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5.9
The blast pattern
Abrasive leaving the blast wheel blades is not thrown in all directions. Scatter is restricted to an angle of about
80°. This is achieved through the use of a control cage which surrounds the impeller. The position of the
window in the control cage determines the blast pattern.
Correct adjustment of the control cage and thus of the blast pattern is the most important factor for optimum
working with the blast cleaning machine.
Incorrect adjustment of the control cage results in very high wear and premature blasting-through of the liners
in the blast wheel housing, as well as reduced blasting performance and a possible loss of the rebounce energy
of the abrasive.
The following 5 factors affect the blast pattern:
-The turning direction of the blast wheel must correspond to
the instructions on the housing (arrow indicating the turning direction).
-With increased wear of the blast wheel, blades, impeller and control cage,
the blast pattern will change.
-The size of the abrasive affects the blast pattern. With every exchange of
abrasive, the blast pattern
must be re-adjusted.
-The correct adjustment of the control cage is the most important factor to
obtain an optimum blast
pattern. Each control cage has a lateral window. The position of the window
determines where the abrasive is fed
onto the blast wheel blades and where it hits the surface to be treated.
-Different types and hardness of surfaces.
1
Cage clamp
2
Control cage
Shot valve housing
3
And feed spout rubber
21
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