engraving of roller printing
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M. RUBEL RANA ID# 042 056 041MD. SAIDUR RAHMAN ID# 042 096 041MD. TARIKUL HASAN ID# 042 099 041H. M. KHALED MURSHED ID# 042 040 041MD.HABIBUR RAHMAN ID# 041 008 041ZOBAYER RAHMAN ID# 041 023 041
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