Several important factors to control in the process of pad printing
Pad printing machine printing, the depth of the steel plate, plastic head of the characteristics of hard and soft, size, shape, printing ink, volatile speed, the printing surface characteristics (smooth or rough, the arc size, etc.), working environment control (temperature, for example, color, moisture, dust, etc.).Must deal with the change of the related parameters, and to adjust, can achieve perfect pad printing of success.
First, the depth of the steel determine whether appropriate.
1, measured with depth gauge, conventional pad printing plate depth at about 2.4 microns.Such as small text, line 2 microns.Entity graphic, is also suitable for 3 micron, node may have dark 1.6 microns.Concrete plate depth difference.
2, in accordance with the actual design and the requirements of the ink layer.If again as a graphic, printing work surface roughness, pits or smooth, required plate depth and the printing effect.
For example: if the oil return, by fuzzy, larger possibility for steel plate was too deep, such as a bubble back (blister), may be too shallow.If the pad printing rubber head not printed onto the object, ink has to dry glue head, steel plate is too shallow.If the ink appear uneven glue head (orange peel lines), the steel plate is too deep.Due to the rubber head can only touch the area of a small number of ink plate design, so the etching depth is too large will not have any benefits.Etching depth is 25 micron, glue head can only touch up 12 micron ink film, the rest on the sheet metal.Because of the ink film contains at least 40% of the diluent, this part of the diluent in the ink transfer and dry completely evaporate, so finally stay was printed on the ink layer is about 7 microns.
2, printing ink features: pad printing requirements drive oil and fast dry, avoid glue head can well realize transfer ink, screen printing requirements slow dry, avoid screen plugging.This is the difference between screen printing and pad printing thinner.But under certain conditions, such as high temperature drying screen printing on the oil and water can be used for pad printing.
One-component ink, glue head durability is better.While a two-component inks are usually less corrosive prone to bubble, can make the rubber head silicone oil consumption faster, so could the rubber head to shorten.Rubber head without printed onto the printed material, and the ink dry solid glue head, is thinner, fast dry.When, after the completion of printing was printed on graphic fluff, wiredrawing phenomenon, fast dry.Oil return vague;Is too dry, already into pieces, no adhesion force, fast dry;Printing, fast dry.
Three, pad printing work environment: at room temperature (best for 18 to 20 ° C).Humidity is (best is 60% - 070%).Dust.Light white wall ground, etc.
Four, problems appeared in the process of pad printing solution
Why the printing into often appear bubbles (trachoma) phenomenon.Mainly focus on printing rubber head, steel plate, printing ink from three aspects.
1. The rubber pad printing head shape is not appropriate, peace or radian is wrong.
2. The glue head center (highest) on the design, form the air out, produce bubbles.
3. Rubber aging is tacky, breakage, oil engine-grease cause gum head bad printing.
4. The steel plate etching, reservoir are thick enough.
5. Dry ink is too thin or too slow.
6. Ink too dry or too dry.