cafa 2009 training presentation

2009 CAFA ConventionFebruary 13 – 16, 2009

Indian Wells, CA

CAFA 2009

Coated Abrasive Components Coated Abrasive Components

and Their Effect on

Performance

February 14, 2006

Presented by Mark Boudreau


Indian Wells, CA

Top Size/Stearate

Size Coat

Typical Coated Abrasives Construction

Top Size/Grinding Aid – Third layer grinding aid to reduce friction and heat.

Stearates help prevent loading on soft materials.

Size Coat

Size Coat – Hide glue, Urea resin, or Phenolic resins.

Grain

Backing

Base Coat

Base Coat – Hide glue, Urea resin, or Phenolic resins

Backing – Cotton, Polyester, Poly-Cotton, or Paper


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Cloth Manufacturing

• Produced by spinning of fibers into a filament that is 20 – 30 mm long.

• Filaments are spun into yarns.• Filaments are spun into yarns.

• Yarn is woven into raw cloth.


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Cloth Manufacturing

• Warp is the yarn running the length of the material.

• Weft is the yarn running the width of the material.

• Weft yarn is weaved over and under the Warp yarn in ratios of 1:1, as high as 1:4, with 1:2 the most common.

• Typically the Warp (length) yarn is larger, and therefore stronger, then the Weft (width) yarn.


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Backing Types

Cotton:

– Lower tensile strength due to the non-elastic (low stretch) characteristic of cotton.

– Low tear resistance in both Warp and Weft.

– Cotton must be treated to prevent migration of the base coat resins into the cloth which creates brittleness.

– The treatment of the cotton is detrimental to creating a mechanical bond that optimizes grain retention.


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Backing Types

Polyester:

– Excellent strength and durability due to the elasticity.

– Tear resistance of the width due to the larger threads – Tear resistance of the width due to the larger threads of the Warp.

– Polyester does not require treatment to prevent brittleness.

– The untreated cloth provides a mechanical bond for optimal grain retention.


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Backing Types

Poly-Cotton:

– Mixture of polyester and cotton fibers to create filament which is spun into yarn.

– Typical ratio of polyester to cotton is 65% to 35%.

– Hybrid backing has benefits of both polyester and cotton with good base adhesion and low stretch.


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60

80

100

120

0

20

40

Y X T J F E

Cloth backing type

Cloth backing type and stiffness


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200

250

300

350

400Weight of paper g/m

2

0

50

100

150

200

A B C D E F G

Paper type

Weight of paper g/m

Paper type and weight


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Summary of Grain Characteristics

CeramicZirconia AluminaA/O & S/C

• Single crystal

• Cut rate decays at

start of grinding

• Fracturing - Dulling

• Brittle

• Billions of crystals

• Cut rate remains constant

for 75% of grinding life

• Self-sharpening grain

provides more aggressive

cut

• Tough

• Multi-crystal

• Cut rate decays at

start of grinding

• Self-sharpening

• Tough

CeramicZirconia AluminaA/O & S/C


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Grain Sizing

• The ANSI, FEPA & JIS scales

have grain size differences at

the fine and coarse ends of the

scales

FEPA P

(European Std.)

ANSI

(U.S. Std.)

JIS

(Japanese Std.)

AVG. GRAIN

DIAMETER (µµµµm)

P16 1616

1292

P20 2020

973

P24 2424

743

P3030 30

626

P3636 36

523

P4040

40 412

P5050

50 328

P6060 60

262scales

– JIS separates from ANSI

and FEPA coarser than 36

grit

– ANSI separates from FEPA

& JIS finer than 240 grit

• Micron grading is based on the

average size of the grain

diameter

P80 80 80 196

P100 100 100 157

P120 120 120 122

P150 150 150 98

P180 180 180 76

P220 220 220 66

P240 240 58

P280 240280

52

P320320

46

P360 280360

40

P400 400 35

P500 320 500 30

P600 600 26

P800 400 22

P1000 500800

18

P1200 600 1000 15


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Evolution of Bonding Systems

Hide Glue:

– Water soluble (non-waterproof).

– Elastic characteristics creates a passive grain presentation resulting in uniform finishes.presentation resulting in uniform finishes.

Urea Resin:

– Cheaper than hide glue.

– Water resistant characteristics.

Phenolic Resin:

– Most durable waterproof bond.


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Grinding Aids

Cryolite:

– Sodium Hexafluoroaluminate, Na3AlF6.

– Added into size coat for heat dispersment on metal enhancing performance 10% - 20% as a lubricant enhancing performance 10% - 20% as a lubricant reducing friction.

Top Size:

– KBF4 also known as Potassium Fluoroborate.

– Typically used as a third layer resin to reduce heat in grinding high alloy steels such as stainless steels, titanium, and inconel.

– Adds no benefit to mild steels.


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Bonding Systems Illustrated


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Coating Densities


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BackingElectrode

Electrostatic Coating of

Coated Abrasives (schematic)

Grain Conveyor Belt

Electrostatic FieldAbrasive Grain

Electrode


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Conventional

Abrasive

Coating Technologies

Close Coat

100% Grain Coverage

Open CoatAbrasive

Split Coated

Abrasive

-Higher grinding forces per grain

-Enhanced grain regeneration

-Designed for light to moderate

pressure applications

Open Coat

25% - 80% Grain Coverage

Split Coat


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10 lbs Force

2 lbs Force per Grain

100% Coverage


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10 lbs Force

2.5 lbs Force per Grain

75% Coverage


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10 lbs Force

3.33 lbs Force per Grain

50% Coverage


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100% Coating Split Open-Coat


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Coated Abrasive

Product TypesProduct Types


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Product Types - Supported

• Flap Discs

• Spiral Bands• Spiral Bands

• Discs

• Belts

• QTD

• Body Cones


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Product Types - Unsupported

• Flap Wheels

• Sanding Stars• Sanding Stars

• Overlap Discs

• Slotted Discs

• Rotofinishers

• Slashed Loadings


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Product Types - Wrapped

• Cartridge Rolls

• Cone Points• Cone Points

• Square Pads

• Cross Pads


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Common

Coated Abrasive Coated Abrasive

Problems


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Loading• A loaded abrasive shows

metal packed in between

the abrasive grains

• Most commonly • Most commonly

encountered with non-

ferrous metals

• Can be inhibited by use

of Grease, Calcium

stearate or open-coated

abrasive.


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Stripping - Shedding• When an abrasive

material strips or sheds,

the grain is pulled away

from the backing

• Most often encountered

during high pressure on

the individual grain points

• Consider using 100%

coating on polyester

backing


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Glazing • Glazing is caused by heat

build up due to friction

created by the dulling of the

abrasive grain.

• Most commonly encountered • Most commonly encountered

with harder alloy metals such

as titanium, inconel, and

harder stainless.

• Reduce cutting speeds, top-

size, ceramic grain, open or

split coat abrasive.


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Thank you!Thank you!

Questions?

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