Macfab has four variables with just the abrasives: abrasive size, abrasive type, abrasive quantity, and velocity of the air, to adjust to find the appropriate process to meet customer specifications. If the part requires an etching or micro hole drilled, an Aluminum Oxide type would be used; however, if the goal was cleaning the surface of a part, a Sodium Bicarbonate (baking soda) would be selected. The size of the abrasive can range from 10 µ (micron) (0.0004 inches) up to 250 µ (0.010 inches) determining speed and surface finish capabilities. The velocity of the abrasive can be high enough to cut through the workpiece, or gentle enough to simply remove a coating from a part.

Additional control options include mechanical settings: nozzle shape and size, distance from the part, and angle of the nozzle. The nozzles can have a circular hole or a rectangular hole of sizes from 0.018” to 0.125”. The distance from the end of the nozzle to the workpiece can have a wide impact on the diameter of the cutting action on the workpiece, by a factor of 4 as the distance grows. The angle of the nozzle is important for the deburring operation to be optimized the abrasive stream needs to fully contact the burr to remove it. While it can seem overwhelming, please let our engineering experts at Macfab control these variables to achieve the result you desire.

Another function of shot peening is to improve the surface hardness of a part. This commonly has a customer requesting test samples be supplied of the process. If the MicroBlasting is required for surface hardness improvement, peening, an Almen strip can be used to validate the process. If the surface finish is being improved, a Ra reading may be possible or comparison under a microscope. A Ra of 5 µ is the finest possible with a consistent 150 µ possible.

Macfab’s Airbrasive units are mobile. This allows us to add a MicroBlast operation within the machining process of a part. This helps us reduce costs and lead time by finishing the part in our CNC machines as our primary approach. MicroBlasting provides Macfab with the ability to etch parts as well, so the last operation on the part could improve the surface finish, deburr, and labeled ready for your assembly line.

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Remember to tell us what you want on the part and allow Macfab’s experienced engineers to develop the process as one variable adjustment means the difference between a surface finish and a surface texture.

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