How to accurately calculate the ink costs for your digital press

There are many costs that can impact your profitability when running a production digital press, from power consumption to the substrate you’re printing on. One of the most variable costs is ink consumption, which often varies from job to job and therefore can be difficult to estimate. As you might expect, the content to be printed is the key determining factor, but you also need to consider the resolution, screening method, drop sizes and choice of colorants. This can bring quite a challenge for a press shop when quoting for a job, especially if the client is open to hearing a range of options.

Even with a static job that might be suitable for a test print run to get a cost that can be multiplied for the number of copies, it’s still not ideal to have to spend any time or other resources using the actual press. It’s much better to be able to get an accurate ink cost estimate away from the press, which is where our Job Cost Estimator comes in. It’s available as part of our Direct™ software range as well as our Harlequin Host Renderer™ and ScreenPro™ products. It uses the same setup that drives your printer, calculating a very accurate estimate of the ink cost for a specific job. Self-contained, it doesn’t require any connection to your printer, which makes it ideal when you want to give a job cost indication away from the print shop.

The screenshot shows a calculation performed using our Job Cost Estimator for a 1200x1200 dpi version of our two-page Direct brochure, screened with 4-drop pearl.

The screenshot above shows a calculation performed using our Job Cost Estimator for a 1200×1200 dpi version of our two-page Direct brochure, screened with 4-drop pearl. Under Cost Per Page, this is the average cost per page per colorant based on the two pages that were analyzed, with a final row showing the total (All). This is then multiplied by the total pages and the number of copies to get the Cost Per Job for each row.

Obviously, no costs can be determined without knowing how much the inks cost per liter, so you can set these within the application. Similarly, you will need to configure your printhead(s) to specify how many picoliters of ink are used per drop size.

As you can see from the left image above, we have assigned a different printhead for Black called Budget_PrintHead, which will have fewer picoliters per drop size than the Default_PrintHead shown on the right, to represent a possible response to a hypothetical jump in the price of black ink.

The Job Cost Estimator has been designed to be extensible, so it would be possible in future to incorporate other costs, such as paper, or factor in ink used periodically for nozzle refreshing, for example.

If you’d like to know more about the Job Cost Estimator, watch my short demonstration here:

For more information visit the Direct pages on our website: globalgraphics.com/direct

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About the author:

Ian Bolton, Product Manager, Direct
Ian Bolton, Product Manager – Direct

Ian has over 15 years’ experience in industry as a software engineer focusing on high performance. With a passion for problem-solving, Ian’s role as product manager for the Direct range gives him the opportunity to work with printer OEMs and break down any new technology barriers that may be preventing them from reaching their digital printer’s full potential.

Channelling how many spot colors?!!

Martin Bailey, CTO, Global Graphics Software
Martin Bailey, CTO, Global Graphics Software

Recently my wife came home from a local sewing shop proudly waving a large piece of material, which turned out to be a “swatch book” for quilting fabrics. She now has it pinned up on the wall of her hobby room.

It made me wonder how many separations or spot colors I’d ever seen in a single job myself … ignoring jobs specifically designed as swatches.

I think my personal experience probably tops out at around 18 colors, which was for a design guide for a fuel company’s forecourts after a major redesign of their branding. It was a bit like a US banknote: lots of colors, but most of them green!

But I do occasionally hear about cases where a print company or converter, especially in packaging, is looking to buy a new digital press. I’m told it’s common for them to impose together all of their most challenging jobs on the grounds that if the new press (or rather, the DFE on the new press) can handle that, then they can be confident that it’ll handle any of the jobs they receive individually. Of course, if you gang together multiple unrelated jobs, each of which uses multiple spot colors, then you can end up with quite a few different ones on the whole sheet.

“Why does this matter?” I hear you ask.

It would be easy to assume that a request for a spot color in the incoming PDF file for a job is very ephemeral; that it’s immediately converted into an appropriate set of process colors to emulate that spot on the press. Several years ago, in the time of PostScript, and for PDF prior to version 1.4, you could do that. But the advent of live transparency in PDF made things a bit harder. If you naïvely transform spots to process builds as soon as you see them, and if the spot colored object is involved in any transparency blending, then you’ll get a result that looks very different to the same job being printed on a press that actually has an ink for that spot color. In other words, prints from your digital press might not match a print from a flexo press, which is definitely not a good place to be!

So in practice, the RIP needs to retain the spot as a spot until all of the transparency blending and composition has been done, and can only merge it into the process separations afterwards. And that goes for all of the spots in the job, however many of them there are.

Although I was a bit dismissive of swatches above, those are also important. Who would want to buy a wide format printer, or a printer for textiles, or even for packaging or labels, if you can’t provide swatches to your customers and to their designers?

All of this really came into focus for me because, until recently, the Harlequin RIP could only manage 250 spots per page. That sounds a lot, but wasn’t enough for some of our customers. In response to their requests we’ve just delivered a new revision to our OEM partners that can handle a little over 8000 spots per page. I’m hoping that will be enough for a while!

If you decide to take that as a challenge, I’d love to see what you print with it!