Pad Printing Machine For Finished Paper Products Project Report
In our day today life its quite common that we are using lots of products which are made attractive and informative through textual and pictorial impressions made by pad printing. But out of its all scopes, the printing on the finished paper products was still untouched at a gross level. Here forth, we came up with an idea for the same and started the project on the “DESIGN AND FABRICATION OF PAD PRINTING MACHINE FOR FINISHED PAPER PRODUCTS”.
Pad printing is used for printing on various substrates like Plastics, Metals, Glass and Ceramics, Paper and Cardboard, Leather. But it is primary used in places where the printing area is small and / or the contour or surface of the object is not flat or hard to reach by other printing process. We tried to give emphasis on the pad printing on the finished paper products which is quite yet not achieved so easily at larger scales. We achieved the pad printing on the finished paper products with a minimum operating pressure of 5 bar and by utilizing pneumatic and electrical systems.
The machine is being developed for a paper products manufacturing company at Coimbatore.
It is a fully automated machine working with the help of pneumatic cylinders for its horizontal and vertical movements. The sealed ink cup, silicon printing pad and an etching plate are the major components of our pad printing machine. Our project has the current applications in the company itself being developed for and for its flexibility and efficient working.
Pad printing is used for printing on various substrates like Plastics, Metals, Glass and Ceramics, Paper and Cardboard, Leather. But it is primary used in places where the printing area is small and or the contour or surface of the object is not flat or hard to reach by other printing process. Pad Printing is finding increasing favour in a host of commercial and industrial applications.
Any way you look at it, Pad Printing is an unlikely imaging process. It “borrows” a unique amalgamation of features from gravure, screen printing and rubber stamp printing, yet its most frequent industrial decorating competitor is none of these processes. Instead, Pad Printing most often encroaches on jobs once dominated by Hot Stamping. Even the process itself is somewhat befuddling. If the ink is so attracted by the silicone pad that it leaves the recessed areas of the printing plate, why does it abandon the pad so completely upon touching the substrate? Unlikely as it may be however; this process is finding increasing favour in a host of commercial and industrial applications.
It is adaptable to a variety of shapes and contours on parts with a variation in the surface, yet fine detail and precise copy can be achieved. Four color processes is obtained with exact registration. Pad printing is ideal for decorating toys, plastic house wares, and injection molded components. This technology also lends itself to marking electronic components such as resistors, canisters, and connectors. Any part, plastic, ceramic, or metal can be production marked by this process. The equipment can be semi or fully automated, yet remains a low capital expenditure technology.
DESCRIPTION OF PARTS:
The project consists by following parts:
- Pneumatic Cylinder
- Printing pads
- Ink cup
- Printing ink
- Image plate and print plate making
The pneumatic cylinder and piston arrangement holds the Printing pad. The compressor provides highly pressurized air to the cylinder. The power will be transmitted to the piston rod and the printing pad is actuated. Thus the pad is absorbing ink in shape of art made on the cliché and due to reciprocating motion of the horizontal cylinder it spreads the print on the substrate.
FEATURES OF PAD PRINTING:
Following are the unique features of the Pad Printing process.
- Can print on convex, concave, curved, recessed and discontinuous surfaces allowing product designers a substantially broader range of shapes and designs.
- Pad printing is able to print shapes and surface structures well outside the capabilities of Screen Printing and Hot Stamping opening up a way to decorate a whole new range of products.
- Allows wet-on-wet multicolour printing (without intermediate drying) on non-absorbent surfaces – therefore much reduced down time.
- Is capable of 90 degree wraparound on three-dimensional objects.
- Offers better edge definition and higher resolution than most other printing systems therefore offering a method of decorating high quality high priced items.
- Is a relatively inexpensive printing system particularly for multi-colour and process colour printing which means reduced capital outlay.
- Variety of substrates – Almost any material including glass, ceramic, metal can be printed with suitable inks.
- Ability to print fine details – Resolution is far better than that of screen printing in fact up to 120 lines / Cm (300 lines per inch)
- High resistance of printing inks – Depending on ink type used extremely high resistance against mechanical abrasion or chemicals can be achieved.
- Easy handling and little maintenance – Compared to other printing processes pad printing is easy to learn
- Multi-colour printing: wet on wet – Possibility to apply multiple prints without intermediate drying
- Short tooling-up times – Plates and inks can be exchanged within a few minutes
- Low set up cost – Plates can be produced in-house
- Relatively low space requirement – Compared to other printing machines pad printing equipment is space efficient
- Low drying cost – In the most simple case air drying at room temperature is sufficient.
LIMITATIONS OF PAD PRINTING:
- Size of motive – Motive sizes are limited by plate, pad and efficiency of the pad printing machine. The diameters of the largest efficiently printed motives are currently approx. 30 cm.
- Layer thickness of ink film – The pad process uses plates up to a depth of approx. 20-25μm (at the most 35μm). Thus conventional inks will result in printed ink films of approx. 7μm. This layer thickness can be increased correspondingly by multi-layer printing. Rough particles (e.g. glitter pigments) are difficult to print in an efficient manner
- Printing speed – Even substrates can be printed a lot faster with other printing processes.
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