Flexographic Printing Equipment

Flexographic Printing Equipment Related Information:

Flexographic presses are less complex than those used for other printing processes.

 

A typical flexographic press includes four rollers.

 

  • Fountain or Ink Roller:This is the first roller. It transfers the ink from the ink pan to the meter roller. The fountain roller and meter roller are set to rotate against each other under pressure. The fountain roller is driver slower than the meter roller causing it to squeeze away excess ink from the surface of the meter roller.

 

  • Meter Roller: This is the second roller and is often referred to as the Anilox roll. The meter roller is generally made of steel or ceramic. It is engraved with tiny uniform cells that carry and deposit a uniform ink onto the plate. The purpose of the Anilox roller thus, is to pass on a thin, even layer of ink to the plate.

 

  • Plate Cylinder: This is the third roller. It is placed between the meter roller and the impression cylinder. Plate cylinders come in various sizes. To change the number of times an image prints or repeats around a plate cylinder, the existing plate cylinder can be removed and another easily dropped into position.

 

  • Impression Cylinder: This is the fourth roller. The material to be printed or the substrate passes between the plate cylinder and the impression cylinder. The impression cylinder backs up and supports the substrate as it contacts the printing plate. The gap, or nip, between these two cylinders must be just right to give the proper printing pressure.

 

Flexographic presses typically have four sections

 

  • Unwind and infeed section: Most substrates are fed into the press from rolls or webs. The tension of the roll must be controlled just enough to prevent slack and wrinkles as the paper unwinds into the press.

 

  • Printing section: One printing section has the four rollers mentioned above. Most presses have two or more print stations enabling them to print two or more colors.

 

  • Drying section: High velocity hot air dries the ink. Dryers are also placed between printing sections so that each color is dried before the next one is printed.

 

  • Outfeed and rewind section: The webs are rewound after printing. This is referred to as roll-to-roll printing. Here again, the web tension must be controlled to keep the roll wrinkle-free and uniform as it rewinds.

 

 

Types of Flexographic presses

 

  • Stack flexographic press: The press described above is called the stack press. It has individual color stations that are stacked one over the other. Because of their configuration, stack presses are easily accessible, making on-press changes and servicing easy and economical.

 

  • Common Impression or CI flexo press: It is also known as CIC or Central Impression Cylinder. The CI press supports all of its color stations around a single impression cylinder. The primary advantage of this press is its ability to hold excellent register, which is the placement of one color in relation to others.

 

  • In-line flexographic press: They contain multiple printing units that are arranged in a horizontal row, each standing on the floor. In-line presses are commonly used to print pressure-sensitive labels, corrugated board, and newspapers. One advantage of an in-line press is that additional operations such as die cutting can be done between color stations on the press.

 

  • Newspaper flexographic press:multiple printing units, each unit consisting of two printing stations arranged back-to-back in a common frame. The use of paired stations allows both sides of the web to be printed in one pass.

 

  • Commercial publication flexographic press: Commercial publication flexographic presses are compact high-speed presses with wide web capability that utilize dedicated 4-, 5-, or 6-color units. Typically, two four-color units are paired in one press to allow printing on both sides of the web. Publication flexographic presses generally incorporate infrared dryers to ensure drying of the waterborne ink after each side of the web is printed.

 

Although flexographic printing stops at the end of the press, the web is not always rewound. Instead of entering the rewind, the substrate can go directly to another machine that will convert it into its intended product.

 

Thus flexographic printing equipment consists of largely the press with its four sections and the four rollers of the printing section.