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Key: test item, instrument name, total nonvolatile migration, gravimeter, moisture permeameter

Product

Free‑Fall Dart Impact Tester for Plastic Films & Sheets

STL-A /D
Focusing on packaging and material testing technology, we are committed to quality control in industries such as healthcare, pharmaceuticals, food, packaging, textiles, and new materials. Our products are widely used in enterprises, testing institutions, universities, and research institutes.

Category:

Packaging and Printing

Impact Resistance

Free‑Fall Dart Impact Tester for Plastic Films & Sheets

Functions

Determine the impact resistance of plastic films, sheets, and laminates by measuring the energy required to cause failure.

Identify the 50 % failure energy — the impact mass at which 50 % of specimens fail — using the Bruceton staircase method.

Evaluate the toughness and ductile‑brittle transition of flexible packaging materials under sudden impact.

Working Principle

A conical or hemispherical‑tip dart of specified mass is released from a predetermined height, falling freely onto a clamped film specimen. The impact energy is varied systematically across specimens. After a sufficient number of tests, the 50 % failure mass (and corresponding energy) is calculated using the Bruceton staircase algorithm. This method provides a statistically robust measure of impact performance with fewer specimens than fixed‑height methods.

Compliant Standards

GB/T 9639.1‑2008 — Plastics — Determination of impact behaviour of films by the free‑falling dart method — Part 1: Staircase method

ASTM D1709‑22 — Standard Test Methods for Impact Resistance of Polyethylene Film by the Free‑Falling Dart Method

JIS K7124‑1:1999 — Testing methods for impact resistance of plastic films by the free‑falling dart method

Key Features

Dual‑Method Support (STL‑D): Supports both Method A (standard) and Method A + B (extended range) for comprehensive impact characterization.

Pneumatic Specimen Clamping: Secures the film evenly without wrinkles or pre‑stress, eliminating manual clamping variability and reducing test time.

Automatic Bruceton Calculation: The embedded microcomputer automatically identifies pass/fail outcomes, advances the staircase sequence, and calculates the 50 % failure mass - no manual marking or charting required.

High‑Precision Weights: Weight increments as fine as 0.1 g allow precise energy stepping for accurate failure threshold determination.

Built‑in Observation Lamp: Illuminates the impact zone for clear visual inspection of film puncture, cracking, or yielding.

LCD Display & Micro Printer: Real‑time display of test parameters and automatic printing of results in multiple units (grams, joules, kgf·m).

Intelligent Workflow: Fully automated test sequence - from dart release to result computation - minimizes operator intervention and maximizes throughput.

Technical Specifications

Name	STL-A	STL-D
Test mode	A	A, B
Range	50～2000g
Precision	0.1g
Clamping mode	Pneumatic
Sample size	＞150mm×150mm
Size（L×B×H）ｍｍ	670×400×1300	670×400×2100
Net weight	70Kg	80Kg
Power Supply	AC220/110V 50/60Hz
Selt-supply	Gas resource

Configuration：Principle machine, a set of weights for method A, a set of weights for method B(only for STL-D type machine).

Application Industries & Scenarios

Flexible Packaging & Converting

LDPE / LLDPE Films: Determine impact resistance for grocery sacks, shrink wrap, and stretch film.

Laminated Pouches: Evaluate the toughness of multi‑layer structures used in snack food and pharmaceutical packaging.

Heavy‑Duty Shipping Sacks: Test woven‑polyethylene laminates for drop‑impact survival.

Agricultural Films

Greenhouse Films: Assess weather‑resistant polyethylene films for hail and wind‑driven debris impact.

Mulch Films: Ensure adequate puncture resistance during installation and cultivation.

Silage Bags: Validate impact toughness under cold storage conditions.

Medical & Pharmaceutical Packaging

Blister Forming Films: Test PVC/PVDC and PET/PE laminates for impact resistance during forming and filling.

Transdermal Patch Backings: Evaluate release liner toughness under flex and impact stresses.

Sterile Barrier Pouches: Ensure films withstand accidental drops during handling.

Food & Beverage Packaging

Frozen Food Bags: Test low‑temperature impact resistance of PE and CPP films.

Stand‑Up Pouches: Validate spout‑area film toughness against corner drops.

Vacuum Pouches: Assess impact behavior of high‑barrier nylon‑based structures.

Research & Third‑Party Testing

CNAS/CMA‑Compliant Testing: Issue legally defensible impact reports referencing GB/T 9639 or ASTM D1709.

New Material Development: Compare impact modifiers (e.g., EVA, elastomers) in polyethylene formulations.

Failure Analysis: Investigate field failures due to inadequate film toughness.

Frequently Asked Questions (FAQ)

Q1: What is the Bruceton staircase method and why is it used?

A: The Bruceton method is a statistical up‑and‑down technique used to determine the 50 % failure point of a material. Instead of testing many specimens at random energies, each subsequent test is adjusted based on the previous outcome (pass → decrease mass; fail → increase mass). This converges rapidly on the 50 % failure threshold, requiring far fewer specimens than fixed‑energy methods.

Q2: What is the difference between Method A and Method B?

A: Method A uses a larger dart tip diameter and is suitable for most general‑purpose films. Method B uses a smaller tip diameter, producing higher localized stress — ideal for thinner films or materials that show ductile behavior under Method A. The STL‑D model supports both methods for maximum versatility.

Q3: Is GB 9639 still valid? Which version should I use?

A: GB 9639 is obsolete. The current valid Chinese national standard is GB/T 9639.1‑2008. All new test reports should reference this version to ensure CNAS/CMA acceptance and customer compliance.

Q4: How many specimens are needed for a complete test?

A: The Bruceton method typically requires 20–30 specimens to achieve a statistically reliable 50 % failure mass. Because each specimen is used only once, the pneumatic clamping system significantly speeds up the preparation and testing cycle.

Q5: Can the instrument test rigid sheets or only flexible films?

A: The free‑fall dart method is specifically designed for flexible films and thin sheets (typically ≤1 mm thick). For rigid plastics, a pendulum impact tester (Izod/Charpy) or a drop‑weight tester with a different anvil configuration is recommended.

Q6: What air supply is required?

A: The pneumatic clamp requires a clean, dry compressed air source. Specific pressure requirements are detailed in the operation manual. Ensure the supply is free of oil and moisture to protect the pneumatic components.

Q7: How is the impact energy calculated?

A: Impact energy (in joules) = mass of the dart (kg) × gravitational acceleration (9.81 m/s²) × drop height (m). The instrument displays the 50 % failure mass; the operator can easily compute the corresponding energy using the known drop height.

Function：
It is used to determine the impact resistance of plastic film or sheet. The drop dart falls freely at a given height to impact the specimen. The impact mass and energy of 50% sample were measured.
Standards：GB 9639、ASTM D1709、JIS K7124。
Characteristics：
- comply with national and international standards and correct errors in national and international standards.
- Test methods: A method, A + B double method.
- The lamp for observation is convenient for sample inspection.
- The test process is intelligent and efficient.
- Microcomputer processing of test data.
- The sample is pneumatically clamped and released to reduce the test error and test time.
- The test process does not need manual drawing and marking, and the data parameter system is displayed on LCD.
- The test data system can automatically identify and calculate without manual intervention.
- the test is automatically completed, and the results are displayed in multiple units and printed by micro printer.

Specification:

Name	STL-A	STL-D
Test mode	A	A, B
Range	50～2000g
Precision	0.1g
Clamping mode	Pneumatic
Sample size	＞150mm×150mm
Size （L×B×H）	670mm×400mm×1300mm	670mm×400mm×2100mm
Net weight	70Kg	80Kg
Power Supply	AC220/110V 50/60Hz
Selt-supply	Gas resource

Configuration：Principle machine, a set of weights for method A, a set of weights for method B(only for STL-D type machine).

Keywords:

Thick Material Irregular Sampler

Pendulum Impact Tester - Electronic