How to Prevent UV Curing from Damaging Print Heads

Xaar 1003 inkjet printhead

With proper care & maintenance, inkjet printheads can last a long time.

When it comes to UV inkjet printing, reflective, transparent or glossy substrates do not always ‘play nice’. These substrates can be anything from glass and crystal to simply any type of shiny media that causes UV light to bounce back into the print heads. The problem with UV light reflecting back into the print head is that it results in curing the inks within the nozzles and on the nozzle plate itself. This can cause serious (and costly) damage to the print head and therefore shorten the life of the head unnecessarily.

The following are some tips on how to prevent UV curing from damaging print heads:

  1. Eliminate the use of refractive materials when manufacturing fixtures or printer jigs. When designing a fixture, be sure it is a dark matte finish material, and covers any negative space between parts to block UV light from bouncing back to the print heads.
  2. Consider the angle and intensity of the UV lamps. You should always use the lowest amount of UV possible to gain full cure for your application.  If your machine was not supplied with UV light shims, contact the technical service department to inquire about this feature.
  3. Always print onto substrates that are ‘flat’ or parallel to the head array, and be sure the platen gap is no larger than 1.5mm. If you happen to be printing on a mirrored substrate that is flexible, be sure to attach it to a flat material first.
  4. Be proactive and check the health of your nozzles frequently. Perform an auto cleaning every other platen and to ensure that all nozzles are working, run nozzle checks every hour of production. If you notice that ink is curing either in the nozzles or on the face plate, flush the affected head with maintenance fluid.
  5. Always perform ink nozzle checks at the end of a shift. If any nozzles are missing, clean your print heads before powering down the printer.

Prematurely damaged print heads (due to UV light refraction and reflection) are expensive and unnecessary. Follow the tips above to avoid this issue and ensure proper care and functionality of your inkjet printer.

Tech Tip Tuesday: Ink Mixing – A Pad Printing Best Practice

Ink mixing for pad printing is a fairly simple task. However, when done incorrectly it can adversely affect the whole printing process. This can result in subpar results that leave you not only having to remix your ink, but disrupting production and costing time and money.

Below are a few tips to help you get it right the first time:

  1. Always be sure to use an ‘ink friendly’ mixing cup to maintain ink integrity. See our blog Choosing A Mixing Cup For Pad Printing for tips on this.
  2. Always thoroughly mix the in the source (bulk) container prior to scooping or pouring into the mixing container – this will ensure consistency from the start to finish of the bulk container.
  3.  Always ensure that your measuring scale is accurate, set to zero and on a flat surface.
  4. Use sufficient ink based upon the cup depth and size that is used on your printer to ensure that the ‘etch’ on the cliché is well inked by the cup/cliché motion.
  5. Use the correct amount of hardener and ALWAYS mix ink and hardener prior to adding thinners or additives. Instructions for mixing of additives is written on the bulk liter can and are dependent on the series ink.  A helpful tip – pour ink from can away from markings in order that they remain legible.
  6. Pad printing inks are diluted with 10-20% thinner. Ideal viscosity is predicated on the machine speed ambient conditions (humidity and temp.), the hardness of the pad and the porousness of the substrate being printed on.
  7. If needed, continue to add thinner by the drop in small increments until you have achieved desired thickness. This technique always minimizes the chance of over-thinning your ink. (refer to our viscospatula for instructions)

 

Tech Tip Tuesday: Pad Printing – It’s All About The Pad!

The print pad is one of (if not the) most important aspects of the pad printing process. Made from silicone rubber, it is the perfect ink transfer medium when designed, used and maintained correctly.

The properly molded print pad will have the following features:

  • Excellent adhesion
  • Flawless Ink Detachment
  • Perfect Ink Transfer
  • Stability of Form
  • Resistance to Solvents & Inks

Printing pads comes in all shapes and sizes and are often custom designed. This is because they are created for very specific applications, both unique and specialized.  Below are some important things to keep in mind when it comes to the print pad.

Pad Size

The pad itself should be at least 20% than the image that it is printing on. If the height and width of the pad is less than this, the probability of distortion near the edges of the image is more likely.

Pad Shape

The shape of the image itself is one of the most important factors in determining the shape of the pad.  Use the following guidelines when considering your printing pad:

Rooftop shaped pad – for shorter, wider images (and straight text)
Round / cone pads – for flat surfaces with a round image area.
Square or Rectangular shaped pad  – for square/rectangular shapes.
Half Moon pad – recommended for curved surfaces and longer text.

The other vital factor when it comes to the print pad is the contour (or angle) of the print pad. A steep, opposite angle of the print area is ideal, as to allow for clean transfer of ink by displacing air during pickup and transfer. The absence of a steep enough angle causes air to become trapped between the pad and cliché and damages the ink-to-image transfer.

Pad Hardness

The higher the number is, the harder the pad. This is also referred to as “shore”.  It is determined by the amount of silicone oil when creating the pad. More silicone oil makes for a softer pad, while hard print pads are made using less silicone oil.

Hard pads – Produce sharper images (with less distortedness) and generally better coverage,
Soft pads – Produce longer image life due to more ink placement onto the image,

Pad Lifecycle

While it is easy to understand that softer pads last a little longer because of their flexibility, all pads eventually lose their image transfer quality due to silicone oil depletion inside the pad. At this point, surface application of oil is ineffective and drying out of the pad is inevitable.

While air blowers that produce clean and dry air will increase machine efficiency (and help with clean image transfer), it is important to know when your printing pad has reached its expiration.

Remember to keep your pad printing environment between 68-72 degrees Fahrenheit (which allows ink solvents to evaporate at a normal rate) and humidity between 50-60%. Maintaining this humidity level is crucial in the proper functioning of the ink and evaporation solvents.

Learn more about print pads by visiting our website at www.epsvt.com. There you can also find more information about Engineered Printing Solutions custom solutions, standard pad printers, industrial inkjet, consumables and other auxiliary equipment. Email info@epsvt.com or call 1-800-272-7764 if you would like more information.

Tech Tip Tuesday: Choosing A Mixing Cup For Pad Printing

Before the process of pad printing begins, it is important to know what kind of cup you should (and should not) be using to mix your ink. Mixing solvents with ink is a very important part of the pad printing process, as it to enables the ink to transfer and dry quickly. However, solvents are strong chemicals that will melt right through certain materials. If you’re mixing cup is made of such a material, your going to have a problem before you even get started.

What types of cups to avoid

  1. Styrene – weak organic compound that most solvents will melt through.
  2. Polystyrene foam (e.g. Styrofoam) -breaks down when exposed to a solvent.
  3. Wax coated  – wax can mix in with solvent and affect adhesion.
  4. Ring cup itself – doesn’t allow for easy mixing and can result in costly damage to the cup as well.

What types of cups work well

  1. Waxless paper  – cheap, disposable and durable material that won’t be damaged by a solvent.
  2. Polypropylene – strong, thermoplastic polymer that will also stand up to a solvent.

It is also highly recommended that you test the cup if you have any doubts, by allowing some thinner to sit in the cup for about an hour.

Lastly, we do not recommend reusing any cup. It is time consuming to clean and you risk leftover ink and material breakdown, both of which can affect your ink mixture.

Tech Tip Tuesday: I Am A “New Guy” That Has Plans To Do In House Pad Printing

I am a “new guy” that has plans to do in house pad printing.

I know a closed system is the best for me and in general. I plan to do small amount lots of 250 to 500 printing at a time, as low as 50 at a time. Working with my budget, is is possible to be a multi-color printing one color at a time? To explain a little more: print one color, then print another color on the same piece.

Certainly, it is possible to do short run multi-color printing with a single-color printer provided the following:

1) Your product must have some part that is shaped in such a way to allow it to be used as a point of consistent registration and re-registration.

2) The fixture (or nest) is made in such a way to provide tight and consistent registration on the product. This is usually achieved by making a mold from the actual parts to be printed.

3) The entire lot of product is consistent in shape and the position of the point of registration is also consistent.

Check out our website www.epsvt.com. There you can also find more information about Engineered Printing Solutions custom solutions, standard pad printers, industrial inkjet, consumables and other auxiliary equipment. Email info@epsvt.com or call 1-800-272-7764 if you would like more information.

Tech Tip Tuesday: Why Am I Getting A Washed Out Printed Image?

I have etched thin steel plates that are etched to about 30 microns and am using a sealed cup pad printer.

I run and print 5-10 parts that look great and then the image starts becoming washed out looking with voids. If I leave the machine for a few minutes the print looks good again and then goes back to missing pieces syndrome. I am new to pad printing and would appreciate some advice.

This is indicative of an ink viscosity problem. If your ink is drying too fast, the pad won’t be able to pick the entire image up from the etched area of the cliché. In that case, you’d add a little thinner to the ink – or retarder if the ink is already quite thin. Another option would be to remove any pauses that may be set in the printer controls to slow the drying process a little. If, however, your ink is too thin it will not completely release from the pad. Then, when the pad goes to pick up the image for the next print cycle it will deposit some of the previous image back into the cliché. To remedy this, either slow the print cycle down – putting a pause on the print side of the cycle (and maybe even one on the pickup side) or try directing some hot air at the pad after it has picked up the image to help the ink dry a little more before printing. If this doesn’t help you may want to start with a fresh batch of ink that you know has been set to the correct viscosity.

Check out our ink options at www.epsvt.com. There you can also find more information about Engineered Printing Solutions custom solutions, standard pad printers, industrial inkjet, consumables and other auxiliary equipment. Email info@epsvt.com or call 1-800-272-7764 if you would like more information.

Tech Tip Tuesday: Ink Leaking Over The Edge Of The Cliché

Have you ever had ink leaking over the edge of your cliché?  You have tried to figure out the solutions and investigated the issue by taking the cup off to check if the ink was too thin. When you did that you discovered that the ink might be too thick, but you are still uncertain of what steps to take to fix the problem.

We have a solution for you. There are a couple things that are contributing to the issue: 1. Ink too thick.  This causes the inkcup to hydroplane the resultant of which is the residual ink getting plowed into a pile on the return stroke.  2. Heat accelerating the cross linking process causing increased out gassing.  Cracking or removal of the inkcup filler screw should alleviate this.  “Weak” magnets are not a contributing factor.  The exposed magnets may have a minimal effect with relieving this issue but it is just a band-aid … not … addressing root cause.

Check out our ink options at www.epsvt.com. There you can also find more information about Engineered Printing Solutions custom solutions, standard pad printers, industrial inkjet, consumables and other auxiliary equipment. Email info@epsvt.com or call 1-800-272-7764 if you would like more information.

Tech Tip Tuesday: How do you properly dispose of ink?

Wondering how to properly dispose of ink? We dispose of bulk quantities of “used” ink with pouring it into a 55 gallon drum (for mass collection).  The drum is collected by a waste management company, contracted on a bi-weekly pickup, for disposal in compliance with Department of Transportation (DOT), Environmental Protection Agency (EPA), and state regulations.

Smaller quantities, e.g.: paper towels used for cleaning, are collected in smaller hazmat containers, allowed to dry and placed in with normal rubbish consistent with how printed product would be disposed of.

Check out our ink options at www.epsvt.com. There you can also find more information about Engineered Printing Solutions custom solutions, standard pad printers, industrial inkjet, consumables and other auxiliary equipment. Email info@epsvt.com or call 1-800-272-7764 if you would like more information.

Tech Tip Tuesday: How long after pre-treatment do you need to start printing?

Is it an hour, a day, a week or is there a way to test to be sure the priming function is still viable?

Unfortunately there is no hard and fast answer to how long it can be expected that the pre-treatment will remain in effect.  Largely this is dictated by the make-up of the material to be pre-treated. Different plastics will retain the pre-treatment for differing amounts of time.  Testing would have to be performed to understand the specific product you are printing.

In my experience I’ve seen product keep pre-treat for as long as three weeks however, more often than not, the pre-treatment degrades in a matter of hours as opposed to days.

We are always of the mind to recommend printing product as soon thereafter it is wiped (and the liquid flashes) as is feasible. As a general rule of thumb it is always best to print the product just after pre-treatment has been performed.  Of course … you should wait for the pre-treatment to flash prior to print.

Check out our other Pre-Treatment options at www.epsvt.com. There you can also find more information about Engineered Printing Solutions custom solutions, standard pad printers, industrial inkjet, consumables and other auxiliary equipment. Email info@epsvt.com or call 1-800-272-7764 if you would like more information.

Tech Tip Tuesday: Advantages of Tagless Printing

Engineered Printing Solutions has worked with numerous apparel manufacturers of T-shirts, underwear, and lingerie in developing tagless printing operations to identify brands, sizes, and care labels.

Tagless labeling allows garment manufactures to print directly on the fabric – eliminating the need for sewn-in tags and the cost and labor associated with it.

  • Direct Labeling – Fine and detailed printing directly on fabrics.
  • High speed productivity – More than 1,000 prints per hour are possible.
  • Flexibility – The print can be placed on any part of the garment.
  • Global support – We have many successful operations in Asia, Central and South America, Philippines, the USA and many other locations.

Advantages Of Going Tagless

  • Lower cost than other types of decorating with price per printed label averaging $.002
  • Can print one color on top of another, no post-curing time required
  • Eliminates purchase of labels from outside source
  • No sewn tags to irritate or rub against skin
  • Inks have passed major manufacturers’ wash test requirements
  • Tagless often advertised as premium feature
  • Easy customization and design changes
  • No waste by having to pre-stock labels with possible leftovers.

Equipment Needed To Go Tagless

Our expert teams of engineers and technicians have been involved in the development of “tagless” pad printing for over ten years. We have several pad printers to choose from depending on the size of your image, number of colors and printing volume.

  • KP06 – 2Color “RR” or pad shuttle function allows the part to remain stationary as the pads shuttle back and forth for high quality print registration. Available with two 110mm sealed ink cups and a production rate of ± 600 -700 pcs/hr.
  • EAZY Series – available with a 90 / 130 or Eazy 160 Pad Printer sealed ink cup. Production rate at 1200 pcs/hr.
  • KP05 can be configured as a one or two color printer, tabletop or with an extruded stand, plus other accessories that include a garment rack and a textile anvil. One color printer includes a 90mm sealed cup or two color with two 70mm sealed cups.

All inks are non-toxic and have been certified for 50 plus washes by multiple manufacturers on all common fabrics. The recommended ink PLT6 is compatible with Oeko-Tex® certification.

Check out our Tagless Printing at www.epsvt.com. There you can also find more information about Engineered Printing Solutions custom solutions, standard pad printers, industrial inkjet, consumables and other auxiliary equipment. Email info@epsvt.com or call 1-800-272-7764 if you would like more information.