ISO 12636 pdf download.Graphic technology — Blankets for offset printing
1 Scope
This International Standard defines vocabulary, specifies test methods, characteristics, ordering and labeling information for blankets for offset printing. This International Standard does not apply to untensioned or unclamped blankets for offset printing, nor offset printing sleeves used with gapless presses.
2 Terms and definitions
For the purposes of this International Standard, the following terms and definitions apply. 2.1 across direction direction of the side of the blanket as intended to be applied perpendicular to the direction of rotation 2.2 around-the-cylinder direction direction of the side of the blanket as intended to be applied in the direction of the rotation 2.3 average thicknes mean of four measurements on a cut blanket where the measurements have been made on the points indicated in figure 1， namely on 2 diagonally opposed corners and one each at the middle of the two sides that are perpendicular to each other within a right triangle 2.5 compressibility-deflection average thickness reduction of a blanket measured under a specific pressure, expressed in millimetres 2.6 compressibility-indentation average depth of impression, I , in a blanket measured under a specific pressure, expressed in millimetres or as percentage indentation I p 2.7 elongation increase of the dimension in the around-the-cylinder direction of a blanket under longitudinal stress, expressed in percent of the length at a specified force per width 2.8 packing underlay material placed under the blanket to adjust the effective thickness of the blanket on press 2.9 printing surface side of the blanket that is used for the transfer of printing ink 2.10 shrinkage decrease in thickness due to exposure of the blanket printing surface to a liquid, expressed as a percentage of the original blanket thickness, or as an absolute thickness decrease in millimetres 2.11 sizes dimensions (thickness, width and length) of a cut ready-to-use blanket 2.12 swelling increase in thickness due to exposure of the blanket printing surface to a liquid, expressed as a percentage of the original blanket thickness, or as an absolute thickness increase in millimetres 2.13 tensile strength force per unit width required for breaking a blanket under longitudinal stress in the around-the-cylinder direction2.14 thickness variation difference between the greatest and the smallest thickness value in millimetres
3 Requirements
3.1 Dimensions 3.1.1 Thickness The test method according to 4.1 shall be used. For applications with packing the nominal thickness shall be 1 ,68 mm or 1 ,95 mm. For applications without packing the nominal thickness should be agreed upon between the supplier and the user of the product. NOTE The nominal thickness should be stated in technical descriptions and when ordering. The thickness variations of blankets with an area not in excess of 1 ,5 m 2 shall be less than ± 0,02 mm, those of greater sizes shall be less than ± 0,03 mm. No individual thickness measurement shall yield a value which deviates more than 0,05 mm from the ordered thickness.3.1.2 Accuracy of width and length If one of the sides is 1 m or less, the tolerance shall be ± 3 mm, otherwise it shall be ± 4 mm. 3.1.3 Plan view The sides of the blanket shall form right angles. The difference between the length of the diagonals and the length of any two parallel sides shall not exceed 0,5 %. 3.2 Materials and surface finish No specifications are given. The material formulation and surface finish are the choice of the manufacturer and may be stated in technical descriptions by the supplier. The surface finish may vary, e.g. cast (molded) or ground (buffed). 3.3 Elongation The elongation E shall be less than 1 ,5 %. The test method according to 4.2 shall be used or any other method where results can be correlated to those of the test method. 3.4 Tensile strength For all blankets of thickness 1 ,68 mm or more, the tensile strength shall be greater than 40 N/mm. The test method according to 4.3 shall be used or any other method where results can be correlated to those of the test method. For blankets of lower thickness no specification is given. 3.5 Compressibility No specification is given. Either test method according to 4.4 or 4.5 shall be used. NOTE The use of compressibility-deflection or compressibility-indentation method is the choice of the manufacturer and may be stated by the supplier.