How to Design a Dart Impact QC Plan for Frozen Food Packaging Films

How to Design a Dart Impact QC Plan for Frozen Food Packaging Films

Frozen food packaging is one of the toughest real-world tests for flexible films. Materials that perform well at room temperature can become brittle at -20 °C or lower, leading to cracks during transport, loading, and handling. A well-designed dart impact QC plan helps you detect these weaknesses before products reach the market.

The first step is to define your test conditions. For frozen food, it is rarely enough to test films at standard laboratory temperature only. The QC plan should specify a conditioning step where samples are stored at the lowest expected product temperature (for example, -20 °C for frozen dumplings and vegetables) for a defined time. After conditioning, the films are quickly transferred to the impact tester and evaluated using either Method A or Method B, depending on film construction and expected toughness. This combination of low-temperature conditioning and dart impact testing simulates real cold-chain stress conditions.

Next, you need to establish sample selection and sampling frequency. It is good practice to sample from different positions across the web (center and edges), as mechanical properties can vary across the roll. For each production batch, you may specify a minimum number of impact tests, such as 20 specimens per structure or per line. When multiple film structures are used for different SKUs, each structure should have its own sampling plan and acceptance criteria. Including both machine direction and transverse direction specimens can reveal anisotropy in film performance.

Defining specification limits is the core of a QC plan. Many companies use the impact failure mass (M50) as the primary specification. To set realistic limits, start with a development phase: collect impact data for films that have good field performance and those associated with customer complaints. By comparing these two groups, you can identify a minimum M50 value that separates “safe” from “risky” packaging. This limit can then be written into internal specifications as “Not less than X g at -20 °C, Method A,” or a similar statement.

A robust QC plan also addresses data management and traceability. Each test record should include sample ID, production line, date, operator, conditioning conditions, method (A or B), dart mass sequence, and final M50. Using an instrument with built-in data storage and export helps avoid transcription errors and supports investigations when complaints arise months later. Finally, the QC plan should be documented in a standard operating procedure (SOP), and operators should be trained not only in pressing buttons but also in understanding why test temperature, clamping, and method selection matter.