Paperboard troubleshooting demystified

As a part of the Seekho aur Samjho technical workshop series, Siva Kumar Rampur of ITC covered key aspects of paper terminology, its importance, and applications at the SIES Graduate School of Technology in Nerul on 3 April.

by PrintWeek India | 06/04/2015

Printweek
This is the fourth in the workshop series.
 
The session gave an insight about paper and paperboard, starting with the basic difference between the two. Ramupur said, "A cellulose derived substrate with grammage more than 180grams per sq/m is paperboard, below that is called paper."
 
This session helped students and print supervisors learn basics of paper – its manufacturing process starting from fiber supply, different types of woods, pulping, ply bonding, drying to post drying operations like glazing, sizing, calendering, coating and surface finishing.
 
Different types of pulps basis which boards are categorised into recycled board (WLC), SBS (chemical pulp) and FBB (mechanical pulp sandwiched between chemical pulp) were also covered.
 
During the session, Siva Kumar and Vibhav Upadhyay of ITC PSPD, explained the physical, optical and surface quality parameters related to sheet structure and its formation, aesthetics, printability and runnabality.
 
He also spoke about the application of these properties in styling cartons based on folding, creasing, tearing, direction of printing, etc.
 
The three-hour session also explained the importance of moisture in paperboard and its relation with paper functionality as it is the main factor in retaining its original characteristics.
 
“Optimum moisture content should be 50% ± 2 RH at 23 deg Celcius ± 1 temperature and should be maintained during all production steps till it reaches its end user,” Siva Kumar said.
 
The most interesting part of the session was technical troubleshooting. The ITC representatives explained the most common technical problems faced during printing, their causes and suggestions to overcome them.
 
The attendees were enlightened to know these troubleshoot like dust, delamination, ink fading, bending, blanket damage, picking, hickeys, etc. and their precautions as well as cures.
 
In all 60 participants attended the seminar.
 

Trouble

Cause

Remedy

Hickeys (unprinted void surrounded by printing)

Contaminating particle adhering to plate or blanket

1.    Clean blanket

2.    Dip out ink blanket

3.    Drop fountain blade & clean

4.    Inspect roller condition

5.    Change ink or add fresh ink from new can

Packing – partial filling or absence of colour

Defective ink or coating resulting in pulling off paper fiber or coating

1.    Clean blankets

2.    Change contaminated ink

3.    Reduce impression cylinder squeeze or reduce ink tack.

4.    Try a different production run of paper.

Dust

Loose dust on paper surface adhering on blanket

1.    Inspect all four sides of paper for cut quality

2.    Wipe edges with a glycerine or tack cloth

3.    Trim paper on all four sides

4.    Check the guillotine knife for blunt and change periodically

Blanket damage

Foreign object smashing blanket or plate

1.    Handling operations smoothly

2.    Check knife for blunt

3.    Clear whatever has and can cause damage

Blade line

Occurs during coating operation due to contaminant between coating blasé & paper

1.    Isolate & replace affected paper

Bend/Curl

Exposure to outside atmosphere

1.    Cover the sheets with moisture barrier wrapper before printing and after printing.

Delamination

High-tack inks, partially dried ink on the rollers/blanket or high impression squeeze.

1.    Reduce ink tack on the rolls

2.    Reduce impression squeeze

 

Source: PrintWeek