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Reading Registration Marks – Stop Ruining Your Jobs!

Posted by
Apr 10, 2014 09:10am
Posted in: Shop Talk

If you have ever fought with reading registration marks when cutting a regular print be it laminated, on reflective material or maybe just on a high gloss media, you’re not alone…

light-angleHere’s why it happens

Cutting plotters use optical technology to read the registration marks your printer prints and properly positions the cutting tool.  Some cutters use white or red light sources while others have a camera installed for reading the registration marks. Typical red light optics can be surprisingly difficult with the materials that we use today.

In a perfect world, the light from the optical source shines down to the media surface, reflects back up and is read by the optical sensors and the registration mark is accurately detected. However, irregularities in the media surface or additional layers of protective coatings can introduce factors that make the reading of the reflected light difficult.

Reflective materials, by their very nature, scatter light in a way that decreases the amount of light that is expected to reach the optical sensors which in turn reads the registration marks.  Laminates in general, but especially those with UV inhibiting properties, redirect light and although protecting the media and prolonging the life of printed colour, this extra media layer also decreases the amount of light reaching the optical sensors and can introduce read errors.

Help counteract the effects of the media or laminates on reading registration marks

  1. Avoid running your plotter in direct sunlight, beside a window or close to fluorescent lighting.  The additional light is not necessary and may interfere with the optical sensing unit.IMG_7411
  2. Some RIP software allows the user to choose the colour of the registration marks.  The default colour in the RIP is usually black and we recommend that be kept.
  3. Try printing at higher passes.  More passes will allow a larger amount of ink to setup on the media surface and increase the density of the registration marks.
  4. If you are printing on reflective, put a strip of premask overtop the length of the printed marks, ensuring the marks are covered around all sides.  Then use a new black Sharpie marker to trace over the registration marks showing through the premask.  These changes will allow the detection of a dark mark against a matte background.
  5. If you are laminating, you can try the tips in steps 1- 4, and/or
    1. Use a light abrasive sandpaper to dull the finish of the laminate that is over the registration marks making sure not to grind through the surface of the laminate. You may need to redraw the registration marks on top of the existing ones to help intensify the marks again.
    2. Avoid laminating over the registration mark, staying at least 1” away from the marks and the path your plotter takes between marks.
    3. Try placing a square of premask over and around the area of the registration marks, ensuring you cover 1” on all sizes. After lamination, cut out the laminate and remove the premask area to expose the original mark.
    4. With a new black Sharpie marker, create new marks over top of the printed marks which should be visible through the laminate. The purpose of doing this is to give the optical sensor new distinguishable registration marks free of the distortion caused by reading through the laminate.

Consult an expert

If you work with reflective and laminates or constantly battle with print to cut jobs, you may want to look at some other options to help increase your productivity. Have a qualified ND Graphics technician inspect the unit and verify it is working to the maximum of its ability. Some optics need adjusting over time in order to differentiate between black and white.

Visit our Service Offerings page to find out more! 

Is it time to upgrade your router or plotter?

Many of the newest plotters and cutters are designed specifically to work with laminates and reflective materials.  Explore our full line of routers and plotters online, or fill out the form below to request more information or a quote.

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About the Author 

Jeff has been a field service technician with ND Graphics for over 8 years, prior to which he worked as a certified computer technician for Future Shop.  Having now accumulated so much experience within the industry working with a variety of equipment, and having absorbed a vast amount of knowledge from vendors, other technicians, and from client feedback, he is excited to share some of his insights with customers through his Tech Talk blog series.


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