GMI Equipment Performance 3 — Questions and Answers
Question 1: In flexographic printing, the anilox roller's primary function is to:
- Apply impression pressure to the substrate
- Meter a controlled, consistent volume of ink to the plate (Correct answer)
- Clean excess ink from the doctor blade
- Control drying speed of water-based inks
Correct answer: Meter a controlled, consistent volume of ink to the plate
The anilox roller delivers a precise, metered volume of ink to the flexographic plate through its engraved cell structure.
Question 2: Which of the following best describes the purpose of a blanket in offset lithography?
- To absorb excess fountain solution from the plate
- To transfer the inked image from plate to substrate (Correct answer)
- To protect the impression cylinder from ink contamination
- To provide tension on the paper web
Correct answer: To transfer the inked image from plate to substrate
The offset blanket receives the inked image from the plate and transfers (offsets) it to the substrate, providing a resilient printing surface.
Question 3: What does 'TIR' (Total Indicator Reading) measure in press cylinder evaluation?
- Total ink reduction for a given substrate
- The runout or eccentricity of a rotating cylinder (Correct answer)
- The total image resolution of the plate
- Temperature increase rate of the ink fountain
Correct answer: The runout or eccentricity of a rotating cylinder
TIR measures the total runout (eccentricity) of a cylinder as it rotates, indicating how true and round the cylinder is.
Question 4: In sheetfed offset printing, 'set-off' occurs when:
- The press is set to the wrong speed for the substrate
- Wet ink from one sheet transfers to the back of the next sheet in the delivery pile (Correct answer)
- The plate cylinder fails to register with the blanket
- Ink dries too quickly in the fountain
Correct answer: Wet ink from one sheet transfers to the back of the next sheet in the delivery pile
Set-off is the unwanted transfer of wet ink from the face of a freshly printed sheet to the back of the sheet stacked on top of it.
Question 5: Press operators use a 'star target' on a press sheet primarily to evaluate:
- Color sequence and trapping
- Slur and doubling in the printing impression (Correct answer)
- Ink tack and viscosity levels
- Plate exposure accuracy
Correct answer: Slur and doubling in the printing impression
A star target is a diagnostic target that reveals slurring or doubling by showing distortion or blurring at its center point.
Question 6: The main reason UV inks are used in specialty printing applications is that they:
- Are less expensive than conventional inks
- Cure instantly when exposed to UV light, eliminating drying time (Correct answer)
- Produce softer colors suitable for packaging
- Require no press modification to run
Correct answer: Cure instantly when exposed to UV light, eliminating drying time
UV inks polymerize and cure instantly upon exposure to UV radiation, dramatically reducing drying time and enabling immediate post-press processing.
Question 7: When calibrating a digital inkjet press, 'linearization' refers to:
- Aligning printheads to print in a straight line
- Adjusting ink output so tonal values print proportionally to input data (Correct answer)
- Setting the substrate feed tension to a linear value
- Mapping color profiles from RGB to CMYK linearly
Correct answer: Adjusting ink output so tonal values print proportionally to input data
Linearization ensures that the tonal response of the inkjet press is proportional, so a 50% input value produces a 50% output density.
GMI Equipment Performance 3
In flexographic printing, the anilox roller's primary function is to: