Graco 262960, Instructions Manual

Page: 21 / 68

Operation
3A7467D 21
Refill Pot with Media
As abrasive media leaves the pot during blasting, follow
the
Fill Pot with Abrasive Media procedure, page 17.
NOTE: If the pot loses pressure, follow the Pressurize
the Pot procedure, page, 18 .
Set the Abrasive Metering Value
The optimal setpoint of the abrasive metering valve and
corresponding MediaTrak CPM (cycles per minute)
value varies significantly depending on application and
user desired performance. The
General Application
Guides , page 22, describe the generally accepted
range of CPM setpoints based on the substrate and
blast pressure setpoint. The gray highlighted area
illustrates the typical range of blast pressure setpoints
and their corresponding CPM setpoints for that
substrate.
To find the recommended CPM setpoint, select the table
that most closely matches the substrate that is to be
blasted. Determine the blast pressure setpoint based on
the media that is being used, and the desired surface
profile to be achieved. Then, use the corresponding
lines on the chart to select the appropriate CPM
setpoint.
For inexperienced users, select a blast pressure near
the low end of the highlighted range. Increase blast
pressure and CPM until the desired profile and removal
rate are achieved.
Optimize the Abrasive Metering
Value
To optimize performance, use the High Production or
Media Efficient lines on the charts. CPM setpoints near
the High Production lines will yield the highest removal
rates, and the highest media consumption rates. To
maximize removal rate regardless of media
consumption, use the highest possible blast pressure
and set the CPM to the highest achievable value that
produces a consistent pattern. The CPM setpoint is too
high if the flow from the nozzle starts to sputter.
CPM setpoints near the Media Efficient line will use the
lowest amount of media. To minimize cleanup and
media usage, use a setpoint closer to this line.
Generally, removal rates will be less than average when
setting the CPM according to this line.
The charts on the following page are only guidelines.
They were developed using garnet media in the 30-80
mesh range. Coarser media will produce a deeper
profile, but will require higher CPM setpoints to yield
similar removal rates to the setpoints shown in the
tables. Finer media will yield higher removal rates, but
will not produce as deep of a profile.
Fine tuning and experimentation are necessary to
optimize performance for each application.
See the General Application Guides , page 22.