Grier Abrasive, Inc.

There are many factors involved in the selection of the right abrasive for a particular job. The comments and suggestions herein relate to average or normal conditions. However, there are endless combinations of these factors. Experience will be an important ingredient in matching the right product with a job. Following are some of the important ingredients to proper selection.

MINERALS_________________

Aluminum Oxide is an abrasive consisting of blunt shaped grain and is very tough in its lowest refined form. It is produced in a variety of refinements and by its versatility can be used from very hard to soft applications, making it the most commonly used abrasive.
Silicon Carbide is an abrasive that is hard, and sharp with exceptional strength, but due to its brittleness it breaks down faster than aluminum oxide under heavy loads.
Ceramic Grain abrasive is non-fused ceramic aluminum oxide that is extremely tough in all grades. It provides exceptional durability and cut rates. This grain is more costly, so its merits need to be evaluated against the common aluminum oxides.

MINERAL TYPES_________________

Friable abrasive grain is easily fractured by impact, therefore, constantly exposing fresh cutting crystals to the work piece making it the fastest cutting abrasive.
Semi-friable abrasive grain does not fracture as readily as friable grain, therefore, gives longer life in comparison during the grinding process, but does not cut quite as freely as the friable grain.
ABRASIVE TYPES_________________

A-Aluminum oxide is very tough and is most generally used in resin bond applications.
27A-Aluminum oxide is semi-friable and of average hardness. It is the most widely used medium density fused aluminum oxide. It is produced in a complete range of grit sizes for use in general purpose vitrified applications.
6A-Aluminum oxide is semi-friable, and of average hardness. It is the designation used for segments.
28A-Premium aluminum oxide is friable white grain which has an aggressive cool fast cutting action while holding form well. It is used in the grinding of heat sensitive alloys, taking advantage of its friability and cool cutting ability. This grain is also widely used in grinding of heat treated tool steels, high speed steels, and internal wheels.
9A-Premium aluminum oxide is friable white grain specially used in the production of our segments.
AMA-Aluminum oxide is a friable very aggressive grain for use on the smaller mounted points where a tough composition is needed.
23A-Aluminum oxide is an off white friable very aggressive grain, used in larger mounted point and wheel applications where a tougher application is indicated.
29A-Aluminum oxide is a pure fused abrasive, alloyed with chrome oxide making it pink in color. Although friable and cool cutting, it exhibits marked formholding characteristics. Applications will be found in precision, broad surface and tool room grinding on hard alloy steels.
5A-Aluminum oxide is the designation for the pink pure fused abrasive alloyed with chromium oxide, used in the manufacture of our segments. 36A-Aluminum oxide is a high chromium ruby-colored fused abrasive, free of titania. It is made by fusing high purity calcined alumina and chromium oxide. It is a friable abrasive, somewhat tougher than white, with corner-holding characteristics, which is needed for precision grinding. It is a premium priced grain as compared to 28A-white and 29A-pink, so the merits as compared to these types should be weighed.
C-Silicon carbide is a black, semi-friable medium density abrasive. It is produced in both resin and vitrified points and wheels for grinding hard or brittle materials, such as cast iron, ceramics, and glass: as well as low tensile strength, ductile non-ferrous metals. GC-Silicon carbide is a green in-color, friable, highly pure, medium density abrasive used in vitrified bonded points and wheels. It is most commonly used for grinding hard, brittle materials, such as cemented carbides, where fast cool cutting is desirable.
CG-Aluminum oxide is non-fused ceramic grain that is very tough, pure, and of uniform quality. Applications are in resin and vitrified points and wheels for high stock removal rates and long life. It performs especially well in precision grinding and fine finish applications, without excess heat generation. As it is a premium priced grain, its merits need to be weighed in comparison to the more common specifications, and is most commonly used in combination with other grains for best results. Note:11A is another designation used for CG grain. While not new to industry, is gaining in popularily, particularly as cost conscious businesses search for products with longer life, less dressing and faster material removal. Ceramic Grains can be mixed with conventional aluminum oxide grains in proportions ranging from 20% to 50%. A 30% blend offers the ideal balance of cost and performance.

• Longer life- in most cases 3 to 5 times longer
• Shape retention -with less dressing, tight tolerances can be maintained
• Less Loading-less time dressing and better cutting
• Cooler Running-less possiblity of thermal damage
• Greater Material Removal- tough, self sharpening and less loading gives greater material removal
• Less Force Necessary-- see the graph for 1018 mild steel
• Material Range- ferrous and non-nonferrous

GRAIN COMBINATIONS_________________

Grain combinations used in various proportions to obtain desired results

CA A mixture of silicon carbide and semi-friable aluminum oxide used in production of resin bonded products only. 78A A combination of 27A and 28A aluminum oxide. 7MA combination of 27A and AMA aluminum oxide 73A A combination of 27A and 23A aluminum oxide 89A A combination of 28A and 29A aluminum oxide 68A A combination of 36A and 28A aluminum oxide 8A A combination of 9A and 5A aluminum oxide 10A A combination of 9A and 6A aluminum oxide 72A A combination of 6A and 8A aluminum oxide 18A A combination of 11A and 28A aluminum oxide 17A A combination of 11A and 27A aluminum oxide BG A combination of C and GC silicon carbide AVAILABLE COMBINATIONS WITH CERAMIC ABRASIVE GRAINS Grier CG 18A White A/O grain and CCG, the most popular mix is a friable very aggressive combination. Grier CG 17A Gray A/O grain and CCG, a semi-friable mix that is less aggressive and therefore gives a longer life. Grier CG 19A Pink A/O grain and CCG in combination that is popular for use with stainless steel, high nickel alloys and high carbon/high chrome materials. Grier CG 16A Ruby A/O grain and CG in a rather new treated mix has been found to perform well with softer metals such as aluminum and brass. When ordering ceramic grains, if a specific finish is desired, you may find that a finer grit size than you normally use is necessary because of the sharpness of CG.

GRAIN SIZE_________________

Abrasive grain comes in a wide variety of grain sizes. For rough grinding and heavy stock removal coarse grit sizes are used, while fine grit sizes are used for work where a finer finish or a desired shape is necessary.

The Bond used in producing abrasive product is what holds the abrasive grains together and has no cutting capabilities of its own. GRIER manufactures product using vitrified, resin, and latex bonds.
Vitrified bond is a glass or ceramic bond which is very hard and comparatively brittle. There are various vitrified bonds that are used to obtain certain desired results or to meet required standards. GRIER manufactures vitrified product in 11, 11B, 13, 13B, 31, 51, 22, and 41 bond.
Resin bond is a strong, tough, resilient material. It absorbs shock better than vitrified. It is used for fast stock removal and is popular with foundries with offhand operations. It works well on stainless steel, brass, bronze, and aluminum. The GRIER designation for resin bond is B.
Latex bond is the bond utilized by GRIER in its soft Griertex product.

HARDNESS_________________

The hardness designation of an abrasive is controlled by the type of bond used and the ratio of bond to grain mix.
Soft grades are generally used on very hard materials, large areas of contact or rapid stock removal.
Hard grades are generally used for soft materials, small areas and longer wheel life.

STRUCTURE_________________

The concentration of abrasive grains for a specific area determines the structure of the product. Induced porosity is obtained by adding a material that will burn off in the firing process to produce a very open structure.

When a bonded abrasive is treated, its pores are generally filled with a substance that will assist in its working capabilities. Treatments reduce loading, aid in cutting, improve wheel life, and lubricate cutting action. Sulfur, resin and wax are the primary treatments used.
Sulfur treating is used to improve cutting action and enable a cooler operation. Sulfur treated abrasives should be used with a flood coolant.
Resin treating hardens the abrasive product and adds lubrication to assist in cutting.
Wax treating is popular when grinding brass or aluminum, for it greatly reduces loading and it lubricates the cutting action.

OTHER CONSIDERATIONS FOR GOOD WHEEL OPERATION_______

Wheel speed is very important to obtain the desired use. An operator should not exceed the speed standards given by the American National Standards Institute’s current safety requirement of maximum speeds, some of which are shown in this catalog. However, it is important to match the abrasive formula to your operational speeds. Specifications will perform differently at different speeds. You should occasionally speed test and torque test your grinder to ensure it is operating at desired levels. There are many factors that can adversely affect your grinder’s capabilities.
Run out of the grinder is a problem that must be constantly monitored. Worn chucks and lack of properly maintained grinders can result in spindle failure, wheel breakage and an unsafe condition for the operator.
Dressing your wheel or point is important to maintain the integrity of your wheel shape, cutting quality, and to minimize loading problems.

TROUBLE SHOOTING_________________

REVOLUTIONS PER MINUTE FOR VARIOUS DIAMETER OF GRINDING WHEELS TO GIVE PERIPHERAL SPEED IN FEET PER MINUTE AS INDICATED

SURFACE SPEED IN FEET PER MINUTE
Diameter of Wheel in Inches																				Diameter of Wheel in Inches
	4,000	4,500	5,000	5,500	6,000	6,500	7,000	7,500	8,000	8,500	9,000	9,500	10,000”	12,000	12,500	14,200	16,000	16,500	17,000
	REVOLUTIONS PER MINUTE					REVOLUTIONS PER MINUTE					REVOLUTIONS PER MINUTE					REVOLUTIONS PER MINUTE
1	15,279	17,189	19,099	21,008	22,918	24,828	26,737	28,647	30,558	32,467	34,377	36,287	38,197	45,837	47,746	54,240	61,115	63,025	64,935	1
1-1/2	10,186	11,459	12,732	14,006	15,279	16,552	17,825	19,099	20,372	21,645	22,918	24,192	25,465	30,558	31,831	36,160	40,744	42,017	43,290	1-1/2
2	7,639	8,594	9,549	10,504	11,459	12,414	13,369	14,324	15,279	16,234	17,189	18,144	19,099	22,918	23,873	27,120	30,558	31,513	32,468	2
2-1/2	6,112	6,875	7,639	8,403	9,167	9,931	10,695	11,459	12,223	12,987	13,751	14,515	15,279	18,335	19,099	21,696	24,446	25,210	25,974	2-1/2
3	5,093	5,730	6,366	7,003	7,639	8,276	8,913	9,549	10,186	10,823	11,459	12,096	12,732	15,279	15,915	18,080	20,372	21,008	21,645	3
3-1/2	4,365	4,911	5,457	6,002	6,548	7,094	7,639	8,185	8,731	9,276	9,822	10,368	10,913	13,096	13,642	15,497	17,462	18,007	18,553	3-1/2
4	3,820	4,297	4,775	5,252	5,730	6,207	6,685	7,162	7,640	8,117	8,594	9,072	9,549	11,459	11,973	13,560	15,279	15,756	16,234	4
5	3,056	3,438	3,820	4,202	4,584	4,966	5,348	5,730	6,112	6,494	6,875	7,257	7,639	9,167	9,549	10,848	12,223	12,605	12,987	5
6	2,546	2,865	3,183	3,501	3,820	4,138	4,465	4,775	5,093	5,411	5,730	6,048	6,366	7,639	7,958	9,040	10,186	10,504	10,823	6
7	2,183	2,456	2,728	3,001	3,274	3,547	3,820	4,093	4,365	4,638	4,911	5,184	5,457	6,548	6,821	7,749	8,731	9,004	9,276	7
8	1,910	2,149	2,387	2,626	2,865	3,104	3,342	3,581	3,820	4,058	4,297	4,536	4,775	5,730	5,968	6,780	7,639	7,878	8,117	8
9	1,699	1,910	2,122	2,334	2,546	2,759	2,971	3,183	3,395	3,608	3,820	4,032	4,244	5,093	5,305	6,027	6,791	7,003	7,215	9
10	1,528	1,719	1,910	2,101	2,292	2,483	2,674	2,865	3,056	3,247	3,438	3,629	3,820	4,584	4,775	5,424	6,112	6,303	6,494	10
12	1,273	1,432	1.592	1,751	1,910	2,069	2,228	2,387	2,546	2,706	2,865	3,024	3,180	3,820	3,979	4,520	5,093	5,252	5,411	12

STANDARD MARKING CHART_________________

rev. 9/14/10
© 2010