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Speed Ratings                 Medium – up to 300/minute
                                        High – up to 600/minute

Printing Blanket Technical Information.

Quality Program - When producing blanket material for component printing, gauge tolerance is much more critical than standard offset printing as 2 to 16 blankets are required on press. Variations in thickness will ultimately appear in the print due to pressure variances.

All our blankets are manufactured to strict gauge tolerances, typically +.0005", and our experience in statistical control have determined this to be accurate. When packaged, the batch numbers are recorded as well as the median thickness of the blanket. Spot checks insure these tolerances are met. A Certificate of Analysis is sent with each shipment.

Printing Challenges
Slippage and inconsistent thickness are the printers two most common challenges. Following is a description of how we have addressed them.

Slippage
This is typically due to the choice of adhesive backing. We have tested a number of products over the years and we presently use the Flexstik product developed for high heat applications. The tape uses rubber adhesives which offer high shear holding power with long term temperature exposures. Relative solvent resistance is high, and manufacturing tolerances are within +.0005".

Inconsistency
All our blanket material is manufactured to tight tolerances of  +.0005" per production run. Batch to batch tolerances are kept within  +.003".

When the blankets are packaged, we are careful to note batch numbers on the label, as well as median thickness. Using this information when choosing blankets for the press will help insure that all are of the same quality.

Solvents & Cleaning
We have worked with a number of products over the years, and suggest that care be taken in selection for both safety and practical reasons. Tests should be conducted to determine whether the solvent adversely affects rollers, plates or blankets.

When working with solvents, it is best to use as little as possible. A damp cloth is preferable as excess solvents can be absorbed into the blanket or rollers. When cleaning the blankets, start in the center and work out to the edges. This will prevent excess solvent from being absorbed into the edges which can cause blanket de-lamination and adversely affect the adhesive backing.

We have developed a cleaning solution which we feel is best suited for the industry. The imagemaster solution is a non flammable, non-toxic, safe product which not only cleans up but reconditions as well. We are very excited about this new product and we will supply samples on request.

Two Piece System
This is one topic which generates a lot of discussion. Under this heading, we hope to inform you about the use of two piece blankets.

With the two piece system, as the name implies, two pieces of blanket material are used to achieve the total thickness of blanket required by the printing press. This normally ranges from .140 to .180" in total thickness, and mainly applies to side wall presses. Most lid presses are designed for one layer of material ranging in thickness from .070 to .090". Various gauges of blanket and adhesive backing allow the flexibility to meet most press requirements.

Using the 2 piece application, the bottom or underlay blanket is applied to the cylinder on the first rotation, and the top or face blanket is then applied on to the underlay. Care should be taken, as in all applications, to avoid air bubbles which will adversely affect the print quality. It should be noted that care must be taken when trimming the face blanket to ensure that the underlay is not damaged and can remain on the press.

This may seem to be an added step to those familiar with the one piece application, but keep in mind that the underlay can be left on the press through repeated changes of the face blanket. This translates into reduced waste and cost.

Sizing the Underlay
When determining the size of the bottom blanket, we recommend that it be at least ½" longer than the print area. When removing the face blanket, start at the trailing edge as the additional ½" of underlay gives it added adhesive power to ensure it will remain on the blanket cylinder.

Also consider whether the blanket can be used for other size applications as well. As an example, consider that you have three blanket sizes such as 3 x 11", 4 x 9" and 5 x 12". The ideal size for the underlay would then be 5.1/4" x 12.1/2". This will reduce your inventory of cut blankets, as well as allow for varied printing applications without requiring replacement of the underlay.

Cutting the Blanket
All blankets are cut with the grain going around the container. Measurements are noted mentioning the "across" measurement first (from top to bottom of container) and the "around" second. This makes it easy to ensure the blanket is cut properly but presents a unique situation in regards to lid blankets which are typically round. We felt that marking the blanket face could affect print quality and we offer a distinct solution first introduced by the Image Group. All lid blankets are die cut with a "nib" or protrusion in the cut, which when placed on the leading or trailing edge of the platen will ensure proper placement. This "nib" aids removal and can be trimmed if required.

Cost Comparison
There is some confusion in trying to determine the actual cost of the blanket. In most cases the price per piece does not accurately portray the final cost of a blanket.

For example: Printer A uses a blanket priced at $1. This blanket can produce 1000 prints and requires 2 stops to wash up. Printer B uses a blanket priced at $2, which produces 2000 prints and also requires 2 wash ups. When you compare prices by piece only, $1 for 1000 pieces is the same as $2 for 2000 pieces, but when you realize that printer A is replacing the blanket twice as often, there is more machine down time to consider as well.

This simple example proves that when determining costs, machine time must also be considered.
 

Last modified: October 08, 2004

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