BLASTING TECHNICAL INFORMATION - MC Finishing
BLASTING TECHNICAL INFORMATIONBLAST FINISHINGBlasting is the process where small angular or spherical particles are propelled at a partby compressed air, or mechanical high speed rotating wheels or water pumps .The blast media type, shape, size, density, and hardness, along with media accelerationand volume of media, combined with blasting distance from the workpiece, angle ofimpact and time cycles are important factors in the blast process capabilities.The blasting equipment is produced to deliver, reclaim and contain the media, containthe part to be blasted and collect the dust from the blasting process. Parts can beprocessed individually as a batch process or can be automated thru the system.Surface affects from the blasting process are:VISUALMECHANICALBright Matte finishDeburringDull Matte FinishDe-flashingSatin finishPaint and coating removalSatin luster finishPeeningBlending of tool marksPre paint and coating adhesionRemoval of weld discolorationHeat treat, mill scale removalSurface cleaningWeld splatter removalGlass frosting and etchingThermal metal spray prep.Pre plate and anodize finishesRust removalMold cleaning
BLASTING TECHNICAL INFORMATIONFACTORS THAT AFFECT BLAST FINISHING ARE:1. Media delivery systems2. Blast containment enclosures, media recovery and dust collection systems.3. Media used in industrial blasting systems1. MEDIA DELIVERY SYSTEMSThere are three media delivery systems that propel and deliver media for high speedimpact to the part being processed.A. Air Blasting ( Pneumatic)B. Mechanical Wheel (airless blasting)C. Hydro blasting (pumped water)A. AIR BLASTING utilizes an air compressors energy to deliver air/media mix atspeeds and volumes to impact the parts being processed.The air speed or pressure of an air compressor is controlled by a pressure regulator.The regulator can increase or decrease the speed of the media delivery. Air pressure ismeasured by pounds per square inch (psi), industrial blasting is effectively donebetween 20 and 90 PSI. The higher the PSI the higher the air speed.The volume delivered of the air/media mix is determined by the orifice or openingdiameter of the nozzle with pressure blast systems or air jet diameter of the suctionblast gun body. Air volumes are measured by surface cubic feet per minute (scfm).The larger the orifice ID opening the larger volume of air/media. Other factors that affectvolume of air into the blast system is media and air hose diameter. Increased airpressure (PSI) also increases the SCFM with a given size orifice.Industrial blasting gun bodies of suction cabinet blast systems range between 12 to 38SCFM. The pressure blast cabinet systems range between 12 to 68 scfm and thepressure blast room systems use up to 254 scfm.Industrial air compressors produce approximately 4.5 SCFM per horse power (hp).Blasting cabinets require 3 to15 hp compressors per nozzle and blast rooms can use upto 53 h.p. per man or nozzle.
BLASTING TECHNICAL INFORMATIONTHERE ARE TWO TYPES OF AIR BLAST DELIVERY SYSTEMSSuctionPressure( used in blast cabinets)( used in blast cabinets, blast rooms, and outdoor blasting)SUCTION blasting uses the venture principle sucking media from a hopper. The air jetis 1/2 the ID of the nozzle and as the air stream is passed through both, it creates a lowpressure which sucks the media from the hopper into the air stream. The mediaacceleration distance is very short ( from the nozzle to the workpiece-approximately4 to 14”). The suction systems work fine and can be continuously blasted as long asthere is blasting media in the hopper.Suction systems do not deliver mediawell at very low air pressures (5 to 25psi) and they have limits on how longthe suction feed hose can be. Veryheavy blasting ( larger steel media)cannot be conveyed into the air streamwith suction blasting. Most industrialblast cabinets are suction systemsand work well with most medias.PRESSURE blasting utilizes various sizes of ASME approved pressure vessels calledpressure pots. The pressure pot contains the media, and as it is energized withcompressed air, it pressurizes the pot. When the air/media mix is released from the potit accelerates from the pot through at least 5-10 feet of hose and then even faster as ittravels thru the ventura of the nozzle. The acceleration rates of air/media mix are muchhigher in pressure blasting than suctionblasting. When the pressure potempties of the media and air, thepressure pot has to be depressurized torefill the pot with media. The pressureblasting systems are much moreproductive when blasting than suctionsystems. Pressure systems can blast allmedias regardless of weight or size andcan also deliver medias at very low psi.
BLASTING TECHNICAL INFORMATIONAIR BLAST SYSTEMS - AIR CONSUMPTION RATESBelow are charts of air volume (SCFM) used in blasting with pressure and suctionsystems utilizing various pressures (PSI) and orifice sizes.CABINET BLAST SYSTEMS - AIR REQUIREMENTSSuction SystemsPressure SystemsSuction-Blast Air Requirements (scfm)Pressure-Blast air requirements (scfm)Pressure (psi) 30 40 50 60 70 80 90 100Pressure (psi) 20 30 40 50 60 80 100 1201/4” nozzle 3/32 jet 6 7 81/4” nozzle 1/8 jet 10 12 155/16” nozz 5/32jet 15 19 237/16” nozz 7/32 jet 31 38 451/8” nozzle3/16” nozzle1/4” nozzle5/16” nozzle3/8” nozzle1017275211 12 13 1519 21 23 2631 37 38 4259 66 73 80615274255818325073102241649113 1426 3049 5578 88109 12617486811316120 2545 5581 97137 152196 220BLAST ROOMS AND OUTDOOR SYSTEMS - AIR REQUIREMENTSAir consumption and media delivery rates are much higher on blast rooms and outdoorblasting systems than in pressure blast cabinets. The air supply hose ID, the mediablast hose ID, the nozzle ID, the pressure pot and pot piping are all much larger on theblast rooms than cabinet systems. The increase in production is also due to the furtherdistance that the nozzle is from the work piece in blast rooms creating a larger blastpattern.Pressure- blast requirements (blast rooms)Nozzle Air (CFM)Air compressor horse powerLbs Sand hour546112 13.5312 35468154067416.544881184949721.5582Air (CFM)Air compressor horse power89 101 11320.0 22.5 25.512628.013730.515234.03/16”#3AIR (CFM)Air compressor horse powerLbs Sand hour3071711/4 “#45/16”#5120
BLASTING TECHNICAL INFORMATION3/8”#6Lbs Sand hour534Air (CFM)Air compressor horse powerLbs Sand hour126 143 16128.0 32.0 36.0754 864 960Nozzle 49.01,152 1,320909121001207/16”#7Air (CFM)Air compressor horse powerLbs Sand hour170 194 217240 25438.0 43.5 48.5 53.5 56.51,032 1,176 1,312 1,448 1,58430067.01,8001/2”#8Air (CFM)Air compressor horse powerLbs Sand hour224 252 28039033850.0 56.0 62.5 69.0 75.01,336 1,512 1,680 1,856 2,02439287.52,352AIR BLAST PRODUCTION RATESBlast nozzle spray patterns are affected by orifice size, air pressure, and distancefrom the workpiece.The total diameter of the blast pattern increases as the distance from the workpieceis increased. The hot spot (where work speed is maximized) can be obtained atlarger distances from the workpiece with pressure air blast systems.CABINET SUCTION BLASTINGCABINET PRESSURE BLASTING
BLASTING TECHNICAL INFORMATIONCABINET BLAST PRODUCTION RATESBelow is an estimate of abrasive delivery rates per hour and sq. ft. of blast area insq. ft. per minute with various orifice I.D.ʼs and 80 p.s.i.I.D.CFMPSIBlast Area Sq.Ft./MinuteAbrasive Unit Hr.3/32”7801/280 lbs1/8”15801 to 1-1/2120 lbs5/32”25801 to 2-1/2160 lbs3/16”1/4”408080803 to 3-1/24 to 4-1/2216 lbs400 lbsBLAST ROOM AND OUTDOOR BLAST PRODUCTION RATESBLAST SPECIFICATIONSESTIMATED BLAST CLEANING RATESNO 1 WHITE METAL BLASTSSPC-SP5Approx. Sq. Ft. Cleaning Per Hourat 90 PSILoose Mill ScalePitted PaintNO 2 NEAR WHITE BLASTSSPC-SP10Approx. Sq. Ft. Cleaning Per Hourat 90 PSILoose Mill ScalePitted PaintNO 3 COMMERCIAL BLASTApprox. Sq. Ft. Cleaning Per Hourat 90 PSI#7 NOZZLE170 Sq. Ft85 Sq. Ft.Tight Mill ScaleLayered Paint180 Sq. Ft.90 Sq. Ft.Tight Mill ScaleLayered Paint420 Sq. Ft.200 Sq. Ft.Tight Mill ScaleLayered Paint840 Sq.Ft.830 Sq.Ft.Tight Mill ScaleLayered Paint#7 NOZZLESSPC-SP6Loose Mill ScalePitted PaintNO 4 BRUSH - OFFSSPC-SP7Approx. Sq. Ft. Cleaning Per Hourat 90 PSILoose Mill ScalePitted Paint140 Sq. Ft.70 Sq. Ft.146 Sq. Ft.72 Sq. Ft.#7 NOZZLE270 Sq. Ft.140 Sq. Ft.#7 NOZZLEFor more information on blast specifications contact SSPC.orgB. MECHANICAL WHEEL BLASTINGWheel blast system utilizes a high speed rotation wheel usingcentrifugal force to propel the media. The wheel size designand rotation speed affect the velocity and pattern of the media.835 Sq.Ft.825 Sq.Ft.
BLASTING TECHNICAL INFORMATIONThe abrasive is fed into the rotating wheel. The impact on the media by the hardrotating wheel usually restricts media selection to a very tough steel or stainless steelshot or grit.Machines can be built with multiple wheels for automation. Automated systems includebasket, table, spinner hangers and continuous conveyor processing.Wheel blast systems are a less expensive way to blast (due to higher mediarecycleability and automation) than air blasting by a factor of 10. Their disadvantageare restrictions to very few mediaC. HYDRO BLASTINGThis blasting system uses a pressurized water stream generated by pumps that arecapable of pumping an abrasive charged water supply at high rates of speed.The Hydro Systems are good for conveying very fine abrasives. They are also usedin cleaning gunky, greasy parts, and containing toxic materials.The wet blast systems are very good at blasting surfaces without damage andblasting internal surfaces.ALL INDUSTRIAL BLAST SYSTEMS HAVE THE FOLLOWING COMPONENTS:Delivery Systems (Air or Wheel Blasting)Containment Systems (Hand cabinets, Automated enclosures, and Blast rooms)Reclaim SystemsDust CollectionContainment SystemsHand cabinets, automated enclosures and blast rooms are built to handle varioussize and shapes of parts. The containment systems are built to control andcontain the blast media and parts within the enclosures.The enclosure systems usegravity for the blasted media to drop down to a collection area so the media canbe conveyed to the reclaim system. Blast systems can have inexpensive orpremium containment systems. Matching the right containment system to theapplication is very important.
BLASTING TECHNICAL INFORMATIONMedia Reclaim SystemsRecoverable medias used in industrial blast systems will run from 5 to 100times through the blast system. These recoverable medias need to becleaned, sized and returned to the blast system after being blasted. The mediareclaim system accomplishes this. The reclaimer keeps finish and productionrates consistent. Media reclaim systems can be Air Cyclones or MechanicalSystems.Dust CollectionAll Industrial blast systems utilize dust collectors to allow blast systems tobe indoors. The dust collector removes the fine blasting dust keeping themedia clean and operators safe through visibility and breathable air. Dustcollectors remove 99% of 1 micron or larger material. Hepa filters can beadded to remove dust particles down to 1/2 micron.Dust collectors are sized to thecabinet size, media type, and amount of blast nozzles or wheels being used.BLAST MEDIASRecoverable blasting medias are used in industrial blasting. Indoor blastingsystems require medias with extended life. Blast media, type, shape, sizeand hardness affect the process and materials theyʼre capable of blasting.Spherical medias are used for peening and produce smoother surface finishes.Angular medias chip at a parts surface; removing paint, rust and scale quicker,with better results than round medias. Angular medias produce a roughersurface finish and produce superior anchor patterns for paint and coatingadhesions. Higher blast pressures increase production but reduce media life.Blasting harder workpieces also reduces media life.Recoverable blasting medias have two basic shapes. Round (spherical)and angular. The most common recoverable industrial blast medias are:Spherical shaped mediaAngular shaped mediaCeramic beadsAluminum oxideSilicon carbideGlass beadsCeramic gritStainless gritStainless shotCrushed glassSteel gritAluminum Oxide (AL2O3) is a man made fused alumina that is very tough; angularblocky shaped, medium density, with a hardness of 9 on the Mohs scale. This
BLASTING TECHNICAL INFORMATIONabrasive is designed for high blasting pressures up to 90 PSI. Aluminumoxide is very good for light deburring and surface prep (bonding strength)prior to painting and coating. AO creates a dull matte finish.Aluminum oxide has medialife of approximately10-12 times through the blast system.Typical Aluminum Oxide blasting applications: cleaning of investment castingsScale removalThermal spray coating prepRust removalHard oxide removalHeat treat and mill scale removalGlass frosting and etchingMonument lettering and carvingAir craft engine overhaulMatte finishingsurface prepdurability up to 20 passesNo free silicasGrit Size Conversion for AO and SICGrit SizeInches (average) 80.00480.00350.00300.0025122102897663Silicon Carbide (SIC) is a man made abrasive that is very sharp and friable. SC is veryhard at 9.5 on the mohs scale. It is used to blast very hardmaterials such as tool steels, glass and ceramics. SCcreates a dull matte finish. The grit sizes available are thesame sizes as aluminum oxide. SC blasts at pressures upto 90 psi and has an approximate life of 9-12 times thru theblast system.Typical Silicon Carbide blasting applications Sizing same as aluminum oxideBlasting hard metalsGlass etchingCeramic recast removalVery tough scale removalHeavy profile and metal preparationBefore brazing and weld applications requiring no aluminum oxide contamination
BLASTING TECHNICAL INFORMATIONGlass Beads and Glass Grit Glass bead is a round glass used in peening and surfacefinishing on tight tolerance machined surfaces. Glass Beads create a bright mattesurface finish with no surface contamination or damage. As a round particle beads arevery slow on removal of paint, rust, or scale. Glass grit is the angular counterpart ofglass beads. Glass grit is very aggressive on a blasted surface.Glass beads are blasted at pressures between 40-80 psi. Glass bead media life cyclesare 9 - 12 times thru the blast system.Typical Glass Bead blasting applications: Light deburringGrit Size Conversion Chart for Glass Beadssurface cleaningMil-G-9954A Average Inches Average Micron US Screen SizePeening#3.028372520-30 meshBlending machine marks#4.018751230-40 meshRemoval of welding discolor#5.013936340-50 meshBlasting tight tolerance parts#6.010525650-70 meshProduces a bright matte finish#7.008421560-80 meshPre Anodize finishing.#8.007118170-100 mesh#9.006015380-120 mesh#10.0047120100-170 mesh# 11.0039100120-200 mesh# 12.003385140-230 mesh# 13.002668170-325 meshCeramic Blast Media Ceramic Beads are spherical shapedmedia with high mechanical strength and high wear rates.Ceramic is impact resistance creating very little dust. Theceramic beads keeps its round consistency and is chemicallyinert. Ceramic blast processes produce a smooth bright satinfinish. The ceramic beads density creates higher impact speedmaking it a good choice for deburring and peening. Blastpressure recommendations are between 40-65 psi with mediacycle lives between 70-90 times thru the blast system.Ceramic blast media is very versatile and can be blasted with alldelivery systems,( air, wheel and water) Ceramic beads is astandard peening material for titanium parts. Ceramic grit isangular and is excellent for etching parts with extended media life.
BLASTING TECHNICAL INFORMATIONTypical Ceramic Media blasting applications Peening Titanium Non contamination High impact for deburring Long media life applications Bright surface finish requirements Aircraft and medical partsStainless Steel Blast Media is available in both shot (cut wireconditioned and casted) and grit. Stainless media is available in302-304 and 316 alloys. Stainless is a softer but heavier media that isa good choice for short blasting times, deburring, and rust freesurfaces. It produces a brighter finish with reduced blast machinewear rates. Stainless shot obtains some the highest media recoveryrates of up to 150-200 cycles through the blast system.Blasting pressure can be as high as 90 PSI.Typical Stainless Steel blasting applications: Blast cleaning, de-burring, surface refinement, surface finishingAll types of aluminum castings and forgingsZinc pressure die castingsNon-ferrous metals and special alloysStainless steel castings and forgingsStainless steel equipment fabricationGranite and stone industrySteel Shot and Grit MediaSteel blast media is produced in round/spherical shape (conditioned cut wire and castshot) and angular steel grit. Steel abrasives are very durable making it the first choicein blast rooms and automated wheel applications. The hardness rangesbetween 40 to 65 Rockwell. Conditioned cut wire (rounded) is the primary choicefor shot peening over cast shot that produces an unfavorable angular breakdownwhile blasting. Steel shot and grit is very often mixed to achieve both anchorpatterns with good finishes. Steel shot can be blasted with very high pressures ofup to 110 PSI. Media cycle lives are between 80-100 times through the blast cycle.
BLASTING TECHNICAL INFORMATIONSteel shot and grit blasting applications: Blast Rooms for long media lifeWheel blasting for long media lifePaint prep on steel partsDeburringScale and rust removalAluminum Casting and weldment blastingPipe blasting (ID & OD)SHOT & GRIT SIZINGSteel ShotSteel GritS390 All Pass No. 12 Screen5% Max on #14 Screen85% Min on #18 Screen96% Min on #20 Screen.0661 - 1.70.0555 - 1.40.0394 - 1.00.0331 - 0.850G25 All Pass on # 16 Screen .0469 - 1.1870% Max on # 25 screen .0278 - 0.71080% Min on # 40 screen .0165 - 0.425S330 All Pass No. 12 Screen5% Max on #14 Screen85% Min on #18 Screen96% Min on #20 Screen.0555 - 1.40.0469 - 1.18.0331 - 0.85.0278 - 0.710G40 All Pass on # 18 Screen .0394 - 1.0070% Max on # 25 Screen .0165 - 0.42580% Min on # 40 screen .0117 - 0.300S280 All Pass No. 16 Screen5% Max on #18 Screen85% Min on #25 Screen96% Min on #30 Screen.0469 - 1.18.0394 - 1.00.0278 - 0.710.0234 - 0.600G50 All Pass on # 25 Screen .0278 - 0.71065% Max on # 50 Screen .0017 - 0.30070% Max on # 80 Screen .0070 - 0.180S230 All Pass on #18 Screen10% Max on #20 Screen85% Min on #30 Screen97% Min on #35 Screen.0394 - 1.00.0331 - 0.850.0234 - 0.600.0197 - 0.500G80S170 All Pass on #20 Screen10% Max on #25 Screen85% Min on #40 Screen97% Min on #45 Screen.0331 - 0.850.0278 - 0.710.0165 - 0.425.0139 - 0.355G120 All Pass on # 50 Screen .01117 - 0.30060% Max on # 120 Screen .0049 - 0.12570% Min on # 200 Screen .0029 - 0.075S110 All Pass on #30 Screen10% Max on #35 Screen80% Min on #50 Screen90% Min on #80 Screen.0234 - 0.600.0197 - 0.500.0117 - 0.300.0070 - 0.180All Pass on # 50 Screen .0165 0.042560% Max on # 80 Screen .0070 - 0.18075% Min on # 120 Screen .0049 - 0.125
BLASTING TECHNICAL INFORMATIONMEDIA OVERVIEW:
BLASTING TECHNICAL INFORMATIONRECOVERABLE MEDIA LIFE CYCLESMedia Life CyclesSilica sand% Breakdown1100%Garnet3-525%Plastic Media7-913%Glass Bead9-1210%Silicon carbide9-1011%Aluminum oxide10-129%Ceramic media70-901.2%Steel shot, gritStainless shot, grit80-100150-2251%0.5%RECOVERABLE MEDIA COSTINGCostingMedia Cost Per HourHourly Delivery Rate x % Breakdownx Cost per LbMedia Cost to Blast a partHourly Delivery Rate x % Breakdownx Cost per Lbx Part cycle time (% of Hour)Other factors in total blasting cost include; air compressors, labor, blast systemcosts and media disposal fee. If blasting heavy metals use a highly recyclablemedia.
BLASTING TECHNICAL INFORMATIONOVERVIEW: OF BLAST FINISH
BLAST FINISHING Blasting is the process where small angular or spherical particles are propelled at a part by compressed air, or mechanical high speed rotating wheels or water pumps .
oitted to Ecellence in Mining Safety Last Modified: Page: JAN 2013 2 of 21 www.coresafety.org MODULE 12 (C ONT.)Surface Blasting Safety Procedures Blasting Materials Surface delays, detonators or blasting caps, boosters, safety fuse, down-line and other explosives used for blasting.
4. Identify best practices for drilling and blasting operators to implement while undertaking Close Proximity blasting operations. 5. Act as a supplement to applicable local, provincial, state, and federal by-laws and/or regulations pertaining to aspects of drilling and blasting activities. 6. Identify best practices to assist drilling and blasting
Chapter 296-818 WAC Abrasive Blasting _ Page 1 WAC 296-818-099 Definitions. Abrasive. A solid granular substance used in abrasive blasting operations. Abrasive blasting. The forcible application of an abrasive to a surface using either: (a) Pneumatic or hydraulic pressure; or (b) Centrifugal force. Abrasive-blasting respirator. A supplied air or a continuous flow respirator constructed with a
FINISHING EQUIPMENT GROUP SALES - SERVICE - HIRE TRAINING - INSTALLATION _ NORTH EAST BRANCH Hogg Blasting & Finishing Equipment Ltd Washington. UK. NE37 1PR Tel. 0191 415 3030 info@hoggblasting.com NORTH WEST BRANCH Abraclean Ltd and Jedtec Finishing Equipment Manchester. UK. M11 2QA Tel: 0161 480 8087 info@sfeg.co.uk Shot Blasting .
blasting of cornices increases efficiency, boring holes along the presumed tension line exposes the ava-lanche blaster to considerable danger. Safety in borehole blasting depends critically on: 1. The blasting crews ability to judge correctly the safe working line. techniques for working with this high explosive (See Chapter 5 - Detonating Cord).
Underground Mining Development . Different Access to Ore Bed . Mining Cycle . Some Examples . Surface mining Development . Blasting . Explosives . Drift or Tunnel Blasting . Blast Pattern Design . Firing Sequence . Smooth Wall Blasting . Supporting . Objective . Material Used and reinforced . Basic
permissible dry outdoor blasting as complying with specific performance standards. The performance standards require that the abrasives shall not contain more than 1 % by weight material passing a #70 U.S. standard sieve before blasting, and . that . after blasting the abrasives shall not contain more than 1.8% by weight material 5 microns or smaller.
associated with abrasive blasting. This Code may be a useful reference for other persons interested in the duties under the WHS Act and WHS Regulations. This Code applies to all workplaces covered by the WHS Act where abrasive blasting processes are carried out and where abrasive blasting products and equipment are used and stored.
