Garment decorators looking for a complimentary business sideline to screenprinting and embroidery on shirts and uniforms should take a good long look at the printing process known as Pad Printing. The range of promotional products imaged with this process - including golf balls, pens, key chains, drink glasses and an ever changing parade of clever giveaway gizmos - goes hand in hand with T-shirts and caps, allowing one stop shopping for existing customers who are looking for advertising giveaways and other promotional ideas to get their logos and messages in front of customers.

Pad Printing is also a unique, desirable specialty print processes that can be in high demand if you have manufacturing businesses in your region. It is used extensively in the automotive and consumer goods industry to mark odd shaped objects - everything from the pictograms on the buttons in your car to the logo on your sun glasses to the decorations on thousands of toys.

A farmer in the small town of Mt. Vernon, Washington, even uses them to print tens of millions of jack’s lantern faces on small pumpkins every year for Halloween, and then sells them by the truckload nationwide through Walmart. Pad printing is everywhere you look, but pad printers aren’t, sounds like a business opportunity to me!

Pad printing’s defining characteristic is the ability to print on concave, convex, or compound shapes. Where other common print processes require material to be flat, thin and flexible to fit through rollers, pad printing machines are adaptable to a range of shapes and materials.

Metal, plastic, glass, wood, round, square, egg shaped, conical or cup shaped - if you can hold it still, you can probably print it with a pad printer. A flexible silicon rubber pad custom formed to a specific shape is used to first press down onto an inked plate that contains the image to be printed.

As the pad presses the plate and picks up the ink it distorts the image due to the special shape and the flexibility of the foam. The pad is then moved into a position over the object to be printed and pressed down or sideways against it. The pad transfers the inked image as it contacts the part or object being printed, the image appearing normally as the pad follows the contours or curves and undistorts the image.

In most cases, the thin printing plates used are made from light sensitised plastic or metal. The plastic plates can be processed easily with a film positive and a UV light source much like screenprinting, with a final washout to expose the lightly indented image which will carry the ink for the print.

Metal plates require etching to process, and are used for long production runs. New technology using a laser engraver allows for computer-to-plate (CTP) processing. Both types of plates are magnetically held in position in an ink tray known as a clichŽ.

During the print cycle of the pad, when it is moving over and then printing the object, a simultaneous inking and then scraping of the surface of the printing plate occurs. Older style machines drag a small brush laden with ink that covers the plate and the recessed image. A metal doctor blade follows, scraping ink off the surface leaving only ink in the image area. Newer models use a ceramic cup which contains the ink.

It slides over the image and then slides back, performing the function of the spreader brush and the doctor blade all in one. A ceramic cup’s other advantage is it completely contains the ink, slowing the drying-in of the image associated with evaporative inks on open plate machines, and it also minimises ink fumes for the operator.

Most inks are solvent based, with many requiring hardening agents to effect cure on hard to print materials, or to promote wear resistance. Although generally much more costly than screenprinting inks, pad printers use a lot less per image.

Most dry very quickly without a dryer, although highly automated printers will have integrated drying chambers or heaters for a quick cure. Some ink manufacturers have introduced UV curable pad inks, but the bulk of the market continues to use solvent based, due to ease of use, wide range of printable materials, and issues around UV inks curing properly on 3D objects.

Although there are a few European based manufacturers, the bulk of pad printers are made in Asia, and are used extensively there in a range of manufacturing industries, from electronics to doll making and everything in between.

Machine types range from inexpensive one colour table top manually operated models to high speed six colour printers with automated load and unload features. Automatic machines are mostly driven with compressed air, although there are a few manufacturers who build mechanically driven models.

Size is an issue in pad printing, with most entry level machines printing areas around two or three inches, in one or two colour configuration. Some models allow pads and images up to 10%. Custom machines can go larger, or be configured for specific production requirements, with appropriate tooling of jigs and index tables or conveyors. Flame treating for difficult materials, combination side and top printers, or circular printing are all options depending on the job and the machine.

Getting started in pad printing can be relatively inexpensive, with hand operated one colour machines or small one or two colour automatics that sit on a table top common and available from most manufacturers. Plastic plates can be made with available screen exposure systems and films.

Consumables such as inks, pads, thinners and hardeners are carried by many screenprinting distributors or through specialised pad printing suppliers. More information can be found on the web, with a number of websites featuring Pad Printing forums where readers and suppliers exchange ideas and help solve problems.

Printer friendly version

Email this article to a friend

Bookmark this

---