ThermoFlex Mid and Narrow - Calculating ThermoFlex Mid Scale Factors (SF)

Calculating Scale Factors on ThermoFlex Mid and Narrow Platesetters

Product

Kodak ThermoFlex Mid II
ThermoFlex Mid
ThermoFlex Narrow

Background

Flexo plates are composed of a polyester base layer that is 0.005" (0.127 mm) thick, and a polymer layer of varying thickness.
Note: Letterpress plates are 0.010" (0.25 mm) thick.

When a Flexo plate is loaded onto the drum, the polyester layer retains its original size while the polymer layer stretches around the drum. There is no stretching along the width of the drum. The thicker the plate, the greater the diameter of the exposed area.

A thin Flexo plate wrapped around the drum has a smaller circumference than that of a thick plate.
A thick Flexo plate wrapped around the drum has a larger circumference than that of a thin plate.

The different circumferences can lead to image distortion in which an exposed image is smaller than the expected outcome.

When the plate is removed and placed upon a flat surface, the exposed area shrinks to its original size, which is smaller than the exposed area on the drum.
However, the ThermoFlex Controller software takes into account the plate thickness measurements and the drum diameter to calculate the scale factor (SF). The result provides you with a very precise file size in relation to the exposed area.

Note: The LD factor is calibrated on the production line. The value should appear as Width Factor in the ThermoFlex Controller registry.

Procedure

To ensure that the exposed image is the same size as the expected outcome:

Calculate the scale factor¹ corresponding to the plate thickness using either of the following methods:
- Scale factor formula: Takes into consideration the minute differences between plate types.
- Automatic Scale Factor Calculator: Quickly and automatically calculates the scale factor for the value you enter in the Excel spreadsheet for any given plate thickness. In addition, the calculator enables you to view the size of the image without any scale factor compensation.
Enter the scale factor into the Brisque workstation.

¹Scale Factor

Every plate thickness is assigned a unique scale factor (SF) derived from a mathematical formula. The scale factor, which is entered into the Brisque workstation, compensates for any image shrinkage caused by the different thickness of plates on the drum.

Calculating the scale factor with the scale factor formula

ThermoFlex Mid

Perform the following calculation to work out the required scale factor compensation:

Scale factor = The figure entered into the Brisque workstation in order to compensate for image distortions. Accuracy is to the nearest thousandth decimal place.
Expose diameter = Drum diameter + (2x plate thickness)
Note: On the ThermoFlex Mid flexograph, the drum diameter will remain constant at 328 (mm).
Soft thickness = Plate thickness subtracted from the polyester base thickness
Note: On the ThermoFlex Mid flexograph, the polyester base thickness will remain constant at 0.127 (mm).

Example:

¹ drum diameter, ² plate thickness, ³ polyester base

ThermoFlex Narrow

Perform the following calculation to work out the required scale factor compensation:

Scale factor = The figure entered into the Brisque workstation in order to compensate for image distortions. Accuracy is to the nearest thousandth decimal place.
Expose diameter = Drum diameter + (2x plate thickness)
Note: On the ThermoFlex Narrow platesetter, the drum diameter will remain constant at 247 (mm).
Soft thickness = Plate thickness subtracted from the polyester base thickness
Note: On the ThermoFlex Narrow platesetter, the polyester base thickness will remain constant at 0.127 (mm).

Example:

¹ drum diameter, ² plate thickness, ³ polyester base

Calculating the scale factor with the Automatic Scale Factor Calculator

Technical contact

Viki Arviv

Date submitted

27 Mar 2006