Archiving and reusing offset plates – Productive or not??

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This case study mentions about archiving and reusing offset plates. Abhiram Sathe, who is a veteran in the field of prepress and mentoring customers and fellow colleagues, has been driving a project on analyzing the cost implications of a process used by some printers – the process of storing plates and reusing them for repeat job, often described as a ‘reprint job.’ Are printers being ‘Penny Wise Pound Foolish’ while reusing the plates?

Abhiram Sathe
Abhiram Sathe

Based on offset printing, the Indian print industry is broadly classified into 4 segments – commercial, offset packaging, publishing and newspaper. A prominent change that is happening is printers are adopting the latest technologies and trying to cope up with the ever-increasing demand of print buyers. Apart from adopting the latest technologies, they also tend to be innovative and think of implementing out of the box ideas that help them increase their productivity in a cost-effective way.

There is a proverb in English – ‘Penny Wise Pound Foolish’. This case study mentions about one such attribute that printers often disregard and think that they save on costs with it. Abhiram Sathe, who is a veteran in the field of prepress and mentoring customers and fellow colleagues, has been driving a project on analyzing the cost implications of a process used by some printers – the process of storing plates and reusing them for repeat job, often described as a ‘reprint job.’

Many printers wish to preserve and archive plates for reuse. Almost no plate manufacturer claims ability to re-print as a product feature. The different print segments have different approach and thought process about reusing an offset printing plate.

Commercial Printers feel the need to keep the plates after job is printed just in a case copies fall short due to some error during post press operations. Or they feel that client might come back later demanding more copies; then they can use same plates and optimize profits.

The Offset Packaging Printers are already aware of repeat of jobs. Mostly, they get a supply schedule from their client and they control inventory by printing in small lots thus preferring to re-print from same set of plates. The Publishing Printers also follow a similar process of printing small lots by carefully managing the demand-supply pattern of their clients. One common attribute the offset packaging and publishing printers have is post baking the plates to get multiple reuses and other benefits.

Unfortunately, in preserving the plates for reuse they often disregard the plate/s failure in terms of plate scum, image wear off, ink catchup, uneven print density etc. These issues are known only after plates are mounted on press and printing of job starts. Seldom is the printman aware of abnormalities by barely looking at the archived plate. For a plate that is baked, even if 15Kw energy consumption is ignored (which is in fact huge), the addition of a process itself brings in a variable. There is always a chance of over/under baking based on the age of the baking oven, uneven application of baking gum before baking etc. which may cause delay in makeready. There is wastage of sheets too!!

In short, the re-print process is desired by printers, but plate manufacturers cannot consider this during product design due to technical reasons. Hence it is worth to find out the practical impact of this methodology.

Method:

The objective of this case study was to understand the commercial and productivity implications of archiving the plates after printing. The scope of this exercise was limited to understanding the cost implications (unproductive machine hours) of reusing of plates. The case study involves a survey of 24 printers from different parts of India and having print operations catering to different print segments.

Methodology used to collect the data was as follows:

1. Select printers who preserve plates for re-printing

  • Users who preserve all plates by default after being printed
  • Users who selectively archive certain plates (for a certain job)

2. Get information on rate of success when they use archived plates for reprinting

3. Try and include diversity by type – commercial, packaging etc.; Size – by sales or turnover

Survey:

Critical Survey questions were as follows:

  1. What is the rejection rate of a plate when attempted re-print?

Respondents claimed the rejection as high as 60% and lowest being 30%. The average worked out to 38%. That means if 100 plates are taken to reuse, 38 would fail.

2. What is the time lost to replace with new plate? (making a new plate/s and loading them to the press)

The answer range was 20 min to 7 min. Average is 9.7 min

3. Number of working hours in a day (shift)

Average is 13 hrs.

Key findings:

  1. Average down time for making a new plate, unloading and loading is 9.7 min
  2. Success rate while using an archived plate is 62% And 38% get rejected during re-print.

Extract and averaged out information give us the following estimation around impact of adopting the process of preserving the plate and re-printing. The data mentioned in table is derived from the questionnaire asked during the survey.

Plates stored and used per month under re-print 1000 Average failure rate when plate used to re-print 38 % Actual plates failed per month 380 Average time taken to remake and change the plate (avg. time 9.7min.)* 0.12 (Hrs) * 25% discount if it could be discount if it more than one plate changed at a time Production Time lost in hours per month- remake a plate and load 46.2 (Hrs) 5000 sheets per hour is nominal production. Number of impressions lost per month 231,000

Following additional costs are not considered during this study:

  1. Manpower and material for preserving the plate
  2. Space and facility for archiving, tagging and record maintenance
  3. Delayed realization of scrap value
  4. Make ready sheets

Barring the above costs for consideration, thinking from a technical side, the dots reproduced on a plate are ruptured when they are mounted on the press for printing. No matter how well one stores the plate, to reproduce the quality exactly like the one printed with fresh set of plates cannot be achieved and there is some compromise. This is of critical importance in offset packaging segment as the tolerance levels are very stringent. In fact for any type of printing compromise in the quality is it what the clients really want?

Citing all the above details, one can think for themselves whether there are ‘real’ advantages of reusing the plates or only the ‘perceived’ advantages while reusing. As is often the case, the hidden costs of doing an activity are seldom considered and thus the true costs incurred are not highlighted.

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