Products - Grindwell Norton

Grain Size
Abrasive grains are graded into standard particle sizes using sieves. The grit number of the abrasive represents the number of openings per linear inch of the sieve. There are three popular industry standards namely CAMI (Coated Abrasive Manufacturing Institute of USA), FEPA (Federation of European Producer of Abrasives) and JIS (Japanese Industrial Standards). A comparative chart is given on Page 57. In India, all the Coated Abrasive manufacturers follow the FEPA standard. You may use the comparitive chart when you are looking for an Indian equivalent for an imported product (say, from Norton, USA).

Abrasive Grain Coverage
Coated Abrasive products are generally manufactured in two levels of grain density - open coat and close coat.

	OPK : Openkote 30 to 60% of backing surface is covered, the spaces between the grains facilitate the removal of chips. Used for "clogging" materials like wood.
	CLK : Closekote 80-100% of the backing surface is covered. Offers the greatest number of cutting edges.

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Special Treatment

Some products receive special treatment to make them even more suitable to certain applications.

Nofil Treatment
In order to provide resistance to loading, some products are given a special additional coat of Zinc Stearate.

PSA Treatment
Some products have a special pressure-sensitive adhesive coating on the reverse side of the backing to facilitate easy fastening on back-up pads, rotating plates and grinder etc.

Satining Treatment
Satining is the pressure levelling of the coated abrasive surface by passing it between steel rollers. All abrasive grains are levelled (crushed) thus making absolutely sure that no scratching takes place. Satining is only rarely done for these fine grit abrasives and in special cases, where a scratch-free finish is imperative as it reduces the life of the abrasive.

Super Size Treatment
Some high performance metal working products are manufactured with a size coat designed to :
(a) react with the work material and make it easier to grind or
(b) to act as a lubricant and prevent burning of the workpiece.

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Flexing
Flexing is the controlled breaking of the adhesive bond with the aim of varying the flexibility and aggressiveness of the product. The direction, spacing and sensitivity is carefully controlled. Since flexing breaks the continuity of the bond and thus reducing the strength, minimum flexing is always desirable, unless the application requires greater flexibility. All products are given with a standard flexing which is most appropriate.

	Singleflex : The bond is broken at a 90º angle to the length. the abrasive product is stiff in one direction and flexible in the other. Singleflex is standard on most X-weight products.
	Doubleflex : The bond is broken at two 45º angles to the length. This flex is desirable for sanding shapes and contours, such as mouldings. It is standard on most J-weight products.
	Tripleflex : A combination of Singleflex and Doubleflex. It is specified on applications requiring maximum product conformability, such as sanding irregular contours.

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Belt joints
Belt joints are a crucial part of the coated abrasive product and need to perform consistently in line with the various end uses of the coated abrasive. Keeping this in mind, various types of joints have been designed. They broadly fall into two categories.

Lap Joint
Lap joints are formed by overlapping and sticking the two ends of the coated abrasive to each other. Depending on the application and the grit of the product, modifications are available. NTS ( no top skive) - No grain is removed from the top of the joint thereby providing maximum resistance to shedding. This is done for coarse grits. MTS (medium top skive) - Some amount of grain is removed from the top of the joint. FTS (full top sKIve) - All the grain is removed from the top of the joint for bump free operation.

Butt joint
Butt joints are formed by butting the two ends of the abrasive material without overlapping. A thin strong adhesive tape is bonded to the print side of the joint. Since there is no overlap, the joint is bump free and can be run in both directions.

Norlok Joint
This is a special type of butt joint where two ends of the abrasive material are cut in an interlocking sinusoidal pattern that offers resistance to hinging and joint fatigue.

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How to order a Coated Abrasive Product
For standard products use the Stock List No. as appearing in the Coated Abrasives Price List (Example : ZC4, AB13, ZW11, etc.) For non-standard products you may give the following details :-

E.g.

Shape	Size	CAP Code	Grit	Special Instruction

Belt	100*3500	R283	60	-

You may use the Stock No. of the above item, when you are ordering the second time or repeat all the details as above. Change in any of the above parameters will make the product different and it will have a different Stock No.