Pendulum Energy-Loss Operating Principle
The Qualitest Puncture Tester operates on a 90° arc pendulum energy-loss principle to determine the work absorbed when forcing a standardized steel head through corrugated board.
A square 175 × 175 mm (6.9" × 6.9") specimen is secured between rigid horizontal clamping plates with adjustable pressure (25 to 100 kgf) to prevent sample movement. Upon release, the weighted pendulum swings through its arc, driving a triangular pyramidical steel head through the board.
Comparing the initial arm height to its residual swing height reveals the precise energy absorbed during penetration. This total absorbed impact energy comprises two distinct mechanical components:
- Puncture and Tear Force: The work required to break through outer linerboard facings and internal fluting.
- Flap Clearance: The additional force needed to push torn triangular flaps completely clear of the impact path.
Impactor Geometry and Machine Specifications
To maintain strict compliance with TAPPI T803, ISO 3036, and JIS P 8134, the system enforces precise impactor and clamping specifications.
The head features a right-angled triangular pyramid measuring 1" (25.4 mm) in height (25 ± 0.7 mm) with edges honed to a smooth 1.5 mm radius. Positioned directly behind the head is a loose metal slip collar. Upon penetrating the specimen, the collar detaches and remains inside the hole, holding the cardboard flaps open so the returning pendulum arm suffers no drag friction.
Operators select from five exchangeable scale capacities (0-26.75 kg-cm, 0-53.5 kg-cm, 0-107 kg-cm, 0-214 kg-cm, and 0-428 kg-cm) to match lightweight single-wall board or heavy double-wall containerboard.
Machine Specifications & Standards Compliance
| Parameter | Qualitest System Specification | Compliance Standards |
|---|
| Impactor Geometry | Right-angled triangular pyramid head | TAPPI T803, JIS P 8134, ISO 3036 |
| Impactor Height | 1" (25.4 mm) / Regular height 25 ± 0.7 mm | TAPPI T803, JIS P 8134 |
| Edge Radius | Smoothly honed 1.5 mm curve | TAPPI T803, ASTM D781 |
| Specimen & Plate Area | 175 × 175 mm (6.9" × 6.9") effective clamping | JIS P 8134, ISO 3036 |
| Clamping Force | Adjustable 25 to 100 kgf | TAPPI T803, FEFCO No. 5 |
| Selectable Scale Capacities | 0-26.75, 0-53.5, 0-107, 0-214, and 0-428 kg-cm | TAPPI T803, JIS P 8134 |
| Pendulum Arm Path | Precision arc of 90° | TAPPI T803, ISO 3036 |
| Machine Dimensions | 85 × 40 × 76 cm (140 kg total weight) | Industry Calibration Standards |
Measuring Dynamic Point Impacts vs. Stacking Strength
Standard Box Compression Tests (BCT) evaluate top-to-bottom load strength, but fail to predict resistance against localized point punctures from pallet corners or handling equipment.
Industry testing demonstrates that box compression strength and puncture energy measure separate material characteristics:
- Box Compression Strength (BCT): Evaluates static stacking resistance under uniform vertical load.
- Puncture Resistance: Evaluates dynamic toughness against concentrated point impacts.
Puncture performance depends on the combined strength of facing paper, fluting medium stiffness, adhesive bond quality, and bending rigidity. Testing both faces of asymmetric or multi-wall 175 × 175 mm samples ensures an accurate energy rating across both linerboard orientations.
Environmental Controls and Scale Capacity Selection
Ambient testing conditions and raw material properties directly influence pendulum energy readings:
- Humidity and Fiber Saturation: Controlled conditioning at 23°C and 50% relative humidity (per TAPPI T402 / ISO 187) is required. At relative humidity levels exceeding 75%, absorbed moisture causes paper fibers to reach saturation, causing puncture values to drop sharply.
- Linerboard Grammage and Tensile Energy Absorption (TEA): Paper basis weight (g/m²) and Tensile Energy Absorption (TEA) serve as primary indicators of puncture capacity.
- Scale Capacity Matching: Selecting the appropriate scale range (26.75 kg-cm for light papers up to 428 kg-cm for heavy board) ensures optimal measurement resolution across varying paper grades.
