Welcome to Printex

Frequently Asked Questions: Printing

1. How does pad printing work?

Please see our excellent Introduction to Pad Printing, available on the web (or call customer service to request a copy).

2. Is pad printing easy, like making a photocopy?

According to our customers, pad printing is more difficult than photocopying and slightly easier than screen printing. It incorporates some old-world principles, as well as many new technological improvements that make it more of a science now than the old idea of it being an "art". The successful pad printing machine operator will be a bit of a technician at heart that follows procedures and recipes carefully.

3. How do I determine if pad printing is the best way to mark my product?

As with any other technology, you must weigh its benefits and limitations against your project's requirements to determine if you have the right match. We at Printex are always available to discuss your application with you in a plain English no-nonsense fashion.

If we have recommended pad printing to you, rest assured this is the best way (and possibly the only way) to mark your product effectively.

4. How do I select the right Printex machine for my application?

The primary criteria for selecting equipment are: image size, overall part size and geometry, the print position(s) per part, the number of colors per image and the number of parts per minute (or day) required. With any application, there is likely to be more than one equipment model which will accomplish the task. For most first-time pad printers, choosing the right machine is a daunting task. We at Printex routinely evaluate current and possible future applications for our customers and provide a written quotation for the recommended equipment.

5. Could I run my pad printer as fast as I want?

Cycle times vary widely, with a handful of interdependent factors. Most machine manufacturers (Printex included) quote top machine speed in their literature and specifications. Actual printing rates will depend as follows:

Inks.
Pad printing inks dry quickly, but not instantly. Even inks that are designed to print "wet", such as UV-curing inks, need a short gel time before being transferred in order to obtain acceptable results. This time window will vary with climatic conditions, ink type, plate depth, coverage, etc. The time could be as little as one second to as much as 10 seconds or more. Typically, it is 3-4 seconds without forced acceleration, such as air flow or heat.

Pads.
Being a soft, three-dimensional shape, large pads may tend to vibrate at higher machine speeds. Vibration during ink pickup or transfer will yield unacceptable print results, so the machine must be slowed to allow the pads to remain steady. Additionally, pads that compress over a large print area will offer some resistance to machine movements, slowing the cycle further.

Operator and/or Auxiliary Operations.
Just how quickly can an operator load and unload your parts without fumbling? Must the operator stop periodically to move trays of parts, open boxes, or perform some other necessary function? What about upstream or downstream operations with which you must synchronize your pad printing process?

These are some of the elements that will actually determine in real time the speed at which you could run the machine.

6. Can pad printing machines print with other fluids besides ink?

Yes. In addition to cosmetic ink markings, pad printers have been used to apply conductive materials, lubricants, solder paste, wax, adhesive coatings, biomedical chemicals and more. The pad printer does not care what media it is transferring, as long as it meets a few basic criteria:

The viscosity is similar to pad printing inks.
Tthe material is cohesive (does not bead up or lose it's shape when lifted out of the plate).
The material is reasonably homogenous (does not separate or precipitate).
The material transfers onto the pad, rather than stick to the printing plate.
The material sticks better to the target object (substrate) than to the printing pad.
Tthe material does not corrode the printing plate, attack the pad or machine parts.

We do not intend to make this sound easy. Printing of specialty fluids requires much testing and validation, but most times can be done.

7. Is pad printing good for applying serial numbers or date/lot codes?

Possibly - it depends upon the frequency at which the variable information changes. Serial numbers typically change with each individual part. Since pad printing is a plate-based process, this would require a new printing plate to be made for each part, or a re-adjustment of pad and part position which is impractical. Date codes and lot numbers may change after several hundred or several thousand parts and therefore may be feasible with pad printing, using relatively inexpensive photopolymer plates. One must weigh the cost of a printing plate and the down-time required to change the plate in the machine when considering this method.

8. Could I pad print very large images or objects, such as a 10" x 20" panel, or a 55-gallon drum?

Possibly, but you are advised to explore other methods of marking or labeling for those items. Printex has produced pad printing machines large enough to print the control panels on barbecue grills and an 8.5"x11" sheet with 100% coverage. Due to the nature of pad printing, these machines and the printing pads they utilize are necessarily very large and expensive. They apply hundreds of pounds of pressure to the part during printing. On the other hand, screen printing can be used to easily print poster-sized flat items with relative ease, and it is (by comparison to pad printing) a simple matter to apply a label to the side of a 55-gallon drum. As you may have gathered, pad printing is most efficient for smaller items and images.

9. Can pad printing reproduce photographic images?

Yes, in both black-and-white and color. The pre-press preparation is a little different than what is required for standard offset printing. Photo-quality pad printing is among the most challenging of pad printing applications, particularly when attempting a high-resolution reproduction, but the results can be quite impressive.

10. Could I pad print parts while they are moving on a conveyor?

No. Standard pad printing requires that the part be stationary and secured during the ink transfer.

11. When pad printing multi-color images, does the ink have to dry between colors?

No. Pad printing inks are designed to be fast drying, and their drying speed is enhanced by the thin ink film layer therefore, "wet-on-wet" multi-color pad printing is possible. In practical use, best results are usually achieved with moderate cycle times (less than 1000 cycles per hour). Occasionally the use of air flow across the pads or printed parts to accelerate the evaporation (flashing) of solvents from the printed ink is necessary.

12. Could I mount my Printex sealed inking pad printer sideways or upside down?

No. Printex Sealed Inking Pad Printers are designed to operate upright. The Sealed Ink Cup works on the principle of gravity. Gravity pulls the ink down into the artwork etching on the plate. However, Printex offers the RP-machine series and potential modifications of the same as a solution for vertical and upside-down printing.

13. Could I incorporate pad printing on a machine that performs other work as well?

Yes, as long as the basic requirements of pad printing are met. Printex provides solutions to mate with existing automation, and can design and manufacture custom systems which incorporate pad printing with pre- and post-print secondary operations. If you have a need for this service, please fill out and send our electronic quote request form, and we will contact you to discuss the detail.

Toll-free telephone support is available from 8 a.m. Eastern Standard Time to 4 p.m. Pacific Standard Time.
Call (800) 982-1928.

Or, you can e-mail your technical support issue using the form on this page. Be sure to fill in all fields.
A support representative will contact you by e-mail or telephone as quickly as possible.