Roll chatter is an undesirable condition that you can hear immediately when you enter the roller compactor/chilsonator
area. It has a distinct a sound like a piano out of tune. It means that you have something wrong with the process; one of
the four critical processing parameters is not optimized. In order understand what the process is and possibly what has
gone wrong, let’s look at an illustration of a typical process:




















As you can see, there are four variables. The blue arrows indicate feed rates of powder while the red arrows indicate
pressure roll pressure and roll turn or revolutions per minute (rpm). Of the four critical parameters, horizontal screw
speed is the least critical for success. Roll chatter may occur when one or more of these four conditions does not match
the other three settings. Usually roll chatter is caused by a variable powder feed rate into the rolls or a roll speed that is
too fast.
Further, roll chatter may also be caused by air entrapment in the powder. Air may accumulate for more than one reason
or for several reasons. Common reasons are a predisposition of the product to entrap air, a combination of natural fiber
containing materials and heavier, denser minerals or simple transportation and agitation resulting in air entrapment.













When roll chatter does occur, there are several ways to fix this problem. Fix the powder flow problem first. Premix the
powder to ensure standardized flow rates, slow down the vertical feed rate into the pressure rolls or slow down the roll
speed. You may also  want to purchase a powder de-aerater which will help eliminate excessive air build up.  
So roll chatter is really a result of non optimized process settings or perhaps attempting to roller compact a powder that
tends to entrap air.  
Tech Tip For Granulating:
Understanding and Preventing Roll Chatter in The Roller
Compactor/Chilsonator Area
Solid Dosage Training, Inc.
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Granulating