PAD PRINTING INK CUP

There are two types of pad printing machine inking systems—a seal ink cup and a doctor blade system. These two systems have gained widespread implementation worldwide. The sealed-cup systems have seen widespread adoption in North America for decades, but they are finally taking over in other parts of the world. Open inkwell systems are still popular throughout the world. For both new and existing equipment buyers, we offer pad printing consumables for open inkwell and sealed ink cup pad printing equipment systems. Learn more about these pad printing ink cups and rings.

pad printing ink cups

WHAT IS A PAD PRINTING INK CUP?

A pad printing ink cup, also known as an ink cup, is a key component of a pad printing machine, fitted with or without magnets, an O-ring, and a sharp ceramic or tungsten ring for scraping ink on all types of plates (cliches). The ink cup acts as an ink reservoir—it holds and deposits the precise amount of pad-printing ink onto the etched image on the plate.

The functions of the ink cup system are to maintain the ink viscosity. Additionally, it acts as a sustainable system that limits solvent evaporation and the VOCs released into the printing environment.

Pad printing supplies for your pad printing machine
types of sealed cup systems for pad printing

TYPES OF SEALED CUP SYSTEMS

There are two types of sealed cup systems: a magnetic ink cup and a non-magnetic ink cup. Both ink cup types achieve excellent results when doctoring printing plates.

Magnetic ink cups have magnets that exert force between the plate (cliché) and the cup. This force prevents the ink from leaking as the cup moves back and forth. Additionally, its implementation is easy, especially with multi-color pad printer systems. This makes the construction of machines cost-effective.

Non-magnetic ink cups do not have magnets. The pad printing machine applies the pressure either to an outer flange or a center hole. These types of cups are excellent for high-speed applications where the cup is held in place while the plate moves back and forth.

COMPONENTS, FEATURES, AND FUNCTIONS OF A PAD PRINTING INK CUP

The ink cup assembly has several components (body, ring, O-rings, and vent plugs). Let us review each component and its functions below.

  • Cup body: this is the closed container that holds the pad printing ink. The cup body prevents the ink from drying out by limiting the amount of solvent evaporating into the environment.
  • Doctor rings are made from ceramic (Zirconia) or tungsten carbide materials. Tungsten carbide rings are very sharp, corrosive, and wear the plate material quickly—especially photopolymer plates. Lastly, because carbide rings have a cross section of 0.003” and taper from the outside of the ring, this makes them brittle and prone to damage. Ceramic ink cup rings, on the other hand, are easy to manufacture, have self-lubricating qualities, and are resistant to wear and corrosion. Additionally, these ink cup supplies work exceptionally well across all different types of plates (photopolymer, thin, and thick-steel printing plates).

The function of the ring is to remove excess ink from the surface of the plate, leaving ink only in the engraved etch.

  • O-ring: Ink cup O-rings are made from Viton and silicone rubber compounds, which are resistant to solvents. There are two O-rings on a cup. One around the vent plug—this seals the plug, hence preventing solvent and fumes from escaping from the cup. These O-rings are located around the cup body, beneath the ink cup ring. The function of these O-rings is to reduce the vibration while the cup is moving back and forth. It also seals the cup, acts as a shock absorber, and prevents the ink from leaking.
  • Vent plug: This is an important part of the cup assembly. The function of the vent plug is to let air (gas) out of the ink cup, which in turn helps the cup set properly on the plate. Air builds up, preventing a complete seal between the cup and plate, which results in ink bleeding.
ink cup types

THE BENEFITS OF INK CUPS IN PAD PRINTING

The ink cup systems have several advantages over open ink wells. These include:

  • Prevents inks from drying out—this is an excellent feature for long production cycles. Additionally, this feature is excellent during breaks and in between printing cycles.
  • Easy changeover: especially for double-sided ink cup rings, when one side is damaged, it is easy to flip the ring on the other side and keep the production going.
  • Ink stirring: as the cup moves back and forth, it is constantly mixing the ink, which ensures that the pad printing ink, hardener, and solvent are optimally mixed. This maintains ink viscosity, which is important for achieving uniform prints.

It is therefore very important to ensure proper maintenance and adjustment of the ink cup. These will result in achieving high-quality prints and minimizing ink waste.

 

PAD PRINTING RINGS

The ink cup is a crucial component of a pad printing machine. The ink cup acts as a reservoir, which holds the pad printing ink. Components of the ink cup include the body, O-ring, vent plug, and a ring (ceramic or tungsten). The O-ring absorbs shock when the machine is rocking back and forth. The ink cup ring cleans the excess ink from the image.

We offer the widest variety of pad-printing rings to fit any pad-printing machine.

Still have questions about ink cups and rings? Contact us or visit our support hub!

ink cup rings