Abrasives Lesson 11: Sheets, Discs, and Rolls

Lesson 11

Sheets, Discs, and Rolls

A surprisingly large volume of coated abrasives is sold in the form of sheets, rolls, and discs for use in hand or mechanical applications. Many of these are used in general maintenance, paint preparation, or for cleaning and polishing metal parts. Practically every manufacturing plant is a potential customer for sheets, discs, or rolls for this type of general use. Every furniture plant and pattern shop has some hand or mechanical operation where coated abrasive sheets or discs are used for final clean up and repair. Automotive assembly plants are a major consumer of waterproof paper sheets for hand sanding the body primer coat that cannot be sanded with mechanized equipment.

Discs

Coated abrasive discs of various types (backing, bond, etc.) are used in many portable machine applications where the shape or size of the part being ground rules out most other forms of coated abrasives (i.e., rolls, sheets).

Coated abrasive discs are used in all types of metal fabrication shops, metal, and wood furniture plants where their main purpose is to im­prove or restore the scratch pattern prior to and during finishing. They are also used for automotive metal finishing, auto body repair, metal caskets, plastics, and the boat building industry.

Since several weights of paper are available, the selection of the correct product will be governed by the required flexibility for the operation as well as the type of support behind the discs.

There are several different product types that are converted into disc form. Zinc stearate coated products, in paperweights A wt. 40#, C wt, 70# and D wt. 90#, are used where loading is a common problem. Garnet, silicon carbide, and aluminum oxide grains are used in zinc stearate coated products. Garnet zinc stearate coated products are used exclusively on wood for touch up and repair in the cabinet rooms. Silicon carbide products are used in a variety of applications including wood, metal, and plastic. Aluminum oxide products can be found in wood as well as metal fabrication and primary automotive applications. Resin papers, primarily E wt. and F wt. with Alo gram, are used where backing toughness and bond durability are required. Resin paper products are fortified or modified with a filler that contributes to increased life. Resin belts or discs do not load or clog with material and are more resistant to heat and moisture than glue bond products.

They are generally used for heavier duty work such as deburring, intermediate finishing in metal fabrication, breaking corners down, and repairing wood furniture.

In many applications where both resin paper discs and zinc stearate coated paper discs are used, the primary method of adhering the disc to the backup pad is with an adhesive. For these applications, paper discs are coated with a pressure-sensitive adhesive. The most common sizes using this system are 5" and 6" discs.

Almost all coated abrasive products are available in disc form. Besides paper discs, cloth discs are also used in manufacturing. Usually, cloth discs are used on large stationary disc grinders. Cloth discs are also available coated with pressure-sensitive adhesive. The maximum diameter of cloth discs is governed by the maximum width in which the material is coated.

Cloth discs without pressure-sensitive adhesive can also be found in the form of slotted discs. Discs with inside slots and outside slots are used in metal and wood sanding applications. An example of this is found in spool sanding in woodworking where a disc with 16 outside slots is used to sand contoured edges on panels.

Sheets

With the exception of fiber backed products, all coated abrasive commodities are available in the form of sheets. Size is usually limited to the maximum width in which the material is coated. However, the following sizes are most common:

9" x 11"
9" x 13-3/4"
9" x 10"
2-3/4" x 17-1/2"
4-1/2" x 5-1/2"
4-7/16" x 4-7/16"
3" x 8"
3" x 11"
3-1/8" x 7-1/4"
2-3/4" x 9"
3-2/3" x 9"
4-1/2" x 11"

Sheets are produced from the same abrasive products as discs and are generally found in the same application areas.

Rolls

Rolls are normally manufac­tured in 50 yd. lengths and in widths ranging from a minimum 5/16" to a maximum of 54" Customers purchase coated abrasives in roll form for general purpose use, tearing off the material as needed or for very specific applications where the roil length becomes important. For example, in the furniture industry, customers often fabricate their own belts (narrow belts) and purchase rolls in lengths that enable them to cut multiples of the belt lengths required. Other customers cut rolls into sheets of special sizes as for drum sanders. The length specification on roll goods is rarely a problem because most requirements fall within sizes that are generally available.

Some customers buy full-width jumbo rolls either with trimmed or untrimmed edges. The usual sizes sold in full-width rolls are 24", 28" and 36". Customers who purchase full-width untrimmed rolls usually fabricate them into belts that are subsequently torn to narrower widths. This is primarily done in larger furniture plants.

The following are common roll types and their applications:

Economy Rolls

Economy rolls are usually used for general-purpose maintenance work. Standard flex for economy rolls should be a 45, and common sizes are 1/2", 3/4", 1", 1-1/4", 1-1/2", 1-3/4", 2" and 2-1/2".

Crankshaft Rolls

Crankshaft rolls are used for crankshaft polishing and are available either plain or serrated (slits on the edge).

Shredded Rolls

Shredded rolls have interrupted slits cut lengthwise through the backing. They are used as loadings for turning sanding in woodworking, or by customers who make up their own Vonnegut Brush Back sander loadings. Shredded rolls are available with either a parallel or staggered shred in widths up to 6" Straight or parallel shred is usually recommended for wood sanding, while staggered shred is used for metal finishing applications.

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Available Products by Shape and Application

Sheets, Discs, Rolls

1. Fastcut Resin Paper:

A-E 444F 80, 100 grit
A-E 625F 80 grit
A-E 655F 60 - 320 grit
A-E 675F 80 - 220 grit
A-W 678F 80 - 180 grit

Specific Markets:

a. Automotive Assembly Plants - to remove scratches, file marks, spot welds, and blending
b. Metal Fabrication – deburring, roughing, and intermediate finishing operations
c. Metal Caskets & Metal Furniture - roughing and intermediate finishing, blending, and fiber disc scratch removal
d. Wood Furniture & Cabinets -. clean up and repair prior to stain and finish

2. Dri-Lube Paper:

A-D 115D 60, 80 grit
A-A 115D 120 - 320, 400 grit
C-A 115D 180 - 320 grit
C-A 110D 80 - 400 grit
C-C 115D 100 - 150 grit
G-A 110D 180 - 280 grit

Specific Markets:

a. Automotive Assembly Plants (touch up and repair) - type 115 is normally used in the automotive trade
b. Furniture (white wood and sealer sanding) - both the type 110 and 115 are used for mechanical and hand applications in sheets and discs
c. Truck and Farm Machinery - blending and repair
d. Boat Manufacturing - fiberglass and wood blending, finishing

3. P.S.A. Dri-Lube Paper:
Dri-Lube paper is also used in the above markets in the form of discs with a pressure-sensitive adhesive applied to the backside of the disc. The discs are mounted to a release paper in roll form. These rolls are packaged in a self-dispensing box,

The following products are available in PSA disc roll form:

A-D 115D 80 grit
A-A 1150 120 - 320, 400 grit
C-A 115D 80 - 400 grit
Note: 150 and coarser -125 discs/roll: 180 and finer - 250 discs/roll

4. Sand Screen:

The open mesh construction of "Sand Screen" makes it ideally suited for applications where loading or grind swarf build-up is a problem. Sand Screen is available in both aluminum oxide and silicon carbide. It can be used either wet or dry.

Products are:
A-M 765 L 320, 360, 400 grit

Specific Markets:

a. Automotive Assembly Plants - used in disc form to wet sand either primer coats or the color coat. Used with a sponge backup or an air driven grinder. The choice of grit size to be used is dictated by the paint system employed.
C-M 755S 80 - 320, 400 grit

a. Floor Resurfacing - in disc form to recondition and maintenance of floor types such as:
- asphalt tile
- gymnasium (wooden and composite)
- terrazzo tile
b. Molded Ceramics - flash removal

5. Waterproof Paper:

Waterproof paper is a coated abrasive product manufactured for wet sanding operations. Waterproof products can also be used dry. Fastcut Waterproof Paper:

C-A 965F 220 - 600 grit
C-C 965F 60 - 180 grit

Specific Markets:

a. Automotive primer coat sanding
b. Furniture rubbing - lacquer or synthetic

Flexbac Waterproof Paper:

A-A 945 E 240, 300, 400, 600 grit

Specific Markets:

a. Automotive primer coat sanding
b. Automotive color wet sanding before lacquer rubbing to remove "orange peel"

6. Flexbac Metal Cloth:

A-J 115E
A-J 255E
A-X 255 E

Specific Markets:

a. General-purpose: product for a wide range of metal finishing operations.

7. Fastcut Belt Paper:

A-E 115F
A-E 155 F
G-E 155F

Specific Markets:

a. Furniture and cabinet - slashed rolls
b. General metal finishing

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Questions on Lesson 11

1. The type of oversize coating used on Dri-Lube paper to help prevent loading is:
a. soap
b. resin
c. zinc stearate

2. Waterproof paper is designed primarily for wet applications but can be also used dry:
a. true
b. false

3. There are discs in a PSA roll of A80D115A:
a. 250
b. 125
c. 150

4. The backing weights in pounds for Dri-Lube paper are:
a. 50, 80, 100
b. 40, 50, 60
c. 40, 70, 90
d. 40, 80. 90

5. Sandscreen is ideally suited for applications where buildup is a problem:
a. loading
b. grinding swarf
c. Both A & B
d. none of the above

6. The two grain types used in the manufacture of waterproof paper are and:
a. garnet and aluminumoxide
b. silicon carbide and garnet
c. silicon carbide and aluminum oxide

7. Resin paper products are more resistant to than glue bond products:
a. heat
b. cupping
c. moisture
d. A & B
e. A & C
f. B & C

Courtesy Carborundum Abrasives