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Are You Getting the Most Out of Closed Loop Colour for Offset?

Make up a Viable Closed Loop Control System

By Colour Graphic ServicesPublished 3 years ago 4 min read
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There has never been more pressure on offset productivity and efficiency than now. Print runs are continuing to get shorter - customers demanding faster job turnaround times – which translates to more make readies and reduced profit margins. There is no question that if you have made an investment in auto scanning hardware system you are already ahead of the game. But are you getting the most out of it?

There are a number of parts or components to a closed loop colour control system and it is the sum of all these elements that really decides how much money you save by reducing your make ready costs.

To Start Let’s Look Into the Elements That Make Up a Viable Closed Loop Control System:

  • Ink Pre-Set software – This is the software that usually takes a ‘CIP’ file that has been created by your CtP RIP. The CIP file contains the ink coverage information for each separation (CMYK + spots) and the ink preset software converts the data to ink key and sweep settings for each unit on the press.
  • Auto Scanning Spectrophotometer – This is the physical hardware component – the actual scanning instrument that scans and measures the colour bar (CB) patches from the printed sheet. Usually configured on the press console – aligned with the CB and automatically scans measuring each patch for each ink zone or key.
  • Computer Control and Interface to the Press – A computer platform is required (usually Windows PC), with a combination of sophisticated software and hardware to connect with the press console. Press manufacturers use different ways and protocols to interface or communicate with the press console – it could be a DPI (direct press interface) or a disk drive or via LAN (local area network) or even special hardware that emulates a memory type card. There is usually a way to communicate and interface with every press console available.
  • Closed Loop Management System – This is the software element that brings everything together – the measured data from the auto scanning spectrophotometer – configuration of the specific press - operator control of the data for manual or automatic ink key corrections on press – colour standards for CMYK and spots or specials – production job management. This software is run on the aforementioned PC and can have a touch screen for ease of use.

How does It All Work?

First the operator chooses the designated job with the ink pre-set data and sends that data to the press console. The software also manages the measurement instrument and displays the scanned data in an easy to follow and understand format.

Ink key correction data can then be sent to the press. This is closed loop colour control in a ‘sense’ as you are adjusting the printed result based on the scanned measurements, making automated ink key adjustments and then the process is repeated to correct and maintain the desired evenness and colour. And yes, we are saying closed loop in a ‘sense’ as there is more that can be done to completely close the loop!

The initial ink key setting may not be in tune with how you are running the press for production. Fine tuning of the incoming ink pre-set data is required over time so the press can achieve the desired printed colour faster with each start up and make ready.

Depending on your kind of work this can be completed relatively quickly – sometimes within days and weeks when new closed loop goes in.

How is it Done?

When each production job is finished the ink key settings are recorded and then over time this can be compared to the initial ink key pre-set data. The ink ‘profile’ can be fine-tuned and adjusted for each process and spot so that the initial ink pre-set is closer and closer to the optimum settings for how the press is run for continued and successful production. This translates to much faster make ready for each job. Closing this final and strategic loop can get you to 95% or better on being at the correct production quality level.

Now consider the savings over time – with a completely closed loop system you can reduce make ready from thousands and many hundreds of sheets down to a 100-200 sheets. Doesn’t sound like a lot – over time it can add up to a lot of savings when applied to every job on the press.

There additional benefits of closed loop as well. Targets and standards can be maintained easily from within the system – reprints can be achieved, with less hassle to the previous colour as the job is saved with all the ink settings. The press operator will have more time to ensure the print quality is up to scratch – registration spot on - hickeys and other defects that can occur from time to time will be picked up.

The return on investment can be faster than you think, often within 6 months. Colour is a very important part of overall print quality, but if you can get it right, every time, you will move to be being a more successful profitable company – saving money on each job is the power of complete closed loop control.

To find out more about print quality management and printer colour management, please contact us at [email protected]

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About the Creator

Colour Graphic Services

Established in 2004, Colour Graphic Services is an Australian owned and operated company specialising in providing expert colour management solutions across Australia and New Zealand at highly competitive pricing.

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