Hot stamping is a key process in the post printing processing of paper printed products, which can greatly increase the added value of printed products. However, in actual production processes, hot stamping failures are easily caused due to issues such as workshop environment and improper operation. Below, we have compiled 9 of the most common hot stamping problems and provided solutions for your reference.
01 Poor hot stamping
Main reason 1: Low hot stamping temperature or light pressure.
Solution 1: The hot stamping temperature and pressure can be readjusted;
Main reason 2: During the printing process, due to the excessive amount of dry oil added to the ink, the surface of the ink layer dries too quickly and crystallizes, resulting in the inability of the hot stamping foil to be printed.
Solution 2: Firstly, try to prevent crystallization during printing; Secondly, if crystallization occurs, the hot stamping foil can be removed, and the printed product can be air pressed once under heating to damage its crystallization layer before hot stamping.
Main reason 3: Adding wax based thinning agents, anti sticking agents, or non drying oily substances to the ink can also cause poor hot stamping.
Solution 3: First, apply a layer of highly absorbent paper to the printing plate and press it again. After removing the wax and oily substances from the background ink layer, proceed with the hot stamping operation.
02 The image and text of hot stamping are blurry and dizzy
Main reason 1: The hot stamping temperature is too high. If the hot stamping temperature of the printing plate is too high, causing the hot stamping foil to exceed the limit it can withstand, the hot stamping and hot stamping foil will expand around, resulting in dizziness and faintness.
Solution 1: The temperature must be adjusted to an appropriate range based on the characteristics of the hot stamping foil.
Main reason 2: coking of hot stamping foil. For the coking of hot stamping foil, it is mainly due to the prolonged shutdown during the hot stamping process, which causes a certain part of the hot stamping foil to come into contact with the electric high temperature printing plate for a long time and cause the phenomenon of thermal coking, resulting in dizziness after image and text hot stamping.
Solution 2: If there is a shutdown during the production process, the temperature should be lowered, or the hot stamping foil should be moved away. Alternatively, a thick piece of paper can be placed in front of the hot stamping plate to isolate it from the plate.
03 Blurred handwriting and paste
Main reasons: high hot stamping temperature, thick coating of hot stamping foil, excessive hot stamping pressure, loose installation of hot stamping foil, etc. The main reason is the high hot stamping temperature. During the hot stamping process, if the printing plate temperature is too high, it can cause the substrate and other film layers to transfer and stick, resulting in unclear handwriting and plate pasting.
Solution: During hot stamping, the temperature range of the hot stamping foil should be adjusted appropriately to lower the hot stamping temperature. In addition, hot stamping foil with a thinner coating should be selected, and the appropriate pressure should be adjusted, as well as the pressure of the rolling drum and the tension of the winding drum.
04 Uneven and unclear edges of graphics and text
Main performance: During hot stamping, there are burrs on the edges of the graphics and text, which affects the printing quality.
Main reason 1: Uneven pressure on the printing plate, mainly due to uneven layout during plate installation, resulting in uneven pressure on various parts of the plate. Some of the pressure is too high, while others are too low, resulting in uneven force on the graphics and text. The adhesive force between each part and the printing material is different, resulting in uneven printing.
Solution 1: The hot stamping plate must be leveled and compacted to ensure even hot stamping pressure, in order to ensure clear graphics and text.
Main reason 2: If the pressure on the printing plate is too high during hot stamping, it can also cause uneven graphic and textual prints.
Solution 2: Adjust the hot stamping pressure to the appropriate level. To ensure that the pad of the embossing machine is accurately fitted according to the area of the pattern, without displacement or movement. This way, it can ensure that the graphics and text match the pad layer during hot stamping, and avoid hairiness around the graphics and text.
Main reason 3: Uneven pressure after hot stamping on the same plate.
Solution 3: This is because there is a great disparity in the area of images and texts. The pressure on large areas of images and texts should be increased, and the pressure on large and small areas can be corrected and adjusted by using the pad paper method to make them equal.
Main reason 4: Excessive temperature during hot stamping can also cause uneven graphic and textual prints.
Solution 4: According to the characteristics of hot stamping foil, control the hot stamping temperature of the printing plate reasonably to ensure that the four edges of the image and text are smooth, flat, and free from hair.
05 Incomplete and uneven graphic and textual imprints, missing strokes and broken strokes
Main reason 1: The printing plate is damaged or deformed, which is one of the important reasons for incomplete image and text imprints.
Solution 1: If damage is found to the printing plate, it should be repaired or replaced immediately. The deformation of the printing plate makes it unable to withstand the applied hot stamping pressure. The printing plate should be replaced and the pressure adjusted.
Main reason 2: If there is a deviation in the cutting and conveying of hot stamping foil, such as leaving too small edges during horizontal cutting or deviation during winding and conveying, it will cause the hot stamping foil to not match the printing plate's graphics and text, and some graphics and text will be exposed, resulting in incomplete parts.
Solution 2: To prevent such problems, when cutting hot stamping foil, make it neat and flat, and increase the size of the edges appropriately.
Main reason 3: Improper conveying speed and tightness of hot stamping foil can also cause this fault. For example, if the hot stamping foil receiving device becomes loose or displaced, or if the coil core and unwinding shaft become loose, the unwinding speed changes, and the tightness of the hot stamping paper changes, causing deviation in the position of the image and text, resulting in incomplete image and text.
Solution 3: At this point, it is necessary to adjust the winding and unwinding positions. If the hot stamping foil is too tight, the pressure and tension of the rolling drum should be adjusted appropriately to ensure appropriate speed and tightness.
Main reason 4: The printing plate moves or falls off the bottom plate, and the pad of the stamping mechanism shifts, causing changes in the normal hot stamping pressure and uneven distribution, which can result in incomplete image and text imprints.
Solution 4: During the hot stamping process, the quality of the hot stamping should be regularly inspected. If any quality problems are found, they should be immediately analyzed and the printing plate and padding should be checked. If the printing plate or padding is found to be moving, adjust it in a timely manner and place the printing plate and padding back in place for fixation.
06 Impossible hot stamping or blurred graphics and text
Main reason 1: The hot stamping temperature is too low, and the printing plate hot stamping temperature is too low to reach the minimum temperature required for the electrochemical aluminum foil to detach from the film base and transfer to the substrate. During hot stamping, the gilding paper is not completely transferred, resulting in patterning, exposure of the bottom, or inability to hot stamp.
Solution 1: If this quality issue is found, it is necessary to adjust the temperature of the electric heating plate in a timely and appropriate manner until a good printed product is hot stamped.
Main reason 2: Low hot stamping pressure. During the hot stamping process, if the hot stamping pressure of the printing plate is too small and the pressure applied to the electrochemical aluminum foil is too light, the hot stamping paper cannot be smoothly transferred, resulting in incomplete hot stamping images and texts.
Solution 2: If this situation is found, it should be analyzed first whether it is due to low hot stamping pressure, and whether the appearance of the imprint marks is light or heavy. If it is due to low hot stamping pressure, the hot stamping pressure should be increased.
Main reason 3: Excessive drying of the base color and surface crystallization make the hot stamping foil difficult to print.
Solution 3: During hot stamping, the dryness of the base color should be within the printable range and immediately printed. When printing the background color, the ink layer should not be too thick. When the printing volume is large, it should be printed in batches, and the production cycle should be appropriately shortened. Once crystallization phenomenon is found, printing should be stopped immediately, and faults should be found and eliminated before continuing printing.
Main reason 4: Wrong model or poor quality of hot stamping foil.
Solution 4: Replace the hot stamping foil with a suitable model, good quality, and strong adhesive force. The substrate with a large hot stamping area can be continuously hot stamped twice, which can avoid blossoming, exposure of the bottom, and inability to hot stamp.
07 Hot stamping matte
The main reason is that the hot stamping temperature is too high, the hot stamping pressure is too high, or the hot stamping speed is too slow.
Solution: Moderately reduce the temperature of the electric heating plate, reduce pressure, and adjust the hot stamping speed. In addition, it is important to minimize idling and unnecessary parking, as both idling and parking can increase the temperature of the electric heating plate.
08 Unstable hot stamping quality
Main performance: Using the same material, but the quality of hot stamping varies from good to bad.
Main reasons: unstable material quality, problems with temperature control of the electric heating plate, or loose pressure regulating nuts.
Solution: First replace the material. If the fault persists, it may be a problem with temperature or pressure. The temperature and pressure should be adjusted and controlled in sequence.
09 Bottom leakage after hot stamping
Main reasons: Firstly, the pattern of the printing material is too deep, and the printing material should be replaced at this time; The second issue is that the pressure is too low and the temperature is too low. At this point, the pressure can be increased to increase the temperature.
Post time: May-08-2023
