for example, oscillating, vibrating, and/or rolling. The movement pattern of the container may include, for example, linear, arcuate, elliptical, or random oscillations. In some preferred embodiments, the movement of the container comprises a linear reciprocating movement. The method of abrading a workpiece may be batch or continuous.

The method according to the present disclosure may be performed, for example, using a vibration system comprising a container. The container may be hermetically sealed, or in some embodiments, the container may have one or more openings (e.g., through which the workpiece extends into the container). The system may also include an actuator (e.g., a mechanical actuator) capable of vibrating the container. Preferably, the control module controls the actuator such that the container vibrates under a resonant or near-resonant condition (e.g., resonant acoustic condition) throughout the surface modification. The use of a vibrational resonance condition ensures efficient use of the supplied energy. Commercially available mixing devices capable of accomplishing the above are sold by Resodyn Acoustic Mixers, Butte, Montana, of Batt, Montana, USA. The laboratory scale apparatus included LabRAM I and LabRAM II controlled batch mixers. Large scale units are sold under the trade names OmniRAM, RAM5 and RAM 55. These devices typically resonate at 20Hz to less than 1kHz, preferably 40 Hz to 100 Hz, more preferably 40 Hz to 80 Hz, and more preferably 55 Hz to 65 HzOperating at a dynamic frequency, but this is not required. The vibratory mixer is also characterized by an actuator displacement of about 0.5 inches (1.3cm), which may be accompanied by an accelerating g-force of at least 20-g, 30-g, 40-g, 50-g, or even at least 60-g, where g-9.8 m/s ² But this is not essential. Further details regarding suitable resonant acoustic mixers can be found, for example, in U.S. Pat. Nos. 7,188,993(Howe et al) and 9,808,778(Farrar et al).

In practice, the loose abrasive granules and the workpiece are disposed within a container. The workpiece may be loose within the container or fixed in a given position relative to the container (e.g., mounted to a wall of the container). The latter configuration may be desirable where selective alteration of a portion of the workpiece surface is desired. The latter configuration may also be desirable if the workpiece has a large mass and/or is delicate, in order to prevent collisions between the workpiece and the container wall. Advantageously, loose abrasive granules bounce off the sides and top of the container during vibration, causing the workpiece to be bombarded from all angles.

Two or more types, combinations, shapes and/or sizes of loose-abrasive agglomerates may be used. Examples of suitable loose abrasive granules include: coated abrasive articles (e.g., having a make coat and a size coat), nonwoven abrasive articles (e.g., surface-dressing abrasive articles, including lofty open-celled webs), wound-up wheels, and laminated wheels. Such abrasive particles are known in the art.

Referring to fig. 2, an exemplary coated abrasive article 200 has a backing 220 and an abrasive layer 230 according to the present disclosure. Abrasive layer 230, in turn, comprises abrasive particles 240 secured to a major surface 270 of backing 220 by make layer 250 and size layer 260.

Referring to fig. 3, an exemplary coated abrasive article 300 has a backing 320 and an abrasive layer 330. Abrasive layer 330, in turn, comprises abrasive particles 340 according to the present disclosure and a binder 345.

More details regarding coated abrasive articles and/or structured abrasive articles having a make coat and a size coat and methods of making the same can be found, for example, in U.S. patent 4,734,104 (Broberg); 4,737,163 (Larkey); 5,203,884(Buchanan et al); 5,152,917(Pieper et al); 5,378,251(Culler et al); 5,436,063(Follett et al); 5,496,386(Broberg et al); 5,609,706(Benedict et al); 5,520,711 (Helmin); 5,961,674(Gagliardi et al) and 5,975,988 (Christianson).

Referring now to fig. 4A and 4B, an exemplary nonwoven abrasive article 400 includes a lofty, open, low density fibrous web 410 formed from entangled filaments 410. Abrasive particles 440 are secured to web 410 by binder 420.

The wound up grinding wheel can be made as follows: for example, as described above, nonwoven abrasive article 510 is wound under tension around core member 530 (e.g., a tubular or rod-shaped core member) such that the nonwoven abrasive article is compressed, and then impregnated with a curable binder precursor and cured. Fig. 5 shows a wind-up grinding wheel 500.

Similarly, a lay-up wheel may be made, such as a wind-up wheel, except that instead of winding the fiber web coated with the size coat precursor, the fiber web is laminated and compressed prior to curing. Fig. 6 shows a nonwoven lay-up abrasive wheel 600 having a plurality of nonwoven abrasive layers 610.

Additional details regarding nonwoven abrasive articles, abrasive wheels, and methods of making the same can be found, for example, in U.S. Pat. Nos. 2,958,593(Hoover et al); 5,591,239(Larson et al); 6,017,831(Beardsley et al); and U.S. patent application publications 2006/0041065 A1 (Barber, Jr.) and 2018-.

The workpiece may be any object that is commonly manufactured wherein the surface of the workpiece requires abrasion. Examples include camshafts, crankshafts, and turbine blades. Exemplary workpieces include metal components (e.g., may be sintered metal parts manufactured by rapid prototyping/3D printing). Examples of workpiece materials include metals and metal alloys (e.g., aluminum and low carbon steel), dissimilar metal alloys, ceramics, glass, wood-like materials, composites, painted surfaces, plastics, reinforced plastics, stone, and/or combinations thereof. The workpiece may be flat or have a shape or profile associated therewith.

Loose abrasive granules may be obtained by chopping the corresponding abrasive material in a manufacturing process, for example, converting manufacturing waste (e.g., scrap) or abrasive article waste. Although certain aspects of the disclosure need not be practiced; in some embodiments, however, it may be desirable to provide loose abrasive granules according to a predetermined specific particle size distribution (e.g., a unimodal distribution or a multimodal distribution) and/or composition specification (e.g., two different coated loose abrasive granules or a combination of coated and nonwoven loose abrasive granules). It may also be desirable to provide loose abrasive agglomerates in a random or specified shape.

Selected embodiments of the present disclosure

In a first embodiment, the present disclosure provides a plurality of chopped loose abrasive granules, wherein the chopped loose abrasive granules each comprise abrasive particles fixed to a substrate and have a largest dimension of 0.25 to 3 centimeters (cm), preferably 0.3 to 2.6cm, more preferably 0.5 to 2.5cm, and more preferably 0.7 to 2.5cm, on a respective basis.

In a second embodiment, the present disclosure provides a plurality of chopped loose abrasive granules according to the first embodiment, wherein the plurality of chopped loose abrasive granules has a predetermined particle size distribution, preferably a unimodal distribution or a multimodal distribution.

In a third embodiment, the present disclosure provides a plurality of chopped loose abrasive granules according to the second embodiment, wherein the predetermined particle size distribution has at least two modes; for example, a bimodal distribution or a trimodal distribution.

In a fourth embodiment, the present disclosure provides a plurality of chopped loose abrasive granules according to any one of the first to third embodiments, wherein at least some of the chopped loose abrasive granules comprise a chopped coated abrasive article.

In a fifth embodiment, the present disclosure provides a plurality of chopped loose abrasive granules according to any one of the first to third embodiments, wherein at least some of the chopped loose abrasive granules comprise a chopped lofty open cell nonwoven abrasive article.

In a sixth embodiment, the present disclosure provides a plurality of chopped loose abrasive granules according to any one of the first to third embodiments, wherein at least some of the chopped loose abrasive granules comprise a chopped stacked or rolled-up abrasive article.

In a seventh embodiment, the present disclosure provides a plurality of chopped loose abrasive granules according to any one of the first to third embodiments, wherein on a respective basis, at least some of the underlayment comprises a resilient foam.

In an eighth embodiment, the present disclosure provides a plurality of chopped loose abrasive granules according to any one of the first to third embodiments, wherein at least some of the substrates each comprise a metal foil.

In a ninth embodiment, the present disclosure provides a plurality of chopped loose abrasive granules according to any one of the first to eighth embodiments, wherein at least some of the abrasive particles comprise crushed abrasive particles.

In a tenth embodiment, the present disclosure provides a plurality of chopped loose abrasive granules according to any one of the first to ninth embodiments, wherein at least some of the abrasive particles comprise shaped abrasive particles.

In an eleventh embodiment, the present disclosure provides a plurality of chopped loose abrasive granules according to any one of the first to tenth embodiments, wherein on a per-basis, the abrasive particles are secured to a substrate by a binder material.

In a twelfth embodiment, the present disclosure provides a plurality of chopped loose abrasive granules according to the eleventh embodiment, wherein the binder material comprises a cross-linked organic binder material.

In a thirteenth embodiment, the present disclosure provides a method of abrading a surface of a workpiece, the method comprising:

providing a container comprising:

a workpiece; and

agitating the container with sufficient energy such that at least some of the loose abrasive granules contact and abrade at least a portion of the surface of the workpiece.

In a fourteenth embodiment, the present disclosure provides a method according to the thirteenth embodiment, wherein the container has a maximum holding capacity, and wherein the total volume of the plurality of loose abrasive granules is at least 25% of the maximum holding capacity of the container.

In a fifteenth embodiment, the present disclosure provides a method according to the fourteenth embodiment, wherein the total volume of the plurality of loose abrasive granules is at least 50% of the maximum holding capacity of the container.

In a sixteenth embodiment, the present disclosure provides the method of any one of the thirteenth to fifteenth embodiments, wherein the vessel is agitated by linear displacement.

In a seventeenth embodiment, the present disclosure provides the method according to any one of the thirteenth to sixteenth embodiments, wherein the method is continuous.

In an eighteenth embodiment, the present disclosure provides a method according to any one of the thirteenth to seventeenth embodiments, wherein the workpiece comprises a metal.

In a nineteenth embodiment, the present disclosure provides the method of any one of the thirteenth to eighteenth embodiments, wherein the workpiece comprises a plastic.

In a twentieth embodiment, the present disclosure provides the method according to any one of the thirteenth to nineteenth embodiments, wherein the loose-abrasive granules comprise a plurality of chopped loose-abrasive granules according to any one of the first to twelfth embodiments.

Objects and advantages of this disclosure are further illustrated by the following non-limiting examples, but the particular materials and amounts thereof recited in these examples, as well as other conditions and details, should not be construed to unduly limit this disclosure.

Examples

All parts, percentages, ratios, etc. in the examples and the rest of the specification are by weight unless otherwise indicated.

The system used in all of the examples described below was a LabRAM resonant acoustic mixer from Raxodean Corporation of Batt, Montana, USA (Resodyn Corporation, button, Montana). The machine equipped with the sealed mixing vessel was run in automatic frequency mode at 100% intensity. Roughness measurement (R) _a ) Measured using a Marsurf PS 10 stylus profilometer, and S _a Roughness measurements were recorded using a MikroCAD surface metrology system.

Example 1

This example demonstrates the grinding of aluminum alloys with cloth-backed electrocoated abrasive pellets.

The workpiece was a machined aluminum alloy (grade BS EN 7556082-T6) 16mm by 3mm by 50mm cube. Initial surface roughness R of workpiece _a Is 4.3 microns. The work piece was placed in a polypropylene container having an internal height of 55mm and an internal diameter of 80 mm. 53g of 3M 947A 120+ cloth backed electrocoated abrasive (short cut into 1 cm. times.1 cm squares) was placed in the container with the workpiece, and the container was sealed with a lid. The LabRAM in automatic frequency mode with 100% intensity operation for 15 minutes. Roughness R of the workpiece after 15 minutes of machining _a Is 2.1 microns. The mass loss of the workpiece during machining was 0.05g (0.8% of the total initial mass).

Example 2

This example demonstrates the additive manufacturing of tool steel by abrasive grit lapping with microreplicated cloth backed abrasive grit.

The workpiece was an additive manufactured tool steel pipe fitting printed by DMLS with a wall thickness of 2mm and a diameter of 20 mm. Initial roughness R of the outside of a pipe _a Is 6.8 microns and the initial roughness of the tube interior is 12.0 microns. To the workpiecePlaced in a polypropylene container having an internal height of 55mm and an internal diameter of 80 mm. 50g of 3M 307EA A100 Trizact tape (cut into a rectangle of 1.27 cm. times.1 cm) was placed in the container with the work pieces, and the container was sealed with a lid. The LabRAM was run in the automatic frequency mode at 100% intensity for 15 minutes. Roughness R of the outer surface of the pipe after 15 minutes _a 3.0 microns and the roughness of the inner surface of the tube was 6.8 microns. The mass loss of the workpiece was 0.17g (1% of the total initial mass).

Example 3

This example demonstrates the grinding of aluminum alloys with foam-backed electrocoated abrasive granules.

The workpiece was a machined aluminum alloy (grade BS EN 7556082-T6) 16mm by 3mm by 50mm cube. Initial surface roughness R of workpiece _a Is 4.5 microns. The work piece was placed in a polypropylene container having an internal height of 55mm and an internal diameter of 80 mm. 20g of 3M P1000 Hookit flexible foam abrasive discs (foam backed electrocoat abrasive, cut into 1.5cm by 1.5cm squares) were placed in a container with the work pieces. The container is sealed with a cap. The LabRAM was run in the automatic frequency mode at 100% intensity for 15 minutes. Roughness R of the workpiece after 15 minutes of machining _a Is 2.5 microns. The mass loss of the workpiece during machining was 0.02g (0.3% of the total initial mass).

Example 4

This example demonstrates the additive manufacturing of tool steel ground with foam backed double coated abrasive granules.

The workpiece was an additive manufactured tool steel pipe fitting printed by DMLS with a wall thickness of 2mm and a diameter of 20 mm. Initial roughness R of the outside of a pipe _a Is 12.2 microns and the initial roughness of the tube interior is 12.8 microns. The work piece was placed in a polypropylene container having an internal height of 55mm and an internal diameter of 80 mm. A 3M 737U 400+ paper backed coated abrasive was laminated to both sides of a flexible foam sheet (0.5 cm thick) and this construction was chopped into 1cm x 1cm squares. 18g of foam-backed double coated abrasive pellets were placed in a container with the workpiece and the container was sealed with a lid. Make itThe LabRAM was run in the automatic frequency mode at 100% intensity for 15 minutes. Roughness R of the outer surface of the pipe after 15 minutes _a 8.7 microns and the roughness of the inner surface of the tube was 5.2 microns. The mass loss of the workpiece was 0.21g (1.3% of the total initial mass).

Example 5

This example demonstrates the grinding of additively manufactured tool steel with stacked wheel granules.

The workpiece is an additive manufacturing tool steel pipe fitting printed by DMLS, and has the wall thickness of 2mm and the diameter of 20 mm. Initial roughness R of the outside of the tube _a Is 7.4 microns. The work piece was placed in a polypropylene cylindrical container having an internal height of 55mm and an internal diameter of 80 mm. A3M Scotch-Brite deburring tool and Finish PRO 6C Med + lap grinding wheel (0.125 inch thick) was short cut into 0.5cm by 0.5cm squares. 30g of the laminated abrasive bodies were placed in a container together with the workpiece, and the container was sealed with a lid. The LabRAM in automatic frequency mode with 100% intensity operation for 15 minutes. Roughness R of the outer surface of the pipe after 15 minutes _a Is 2.6 microns. The mass loss of the workpiece was 0.21g (1.3% of the total initial mass).

Example 6

This example demonstrates the use of lofty nonwoven abrasive agglomerates to abrade aluminum alloys.

The workpiece was a machined aluminum alloy (grade BS EN 7556082-T6) 16mm by 3mm by 50mm cube. Initial surface roughness R of workpiece _a Is 4.1 microns. The work piece was placed in a polypropylene cylindrical container having an internal height of 55mm and an internal diameter of 80 mm. 30g of 3M 7446S-CRS Scotch-Brite (lofty nonwoven abrasive sheet, cut into 1cm by 1cm squares) was placed in a container with the work piece. The container is sealed with a cap. The LabRAM in automatic frequency mode with 100% intensity operation for 15 minutes. Roughness R of the workpiece after 15 minutes of machining _a Is 2.2 microns. The mass loss of the workpiece during machining was 0.02g (0.3% of the total initial mass).

Example 7

This example demonstrates the grinding of aluminum alloys with paper-backed electrocoated abrasive pellets.

The workpiece was a machined aluminum alloy (grade BS EN 7556082-T6) 16mm by 3mm by 50mm cube. Initial surface roughness R of workpiece _a Is 4.2 microns. The work piece was placed in a polypropylene cylindrical container having an internal height of 55mm and an internal diameter of 80 mm. 29g 3M P500334U (coated abrasive with paper backing laminated into brushed nylon, chopped into 1cm by 1cm squares) was placed in the container with the workpiece and the container was sealed with a lid. The LabRAM in automatic frequency mode with 100% intensity operation for 15 minutes. Roughness R of the workpiece after 15 minutes of machining _a Is 2.8 microns. The mass loss of the workpiece during machining was 0.04g (0.6% of the total initial mass).

Example 8

This example demonstrates the grinding of additively manufactured tool steel with paper-backed electrocoated abrasive pellets (waster pipe).

The workpiece was an additive manufactured tool steel pipe fitting printed by DMLS with a wall thickness of 2mm and a diameter of 20 mm. Initial roughness of pipe external _a Is 11.8 microns. Initial roughness of pipe interior _a Is 12.4 microns. The work piece was placed in a polypropylene cylindrical container having an internal height of 55mm and an internal diameter of 80 mm. The abrasive agglomerates were 3M 255P P80 tubes. 3M 255P is a paper backed coated abrasive laminated to a brushed nylon. The tubes are circular pieces of coated abrasive that are removed to create dust extraction holes (in this case, 18mm, 10mm, and 7mm in diameter) in the coated abrasive discs. The 60g tube was placed in a container together with the workpiece, and the container was sealed with a cap. The LabRAM was run in the automatic frequency mode at 100% intensity for 15 minutes. Roughness R of the outer surface of the pipe after 15 minutes _a 3.5 μm, roughness R of inner surface of pipe _a Is 7.0 microns. The mass loss of the workpiece was 0.29g (1.8% of the total initial mass).

Example 9

This example demonstrates the use of lofty nonwoven abrasive agglomerates to abrade additively manufactured polymers.

The workpiece is a FormLabs transparent resin (methacrylate containing a photoinitiator) pipe manufactured by additive manufacturing, and has the wall thickness of 2mm and the diameter of 20 mm. Print the workpiece (initial roughness S) by SLA (stereo illumination type technique) _a 24 microns). The work piece was placed in a polypropylene cylindrical container having a volume of 200ml and an internal diameter of 60 mm. 25g of 3M 7447A-VFN Scotch-Brite (lofty nonwoven abrasive sheet, cut into 1cm by 2cm squares) was placed in the container with the workpiece, and the container was sealed. The LabRAM was run in the automatic frequency mode at 100% intensity for 20 minutes. After 20 minutes, the surface roughness S of the pipe _a 2.7 microns (89% improvement). The mass loss of the workpiece was 6% of the total initial mass.

Example 10

This example demonstrates a comparison of grinding an aluminum alloy with coated abrasive granules and loose abrasive particles.

The workpiece was a machined aluminum alloy (grade BS EN 7556082-T6) 16mm by 3mm by 50mm cube. Initial surface roughness R of workpiece _a Is 4 to 4.5 microns. The work piece was placed with the grinding media in a polypropylene cylindrical container having an internal height of 55mm and an internal diameter of 80mm, and the container was sealed with a lid. The grinding media comprised 60g 3M P80255P tubes (coated abrasive granules), or 24g, 60g, or 100g P80 semi-friable fused alumina BRFPL loose-abrasive particles (Imerys). The reasons for selecting these loose abrasive particles are detailed in table 1. The LabRAM was run in the automatic frequency mode at 100% intensity for 5 minutes. The results of mass loss and surface finish improvement are shown in table 1. The coated abrasive agglomerates are significantly more effective than loose abrasive particles with respect to mass loss and surface finish improvement of the workpiece.

All cited references, patents, and patent applications in this application are incorporated by reference in a consistent manner. In the event of inconsistencies or contradictions between the incorporated reference parts and the present application, the information in the present application shall prevail. The preceding description, given to enable one of ordinary skill in the art to practice the claimed disclosure, is not to be construed as limiting the scope of the disclosure, which is defined by the claims and all equivalents thereto.

Claims

1. A plurality of chopped loose abrasive granules, wherein the chopped loose abrasive granules each comprise abrasive particles fixed to a backing on an individual basis and have a largest dimension of 0.25 centimeters to 1.5 centimeters.

2. The plurality of chopped loose-abrasive granules according to claim 1, wherein said plurality of chopped loose-abrasive granules has a predetermined particle size distribution.

3. The plurality of chopped loose abrasive granules of claim 2, wherein said predetermined particle size distribution has at least two modes.

4. The plurality of chopped loose abrasive granules according to any one of claims 1 to 3, wherein at least some of said chopped loose abrasive granules comprise a chopped coated abrasive article.

5. The plurality of chopped loose-abrasive granules according to any one of claims 1 to 3, wherein at least some of said chopped loose-abrasive granules comprise a chopped lofty open-celled nonwoven abrasive article.

6. A plurality of chopped loose abrasive granules according to any one of claims 1 to 3, wherein at least some of said chopped loose abrasive granules comprise a chopped, stacked or rolled abrasive article.

7. The plurality of chopped loose abrasive granules according to any one of claims 1 to 3, wherein on a respective basis, at least some of said underlayers comprise a resilient foam.

8. The plurality of chopped loose abrasive granules according to any one of claims 1-3, wherein at least some of said substrates each comprise a metal foil.

9. The plurality of chopped loose abrasive granules according to any one of claims 1-8, wherein at least some of said abrasive particles comprise crushed abrasive particles.

10. The plurality of chopped loose abrasive granules according to any one of claims 1 to 9, wherein at least some of said abrasive particles comprise shaped abrasive particles.

11. The plurality of chopped loose abrasive granules according to any one of claims 1 to 10, wherein on a respective basis, said abrasive particles are fixed to said substrate by a binder material.

12. The plurality of chopped loose abrasive granules according to claim 11, wherein said binder material comprises a cross-linked organic binder material.

13. A method of abrading a surface of a workpiece, the method comprising:

providing a container, the container comprising:

loose abrasive bodies, wherein at least a majority of the loose abrasive bodies have a largest dimension of from 0.25 cm to 3cm, and wherein each loose abrasive body comprises, on a per se basis, abrasive particles secured to an organic substrate by a binder material; and

a workpiece; and

14. The method of claim 13, wherein the container has a maximum holding capacity, and wherein the total volume of the plurality of loose abrasive granules is at least 25% of the maximum holding capacity of the container.

15. The method of claim 14, wherein the total volume of the plurality of loose abrasive granules is at least 50% of the maximum holding capacity of the container.

16. The method of any one of claims 13 to 15, wherein the container is agitated by linear displacement.

17. The process of any one of claims 13 to 16, wherein the process is continuous.

18. The method of any of claims 13-17, wherein the workpiece comprises a metal.

19. The method of any of claims 13-18, wherein the workpiece comprises plastic.

20. The method of any of claims 13-19, wherein the loose-abrasive granules comprise a plurality of chopped loose-abrasive granules according to any of claims 1-12.