Brookfield RST Rheometer - Manual (Page 54)

Brookfield Engineering Labs., Inc. page 54 Manual No. M14-223
Appendix B RST-CPS Rheometer Gap Setting Procedure for Cone and
Plate Spindles
This procedure is for the RST-CPS Rheometer. Both manual and automatic gap setting are explained.
B.1 Manual Gap Setting
Begin the procedure with the rheometer head in the raised position and no spindle attached.
Set the micrometer dial located behind the plate to the zero position. This will place the head of the
rheometer in the initial position to start the gap setting procedure. It may be desirable to rotate the
micrometer in a counterclockwise direction at first and then return to the zero position. This will remove
hysteresis in the column of the instrument.
Attach the cone or plate spindle to the rheometer. Loosen the set screw on the shaft of the spindle.
Lower the rheometer head and bring the spindle into contact with the plate. Tighter the set screw. Lift
the rheometer head to the raised position.
Review the data sheet for the cone spindle and note the “truncation” value. It will be a number near the
value of 0.050 mm (50 microns). Adjust the micrometer dial to the position that agrees with the truncation
value. Accomplish this by rotating the micrometer dial in a counterclockwise direction. Each division line
on the micrometer dial equals 0.010 mm (10 microns). When the micrometer dial has been moved to the
correct position, the gap is set and testing may begin.
For plate spindles the gap setting procedure is similar. Move the micrometer dial to the setting that
provides the correct spacing for the material that is being tested. The correct spacing is normally
determined by the largest particle size in the material; best practice is to set the gap 5 to 10 times greater
than the largest particle. If the largest particle is 0.010 mm, then the gap should be 0.050 to 0.10 mm (50
to 100 microns). If the material does not have particles, but is highly viscous, experiment with various gap
settings to determine what will give the most repeatable viscosity measurements.
B.2 Automatic Gap Setting in Run Single Mode
Go to the Home Screen (Main Screen). Press the Run Single button. The next screen tells you to “Plug
in measurement system and close coupling!” Attach your spindle. If the RST-CPS recognizes the
spindle, press OK:
Example: Name: RCT-25-1 Serial Number: 00002
If the RST-CPS does not recognize the spindle, the following will appear: “Spindle recognition failed!
Please select measurement system”. Press OK. Select the correct spindle in the next screen. Choices
will include the standard cone and plate spindle geometries that are used with RST-CPS as well as
spindles with specific serial numbers that you have already been entered into memory in your instrument.
Select the appropriate spindle with serial number:
Example: RCT-50-1 #00005 (this is a spindle that is already in memory)
Spindles with serial numbers that are in memory will have cone truncation information that is necessary for
the automatic gap function to work correctly.
Press OK. The next screen will ask: “Do you want to adjust the gap now?” Press “Yes”. The next screen
will say: “Loosen measuring system hexagon screw. Confirm with ‘OK’. After loosening the screw, press
OK.
The RST-CPS head moves downward to the hit point. The screen will display a downward motion for the
rheometer head and say: “Z-Drive moving! Please wait…” When the spindle makes contact with the
plate, the next screen will appear: “Tighten measuring system screw!” When the screw has been
tightened, press OK. The next screen will say: “Z-Drive moving! Please wait….” The head will return to
the up position.