Pad printing process flow and application precautions

Pad printing technology first appeared in Europe , A dial for printing watches , In the last century 80 Introduced into China in the s , Because it can be used in a small area , Printing on irregular concave and convex products , Have a great advantage . With the continuous development of China's manufacturing industry , Pad printing technology is more and more widely used , Electronics , toy , The proportion of pad printing technology used in surface printing of various products such as plastics accounts for 50％ about .

 

01

Introduce

Pad printing is one of the special printing methods , That is, steel （ Or copper 、 Thermoplastics ） gravure , Curved surface pad printing head made of silicone rubber material , Dip the ink on the gravure plate onto the surface of the pad printing head , Then press it on the surface of the object you want to print 、 Patterns, etc .

02

Technological process

The graphic content of pad printing needs to be etched on the steel plate first , After cleaning the steel plate, evenly apply a layer of photosensitive adhesive , Stick a printed film with pictures and texts , Exposure to ultraviolet light will harden the image and text free area , Develop with developing water to present the pictures and texts on the film on the steel plate , Pour corrosive solution into the steel plate so that the depth of graphic corrosion on the steel plate does not exceed 0.5 mm . It can also be directly etched on the steel plate by laser .

The transfer head is made of elastic silicone , The shape is round , Rectangle and square , This kind of shape can better contact with the etched plate and the printed product , Transfer pictures and texts to products of different shapes on flat steel plates , In this process, the rubber head will be deformed due to different pressure and action surface of the rubber head , In order to make the transferred pictures and texts not deformed, we should choose different soft and hard according to the product shape , Big and small rubber heads , To adapt to the deformation of the rubber head to achieve the desired effect .

Apply the ink to the etch board , A telescopic scraper scrapes away the excess ink , The remaining ink will remain in the etch plate pit .

Pad printing head made of silica gel material , Stick the ink in the concave to the surface of the pad printing head .

Then press the surface of the product to be pad printed, and the graphics and text on the concave will appear , Finally dry , Check the packing .

03

Characteristics and application of pad printing

advantage ：

1、 Wide application ： Pad printing is generally used in grooves 、 Workpiece that cannot be processed by silk screen printing, such as the back of the workpiece . As the pad printing machine is an automatic equipment, its precision is high , Therefore, chromatic printing can be carried out , In theory, chromatic number can be infinite , But the actual operation will not exceed 7 color .

2、 Easy to operate ： The equipment is fully automatic

3、 The cost is low ： Except that the equipment is much more expensive than the screen printing machine , But other cost factors are the same as silk screen printing

shortcoming ：

1、 The effect is ordinary ： The visual effect of the finished product is slightly smoother than that of silk screen printing , But not far away

2、 Area limit ： Because the silicone pad printing head works elastically , And the production size has an upper limit , Therefore, pad printing cannot produce patterns with too large area

3、 Color scale limits ： Although pad printing can be chromatic operation , However, due to the corrosion of the steel plate, the edges of the machined grooves are clear , So you still can't make gradients

4、 Construction taboos ： In the use of UV In case of ink construction , Need to use a dark room or pay attention to shading , prevent UV Ink curing damages pad printing die head and steel plate

application ：

For vehicle interior ,3c Surface printing of electronic products and sports equipment

04

matters needing attention

1. Bubbles or sand holes

Pad printing head is too soft , The rubber head is flat and not easy to exhaust , The surface of the rubber head is damaged ; The steel plate is not etched properly ; The ink is too thick or dries too fast ; There is dust or oil stain on the product surface ; The ink has deteriorated or expired

resolvent ： Replace the appropriate rubber head ; Redo the pad printing steel plate ; Add corresponding additives ; Clean the surface with alcohol ; Replace with new ink

2. Pad printing silicone head is not durable

① There is no problem with pad printing silica gel . The problem is that the silica gel is not filtered well , There are impurities ; Or during packaging , Manual subpackaging , Barrels or plastic bags are not cleaned , The pad printing silicone head is not durable

② It has a lot to do with the amount of silicone oil in silica gel , The more silicone oil is added , The softer the rubber head is , Because silicone oil will destroy the amount of silicone , Produce non durable , Easy to age, etc

③ Silicone application manufacturer , Do not understand the performance of silica gel , The service life of pad printing silica gel is closely related to the size of the pattern to be printed . If you're printing big pictures , Be sure to use a larger rubber head , If the pattern printing is small , You can use a small rubber head （ Adjust the size of the rubber head according to the pattern size , The ratio of the size of the glue head to the pattern 3：1）

3. Ink drawing

The ink viscosity is too high ; The rubber head rises too fast ; The surface of the rubber head is damaged or deteriorated after too long use

resolvent ： Adjust the ink for the best viscosity or consistency ; Adjust the rising speed ; Replace the rubber head ; Add filler into the ink , Improve wire drawing

4. The pattern is blurred

Pad printing head is too soft ; The clamp is loose ; The rubber head falls too fast ; The steel plate is etched too deeply ; The ink is too thin or too thick ;

There is dust or oil stain on the product surface , Clean the surface with alcohol

resolvent ： Replace the rubber head with suitable hardness ; Check whether the fixture for fixing the product is loose ; Adjust the descending speed of the rubber head ; Replace the steel plate with moderate depth ; Use additives to adjust the consistency

5. The rubber head is not stained with ink

There is oil stain on the surface of the rubber head ; The ink is too thick ; Ink drying speed is too fast ; The etched pattern is too shallow , Or defective printing plates ; The angle of the rubber head is too large ; The large pattern color block scraper scrapes away the ink in the middle of the pattern ; The ink taking pressure is too high

resolvent ： Use alcohol tape to clean ; Add an appropriate amount of diluent ; Use a slow drying thinner ; Change the printing plate ; Use a rubber head with a slightly flat angle ; Add mesh or use thick steel plate ; Reduce the ink extraction pressure