GCM2222- Intro to Packaging Production Quiz 3

Adhesion

Molecular bonding

Block Test

a test used to measure the tendency of surfaces to stick together

Corona treating

An electronic process that increases adhesion proper es. The process is used primarily for polyolefins requiring prin ng coa ngs, lamina on, glues, etc. A corona is created when a high voltage charge is produced in the air adjacent to an insulator. The ionization is adjacent to the moving web of film. A corona must be high enough to• ionize the air and low enough not to spark or damage the web.

Doctor Blade

Also known as a reverse angle doctor blade. Usually, it is a steel or stainless steel blade approximately 0.004 to 0.006 inch thick with a precision ground beveled edge. The beveled side of the blade does not rest against the anilox roll, but the sharp edge it provides shears the ink off the surface of the anilox roll. Meter roll pressure against the anilox roll is backed off to allow a heavy ink film transfer. The doctor blade is posi oned against the anilox roll with very slight pressure to scrape the surface of the anilox roll and leave only the ink in the cells. Doctor blades provide a more consistent ink film than meter rolls alone and maintain the consistency during speed changes. Plas c blades of approximately 0.060 inch thickness are more recent developments to help minimize anilox roll wear. Doctor blades must be changed with every job change because they usually wear in to a particular anilox roll and can cause streaking if used with a different anilox roll.

Enclosed Doctor Blade

An enclosed chamber containing a doctor blade at the top and bottom with seals on each end. Ink is pumped into the chamber, and a drain is provided to recirculate the excess ink back to the pump. The unit mounts directly to the anilox roll to replace the meter roll and can be used in either forward or reverse rota on print stations. Ink containment is usually a benefit with enclosed doctor blades because ink slinging is eliminated. As with the other doctor blade systems, this unit uses the same type of blades, and the blades must be changed with every job.

Extender

material added to ink to reduce its color value

Foil Stamping/ Hot Foil Stamping

A form of graphic decoration in which a thin layer of foil is applied to the web by a pressure die that can be heated up to 300°F (148.9°C). Cold foil stamping is also possible. A heated die must have li-off capability to prevent scorching of the web when the web is stopped. Foil stamping can also be used for applications that require the web to have a raised relief or tac le feel.

Hot Melt

Hot melt systems are used to apply heated glues, inks, and coatings to the substrate through impact and nonimpact devices.

Impression Roll

Also known as an impression cylinder. The impression roll is driven from the print station gearbox and serves a dual purpose. It serves as a pacing member as well as an impression roll providing a solid surface for the web when the plate roll is pressed against it during the printing process. A gear is mounted on the impression roll to drive the plate roll. Due to the pacing func on impression rolls provide, rolls for a given print station must be equal or less than the diameter of the impression roll in the next station in the print process. There are several terms for this roll size progression roll stepping, gain, staging of rolls, etc. This stepping of rolls helps to maintain tension in the web.

Inking System

For flexographic printing, the inking system can include the ink fountain, anilox roll, meter roll, doctor blade, enclosed doctor blade, ink wipers, and ink pumps. Inking systems for other processes vary.

Makeready

All preparation work done on a job from image assembly to the actual press run.

Pacing Roll

Any roll in a press connected to some source of mechanical power over which the web is wrapped.

Plate Roll Undercut

All plate rolls used on the Mark Andy presses are undercut. Plate rolls are used with printing plates, which have the image of the desired print. The printing plates are fastened to the plate roll with double-sided tape. The print repeat length is determined by the total diameter of the combined plate roll, tape, and the printing plate. Therefore, the plate roll must be undercut to maintain the required repeat diameter. The undercut amount is· equal to the additional diameter added by the tape and the printing plate.

Registry Through the Roll

Pertains to measurements taken at several places through an en re roll of web to determine if the press is maintaining the same registry accuracy from the start of a roll to the completion of a roll. This points out any tendencies the press may have. One example would be a constant registry pullout caused by the tension system not being able to isolate the rewind properly from the converting sec on. As the rewind roll grows, it changes the amount of pull through the exit pacing station, thus causing a registry error or pullout.

Rider Rill

A roll that rides on the rewound product roll as it is being wound onto the rewind coreholder. The rider roll is placed at the point of contact of the web to the product roll to press out any air that might get trapped in the roll, thus winding a ghter, more stable product roll. Rider rolls are useful, but they can cause problems with winding if not setup properly. If the rider roll applies too much pressure to the product roll, the product roll drive mechanism can slip or reduce speed and form a loop in the web. This will then cause an uneven roll · to be wound because there is. no tension in the web. Uneven rider roll pressure across the web causes the product roll to telescope and become unstable rather than more stable.

Separations

A term used to describe the creation of halftones for an original color photograph used in process printing.

Slur

a printing condition caused by slippage

Stacker

A conveying system that takes the sheeted product from the sheeting die and groups it into a preselected number of sheets per stack. The sheets can be stacked on edge, stacked in receding stacks, or added under the stack.

Undercut

The amount that cylinders are made smaller to accommodate stickyback and plate material while still keeping the cylinder in pitch with the gear being used.

Waste Removal

Normally performed with a waste wind-up unit to remove the waste matrix a er the web has been diecut. If continuous opera on is required, turret waste wind up units or vacuum systems can be used to remove the matrix. Vacuum systems can be used in conjunction with a pin stripper to positively remove slugs from the web and vacuum them away.