|
 |
|
|
Blasting
is the acceleration of particles by air or mechanical means to a
surface or work piece to achieve a variety of physical effects.
Surface effects are determined by media type, size, speed, and direction
of impact. The visual appearance of a blasted surface tends to be
a dull to bright satin-matte finish.
A
number of mechanical applications are listed below:
| |
*Pre-Paint Adhesion |
*Heat Treat Scale Removal |
| |
*Pre-Plate Finishing |
*Mill Scale Removal |
| |
*Surface Cleaning |
*Rust Removal |
| |
*Peening For Strength |
*Coating Removal |
| |
*Blending Machine Marks |
*Deburring |
| |
*Deflashing Plastic & Rubber |
*Weld Discoloration Removal |
| |
*Glass Etching |
*Mold Cleaning |
All Recoverable Blast Systems, Cabinets
or Rooms consists of:
| |
1. Delivery System |
| |
2. Containment System |
| |
3. Media Reclaiming - Cleaning System |
|
PNEUMATIC
BLASTING
 Pneumatic
blasting uses an air compressor to accelerate an air stream combined
with media onto a work piece. There are two types used to accelerate
the air; 1) Suction and 2) Pressure.
SUCTION
The Suction Blast System uses the venture principal, incorporating
an air jet one half the inside diameter of the nozzle. This creates
a negative pressure that sucks the media into the gun body from
the hopper. The total acceleration of the media in the air stream
is 8 to 16". A Suction Blast System can operate continuously
without shutdowns to refill media and can be easily automated
with multiple gun bodies.
|
|
 Pressure
Systems utilize a pressure pot that when pressurized with media
in the pot, accelerates the media from the pot through the blast
hose to the nozzle. The total media acceleration distance of 6'
and greater generates a velocity of 250 fps. By applying basic physics,
(impact energy = 1/2 mass X velocity squared) it becomes apparent
that pressure systems are highly efficient. When the mass of the
media is doubled, the kinetic energy is doubled. When the velocity
of the media is doubled, the kinetic energy is quadrupled.
Blast
production rates are higher with pressure systems than with suction.
Some variables that will affect production rates are blast media
type, size, quantity, blast pressure, distance, and the angle of
the blast stream in relation to the work piece and operator experience.
TOP
|
AIRLESS
(MECHANICAL WHEEL) BLASTING
This
type of blast system delivers media by means of a mechanical wheel
which propels the media at the work piece. Airless blasting lends
itself to automation with single or multiple wheels positioned to
cover various sizes and types of parts.
A
very common media used in this system is steel shot or grit. Blast
pattern, operation mix and abrasive flow are very important to these
systems. Below are recommendations that may help in understanding
airless blasting.
I.
BLAST-PATTERN
1. Inspect wheel parts daily for wear.
*Impeller-change when segments are worn 1/8".
*Control Cage-change when beveled edge is worn 1/4".
*Blades/Vanes-change when worn 1/2 their thickness.
2.
Check blast-pattern (hot spot) regularly.
*Blast the test plate at normal work height for 20 to 30 seconds.
*Adjust hot spot approximately 8" in advance of wheel center
line.
3. 2% sand and fines in the abrasive operating mix will increase
wear on wheel parts 50%.
4. Maintain records of parts replacement by wheel hours so that
a preventative maintenance program can be established. II. OPERATING MIX 1. Add new abrasive each work shift. Keep storagehopper 1/2 to
2/3 full.
2. Screen abrasive operating mix weekly.
3. Add back to machine each work shift abrasive that has leaked
out.
4. Inspect air wash separator each work shift.
*Scalping Screen-holes, flights, and blockage.
*Shed Plate-full abrasive curtain, holes.
*Dribble Pipe-dribble valves in working order.
*Usable abrasive in dribble pipe waste.
*Dust collector pipes-inspect for dust, abrasive build-up and holes.
5. Inspect separator and dust collector baffles for proper settings
and wear. III. ABRASIVE FLOW - Low Wheel Amps
1. Clean our scalp screens each work shift.
2. Inspect wheel parts daily for wear.
3. Inspect abrasive fed control valve for proper abrasive flow.
Excessive abrasive will flood wheel and lower wheel amps.
4. Inspect for loose and missing drive belts.
5. Show proper full load amps above each ammeter. Record ammeter
reading each work shift.
6. Check ammeter calibration monthly.
TOP
|
OVERVIEW
OF MEDIA SELECTION
The
relationship of using the correct blast media and achieving the
desired results, while maintaining cost control is very important.
Factors
to consider include the effects the media will have on a surface
and the actual cost, not just the initial cost. If a media
costs three times as much as another, but the attrition rate is
twenty times less, it becomes more economical to use. As
a general rule, round media tends impact a wide area, angular media
will cut into a work surface. The heavier the media, the deeper
the impact, whereas light weight particles have less impact. Hard
media will concentrate their work, and soft medias will spread the
effect. The
table below will give a guideline on commonly used recoverable media
and the applications.
Table
1. Media Guide |
|
Glass
Bead |
Ceramic
Shot |
Stainless
Cut Wire |
Steel
Shot |
Steel
Grit |
Aluminum
Oxide |
Silicon
Carbide |
Garnet |
Crushed
Glass |
Plastic
Media |
Agri
Shell |
| Finishing |
YES |
YES |
YES |
YES |
YES |
YES |
YES |
YES |
YES |
NO |
NO |
| Cleaning/Removal |
|
YES
YES |
YES |
YES |
YES |
YES |
YES |
YES |
YES |
YES |
NO |
| Peening |
YES |
YES |
NO |
YES |
NO |
NO |
NO |
NO |
NO |
NO |
NO |
| Surface
Profiling (Etch) |
NO |
NO |
YES |
NO |
YES |
YES |
YES |
YES |
YES |
NO |
NO |
| Working
Speed |
MED |
MED |
MED |
MED |
MED-HIGH |
HIGH |
VERY-HIGH |
HIGH |
HIGH |
MED-HIGH |
LOW-HIGH |
| Recyclability |
HIGH-LOW |
HIGH |
HIGH |
VERY-HIGH |
VERY-HIGH |
MED-HIGH |
MED-LOW |
MED |
MED-LOW |
MED |
LOW |
| Probability
of Metal removal |
VERY-LOW |
VERY-LOW |
MED-HIGH |
VERY-LOW |
MED |
MED-HIGH |
MED-HIGH |
LOW-MED |
VERY-LOW |
VERY-LOW |
VERY-LOW |
Hardness,
MOH Scale
(Rockwell Rc) |
5.5 |
7
(57-63) |
6-7.5
(35-55) |
6-7.5
(20-66) |
8-9
(40-66) |
8-9 |
9 |
8 |
5.5 |
3-4 |
1-4.5 |
| Bulk
Density (lb/cu ft) |
100 |
150 |
280 |
280 |
230 |
125 |
95 |
130 |
100 |
45-50 |
40-80 |
| Mesh
Sizes |
30-440 |
8-46 |
20-62 |
8-200 |
10-325 |
12-325 |
36-220 |
16-325 |
30-400 |
12-80 |
MANY |
| Typical
Blast Pressure(psi) |
20-55 |
20-90 |
20-90 |
20-90 |
20-90 |
20-90 |
20-90 |
30-80 |
20-50 |
20-60 |
10-40 |
| Shape:
A=Angular; S=Spherical |
S |
S |
A |
S |
A |
A |
A |
A |
A |
A
or S |
A |
| |
TOP
|
BLAST MEDIA COMPARISON / AIR BLAST
Media
Description |
Approx Price
Per Lbs |
Life Cycle
Through Blast |
 |
| Non-Free Silica Blast Media |
0.10Lb |
1-2 Cycles |
| Starblast |
0.18Lbs |
3 Cycles |
| Garnet |
0.22Lbs |
10-11 Cycles |
| Glass Bead |
0.33Lbs |
10-11 Cycles |
| Aluminum Oxide |
0.50Lbs |
12-14 Cycles |
| Cast Steel Grit & Shot 48-55 Rc |
0.50Lbs |
100 Cycles |
| Cast Stainless Steel Shot |
3.25Lbs |
300 Cycles |
| Ceramic Media |
2.95Lbs |
80-100 Cycles |
| Plastic Media |
1.16Lbs |
8-9 Cycles |
| |
|
|
|
Disposal fees not included.
Prices and breakdown rates are approximate. Operating
Costs are based on one 3/8" nozzle @ 80PSI/approximate 960
lbs./hr divided by the number of cycles.
Example: 960/300=3.2 Lbs. Consumption per hour. |
 |
|
| |
| |
|
|
|
| |
CONSUMPTION
LBS. PER HOUR |
COST
PER LBS. |
COST PER
HOUR TO BLAST |
Non-Free Silica
3/8" Nozzle @ 80 PSI 960 lbs. per hour |
640 x |
$0.10 |
$48.00* plus disposal fee |
Starblast
3/8" Nozzle @ 80 PSI 960 lbs. per hour |
320 x |
$0.18 |
$57.00* plus disposal fee |
Garnet
3/8" Nozzle @ 80 PSI 960 lbs. per hour |
240 x |
$0.22 |
$52.80* plus disposal fee |
Glass Bead
3/8" Nozzle @ 80 PSI 960 lbs. per hour |
91 x |
$0.33 |
$30.03* plus disposal fee |
Aluminum Oxide
3/8" Nozzle @ 80 PSI 960 lbs. per hour |
74 x |
$0.50 |
$37.00* plus disposal fee |
Shot Grit 44-55 Rc
3/8" Nozzle @ 80 PSI 2800 lbs. per hour |
28 x |
$0.50 |
$14.00* plus disposal fee |
Stainless Steel
3/8" Nozzle @ 80 PSI 2800 lbs. per hour |
9 x |
$3.25 |
$29.25* plus disposal fee |
Ceramic Media
3/8" Nozzle @ 50 PSI 754 lbs. per hour |
8 x |
$2.95 |
$23.60* plus disposal fee |
Plastic Media
3/8" Nozzle @ 50 PSI 367 lbs. per hour |
43 x |
$1.16 |
$49.88* plus disposal fee |
| |
|
|
|
|
| |
|
TOP
|
PRESSURE NOZZLE INFORMATION
Blast nozzle size and air pressure (psi) effects on air
compressor size andmedia pounds per hour delivered.
GRIT CONSUMPTION / AIR
REQUIREMENTS (AIR MIXED WITH GRIT)
Nozzle
Inside
Orifice |
|
Pressure
at Nozzle (psi) |
| 60 |
70 |
80 |
90 |
100 |
120 |
140 |
| 3/16" |
Air (CFM) |
30 |
33 |
38 |
41 |
45 |
-- |
-- |
| Horsepower |
7.0 |
7.5 |
8.0 |
9.5 |
10.0 |
-- |
-- |
| Lbs Sand Hour |
171 |
196 |
216 |
238 |
264 |
-- |
-- |
| 1/4" |
Air (CFM) |
54 |
61 |
68 |
74 |
81 |
97 |
111 |
| Horsepower |
12.0 |
13.5 |
15.0 |
16.5 |
18.0 |
21.5 |
24.6 |
| Lbs Sand Hour |
312 |
354 |
406 |
448 |
494 |
582 |
666 |
| 5/16" |
Air (CFM) |
89 |
101 |
113 |
126 |
137 |
152 |
173 |
| Horsepower |
20.0 |
22.5 |
25.5 |
28.0 |
30.5 |
34.0 |
38.7 |
| Lbs Sand Hour |
531 |
604 |
672 |
740 |
812 |
912 |
1038 |
| 3/8" |
Air (CFM) |
126 |
143 |
161 |
173 |
196 |
220 |
249 |
| Horsepower |
28.0 |
32.0 |
36.0 |
38.5 |
44.0 |
49.0 |
55.5 |
| Lbs Sand Hour |
754 |
864 |
960 |
1052 |
1152 |
1320 |
1494 |
| 7/16" |
Air (CFM) |
170 |
194 |
217 |
240 |
254 |
300 |
340 |
| Horsepower |
38.0 |
43.5 |
48.5 |
53.5 |
56.5 |
67.0 |
76.0 |
| Lbs Sand Hour |
1032 |
1176 |
1312 |
1448 |
1584 |
1800 |
2040 |
| 1/2" |
Air (CFM) |
224 |
252 |
280 |
309 |
338 |
392 |
443 |
| Horsepower |
50.0 |
56.0 |
62.5 |
69.0 |
75.0 |
87.5 |
98.9 |
| Lbs Sand Hour |
1336 |
1512 |
1680 |
1856 |
2024 |
2352 |
2658 |
| 5/8" |
Air (CFM) |
356 |
404 |
452 |
504 |
548 |
611 |
692 |
| Horsepower |
79.5 |
90.0 |
100.5 |
112.0 |
122.0 |
136.0 |
154.0 |
| Lbs Sand Hour |
2136 |
2424 |
2712 |
3024 |
3288 |
3666 |
4152 |
|
|
| |
TOP
|
| PRESSURE POT
BLAST CLEANING GUIDE |
| |
|
|
|
|
|
|
|
|
|
NOZZLE
SIZE |
CFM -
90 PSI |
AIR HOSE
SIZE |
BLAST HOSE
SIZE |
LBS MEDIA
PER
HOUR
@ 90 PSI |
APPROX. SQ FT CLEANING PER HOUR @ 90 PSI |
WHITE METAL |
NR WHITE METAL |
COMMERCIAL |
BRUSH OFF |
| #4 -
1/4" |
74 CFM |
1-1/4" |
1" |
448 LBS/HR |
LOOSE
MILL SCALE
TIGHT MILL SCALE
PITTED PAINT
LAYERED PAINT
|
50 SQ FT
40 SQ FT
26 SQ FT
20 SQ FT |
55 SQ FT
45 SQ FT
28 SQ FT
21 SQ FT |
130 SQ FT
85 SQ FT
63 SQ FT
40 SQ FT |
260 SQ FT
255 SQ FT
250 SQ FT
245 SQ FT |
| #5 -
5/16" |
126 CFM |
1-1/4" |
1-1/4" |
740 LBS/HR |
LOOSE
MILL SCALE
TIGHT MILL SCALE
PITTED PAINT
LAYERED PAINT
|
85 SQ FT
70 SQ FT
40 SQ FT
35 SQ FT |
90 SQ FT
75 SQ FT
45 SQ FT
40 SQ FT |
240 SQ FT
140 SQ FT
110 SQ FT
70 SQ FT |
430 SQ FT
425 SQ FT
420 SQ FT
415 SQ FT |
| #6 -
3/8" |
173 CFM |
1-1/2" |
1-1/4" |
1052 LBS/HR |
LOOSE
MILL SCALE
TIGHT MILL SCALE
PITTED PAINT
LAYERED PAINT
|
120 SQ FT
100 SQ FT
60 SQ FT
50 SQ FT |
125 SQ FT
105 SQ FT
65 SQ FT
52 SQ FT |
300 SQ FT
200 SQ FT
150 SQ FT
100 SQ FT |
610 SQ FT
605 SQ FT
600 SQ FT
595 SQ FT |
| #7 -
7/16" |
240 CFM |
1-1/2" |
1-1/2" |
1448 LBS/HR |
LOOSE
MILL SCALE
TIGHT MILL SCALE
PITTED PAINT
LAYERED PAINT
|
170 SQ FT
140 SQ FT
85 SQ FT
70 SQ FT |
180 SQ FT
146 SQ FT
90 SQ FT
72 SQ FT |
420 SQ FT
270 SQ FT
200 SQ FT
140 SQ FT |
840 SQ FT
835 SQ FT
830 SQ FT
825 SQ FT |
| #8 -
1/2" |
309 CFM |
2" |
1-1/2" |
1856 LBS/HR |
LOOSE
MILL SCALE
TIGHT MILL SCALE
PITTED PAINT
LAYERED PAINT |
210 SQ FT
180 SQ FT
105 SQ FT
85 SQ FT |
225 SQ FT
185 SQ FT
110 SQ FT
90 SQ FT |
540 SQ FT
355 SQ FT
270 SQ FT
180 SQ FT |
1070 SQ FT
1065 SQ FT
1060 SQ FT
1055 SQ FT |
| |
TOP
|
Aluminum
Oxide
Aluminum Oxide is widely used as a tough recoverable
media for quick removal of paint, rust, and scale removal. It has
also been specified for Pre-paint adhesion. Other applications include:
 *Cleaning
of investment castings
*Scale removal in steam turbines
*Surface preparation for thermal spray coatings
*Rust removal
*Hard oxide removal (titanium, zirconium, etc.)
*Mill scale removal
*Heat treat scale removal
*Glass etching or frosting
*Monument lettering
*Aircraft engine overhaul
*Matte finishing
When propelled by air, aluminum oxide acts as a powerful multi-edged
abrasive tool that will penetrate the work piece, while leaving
an exceptional clean, etched surfaces.
It is used on metal, glass, ceramic, marble, granite and other stone
surfaces. Aluminum oxide is manufactured in block shapes with multiple
sharp cutting edges.
| Grit
Size |
Inches
(Average) |
Microns
(Average) |
| 16 |
0.043 |
1092 |
| 20 |
0.037 |
940 |
| 24 |
0.027 |
686 |
| 30 |
0.022 |
559 |
| 36 |
0.019 |
483 |
| 46 |
0.014 |
356 |
| 54 |
0.012 |
305 |
| 60 |
0.010 |
254 |
| 70 |
0.008 |
203 |
| 80 |
0.0065 |
165 |
| 90 |
0.0057 |
145 |
| 100 |
0.0048 |
122 |
| 120 |
0.0040 |
102 |
| 150 |
0.0035 |
89 |
| 180 |
0.0030 |
76 |
| 220 |
0.0025 |
63 |
The
conversions listed are for various grits sized according to Bureau
Of Standards specifications, under Simplified Practice Recommendation
118-50.
TOP
|
CERAMIC
BEADS
Ceramic media can be blasted with air, wet or dry, and airless
systems. It is a very quick accelerating media, usually blasted
at a maximum of 55 p.s.i. When used on stainless steel, it produces
a very pleasant, bright matte finish. It is also very popular
for peening titanium.
 Treatment
Characteristics:
*Very good impact resistant
*Low dust
*Consistent surface finishing
*Low embedment
*No surface contamination (Fe O :0.1% max.)
*High depth of compressed layer
Typical physical properties:
| Theoretical
density |
|
3.85
g/cm |
| Relative
density |
|
3.76 |
Bulk
weight |
|
5.3
kg/l |
Microhardness
Vickers |
|
7
to 9 GPa at 500g |
Equivalent
Rockwell |
|
50
to 65 HRC |
ZIRSHOT
ZIRSHOT
is especially adapted for shotpeening and
peening and applications which require improved
sphericity and narrow size distribution.
| Description |
|
Nominal
Diameter |
|
|
MESH |
mm |
inches |
| Z850 |
16/20 |
0.850-1.180 |
.033-.046 |
| Z600 |
20/30 |
0.600-0.850 |
.023-.033 |
| Z425 |
30/40 |
0.425-0.600 |
.017-.023 |
| Z300 |
40/50 |
0.300-0.425 |
.012-.017 |
| Z210 |
50/70 |
0.210-0.300 |
.008-.012 |
ZIRSHOT Available Sizes:
ZIRBLAST
is used in surface treaments such as cleaning,
deburring, finishing.
| Description |
|
Nominal
Diameter |
|
|
MESH |
mm |
inches |
| B20 |
20/30 |
0.600-0.850 |
.023-0.33 |
| B30 |
30/40 |
0.425-0.600 |
.017-.023 |
| B40 |
40/60 |
0.250-0.425 |
.010-.017 |
| B60 |
60/120 |
0.125-0.250 |
.005-.010 |
| B120 |
120/200 |
0.070-0.125 |
.003-.005 |
| B125 |
-120 |
0-0.125 |
.000-.005 |
TOP
|
 GLASS
BEADS
This media generally gives a brighter matte finish. It maintains
tighter work piece tolerances and is normally blasted between 40-80
p.s.i. Glass
Bead Impact Media:
* are consumed at a slow rate and can survive multiple impacts,
allowing for continuous recycling of the media.
* are chemically inert and will not leave ferrous or other undesirable
residues on the surface of the workpiece.
* impart a controlled, clean finish on a variety of metals.
* clean quickly without significant metal removal.
Typical Application
for Glass Bead Blasting:
Cleaning:
* cleans and preps the surface of metal parts without changing tolerances,
or imparting ferrous pollutants.
* combines cleaning, finishing and peening in one operation.
Finishing:
* creates a wide range of unique surface finishes that are easy
to reproduce.
* blends machine marks, seals pores and the results offer the advantages
of
glass bead peening.
Peening:
* reduces the tensile stress in metal parts, increasing the fatigue
limit.
* reduces the stress corrosion cracking.
Deburring:
* removes burrs without damaging the parts and offers a peened surface
in one operation.
Glass Bead Facts:
Coarse Beads:
Remove larger, tougher soils; Peen to more intense levels; Peen
to deeper zones
in surface; Produce higher surface RA; Produce brighter surface;
Consume faster at
same pressure as fine beads; In practice, may consume slower than
fine beads.
Fine Beads:
Removes smaller;lighter soil; More impacts per pound; Clean faster;
Peen to less
intense levels; Peen outer zones of surfaces; Reach into keyways,fillettes
and small
areas; Produce lower surface RA; Produce matte finish; Consume slower
at same
pressure as coarse beads; In practice, may consume faster than coarse
beads.
All Beads:
Contain no free silica (environmentally friendly); Recycle many
times;
Clean efficiently at 45-60 degree nozzle angle.
Bead size, shape of workpiece, angle of nozzle, distance of nozzle
to surface area,
air pressure, and type of delivery system (suction versus direct
pressure blast) are
factors affecting final surface appearance and media consumption
parameters.
TOP
|
 PLASTIC
MEDIA
This
light weight angular plastic media was originally developed to strip
paint from aircraft without damaging the thin grade of the original
aircraft skin. Plastic media is typically blasted with light air
pressure (20-40 p.s.i.)
There are four or five major types of plastic media that are used
to meet a variety of applications, some of which are listed below.
Aircraft
Paint Removal. Removes most types of paint from typical
aircraft substrates, while leaving anodized and alclad surfaces
intact. Is employed on a wide variety of off-aircraft components
- resulting in significant savings over chemicals.
Boats. Bottom paint stripping from aluminum, fiberglass
and dense hardwood hulls. Rapid removal of dried barnacles.
Cleans brass of oxides and other coatings. Detects and exposes
blisters on fiberglass hulls.
Burr Removal. Removes light burrs from components while
maintaining integrity of finished part.
Clear Epoxy Optical Sensors. Only media capable of
removing resin bleed without opaquing surface. Eliminates
individual time-consuming masking requirements.
Composite Structures. Can strip paint and surface coatings
from fiberglass, carbon-graphite, epoxy, and other resin rich
components without bloom or fiber damage.
Die Casting. Removes light flash from cast components
without affecting critical surface dimensions.
Electronics Deflashing. Used both in dry and wet blast
to remove flash from electronic components and for surface
preparation on PCB's.
Encapsulated Electronic Parts. Will not damage delicate
parts or mar sufaces. Leaves product surface smear free, ready
for identification printing or soldering. |
|
Engine
Components. Carbon deposits and paint can be easily dry
stripped with no wear to critical mechanical dimensions, including
aluminum parts.
Ground Vehicle Paint Removal. Paint is readily removed
from auto, truck, railcar, and bus bodies.
Lead Frames. Prepares lead for easier and more uniform
tinning and coating procedures. Removes resin bleed without
impinging surface.
Mold Cleaning. Readily cleans molds used in rubber,
plastic, glass and die cast molding without affecting surface
dimensions. Edges are not radiused, mold life is prolonged,
cracks in molds are not smeared over, and flash on parts is
reduced.
Paint Rejects. Can be substituted for chemical stripping.
In many applications, major time savings can be realized.
Effective on most paint systems including powder coating.
Plastic Molded Parts. Effectively removes flash from
parting lines on thermoset plastic parts. Removes surface
anomalies without damage to the part.
Surface Prparation. Etching circuit boards before printing.
Pre-laminate roughening. Prepaint surface prep on plastics.
Surface Sealants. Tenacious sealants and adhesives
can be safely removed without damage to the substrate. |
PHYSICAL
CHARACTERISTICS
|
POLYEXTRA
Type I |
POLY
V
Type V |
POLYPLUS
Type II |
POLYHARD
Type III |
| Hardness |
|
|
|
|
| Barcol |
34-42 |
46-54 |
54-62 |
64-72 |
| MOHS |
3.0 |
3.5 |
3.5 |
4.0 |
| Specific
Gravity |
|
|
|
|
| gms/cc |
1.15-1.25 |
1.15-1.20 |
1.47-1.52 |
1.47-1.52 |
| Bulk
Density |
|
|
|
|
| lbs./cu.
ft. |
45-48 |
45-48 |
58-60 |
58-60 |
Maxumum
Operating
Temperature deg. F. |
250 |
200 |
300 |
350 |
| Chemical
Nature |
inert |
inert |
inert |
inert |
TOP
|
 WALNUT
SHELLS
Shells
are used in a number of delicate blasting operations, eliminating
scratching or pitting of surfaces. One of the largest uses today
is deflashing of molded plastic parts. Some other applications include:
| Blast
Cleaning |
|
Jet
Engines
Baking Pans
Industrial Fans
Iron Core Boxes
Turbine Generators
Plastic and Rubber Molds
Tanks, Ducts and Other Inaccessible Areas
Metal, Glass and Wood Surfaces for Refinishing |
| Deburring |
|
Metal
Stampings
|
| Deflashing |
|
Metal
Castings
|
| Polishing |
|
Gems
and Jewelry
|
| Texturizing |
|
Plywood
(Blasting to Raise Grain]
|
| Tumbling |
|
Plastic,
Hard Rubber and Metal Parts
|
Shelblast can be used in an air, mechanical (wheel-type), vapor or
liquid blasting systems. It is recommended that Shelblast be used
in an automatic closed system for both good housekeeping and good
economics. It is available in seven sizes from very coarse, for cleaning
large parts rapidly, to super fine for cleaning delicate electronic
parts with fine openings and grooves.
AD-1B
AD-2.5B
AD-3B
|
|
(- 6 + 10 mesh)
(- 8 + 12 mesh)
(- 12 + 20 mesh]
|
|
AD-4B
AD-6B
AD-7B
|
|
(- 14 + 30 mesh)
(- 18 + 40 mesh)
(- 35 + 60 mesh)
|
AD-9B
(- 40 + 100 mesh)
Mesh designations are U.S. Standard Screen Sizes
Shelblast is relatively dust free with particle size concentrations
in the upper end of the mesh range which means more cycles before
it is removed as fines. There is typically less than 1% loss in weight
per cycle.
PROPERTIES:
Shelblast products have the following characteristics:
|
Dry Packing Density (Lbs. per Cu. Ft.)...........
Flash Point (Closed Cup)................................
pH Value at 25 C (In Water)............................
Free Moisture (80 C for 15 Hrs.).....................
Specific Gravity..............................................
Hardness - Vickers No...................................
MOHS Scale...................................................
|
|
42-47
380 F
4-6
3-10%
1.35
25-30
3-4
|
TOP
|
SILICON
CARBIDE
This media is sharper and harder than Aluminum Oxide. It has very
quick cleaning or blasting properties because of the slivery shape,
which fractures and stays sharp.
The hardness of approximately 9.5 MOHS, which makes it an excellent
choice for blasting hard surfaces such as glass, marble, and granite.
Silicon Carbide is considered to be one of the most aggressive forms
of media in the blasting industry today.
Silicon
Carbide (SiC)
Hardness Comparion
Crystal Shape
Heat Generation
Lubricants
Grits Available
Heat Conductivity
|
|
9mohs 10x softer
SiC:sharp, pointed
Hot
Greases, water or none
6-2400
Low
|
TOP
|
STEEL
SHOT AND STEEL GRIT
 These
forms of media are very dense and durable. They are used in Airless
and Pneumatic Blast Systems.
The round shot gives a better finish than that of the grit, however
grit cleans faster due to the angular shape. Both shot and grit
are a popular choice of blasting media because of the high reclaim
ability. (Losing
approximately 1 Lb. per 100 Lb. blasted at 90 p.s.i.) The majority
of all Automated Airless
Blast Systems are using steel shot, grit, or a mixture of the
two. Stainless is used on non-ferrous applications.
 Typical
hardness for rapid cleaning and long wear life is 44 to 46 RC.
Softer RC does not clean as well and harder RC tends to break
down faster, while the size of the abrasive being an important
factor. Removing heavy sand on scale may require a particular
size. To keep cost low, always use the smallest size possible.
Typical Applications:
|
*Heat Treat Removal
*Mill Scale Removal
*Paint Removal |
|
*Sand Removal From Castings
*Pre-Paint Adhesion
*Peening |
SAE
Shot & Grit Size Specifications
Screen Opening Sizes and Screen Numbers with Max. and Min. Cumulative
Percentage Allowed on Corresponding Screens.
|
HIGH
LIMIT SCREEN |
NOMINAL
SCREEN |
LOW-LIMIT
SCREEN |
Shot
Number |
S-780
S-660
S-550
S-460
S-390
S-330
S-280
S-230
S-170
S-110
S-70
|
|
Max%
retained |
Screen
no.
&aperture |
Max%
retained |
1%
1%
1%
1%
1%
1%
1%
1%
1%
All Pass
All Pass
|
7(0.111)
8(0.0937)
10(0.0787)
10(0.0787)
12(0.0661)
14(0.0555)
16(0.0469)
18(0.0394)
20(0.0331)
30(0.0232)
40(0.0165)
|
---
---
---
5
5
5
5
10
10
10
10
|
|
Screen
no.
&aperture |
Min%
retained |
Screen
no.
&aperture |
---
---
---
12(0.0661)
14(0.0555)
16(0.0469)
18(0.0394)
20(0.0331)
25(0.0280)
35(0.0197)
45(0.0138)
|
85
85
85
85
85
85
85
85
85
80
80
|
10(0.0787)
12(0.0661)
14(0.0555)
16(0.0469)
18(0.0394)
20(0.0331)
25(0.0280)
30(0.0232)
40(0.0165)
50(0.0117)
80(0.0070)
|
|
Min%
retained |
Screen
no.
&aperture |
97
97
97
96
96
96
96
97
97
90
90
|
12(0.0661)
14(0.0555)
16(0.0469)
18(0.0394)
20(0.0331)
25(0.0280)
30(0.0232)
35(0.0197)
45(0.0138)
80(0.0070)
120(0.0049)
|
|
Grit
Number |
G-10
G-12
G-14
G-16
G-18
G-25
G-40
G-50
G-80
G-120
G-200
|
|
Max%
retained |
Screen
no.
&aperture |
Max%
retained |
1%
1%
1%
1%
1%
1%
1%
1%
All Pass
All Pass
All Pass
|
7(0.111)
8(0.0937)
10(0.0787)
12(0.0661)
14(0.0555)
16(0.0469)
18(0.0394)
25(0.0280)
40(0.0165)
50(0.0117)
80(0.0070)
|
|
|
Screen
no.
&aperture |
Min%
retained |
Screen
no.
&aperture |
| |
80
80
80
75
75
70
70
65
65
60
55
|
10(0.0787)
12(0.0661)
14(0.0555)
16(0.0469)
18(0.0394)
25(0.0280)
40(0.0165)
50(0.0117)
80(0.0070)
120(0.0049)
200(0.0029)
|
|
Min%
retained |
Screen
no.
&aperture |
90
90
90
85
85
80
80
75
75
70
65
|
12(0.0661)
14(0.0555)
16(0.0469)
18(0.0394)
25(0.0280)
40(0.0165)
50(0.0117)
80(0.0070)
120(0.0049)
200(0.0029)
325(0.0017)
|
|
ROTOBLAST STEEL SHOT
| Pellets
per pound |
S-780
S-660
S-550
S-460
S-390
S-330
S-280
S-230
S-170
S-110
S-70
|
|
9,353
16,200
23,625
38,118
74,238
114,835
206,420
376,585
852,632
2,520,000
9,651,064
|
TOP
|
| | | |
