Troubleshooting the Blast Cleaning Process

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Troubleshooting The Blast Cleaning Process

troubleshooting blast cleaning process

Guidelines for controlling the three basic blast cleaning operating variables

These three variables account for as much as 90% of all problems adversely affecting quality of finish, cleaning productivity, and operation costs.

porper blast pattern aim

  • 1) Check location of blast-pattern “hot spot” regularly. (Test-blast a metal target plate placed at normal work height for 20-30 seconds. Hot spot should be approximately 8” in advance of wheel center-line.)
  • 2) Inspect daily, degree of wear of wheel components:
    • Impeller: Change when leading edges exceed ⅛" wear.
    • Control Cage: Change when beveled edge exceeds ¼" wear
    • Vanes/Blades: Change when grooving is ½ thickness of blade.

Excess wear of wheel components distorts blast pattern and causes “hot spot” to shift (10% shift can cause 25% loss of cleaning efficiency.)

  • 3) Do not permit sand or excess fines in the work mix. (2% Sand content can double wear rate on wheel components.)
  • 4) Establish records of parts replacement vs. wheel hours operated, so preventative maintenance can be utilized.

balanced work mix

  • 1) Screen analyze work-mix weekly.
  • 2) Add new abrasive every operating shift.
  • 3) Do not allow abrasive spillage/leakage to accumulate; return to machine daily.
  • 4) Check Separator/Ventilating system regularly:
    • Scalp screens: Holes? Blockage?
    • Shred Plates: Holes? Be sure a full abrasive curtain exists.
    • Keep dribble valves on all separator or expansion-trap discard pipes.
    • Dust Collector Pipes: Check for dust buildup in pipes.
  • 5) Check separator and dust-collector baffle settings regularly to be sure air-flow is correct.

full anrasive flow

  • 1) Add new abrasive every operating shift and maintain hopper level above ⅔ full always.
  • 2) Keep all paper, cardboard, plastic, wood, and other trash out of the blast cleaning equipment
  • 3) Be sure scalp screens are clean and not plugged.
  • 4) Check wheel components daily for excess wear.
  • 5) Check feed control valve to be sure it is functioning properly.
  • 6) Check for worn or loose drive belts.
  • 7) Post the “Full Amps” target above each ammeter. Record actual readings every shift.
  • 8) Keep ammeters in good working order at all times.

ervin spot check gauge

Check to see where top of work-mlx levels off. = X Mark X on the scale at right

The best protection against inefficient operation is to make frequent analysis of your blast cleaning operations.

FEED HOPPER LEVEL: When too low: Runs the risk of insufficient feed to wheels; Indicates work-mix is out of balance, and cleaning-profiling will be poor.

AMMETER READINGS: If below full-rated amps, wheel is being short-changed. For each amp below full-rate, approximately 30 lbs of abrasive is not thrown. What isn't thrown can't clean-profile your work.

TARGET POUNDS PER WHEEL-HOUR: SAE-quality cast steel shot or grit, in a properly operated system, should equal .35 lbs per hp per wheel hour usage rate. (Example: wheel hp at 40, times .35 equals 14 lbs per wheel hour usage. If usage is at 21 lbs/wh, consumption is 50% higher than it should be.)

WORK-MIX ANALYSIS (SPOT-CHECK):

W/M x in green-zone represents optimum operation, with respect to:

  • Cleaning-profiling finish: Productivity; and Abrasive consumption.
  • W/M x above the green zone means the w/m is too coarse for efficient and effective cleaning-profiling - Result:
    • Spotty cleaning-profiling, finish too rough, parts warpage, breakage;
    • Blast-cycle time can be 25% to 100% more than normal, or re-blast is required;
    • Equipment wear/tear can increase greatly
    • Shot and grit consumption can increase easily as much as 100%, or more.
  • If the w/m x is in the yellow zone, it is an indication the operation has serious problems - but, when x in the red zone, it means the operation is flirting with disaster.

When the operations analysis indicates trouble - it's time to review the ERVIN TROUBLESHOOTING GUIDELINES shown on the reverse side.

Download a PDF of the full poster here.

or Call Ervin Today at 1-800-748-0055

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P: (734) 769-4600 / TF: (800) 748-0055 / F: (734) 663-0136
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Ervin Industries
3893 Research Park Dr
Ann Arbor, MI 48108
734-769-4600


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