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ENGRAVEING OF THE PRINTED ROLLER

Engrave roller printing In this method, a heavy copper cylinder (roller) is engraved with

the print design by carving the design into the copper. Copper is soft, so once the design is engraved, the roller is electroplated with chrome for durability.

It is modern continuous printing technique developed in the late 19th and early 20th centuries.

Until the development of rotary screen printing; it was the only continuous technique.

The fine design detail possible with this technique has always been its main advantages.

The method of roller engraving

Die and mill method Pantograph method Photographic method By hand method

Graphic Industrial

Process of Die and mill method At first the repeat of design is transferred to a small

mild of steel roller, Then is called die. The top side of this roller is burnished. The circumference of the printing roller is must be

proportional to the die. The burnished die is padded in solution of copper

sulphate. Fe + CuSO4 → Cu + FeSO4 The design is art in the paper by the solution of

sodium sulphite. Then the die is covered by the design paper.

Process of Die and mill method

Then binding with tightly by canvas. This process is run continuously 1 to2 hrs. In this process is used bone ash and charcoal and

heated. After this die is attached by the clamp at mild steel

roller contact, then the steel roller is called mill. The die and mill is rotated at high pressure and the design is replaced in the mill. Then the pressure is removed. Thus the roller is engraved.

Figure: Die and mill method

Where-

M=Mill B=Block S=Adjustable

support F=Fulcrum R=Copper roller W=Weight

Engraving of copper roller

In this method, a heavy copper cylinder (roller) is engraved with the print design by carving the design into the copper. copper is soft, so once the design is engraved, the roller is electroplated with chrome for durability.

Engraving of copper roller

Three different methods of engraving.o By hand with a graver which cuts , in which

the metal away.o By etching the pattern is dissolved out in

nitric acid; ando By machine, in which he pattern is simply

indented.

The defects in the engrave roller printing

Scratches Snappers Lifts Streaks Scumming Lobbing

Scrimps

These are caused by the creases of folds in the cloth. They are visible in the form of a double edge with white unprinted part left over in between, below a crease or a fold in the cloth. scrimp rollers at the back of the drying arrangement must be perfectly set right.

Uneven Printing

This may be caused by several factors such as-

Uneven pressure on the two ends of the design rollers which will show light and deep print in the selvedges.

Uneven lapping of the furnishing rollers. Uneven addition of the colour at one end of the

colour box. Greater percentage of insoluble substance in the

paste. Uneven diameter of the design roller due to constant

polishing of one end of the roller.

Types of scrapers

Metallic scraper Wood scraper Rubber scraper Hand scraper Automatic scraper Roller scraper Flat scraper

Main parts of Roller printing

Color doctor Lint doctor Blankets Back grey Furnishers Color box / tray Color unit

Figure: Roller printing

Figure:Nip of roller printing machine

Figure: Sectional view of roller printing m/c

Figure: Box wheel of roller printing m/c

Figure: Six color roller printing m/c

Advantages of engrave roller printing machine

Higher production without rotary screen printing machine.

14 colors can be used for printing. Medium design can be produced. Can be used for printing any style. Any color is used for printing without higher alkali or

conc. acid. Repeats do not exist as printing is continuous. Higher production by using single color. Complex design is possible.

Disadvantages of engrave roller printing machine

Large design is not possible. Generally, shedding fault is found. Higher coloring effect is not possible as like

block printing. Lower production by using more than one

color. Changing time is high. Engraving the printing roller is expensive

operation.

Distinguish between the Copper roller and screen printing

Parameters Rotary Screen Printing Copper Screen Printing

Design size Generally 64cm Upto 41cm

Colour 24 colour used 16 colour used

sharp line Design is not impossible Design is possible

Shade variation No possibility Possibility

Design change Less time More time

Printing Woven and knitted fabric Woven and tricot fabric

Main elements Rotary screen Engrave copper roller

Printing method Higher used Lower used