How to adjust quality

[JMB]

What is your usual process for fine-tuning a quality job?

1. Number of proofs per test print

2. Number of proofs needed

3. When you decide to stop proofing and start printing the job (when the job is 100% fine-tuned, 90% fine-tuned, etc.)

4. Do you clean the rollers after printing proofs and before starting to print the job?

5. etc.
We have CIP4 and techkon expresso4.
thanks.

 

[SteveSuffRIT]

Hi,
Is this Jose Martinez Blasco of Aldaia , Spain.
I see you have a very similar post on "PrintPlanet".

For "commercial" printing, not packaging, the quality expectations are lower.
With CIP4 ink key presets and an off-line scanning spectro and ISO 12647 calibrated CtP curves, you should be able to start printing (saving, on counter, good) during your 3rd "pull".
A pull is 100 sheets. You can always flag/tag QC/customer samples after that.

 

[JMB]

Is this Jose Martinez Blasco of Aldaia , Spain.
I see you have a very similar post on "PrintPlanet".

Hi yes I'm the same Jose Martinez.

For "commercial" printing, not packaging, the quality expectations are lower.
With CIP4 ink key presets and an off-line scanning spectro and ISO 12647 calibrated CtP curves, you should be able to start printing (saving, on counter, good) during your 3rd "pull".
A pull is 100 sheets. You can always flag/tag QC/customer samples after that.

“How many clean sheets do you typically get out of a pull?”
Thank very much for your help.

 

[SteveSuffRIT]

A "pull" is running enough sheets through the press to see the results of register and color adjustments. I think most press operators pull about 100 sheets. If you're running a "sandwich" or "book" of previously printed waste and then clean sheets, you only need 3-5 clean sheets. That sample size allows you to check for micro differences or patterns within that set due to multiple roll sheeting, multiple rotation of blanket of transfer cylinders (doubling), consistency of print quality defects (hickey, mottle).
Most printers end make-ready (MR) and start running when they are close or good enough knowing they can fine tune while they are running. Close or good enough depends on your reputation and the customers' expectations. Historically this might be +/-.10 or .07 or .05 density units, or now with modern colorimetry, <3, <2.5, <2.0 Delta E. These 3 tolerance limits are often color coded as red, yellow, and green. Just like a traffic signal light, red=stop, yellow=caution, green=OK. Standard Operating Procedures (SOPs) are a balance/compromise between quality and productivity, both effect profitability. I've seen many printers flag QC or customer samples close to the end of a run length, giving them plenty of time to fine tune. In many situations, if they customer receives "good" samples, they assume the entire production run is the same, so accept the job based on the supplied samples only. Perception vs Reality.

 

[JMB]

A "pull" is running enough sheets through the press to see the results of register and color adjustments. I think most press operators pull about 100 sheets. If you're running a "sandwich" or "book" of previously printed waste and then clean sheets, you only need 3-5 clean sheets. That sample size allows you to check for micro differences or patterns within that set due to multiple roll sheeting, multiple rotation of blanket of transfer cylinders (doubling), consistency of print quality defects (hickey, mottle).
Most printers end make-ready (MR) and start running when they are close or good enough knowing they can fine tune while they are running. Close or good enough depends on your reputation and the customers' expectations. Historically this might be +/-.10 or .07 or .05 density units, or now with modern colorimetry, <3, <2.5, <2.0 Delta E. These 3 tolerance limits are often color coded as red, yellow, and green. Just like a traffic signal light, red=stop, yellow=caution, green=OK. Standard Operating Procedures (SOPs) are a balance/compromise between quality and productivity, both effect profitability. I've seen many printers flag QC or customer samples close to the end of a run length, giving them plenty of time to fine tune. In many situations, if they customer receives "good" samples, they assume the entire production run is the same, so accept the job based on the supplied samples only. Perception vs Reality.

When running waste + clean sheets, do you really trust just a few clean sheets?
• What tells you a job is ‘good enough to run’?
How many pulls are you guys running before color is where you want it?

 

[SteveSuffRIT]

JMB,

YES! Concept is smaller sample (3) is representative of larger population (100).
You should be running after the 3rd pull, if you're ISO press-proof calibrated (RIP CtP curves), and CIP3/4 PPF ink key preset, and off-line/closed-loop scanner.
Experience, which is historical data (if/then), provides insight about the quality. You don't need to be perfect to start running live production. Good enough, close enough is fine. This can be defined with % ink keys that are in/out of tolerance limits. With color coded tolerance levels, this means a few/couple red (out), some/several yellow, mostly green (in).

I see you now have a similar post on PrintPlanet.com.

 

[JMB]

“Sorry, I’m not sure I fully understand this — maybe it’s just my basic English.
When you talk about a pull, do you mean running about 100 waste sheets (previously printed stock) and then checking 3–5 clean sheets,
or running 100 sheets of the actual job and evaluating a few sheets from that batch?”

 

[SteveSuffRIT]

A pull is 100 previously printed waste sheets followed by 5 clean virgin sheets.
The 100 sheets is for the press to reach equilibrium in Ink/Water balance.
The 5 sheets is for register and color adjustments.
Is your MR speed the same as your production speed?

 

[JMB]

A pull is 100 previously printed waste sheets followed by 5 clean virgin sheets.
The 100 sheets is for the press to reach equilibrium in Ink/Water balance.
The 5 sheets is for register and color adjustments.
Is your MR speed the same as your production speed?

 

[JMB]

Yes, my MR speed is the same that my production speed.