Precision Rolls for Coating & Laminating

Harper Corporation's LaserKoteT rolls beat chrome and other ceramic rolls as the only choice for coating and lamination applications. Selection of the right LaserKoteT engraving is a scientific process and can be done with a high confidence level. Performance advantages such as long-life, durability and consistency make LaserKoteT rolls the right choice for today's packaging quality and coating standards.

Having mastered the science of coating applications, we guarantee coating weight. With extreme accuracy in our lasers and measurement systems, LaserKoteT precision engravings can save you thousands by reducing material application costs and minimizing waste in the process.

Coating Weight Application Guide
(Direct Gravure Flexo)

Flexographic Coating Boundaries

Gravure Coating Boundaries

What is a LaserKoteT Roll?

LaserKoteT rolls are ultra-hard, laser engraved ceramic rolls manufactured by Harper Corporation, the worldwide leading manufacturer of these rolls for the packaging industry for over seven years.

Before the introduction of LaserKoteT, inexpensive chrome engravings with fairly consistent cell structures, and adequate repeatability from roll to roll were the primary delivery vehicle for coatings and laminations. Today, LaserKoteT precision engravings offer more consistent cell structures and repeatability, as well as the following advantages over chrome:

First we must determine whether your coating is considered thick or thin. We differentiate between these two types of applications because the approach to LaserKoteT roll design for thick or thin film coatings differs dramatically.

Thin Film Coatings

The recommended LaserKoteT cell pattern for thin film coatings is the 60° HEXAGON cell pattern. Harper pioneered this cell pattern for Flexographic printing in the early 1990's.

Thin film coatings require cell volumes ranging from 0.7 to 12.5 BCM's, with engraving screen counts from 120 to 800 cells to the linear inch.

When compared with chrome, the 60° hexagon LaserKoteT roll offers thinner cell walls, wider cell openings and bowl-shaped cells. In addition, the 60° hexagon pattern holds 15% more cells per square inch than 45° engravings. With more cells per square inch, the pattern delivers comparable coat weight with shallower cell depths, resulting in more uniform coating films. Additionally, shallow cells minimize both volume loss and clean-up during a run. The result is more consistent, thinner coatings, and ultimately, less waste in your process.

60° Hexagon

Thick Film Coatings

The recommended LaserKoteT cell patterns for thick film coatings are TRIHELICAL and 45° QUAD shaped engravings.

Thick film coatings require cell volumes ranging from 12.5 to 50 BCM's, with engraving screen counts from 30 to 200 cells per linear inch.

We post-polish these coarse screen rolls after engraving, to smooth out inherently rough cell walls caused by extremely deep cell engraving recast. The higher the cell volume, the greater the need to remove excessive recast. The degree of post-finishing or post-polishing is accomplished under highly controlled volume measurement conditions.

When manufacturing coarse screen engravings, the primary quality parameters are:

• Precise cell volumes to deliver exact coating weight or thickness; and
• Smooth cell walls to offer minimum blade wear conditions to optimize production time.

Developing Specifications
If you are interested in specifying a LaserKoteT roll for your next coating/laminating application, complete the LaserKoteT Worksheet (PDF, Word Document or Plain Text) and e-mail or fax it to us.

If you have any questions, contact our Technical Service Department or give us a call at 800-438-3111 (U.S. / Canada) or +1 704-588-3371 (international). We will be happy to assist you in completing the worksheet and with any other questions you might have.

With a completed worksheet we guarantee the coating weight delivery of your LaserKoteT roll.

Coating Weight Application Guide (for Thick Film Coatings)

*All weights are based on the following technical specifics for a coating material: 8.7 pounds per gallon; 3,000 square foot ream; aqueous- or solvent-based; up to approximately 50 seconds #3 Zahn (400 centipoise) viscosity.

Flexographic Coating Boundaries

Based on hundreds of tests, this flexo process (engraved roll transfers to plate, then to substrate) rarely delivers less than 19% or more than 24% of the cell's wet coating content to the substrate.

The following table indicates approximate maximum thicknesses and weights suitable for flexo application. (Note: This table assumes a coating material of 8.5 pounds per gallon.)

PLEASE NOTE: We can produce LaserKoteT rolls providing higher weights and thicknesses than those listed, but the flexo process usually is not capable of handling or drying such thick films.

Gravure Coating Boundaries

Direct gravure processes (engraved roll transfers directly to substrate) normally delivers 40% to 44% of the cell contents to the substrate.

The following table indicates approximate maximum thicknesses and weights suitable for gravure applications. (Note: This table assumes a coating material of 8.5 pounds per gallon.)

PLEASE NOTE: For variable speed gravure, coating weights and thicknesses can be adjusted by line speed or roll speed, offering some flexibility not available with flexo processes. Curing and/or drying can also be a limiting factor for gravure coatings

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