Product

• Kodak^® ThermoFlex^® Mid
• ThermoFlex Narrow

Background

The objective of this procedure is to find the optimal drum speed for flexo plates at a resolution of 100 dpm (or any other resolution as required).

Note: Test results depend on the plate type, so this test must be performed for each plate type that the customer uses. Test results do not depend on plate size or thickness.

Requirements

• Densitometer
• Loupe
• Flexo plate(s)
• Focus tested and adjusted, as described in the Focus Calibration Test
• Elevation tested and adjusted, as described in the Elevation Calibration Test
• Laser uniformity tested, as described in the Laser Uniformity Calibration Test
• Resolution tested and adjusted, as described in the Resolution Calibration Test
• Delay tested and adjusted, as described in the Delay Calibration Test

Note: For devices with a magnetic drum, use a plate of the same type that does not have the steel back. This type of plate is provided by the plate manufacturer for calibration purposes. If such a plate is not available, follow the special instructions in step 1 of the Selecting the optimal drum speed section.

Procedure

This procedure includes the following stages:

• Testing drum speed
• Selecting the optimal drum speed

Testing drum speed

1. Load a plate.
2. In TIFF FE, from the Launch Pad, select Utilities > Calibrate.
   
3. In the Calibration Type box, select Drum Speed.
   
   
   
4. In the Current Plate list, select the Plate that you are using.
5. Select the test file machineCalibTest.lw.

6. Define the Image offset values:
   
   • Horizontal offset—The value around the drum in mm
   • Vertical offset—The value along the drum in mm
   If you use the same plate for several tests, define different offset values for each test.
   Note: The (0,0) offset coordinate is located at the upper-left corner of the plate.
7. From the Resolution list, select the required resolution value.

Note: Do not modify the value in the Intensity box at this time. (This value should be the value that you use for exposing: 600 mV or 900 mV, depending on the type of diode.)

6. In the Drum Speed box, type the recommended drum speed value, according to the following table:
   

   	Diode strength
   	600 mW	1 W (Mid)	1 W (Narrow)
   Drum speed	81-150	110-180	130-240
   steps	9	8	12

   
   
   Note: For some letterpress plates, the maximum test speed 350 for 1 W diodes and 250 for 600 mW diodes.
   
7. In the Number of Steps box, type the recommended drum speed value, according to the table in step 6.
8. Expose the plate.
   

Selecting the optimal drum speed

1. When the exposure is completed, examine the results.
   
   
   
   If you are using a regular steel-back plate, use a microscope to verify the following:
   • On the 8p section of the test, the joint between each pair of dots is exact. There should be no overlap, nor any space.
     
   • In the 2% and the 98% section of the test, the dot size and quantity of dots appears to be equal.
     
2. Calibrate the densitometer to read the dot area.
   Note: (It is possible to use a CC dot meter instead.)
3. To calibrate the densitometer:
   1. Remove the black layer in the corners of the measured plate so that you can see the clean plate.
      • Regular plates—use masking tape to remove the black layer
      • Asahi, BASF Nyloprint and Toray Torelief plates—expose the solid twice on the plate to remove the black layer
   2. Set the densitometer reading of the clean corner to show a density of 0.
4. Select the strip for which the 50% dot area measures 50%.
5. Measure the density in the solid area. A good density reading should be 0.07 dmin or less.
6. When satisfactory test results are obtained, in ThermoFlex Controller, browse to Database and right-click Res Int.
7. In the Resolution/Intensity Table dialog box, type the drum speed that produces the best exposure.
8. Click Save.

Technical contact(s)

Content owner: Viki Arviv
See the Escalation page for escalation contacts.

Date submitted

22 Jun 2004