Ink Cups for Pad Printing Machines Overview

Ink cups for pad printing machines come in a variety of types and styles. When looking at the pad printing equipment market over the past few years it is apparent that the biggest change in equipment design and implementation has been the widespread use of sealed cup systems over open inkwell doctor blade systems. This is especially true in the US marketplace where sealed cup systems have dominated new pad printing equipment purchases for several years; however, open inkwell systems are still popular throughout the world. Both types of inking systems have a great deal of merit and new equipment buyers often inquire regarding the advantages of one system over another. Check out our wide variety of pad printing ink cups and rings!

Doctor blade system

The doctor blade systems have been run very successfully for many years and are still very popular in a situation where there are long images, several color changes, short print run (less than 500-1000 pieces) and where there are experienced pad printing machine operators who understand the nuances of the pad printing process. You will commonly find open inkwell systems in marketplaces like plastic housing, golf ball, and promotional products where long images, short runs, and experienced operators are commonplace.

A significant advantage of the doctor blade system over the sealed cup system is that it can easily print long images because there is no major limitation as to how wide a doctor blade or plate can be made. Long images on plastic housings like a television, computer monitor, or vacuum cleaner are primarily done using doctor blade machines.

However, recent equipment developments with ink cup technology have made it possible to enable long image printing with the consistency of a sealed cup. A slide system can be mounted to the pad printing machine that sweeps the cup from side-to-side (instead of front/back) across the length of the image. It works extremely well for mid-quality images and has been the method of choice by the medical field for catheter printing. This technology was developed and patented by the author and has become adopted as a standard feature on most ink cups machines offered in the market today.

Types of sealed cup systems

Sealed ink cups for pad printing machines have become so popular because of ease of operation. By limiting solvent evaporation from the ink, the skill level in maintaining the chemical balance of ink is reduced and the process becomes much more predictable and manageable. Less experienced operators can run the pad printing equipment more efficiently.

The two main drawbacks to sealed cup vs. doctor blade systems are the expense of ink cups and doctoring rings and limitation and expense when printing large images.

Many times, it is sensible to have extra ink cups and doctoring rings to help improve efficiency when doing ink changes and as spare parts. When used efficiently, one set of ink cups with pre-mixed ink can be ready to be inserted into the pad printing machine for immediate production, while the other ink cups are removed and cleaned on the side. The disadvantage to this arrangement is that the spare ink cups can be very expensive, especially when purchased from the pad printing machine manufacturers. Therefore, at Inkcups, we have focused on solving this dilemma for the pad printing machine owner by being an alternative source to purchase ink cups from at fair prices. It has proved out to be a powerful value proposition to machine owners.

The largest size ink cups sold on “standard” pad printing machines are generally 135mm or 5″ in diameter, which prints about a 4.5″ diameter image. If image requirements extend beyond a 5″ ink cup, the price of equipment generally goes up significantly and the equipment and ink cups become specialized. To our knowledge the largest ink cups made are roughly 250mm in diameter (10″) which could print a 9″ diameter image on items like play balls, circular saw blades and satellite dishes, however these machines are very specialized and generally custom made.

Nearly all sealed ink cup types can be broken into two categories, magnetic or non-magnetic. Both ink cup types, when integrated into the pad printing machine yield excellent results for clean, properly doctored printing plates.

A magnetic ink cup is basically “self-doctoring unit”. With its extremely powerful magnets, it has all the necessary down-force to clean the plate requiring the pad printing machine to simply pull it back and forth. The magnetic ink cup generally has found its strength in multi-color applications because the pad printing equipment can generally be of simple construction and the multi-color pad printer more cost effective.

Non-magnetic ink cups are designed to have the pressure applied by the pad printing machine to an outer flange or centering hole in the cup. The pressure is applied by a spring-loaded system geared for one ink cup assembly. The spring-loaded system is compact and very effective but is not as simple to deploy on a multi-color pad printing machine. The non-magnetic ink cups seem to have their niche in compact or high-speed machine applications. In these systems, even at high speeds, the spring-loaded hold-down system keeps the ink cup firmly in place while the plate moves in and out.

BENEFITS OF VERSACUP® INK CUPS:

• Lower costs for both ink cups and ceramic rings
• Damaged ceramic rings can be easily removed, flipped over or quickly replaced on site
• Two sided ceramic rings have double the life than single sided rings
• Low-profile design prolongs ink life and reduces ink waste
• Ceramic rings are more robust than brittle steel rings and are less prone to damage
• Ceramic rings extend polymer plate life
• “Encapsulated” magnets reduce time for ink changeover and eliminate plate damage from loose or flaking magnets

Doctor Rings

There has been much debate as to which doctor ring material is best for doctoring printing plates. The market for pad printing supplies originally started with carbide steel doctor rings and many were successfully implemented, however, since the ceramic ring was brought to the US market in 1993 it has been extremely successful as well. We would guess that now the pad printing marketplace is evenly divided between the carbide ring and the new generation ceramic doctor ring. Today, both carbide rings and ceramic rings work extremely well. It is our opinion however, that the ceramic doctor ring offers some advantages.

One of the primary advantages of the ceramic ring has a “self-lubricating” qualities that make I work equally well on thin steel and thick steel and the softer polymer printing plates. The carbide doctor rings are generally sharp and abrasive and will wear a polymer plate material quickly. Another advantage of the ceramic ring is that it is generally thicker, more robust and resistant to damage by during handling. Most ceramic rings taper from the inside and outside diameter to a “point” roughly .006” leaving plenty of material near the tip. Carbide rings, however, taper from the outside diameter only to a “point” with a cross section of .003” leaving only a minimum amount of material near the tip resulting in more damage during operator handling. The combination of the ring profile and the brittle nature of carbide make damage to rings frequently during ordinary use.

The pad printing marketplace has become relatively mature over the last decade and the quality of the products available in the marketplace is very high, so regardless of the type of pad printing machine, Doctor Blade or Sealed Cup you are bound to have a highly successful experience with pad-transfer printing.