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.

Pad Printing Pads: Is Pad Size Important?

Size minimizes distortion
Pad for a Pad Printing MachineAn important variable to consider in quality pad printing is the pad size, especially as it relates to the image size. In pad printing, the larger the pad size used, the less the image is likely to distort in the printing process.

  • Pad size is measured in length, width and height without the base.
  • As a general rule, your pad should measure 10% to 20% larger than the image’s length and width.
  • Remember the “throat” – or the distance between the cliché and the body of the machine – often determines the maximum pad size you can use.

 

Special pad printing pads for large images
In some situations, a large image area must be printed and the machine does not have the power to compress such a heavy pad in a smooth motion.

Cylindrical pad for Pad Printing MachinesTwo solutions to this problem are available:

  • The first is to use a pad with a hollow interior that provides the same surface hardness. The hollow interior also reduces the cost of silicone rubber used in a large pad.
  • The second option is a dual-hardness pad, where the core of the pad is made of a softer material and the outer layer is the harder rubber. Either method helps, but using dual-hardness allows for a more stable pad.
  • Of course a third option would be to use a different imaging process like screen printing.
  • There’s another unusual pad configuration that is like an inflated pig bladder. Specialized machines use hollow pads inflated with air just prior to ink pick-up. The pad stays inflated until it comes into contact with the substrate. Then the air is released. The deflated pad can conform to a wider area of the substrate, printing up to 180 degrees compared to 100 degrees with a standard pad on a cylinder or sphere.

Join the Conversation! Have you had problems with print distortion or image size? Click Cylindrical Printing Pads or call us at 800-272-7764 for our suggestions on pad size usage. We love your challenges!

Print Pad Durometer or Hardness – Same Thing

Albert F. Shore developed the measurement device called a durometer in the 1920s to measure material hardness. As a result of the Shore ratings, the terms hardness and durometer became interchangeable. Many pad print pad manufacturers color code the standard durometers by adding pigment to the silicone itself or by coloring the pad base. The following chart shows the durometer range for each silcone material (color) we typically recommend:

Color                             Hardness
Blue                                  10 – 60
White                               20 – 65
Red                                   30 – 75

The harder the pad, the higher the Shore durometer rating. Three basic pad durometers are standard in the industry and cover most applications. Custom pad durometers are also available through most pad suppliers. We suggest you invest in a durometer gauge, valuable for all pad printers for determining pad hardness and quality control of pads in rotation. This simple tool is available through silicone-rubber suppliers and many general-service dealers in the screen printing and pad printing industries.

Choosing the proper pad hardness for a job is often a combination of experimentation and experience. As a general rule, the harder the pad, the better the performance, the longer the pad life. But hard pads may be impractical in some applications. Here are some guidelines for durometer selection and maintenance:

  • Use softer pads when printing on heavily contoured surfaces or on fragile items.
  • Use a softer pad if the power of your machine can’t compress the pad sufficiently to achieve a satisfactory rolling action.
  • Use hard pads for textured surfaces, or printing an image in a recessed area where the pad must roll over a “step”.
  • Use hard pads in a pad “nest” where a number of pads are spaced with small gaps (for example, printing computer keyboards).
  • Consider a special pad for printing on abrasive substrates and textured finishes. Example applications include automobile control arms like turn-signals and windshield-wipers, when the pad must resist the abrasive nature of the substrate.
  • Avoid using pads of different durometers on the same application. The thickness of the ink deposit will vary on the substrate.

Custom Pads – Custom Service
Confused about durometer? Need help selecting pad durometer for a custom job? We have a full pad department to help and we don’t charge for phone calls! Click Cylindrical Printing Padsor call 800-272-7764 for our undivided attention. We are here to help you!

A Long and Happy Print Pad Life

Our pad department asked me to investigate why a long-time customer had stopped buying our pads. The idea crossed my mind that our pad department was questioning the quality of our pads compared to an unknown competitor’s. So, since I had been planning a trip that included this particular customer, I confirmed a meeting with them.

After our initial welcome, we sat down to talk. I asked them bluntly why they had started using another supplier for their pads without discussing their issues with us first. The customer became defensive, insisting they had not stopped ordering from us. They then brought me on a tour of the production area, where I saw the rows of machines we had supplied some years earlier, all working beautifully – with our pads.

The real shocker was their final disclosure: they were getting about 250,000 cycles plus per pad because they had adopted our recommended method of pad rotation. Based upon the number of machines in operation, we calculated they had saved about $12,000 per year over the past 2 years because of the way in which they cared for their pads.

I thought that I was going into this meeting to battle for this customer’s pad business. I had prepared a strategy of careful analysis and special pricing. I walked away feeling a bit silly when I realized they could have paid a lot more for our pads than we were charging and still remained a loyal customer. But I was happy that we were saving our customer money by selling a superior product and giving away solid, money-saving advice for free. We were heroes.

This true fairy tale ends with “and they all lived happily ever after,” because this particular customer was smart enough to listen to and implement our suggestions. Please understand that these same pads can also wear out after 50,000 imprints, and pad life is very dependent on ink type, substrate and maintenance. 

For additional information, see our previous blog Pad 101. If you’re not getting individualized attention from your supplier, call us. We even customize our service!

Pad 101: Getting The Most Out Of Your Pad Printing Pad

pad printing padThe pad printing pad is one of the most important elements in the pad printing process. Image quality and ink coverage, are affected by your pad print pad. Here are some tips to help you get the best from your print pads and extend their life in the process.

  • What’s my substrate? Your substrate is your blank canvas waiting for printing. Be sure your substrate is free of oils and debris, especially sharp particles that could shorten the life of your pads
  • Why do my pads wear out and/or split? Never use excess pad pressure during printing. Adjust your down-stroke and let the ink do the work. Also, have your machine settings checked regularly. Over-compression and printing on sharp edges result in split pads. Do differentiate between normal wear & tear and damage due to problems.
  • How often do I need to clean my pad? Remove solid debris, dried ink and dust from your pads after each printing. Always use adhesive tape to remove debris, especially when the pad is dry from aggressive thinners. Never scrub, scratch or brush your pads
  • What can I use to clean pads? Try to use tape only, sticky side onto the dirtied surface. This will usually remove most dust and dirt. Only use alcohol-based pad cleaning fluid, the smallest amount required to do the job. Avoid strong solvents. Use them only for initial removal of silicone oil on the surface. After cleaning, apply rejuvenating oil to the surface before resting for at least 24 hours. This will prolong pad life.
  • How many pads do I need? Rest the pad for 24 hours in a cabinet after printing. Have an extra pad to swap out during the rest period.
  • What’s a safe environment? Always protect the pad’s print surface; store uncovered in a clean dry environment.
  • How long should a pad last? Pads should usually handle 50,000 impressions or more. With proper care, we have seen pads last longer than 100,000+ cycles.

Next discussion: Pad shape and durometer – is it right for the job?

Remember: Pads are costly to replace. The better you treat the pad – the longer it will last.

Join the Conversation!  How many impressions/per pad was your record? Have you used Engineered Printing Solutions Pad Finder Wizard? Are there other tools that could help simplify your orders?  This is your forum. Teach us!

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