Print Quality Management Experience

- Jun 29, 2018-

There are many factors that affect the printing quality, such as the quality of raw and auxiliary materials, original quality, plate quality, personnel skills, equipment accuracy, temperature and humidity in the workshop, ink and water balance. Any problem with any one of these factors will directly or indirectly affect the print quality. Therefore, for a printing company, the printing quality management should include the entire process of printing production such as prepress design, printing preparation, printing production, and finished product inspection, so as to fundamentally protect the printing quality of printed products.

Prepress design

The original document is unified according to the product name and stored in the corresponding product folder. After confirming that there are no other associated files, check the received manuscript file. Check items include: whether the resolution of the image reaches 300 dpi, whether the font is missing, and whether the printing is unified using the CMYK color mode (if other color modes are used, it should be modified immediately). Whether it is missing, whether the layout has abnormal effects or does not meet the standard, and whether the text is incorrect or not. If you have any of the above issues, you should give feedback to the customer in time and communicate with the customer. After confirming that the original file is fine, the electronic file (AI format, CDR format) to be output is generated, and then the computer producer conducts a self-check on the electronic file according to the requirements of the production instruction sheet, focusing on checking whether the path of the link map is correct or not. Edition) Whether the size, content, direction (linkage mode) is wrong. After completion of the self-test, a VPS file for easy screen proofing is generated. The full-time inspector conducts self-inspection according to the requirements of the production order, and focuses on checking whether the contents, colors, and other related printing requirements of the document (linkage) are incorrect. After confirmation, the electronic document is confirmed by the business personnel or the customer after digital proofing as required. After confirmation, the electronic document is required to be officially produced according to the instructions.

Printing production

(1)Inspection of raw and auxiliary materials

The raw and auxiliary materials for printing production must be inspected before use. The inspection contents include appearance, quantity, model specifications, and weight. It is necessary to use appropriate testing equipment, tools, and tools during the inspection process. For example, the precoating film corona treatment needs to use the 38# dyne pen to draw a line on the surface of the precoat film with an appropriate force. If the line does not shrink or coagulate after 5 seconds, it indicates that the precoat film is passing electricity. Halo treatment. Another example, when checking the ink adhesion on the surface of the PP film, a simple nail scraping method can be used, and the nails are scraped back and forth at the printing site for 4 or 5 times. The ink is considered to be acceptable without falling off. It is simple and effective.

(2)The first three-level countersign

Before the formal printing production, it is necessary to sign the first sample, and the three-level countersigning shall be carried out, including the leader, quality inspector and monitor. During the printing production process, the operator performed the sampling according to the requirements of Sanqin (commercial mixing, diligent sampling, and ground eraser blankets), compared with the first sample, and discovered that the problem was adjusted in time. Quality inspectors conduct random inspections, record the problems found, notify the operators of timely adjustments, and reasonably deduct points according to the provisions of the quality score, and perform monthly statistics, and deduct relevant bonuses according to their scores, in order to urge operators. Strengthen quality awareness.

(3)Workshop temperature and humidity control

Changes in the temperature and humidity of the workshop will directly affect the performance of raw and auxiliary materials, such as low temperature in winter, easy to make paper stretching and deformation, ink and adhesive fluidity deterioration, which indirectly affect the printing quality. Therefore, the printing shop requires constant temperature and humidity, the general temperature is controlled at (21 ± 2) °C, and the humidity is controlled at 45% ~ 60%. It is recommended to adjust the temperature and humidity of the workshop using air conditioners, heat fans, and air exhaust devices.

(4)Laminated products management

Coated products are particularly concerned with the foreign materials on the surface of the printed products, especially pharmaceutical coated products. In order to avoid the generation of foreign materials in the membrane, in accordance with the requirements of clean production and set-up management, the production workshop is not allowed to open windows, and the drainage vents and factory toilets connected to the outside are added with screens, plastic curtains, floor drains, mosquito killers, and anti-mosquito lamps. Rats and fly mosquito facilities, etc., and often check maintenance. The supervision of the workshop squad leader is responsible for finding problems and reporting to the maintenance department.

Quality inspection

The quality control and management of each process in the printing production ensures that the product quality meets the standard requirements. Quality inspection can be divided into the following three levels.

One-level inspection is "self-test" and is performed by the operator. After receiving the production order, the operator should carefully review and check whether the production instruction sheet, sample sheet, and layout content match. If there is a problem, the relevant personnel should be consulted promptly; if there is no abnormal situation, it can be put into production preparation and the machine can be adjusted to the production state. The proofs produced (specified products use the red-membrane inspection board for defects such as defective blankets) are inspected, and they are signed after the quality standards are met, and formal production is carried out. In the production process, when an abnormal situation occurs, causing an outage to be put back into production, it is necessary to mark the paper strip and carry out a key inspection on the product. For each process product, the operator must mark "waiting inspection" on the turn-up order.

The secondary inspection is the “special inspection”, which is performed by quality inspectors of each process to check whether the production instructions, proofs, and layouts are consistent with each other. In accordance with the product quality standards and inspection methods, the inspection focuses on the contents of this process. Pay attention to the process sampling frequency no less than 4 times, each sampling 2 times, so that the product quality can be controlled at any time. In addition, each product must be inspected by the quality inspector when the product is forwarded. Only products with “qualified” on the order list can be transferred to the next process.

The third-level inspection is the “mutual inspection”, and the quality of the product in the previous process is checked by the next process. The semi-finished product confirmed by the quality inspector of the previous process can flow into the next process, and the operator and the quality inspector of the next process perform mutual inspection on the semi-finished products produced in the previous process, and the unqualified semi-finished products and finished products are inspected. Conduct quality deduction of responsible persons or quality accident assessment in the factory.

Product testing

The inspection of finished products is based on the company's quality standards. If individual products have customer standards, they will be executed according to customer standards. The sampling method of finished products is based on GB/T 2828.1-2012 “Sampling Inspection Procedures Part 1 : Batch Inspection Sampling Plan Retrieved According to Acceptance Quality Limit (AQL)”, and the quality inspection level adopts the general inspection level (II) Normal inspection sampling once, And set the AQL value according to the product type. The inspection items of the finished product storage are carried out with reference to the quality inspection standards of each process, and a checklist of finished goods entry can be separately formulated for important customers, and the key contents of the customer standards can be included in the checklist. The monthly inventory checklist for finished goods is counted and bound into volumes.

Treatment of quality issues

Quality problems can be divided into internal quality problems and external quality problems according to different sources of information. The internal quality problem refers to the quality problems found in the company's internal printing production process. There are feedback from the production workshop, and the quality inspector found. The external quality problem refers to the quality problem that is fed back by the customer. The customer will feedback the quality problem to the salesperson and the salesman will feedback to the quality department. The quality department analyzes the causes of the problems and formulates corrective measures. The responsible department is responsible for organizing the implementation. The quality inspector is responsible for tracking and verification, thus forming closed-loop control.