Improved gravure standard procedure

In the field of rotogravure, the most urgent need is to improve the technical level and improve the quality of the product. This article briefly describes the motivation for establishing a standard throughout the field to improve productivity levels.

At first, the gravure cylinder was first photo-etched and then developed by an acidic solution. It has still been used by some experts. This method is difficult to ensure that the depth of the gravure ink hole is consistent, resulting in different shades of ink, so the printing workers are always looking for ways to improve it. This includes adjusting the ink, reducing the speed of the press, and increasing the difficulty of the production process, all of which waste time and increase costs. The final result ignores the potential capabilities of gravure printing.

The current engraving process has been completely digitized, and the diamond engraving tool is used to carry out the engraving on the drum by an electronic method. However, the emerging technology does not emphasize the consistency of the depth of the ink hole, and this is extremely critical. It determines the quality of printed products and is also the key to gaining competitiveness and profits. The depth of the gravure ink hole controls the amount of ink, the change in hue, and ultimately the overall printing plant's productivity.

Ink hole technology

There are usually millions of ink holes in a group of rollers. Even a small mistake can cause a very small defect. These subtle defects accumulate so that the production process, the worker’s production, and the quality It has a huge impact.

The ideal shape of the ink in the ink hole, the shape of the core of the date, has a uniform thickness of the ink hole wall, a clear jagged surface, and a concave hole to absorb the ink. The ink hole should allow a certain amount of ink to enter and transfer out, and the printing process is more optimized.

The poor ink structure is mainly manifested in:
• After the edges fluffed, the depressions on the surface of the ink hole were blocked and ink entry and transfer were suppressed.
• The thickness of the ink hole walls is uneven, resulting in non-uniform ink deposition, irregular dot gain, scratches, and streaks. These are mainly caused by thin ink discharge holes.
• Distorted ink hole walls deliver different amounts of ink.
The above conditions are caused by some problems in the printing process, including:

- The wear of the squeegee,
- The ink is not clean, there is debris and blisters,
-- There is no ability to set ink density and viscosity parameters,
- Too long preparation time, too much pattern making paper,
- The press is too slow,
- Inconsistent printing effect The structure of the ink hole is shown in:
• There are scale-like burrs on the ink-receiving hole wall to suppress the ink from entering and leaving, and the amount of ink contained in the ink-receiving hole is reduced.
• Irregular ink hole wall thickness.
Deformed ink hole wall.

Some of the above factors may occur to varying degrees in the actual process, or a combination of multiple factors may occur. The established standards require the use of certain technologies to ensure the consistency of the quality of printed products, and thus enable efficient production.

Ink hole consistency must be achieved on all cylinders, within the entire design range, on remanufactured cylinders, and on the modified rollers of existing designs. Continuous consistency can be achieved through reasonable controls and conventions. The consistency of the gravure ink hole can be applied to color printing and spot color printing based on soluble and water-based inks.

Ink hole planing

The non-conformity limits the production efficiency of the gravure printing process. In the case of relatively high productivity levels, the structure of ink holes and screens is improved, and it is possible to optimize the spread of ink and improve the quality of printed products. Under certain control, within the performance range of the printing press, the use of the back planing parameters on the electronic engraving machine, the configuration of the proprietary screen characteristics, thereby improving the tone and lines, and improving productivity, this is entirely possible .

sampling

From the consistency of the ink hole platform, a printing press should determine the optimum ink density and viscosity value based on a series of substrates at an effective printing speed. A dot enlargement curve is drawn by sampling each material, thereby establishing accurate ink density and viscosity standards. Sampling can also compensate for duplicate curves so that dot gain values ​​are easier to predict and produce more efficiently.

Calibrating with the ink hole standard method, the printer has entered a new process control method. Once the workers have determined that the rollers are exactly the same, their process is more descriptive and predictable.

The purpose of sampling is:
• Increased speed of the press • Shorter setup time and less waste • Regardless of whether water-based or solvent-based ink printing is used, the quality of the product can be guaranteed throughout the entire drum web.
Establish ink density and viscosity standard values. Determine density according to process control standards. Make up for dot gain.

Interconnection between departments

Providers of design and printing services can benefit from predictable print performance. In this way, the experts can design and produce according to these parameters, so as to ensure that the quality of the product after production by the rotary gravure printer is the same as that of the imagination.

The ever-evolving gravure printing standard is very similar to the offset printing process, and an inspection and tracking system is defined according to the entire process flow. This system matches the test block with the printed sample and uses this to verify whether it matches the intended target.

prospect

Establishing such a standard is very challenging. It emphasizes the inherent characteristics of gravure and the process requirements of the entire printing process. It confirmed a set of scales, including design, copying, engraving techniques, inks, rollers, and those printing experts who focused on the image transfer process in order to produce and service at a lower cost and with less time.

This standard defines the characteristics of the ink hole, the calibration of the printing press, the analysis method and a set of systems for comparing the quality of the original and the print, but it is not very illustrative. The standard should be individual, that is to say, it should define specific parameters according to the specific operation process of each company in order to achieve the consistency and quality requirements of the production, and reach the highest possible level in the gravure printing industry.

Source: 21st Century Fine Chemicals Network