Tag Archive: Pads

  1. Tech Tip Tuesdays: Frequently Asked Pad Printing Pad Questions?

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    How long should my pad printing pad last?
    Depending on how “rugged” a surface you’re printing on, a pad should last between 50,000 and 100,000 impressions. Improper use, careless machine operation or stray grit however, can decrease the pad’s life.

    What should i watch for when I’m pad printing?
    Make sure your substrate is free of sharp particles and debris. Avoid printing on sharp edges, which can puncture the pad. Use as little pad pressure (downstroke) as you can to pick up and deposit your image. (Tip: Too light an image could be an improperly etched cliche’)

    What causes the most damage to pads?
    Overly aggressive solvents, mechanical damage, poor storage practices, dirt/dust/debris and careless use are the most common causes of damage to pads. Additionally, some inks have aggressive solvents as part of their mix that will be absorbed by the pad and cause the image to “spread” on the pad. This isn’t permanent, as the solvent will evaporate if warmed or left to stand.

    How should I clean my pad?
    The best way to remove ink and debris from your pad surface is with regular packing tape. You may also use a mild solvent, such as alcohol. Always clean your pad before starting a printing job and never use a sharp object on your pad.

    What is the best way to store my pad?
    If a pad arrives in a protective shell or with a protective cover, remove it and do not reuse. It could trap grit and debris that can damage the pad. Never store a pad on top of or compressed against another pad. Handle and store your pads carefully.

    What’s the nest way to extend my pad’s life?
    We sell 8 oz. bottles of Pad Rejuvenator (Ask for Part Number PAD OIL when you call our customer service department.) The other way we recommend extending a pad’s life is to have two pads that you alternate one shift on, one shift off, to “rest” the pad and let it restore to its uncompressed state.

    How do I prevent pad wear?
    Correct design and tooling of fixtures will help eliminate pad wear … a major cause of image distortion.

     

  2. Tech Tip Tuesday: Symptoms of Having Chosen the Incorrect Pad Printing Pad

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    The pad is one of the most important elements in the pad printing process. The correct choice is essential in obtaining good final print results.

    Symptoms of having chosen the incorrect pad printing pad:

    1. Pin holing (pad too soft or too shallow),
    2. Image distortion,
    3. Incomplete transfer (in particular near the peak of the pad),
    4. Inability to pickup entire image (pad too small),
    5. Will not fit on equipment,
    6. Equipment incapable of compressing pad sufficiently for pickup, transfer or both.

    Choosing the correct pad requires some familiarity with the pad print process.  General rule of thumb:

    1. Choose as hard a pad as the process will allow.
    2. Keep the image size to no more than 80% of the print area of a given pad.
    3. When odd form printing … use a large a pad (within reason) as is possible.

    Our customer service team will help you choose the proper pad for your printing application. Some of the questions we will ask (in addition to print area, shape and surface texture) are:

    1. Thickness of the base (1/2″, 3/4″, etc.);
    2. Type of base needed (wooden is standard, or specify flat aluminum or extruded aluminum dovetail);
    3. Machining or drilling needed on base (size and location of tap holes);
    4. Overall maximum pad height, including the base;
    5. Whether the pad needs to be hollow of with a helicoil insert;
    6. How hard or soft the item is being printed (to determine pad durometer);
    7. The size “T” nut needed to attach pad to machine (if needed).
  3. Stuck with Pre-treating for Adhesion?

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    Pad printing’s a great way to transfer images to 3-dimensional parts. Its versatility handling shapes and substrates composition surpass almost every other automated marking method. However, getting that ink to ADHERE to all these parts can present a challenge, especially parts molded from Polyethylene (PE) or Polypropylene (PP).

    These two substrates exhibit a low surface energy (usually measured and described as the “Dyne level”). There are other substrates like those possibly containing Teflon that are also problematic. But PE and PP are so widely used in different industries, we’ll stick (no pun intended) with them for the purposes of this discussion.

    Most ink manufacturers provide inks that are “suitable” for PE and/or PP. In many cases you’d just treat it like any other pad printing job with no issues. However, depending on the customer’s expectations of image durability, this may not prove a viable option. It is, however, the first place to look.

    Pre-treating for adhesion choices

    There are four choices when faced with adhesion issues:

    • Special ink
    • Chemical wipe
    • Flame treatment
    • Corona discharge

    Pre-wiping parts by hand with a chemical that allows the ink to bond is a “second-tier” option, best suited to prototypes and short runs. Many firms hesitate to introduce another chemical into their work flow, and you’ll be exposing operators while increasing run time as well.

    For longer runs and constant production speeds, you really have to look at the final two options – flame or corona – usually in a print cell, or actually integrated either into the machine configuration or in-line.

    Flame treatment is more cost-effective, easily integrated and in some cases, actually provides a better surface pre-treatment. However, some firms choose not to have an “open flame” in their workplace, regardless of the fact that most flamers are heavily guarded and the actual flame is no more than 1” to 2” in length.

    Electrical discharge units (some call it corona while others refer to a plasma-jet) are just that: an electrical charge across or through the substrate that raises the energy level to a point where ink will cross-link and adhere. These are more costly to purchase, but better suited to some substrates.

    Please note that there’s no “magic bullet” when it comes to pre-treatment technologies. Some work better with substrate “A” versus substrate “B.” To complicate matters even further, there are a large number of different blends of plastics, especially PE and PP, while other plastics may include recycled (“re-grind”) material; flame-retardant additives; colors, etc., all of which can affect adhesion characteristics.

    To conclude: your choice is based on throughput speeds and budget, plus environmental issues.

    Your ink or machine supplier will be able to assist you with testing and choices, as you need to find out what works best, will meet your production rates, and is most cost-effective.

    One final note: If you are importing molded parts, be aware that the “blend” of materials may change without notice; what works this month may not work in the future. New batches may require new research. If you can, check with your parts manufacturer and bring that information back to your ink supplier.

    Join the conversation! We have technical ink experts available to answer your questions and work through any problems you may encounter. Confused? Connect with the right person to help. We make the complicated seem easy!

  4. Pad Printing Pads: Is Pad Size Important?

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    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!

  5. Print Pad Durometer or Hardness – Same Thing

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    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!

  6. The Different Pad Shapes

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    Choosing the right print pad for a pad printing job is not an easy decision. Five key pad characteristics (shape, durometer, size, surface finish and material) affect the quality of the printed image. But shape is the most important variable in selecting a pad, so let’s discuss why in today’s blog.

    The Different Pad Shapes
    Pad suppliers offer many pad shapes in their standard inventory, but most are based on three basic shapes:

    • Cylindrical
    • Rectangular
    • Linear

    Although hundreds of pad shapes are available, most are based on these three shapes.

    Each of these shapes could have either curved or flat printing surfaces, depending on the part to be printed. But regardless of what shape the pad has, it must “roll” onto both the cliché and substrate for good printing results. If at all possible, avoid flat-bottomed pads that have a tendency to trap air as it contacts the cliché.

    Air trapped between the pad and the cliché, or between the pad and the substrate, can cause print distortion and pin-holes, a result of uneven ink pickup or imprint. To produce a quality print image, the pad surface must roll onto the cliché picking up the ink, and use the same rolling action depositing the ink onto the image area. The better the roll, the more ink that is transferred. The shape of the pad largely determines how well the pad will roll. This is what makes shape the most important variable in selecting a pad.

    Ordering Custom Pads
    For very unusual parts and imaging needs, sometimes custom pads are a good choice, combining two different profiles on one pad. They are expensive and must be carefully designed and tested to avoid print distortion. For more information, Cylindrical Printing Padshere or call 800-272-7764 to discuss if this is a viable choice for you.