What problems are likely to occur during the packaging production process?

Where Are Common Problems Distributed in Packaging Production

Packaging production involves five stages: design, proofing, printing, forming, and quality inspection, with each stage having its own high-frequency issues. Statistics show that printing accounts for 35% of issues, forming 30%, design 20%, proofing 10%, and quality inspection 5%. The problem distribution is highly correlated with the technical complexity and human involvement of each stage.

Understanding the problem distribution helps allocate quality inspection resources reasonably. Investing 35% of quality inspection resources in the printing stage and 30% in the forming stage can improve the problem detection rate by over 20% through proportional allocation. Blindly distributing quality inspection resources evenly will instead cause missed inspections in high-risk stages.

Design Phase: Mismatch Between Box Style and Process

The most common issue during the design phase is a mismatch between the box style and the manufacturing process. For example, a drawer box is designed but the paperboard thickness selected is 250 gsm, resulting in insufficient box rigidity and easy deformation during the sliding process. Alternatively, a double-layer top-and-bottom lid box is designed, but the die-cut layout fails to account for the registration accuracy between the inner and outer layers, causing the lid to not close tightly after forming.

The root cause of such issues is that design is disconnected from the manufacturing process. Designers focus only on visual effects, without evaluating the compatibility between the box structure and materials, nor considering the feasibility of die-cutting. It is recommended that the design draft be reviewed by a structural engineer before finalization, with particular attention to verifying the compatibility among the box style, paperboard material, and manufacturing process.

Proofing Stage: Color Deviation and Process Performance Not Meeting Expectations

The most common issue in the proofing stage is color deviation. The average ΔE between digital proofing and bulk printing ranges from 2 to 4, exceeding the customer's tolerance for color deviation. Process performance not meeting expectations is also common, for example, the customer expects hot stamping to be bright gold, but the actual proof comes out more matte.

The countermeasure for color deviation issues is color sample management. The customer provides standard Pantone color numbers or physical color samples, and the supplier adjusts the ink according to the color samples and produces small samples for confirmation. Process performance issues require providing process samples or process diagrams before proofing, clearly specifying parameters such as hot stamping foil model, UV thickness, and embossing depth.

Printing Process: Registration Deviation, Color Difference, and Surface Defects

Problems in the printing process are the most concentrated and have the greatest impact on finished product quality. Registration deviation refers to the overlap accuracy deviation of each color plate during multicolor printing, with the industry requirement of ≤0.2 mm; exceeding the standard will result in ghosting or white spots. Color difference is the deviation between the actual printed color and the standard color, with ΔE ≥3 considered unacceptable. Surface defects include scratches, ink spots, dirt spots, etc.

The root causes of the three types of problems are different. Registration deviation originates from equipment precision and operating standards, requiring regular equipment calibration and standardized on-machine operation. Color difference originates from ink ratio and printing environment, requiring the establishment of standard ink color files and control of temperature and humidity. Surface defects originate from equipment cleanliness and workshop environment, requiring standardized cleaning procedures and enhanced environmental control.

Converting Process: Die-cutting Deviation and Gluing Issues

High-frequency issues in the converting process are die-cutting deviation and gluing issues. Die-cutting deviation refers to the dimensional deviation between the actual cut box shape and the designed box shape, commonly caused by knife line offset resulting in inability to assemble the box or poor fit. Gluing issues refer to uneven adhesive application, insufficient adhesive curing, or deviation in pasting position, leading to boxes falling apart or misalignment.

The control points for die-cutting deviation are die-cutting plate manufacturing precision and die-cutting machine adjustment. It is recommended to test die-cutting plate precision with die-cutting samples before each batch of printing, and confirm before mass production. The control points for gluing issues are adhesive model matching, application amount control, and curing time. Different papers and processes require different adhesives; too little adhesive application results in weak bonding, too much causes adhesive overflow.

Quality Inspection Process: Sampling Standards and Missed Defects

The most common issues in the quality inspection process are unscientific sampling standards and missed defects. Loose sampling allows defective products to reach customers, while overly strict sampling increases costs and rework. Missed defects frequently occur with visually similar batch defects, such as color variations within the same batch or process deviations within the same area.

Sampling standards are recommended to be adjusted according to the GB/T 2828.1-2012 attribute sampling system. General Level II with AQL 2.5 is a commonly used standard in the packaging industry, while for key customers or high-value orders, it can be tightened to AQL 1.5. Missed defects need to be addressed through batch inspection and in-process sampling, and cannot rely solely on final finished product inspection.

Cross-Process Issues: Information Transmission Distortion

Information transmission distortion across processes is also a common problem. For example, the customer changes the color but does not notify the printing workshop, and printing still places the order based on the original color. Or the design changes the size but does not notify the die-cutting workshop, and the die-cutting plate remains at the old size. The root cause of such issues is an inadequate communication mechanism.

The solution is to establish a change notification mechanism. Every change confirmed by the customer must be communicated to all relevant processes within 24 hours, and the Production Task Document must be updated. At the same time, establish a visual kanban board, posting change information at the workshop entrance to ensure that every process can see it.

Problems Caused by Material Variation

Material variation is another type of high-frequency issue. Different batches of white cardstock have slight differences in thickness and stiffness, with variations of up to 0.1 mm between batches from the same supplier. The moisture content of grey board and corrugated paper is affected by seasonal changes—higher moisture content in summer makes the paper softer, while lower moisture content in winter makes the paper harder.

The solution to material variation is incoming material inspection. Before each batch of materials is stored, thickness, grammage, and moisture content should be sampled and tested. Batches that exceed the standards should be returned or downgraded for use. For critical items, material stability testing should also be conducted, tracking data from 3 to 5 consecutive batches.

Environmental Factor Influences

Environmental temperature and humidity have a significant impact on printing and forming. The printing workshop temperature should be controlled between 22 and 26 degrees Celsius, with relative humidity between 50% and 65%. Exceeding this range will lead to issues such as poor ink drying and paper deformation. Excessive humidity in the forming workshop will cause slow adhesive curing and paper softening due to water absorption.

Environmental control requires temperature and humidity monitoring equipment and air conditioning systems. Temperature and humidity data should be recorded daily, with air conditioning adjusted or production suspended when standards are exceeded. High-end packaging projects should also establish clean rooms to prevent dust from affecting printing and surface processes.

Emergency Problem Handling

The core of emergency handling for problems in packaging production is rapid response and loss control. Once a problem is identified, isolate the defective products immediately, assess the scope of the affected batch, and notify the customer to negotiate a solution. There are four common solutions: rework, concession acceptance, downgraded use, and scrapping. Rework applies to minor issues; concession acceptance applies to slight deviations acceptable to the customer; downgraded use applies to defects that do not affect the main function; and scrapping applies to severe problems that cannot be salvaged.

After each emergency problem handling, a case should be documented, recording the problem description, cause analysis, solution, and preventive measures. Once archived, these cases form the organization's knowledge base to prevent recurring issues.

Key Points Review

• Packaging production issue distribution: printing 35%, forming 30%, design 20%, proofing 10%, quality inspection 5%.
• Printing core issues: registration deviation, color difference, surface defects.
• Forming core issues: die-cutting deviation, gluing issues.
• Cross-stage issues: information transmission distortion, requiring a change notification mechanism.
• Issue emergency handling: isolation, evaluation, negotiation, archiving — four steps.

The issue distribution in the packaging production process follows identifiable patterns. Allocating quality inspection resources according to the issue distribution, establishing cross-stage communication mechanisms, and setting material inspection standards can reduce the production defect rate from 5% to below 1%.