During the past twenty years, colour absorption. The pad What is pad printing? pad printing machines Introduction mark on any product. a high-quality decoration or marking process that provides printing process is a direct and because it is resistant to Origins of pad printing ded into a variety of shapes, because it can be easily mol- ink transfer. Silicone is used cone rubber as the method for was the implementation of sili- tant factor in this development rapid development. An impor- gone through a period of the pad printing process has The pad printing process Pad printing The origins of the pad printing process are rooted in the Decalcier Process which was primarily used in the Swiss watch making industry. In this process, a gelatine pad was used to add ink to the watch face. In the late 1960's, the implementation Teca-Print AG was founded in 1973 of several technological advance- as "Tecalcos Maschinenbau". ments such as the introduction of sili- cone pads and more efficient machin- The small company manufactured ery and the development of new appli- pad printers and printing accessoi- res. The company was renamed cations provided the perfect opportu- Teca-Print in 1981 and moved into nity for the development of the pad its own manufacturing facility to It is surely the colour of nature that has printing process. meet the growing demands for its inspired man to add colour and deco- products. ration to their immediate environment. As a result, there is hardly a product Today, Teca-Print AG not only con- currently manufactured that does not tinues to provide pad printing Pad printing is an indirect photogravu- equipment, but also peripheral have some colour or embellishment to re process. Depressions are etched equipment and all the accessories make it stand out in the market. into a flat plate or printing block, and needed for pad printing. With the then they are filled with ink. A smooth help of established representatives When considering decoration, manu- silicone pad is used to pick up the ink throughout the world, Teca-Print facturers must not only find a process of the plate. ensures reliable support for all of that will be effective in their marketing our customers. Silicone is used because it is ink repel- and advertising activities, but must lent, and as a result will not absorb any also be cost-effective. Manufacturers, of the ink. when choosing a marking process, must also consider if the process is flexible and reliable. The process that incorporates all of these characteristics, cost effective- ness, flexibility, and reliability, is the pad printing process .
Ink transfert Advantages of pad prin- Fig. 1: Silicone Pad as the Transfer Mechanism ting? What materials can be printed ? Fig. 2: Fig. 3: (Fig. 4) The pad printing process pad blade holder blade a plate spatula inking slide ink well b Pad printing makes it possible to simulta- c neously print on all sides of an object, at different heights or in cavities. The pad printing machine TPE 150 is desi- a) The starting position of the ink slide gned for plate sizes from 100 x 100 mm to before the plate is flooded with ink 150 x 220 mm. Print capacity: 1800 cycles b) The plate is flooded with ink before the Pad printing also allows for ink transfer per hour. printing cycle has begun to occur to a sloping or vertical surfa- c) The doctor blade draws the ink back ce. Tilt-head machines can be used into the reservoir for these fields of application. The pad, regardless of size or hard- Because of the wide variety of inks available, Fig. 3 depicts the actual ink transfer ness, is cone shaped; that is the base pad printing can be done on almost any process. When a printing cycle is trig- of the pad is wider than its point. material. gered, the ink that is lying on the plate This shape is necessary because is drawn back into the ink reservoir by during the print cycle, the pad uses a a doctor blade. The thinner that is in rolling motion to eliminate the air that is the ink evaporates causing the ink to between the surface of the plate and become sticky. The pad is then lowe- There are many advantages that pad prin- the ink. Eliminating the air between the red onto the plate's surface and the ink ting has over other methods of marking. pad and the plate guarantees proper is transferred from the plate to the pad. image pick-up. The ink on the pad is then transferred The first advantage is the use of silicone as to the component. the means of transferring the ink. Silicone is The only area of the pad that has direct a very flexible substance and can be mol- contact with the ink is the area where ded into a variety of shapes for any applica- the image is placed on the pad. All tion. other areas of the pad remain free from ink (Figure 4). This flexible quality enables the pad to print The printing pads Teca-Print use are on uneven surfaces. Pad choice is depen- made of silicone and are available in a dent upon the shape of the product, the variety of shapes and degrees of hard- image size and its positioning. The use of ness. The pad that is selected for any height compensators, as shown in Figure 2, application must be chosen so that it will allow for a simultaneous printing of an can conform to the component's image at different heights. shape without causing any distortion in the image during transfer.
Multi-colour printing Pad quality Fig. 4: Ink layer thickness Fig. 5: The pad printing process surface and its ability to transfer the ink. The actual print life of a standard prin- ting pad - under ideal conditions - would be between 20,00 and a b 500,000 printing cycles. The printing life is dependent on a number of fac- tors including: - the type of ink used - pad shape, size and hardness c d - the shape of the printed part - the type of object surface The printing quality of the pad deterio- e rates over time because the printing surface (which needs to be smooth for undistorted ink transfer) is in contact with the ink and thinner that cause the Pad printing machine TPX 301 for muti- Ink transfert process: colour printing. pad's surface to become rough. a) The thinner evaporates from the surface of the plate and the ink becomes sticky. b) The pad bears down on the srface of Although pad printing does have its the plate and the ink sticks to the pad. limitations, it is no different than other The actual thickness of the ink that is c) The pad is then brought up from the printing processes. Relief printing, for plate. The ink layer is detaches from the transferred from the pad to the com- plate. example, is able to provide excellent ponent is approximately four microns. d) The ink is carried by the pad to the surfa- colour transfer because the ink sub- The ink's thickness is dependent on ce of the component. The thinner evapora- strate is welded film. This process is the type of ink that is used, ink visco- tes from the ink on the pad. The ink beco- very expensive and most manufactu- sity, the etch depth of the plate, and mes sticky. The ink is applied to the com- rers are unable to use this process atmospheric conditions such as heat, ponent’s surface and remains on the profitably. air temperature, and humidity . objekt. e) The pad rises off from the component Screen printing can be used to mark and the ink layer detaches from the pad and stays on the component . large images, but it is not a flexible Because of the rapid conditioning of method and the squeegee cannot the ink, it is also possible to use pad adapt itself to the shape of the object. printing for multi-coloured applications. The quality of image printed on the product is dependent upon the pad's The accessories available for such surface texture. When using a pad for applications include: the first time, the silicone oil must be - The two-colour pad sliding device washed off the pad's surface. This can - Rotary tables be accomplished by using ink thin- - Displacement tables ners. - Transfer carrousels - Linear indexing devices. The actual surface of the pad that will be used for printing must also be Pad printing must be viewed as a cleansed, but with alcohol, not thin- separate and distinct method of prin- ners. It is also important to understand ting, not just as a “refinement" of other that the pad surface should never be printing processes, specifically screen rubbed dry as this damages the pad's printing and relief printing.
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