Technology has moved into such an age that even the gadgets from Star Wars look old as compared to what our children have their pockets. The advancements have continually upgraded in every field since then. One of the positives of computer printing is these advancements in technology which are always developing every day.
We started off from the age of dot matrix printing just for text and have translated into making real life objects with the help of 3D printing. We also are now able to put 2D images on 3D objects by using pad printing.
What is pad printing?
Pad printing is a complete process in which 2D object or pictures transfers onto a 3D model. It is carried out by using an indirect offset printing process that starts off with the base image and pastes it into the 3D object by using silicon pad over the printable surface. The image is transferred from a printing plate.
Where and how is pad printing applied?
There are millions of applications in various industries that are using pad printing to generate 3D models with 2D markings on it. These industries include medical, automotive, promotional, electronics, sports equipment and architecture. Pads are commonly made of silicon rubber which can be molded onto the 3D object based on your design. The silicon rubber is used as a transfer vehicle that loads up the ink from the printing plate and transfers it to the item that must be printed with.
Some of the real-time examples of pad printing include the printing of labels on the keys of a keyboard or the logo of a toy manufacturer on a Frisbee. The print on the back of the pen or even on a hockey stick is made through this process. Printing this way enables putting of images onto any surface that is compatible with silicone rubber. Its unique molding properties allow the silicon pad to stick onto a variety of surface types like flat, cylindrical, spherical, compound angle, textures, concave surfaces or a convex surface.
On a large scale when 2D markings should be endorsed upon 3D models using pad printing and especially when precision is required, CNC or Computer Numeric Control is used. The machines are programmable to ensure production of similar specifications repeatedly. In the CNC press the substrate or a material that is printed on, such as paper, film, plastic, fabric, cellophane, or steel, is stationary and the silicone pads are programmed to print one image at a time. The same image can be printed repeatedly with the output remaining constant. Multicolor printing is achieved by programming all the pads on a stationary substrate at one time, which gives a multi-color print as perceived by the designer.
The robotic dimension in pad printing
The robotic procedures and computerized designing are complex and time taking process when it comes to pad printing through CNC machines. However, this enables the designer to make similar distribution protocols so that the output remains uniform throughout. The device is entirely controllable through servo-motors which also allow different print stroke lengths based on the size of the machine.
Another advantage of CNC machine is that multiple programs can run at the same time due to the programmable nature of the machine. Manufacturers even claim that using presses with pad printing capability that uses Computer Numeric Control gives considerable energy savings to the industry. Saving energy and time is one of the top most priorities of press owners and designers, which enable them to reduce the cost of serial production of pad printed products.
The CNC system comes with a separate machine as well as a modular design. The module can be attached to any standard device which enables the designer to use pad printing in any industry as he wishes so. The complexity of the design depends upon the actual design itself. The design of a simple logo may be non-complex but printing a 2D text or color on a rubber duck with many surfaces may take a lot of time and subtle designing techniques. Usually, the degree of complexity is regulated only by the imagination of the designer of the product(s) and the number of modules he wishes to use to complete his desired series of pad printed products.
What else is possible with pad printing?
Different kinds of output pad prints over various 3D objects can be processed by combining with multiple cups, pad cleaning, different stroke lengths and alternating pad shapes. Another combination of techniques is used to achieve the desired result. This process is used when pad printing is part of a complete production process where the item comes from a process and goes to another one after being printed upon. A conventional pneumatic press is the standard machine that is used throughout the design world since it is way cheaper than CNC machines and doesn't require a lot of maintenance. However, the flexibility of CNC machine aided pad printing has no matched based on the accuracy of design imprint and quality in serial production. If the workload can justify the use of a CNC press for the increase in investment, then the CNC press is well worth considering, especially as it a lot of time and money at the same time while operating.
Once the product prints, it is given a post-print treatment. A substrate of ink adhesion (either Polyacetal or Delrin) is made after the first print. A hot dryer may also be used to further enhance the sticking property of the silicone. Using this method is achieved by blowing hot air over the print for about 2-3 seconds. The temperature of the hot air blown may vary depending upon the kind of surface where the pad printing is applied. However, as a thumb rule, 350ø C is a good starting point.
Technology may move on in a couple of years, but till the time pad printing is a working solution for putting images on a 3D object. The decision to use a standard pneumatic machine or a latest CNC machine should be made on the number and type of use intending to be necessary for the advancement within the field.
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