Embossing Aluminum Foil
Most embossed aluminum foil is produced on rotary web-fed equipment. In several important respects, embossing aluminum foil is one of the easiest methods of obtaining unique decorative and functional effects or characteristics. With inline printing and embossing units, foil packaging materials, wallpapers, or any foil laminated sheet product can be made in designs of limitless combinations of color and form.
But even in embossing plain, unprinted aluminum foil with imaginative patterns and illustrations, in variations of lines or dots, the possibilities are infinite. In fact, any embossing pattern in foil produces two basic effects of commanding visual attraction; (1) three dimensional effects in illustrations or patterns, since all images are in relief; and (2) continual reflective contrasts as the surfaces or the viewers change position.
Embossing thin, annealed foil is performed satisfactorily in continuous roll form by passing the web through a roll stand equipped with one engraved steel roll and a soft matrix roll of paper. The pressure for embossing may be obtained by maintaining the paper roll with the axis in a fixed position and using only the weight of the steel roll to depress the negative pattern into the paper roll. Screw or hydraulic pressures are applied to embossing operations when necessary or desirable. The procedure commonly used for embossing aluminum or laminated foil combinations is illustrated schematically in below.
Laminated foil combinations or heavier gauge foil may also be embossed on equipment consisting of two engraved steel rolls. The design is engraved on one steel roll (male) and the negative to this design on a second steel supporting roll (female). It is essential that these steel rolls be designed and mechanically equipped to register exactly for the embossing operation. Also, both the engraving, and the operation of the embosser, are precisely executed and controlled to avoid cutting the material or marring the engraved roll.
Foil rolled from aluminum embosses so readily that almost any kind of die and any type of equipment will produce a job of acceptable appearance for many applications. Very often, even the paper and adhesive used to produce a foil-laminated embossing stock can be almost anything. However, as with any material or combination, the end-use requirements always dictate the minimum specifications of the materials and methods, used to produce a given product.
For example, temper, gauge, and alloy are the important variable factors as far as the aluminum foil is concerned. Backing materials are selected for end-use compatibility, as are the laminating adhesives. At the same time, the backing paper or film must have the right combination of pliability, strength and formability for the application.
Embossing permits the use of copy next to food or in any other application where the plain or coated foil itself is allowed, but where copy or illustration printed with ink, lacquers, or enamels could not be employed.
The multiple pre-creasing effect achieved by an over-all embossed pattern on aluminum foil generally further improves foil's excellent dead-folding property. This is an advantage in packaging where end-folds, and overlaps, without the use of adhesives, are desired , e.g., butter, margarine, or similar wraps.