Short Span Compression (SCT)

The short span compression test (SCT) is a mechanical testing method used to measure the compressive strength of materials over a very short span. By applying a compressive load to a small section of material, SCT provides an accurate measurement of stiffness and resistance to buckling without the influence of long-span bending.

This method is particularly valuable in industries where materials are exposed to compressive forces in service. In the packaging sector, SCT is used to determine the strength of paperboard in cartons and boxes, ensuring they retain shape and integrity during stacking and transport. In the fibre optics industry, it assesses the compressive performance of optical fibre cables, ensuring they meet durability and reliability requirements.

By focusing on a short span, the method isolates true compressive properties, making it a critical tool for manufacturers and quality assurance teams seeking reliable performance data.

Short span compression testing differs from conventional compression tests because it uses a minimal support length to eliminate bending effects. This ensures results are directly related to the material's intrinsic compressive strength.

The process generally involves preparing a specimen to standard dimensions, clamping it in a fixture with a defined short span, and applying a steadily increasing compressive load until failure. For example, in ISO 9895 testing of paperboard, the span is typically 0.70 mm, allowing precise measurement of compressive strength in materials with grammage between 100 and 400 g/m².

By removing bending influence, SCT delivers data that can predict in-use performance, particularly for thin materials such as high-grade carton board or fibre optic cable sheath layers where structural integrity depends on resistance to crushing.

ISO 9895 - packaging materials

ISO 9895 specifies the method for determining the compressive strength of paper and board over a short span. It defines specimen size, clamping methods, and load application rates to ensure results are consistent and comparable. This standard is widely used for evaluating corrugated and solid fibreboard for shipping containers, retail packaging, and industrial cartons. Compliance helps packaging manufacturers meet strength requirements for handling, stacking, and transport.

EN 60794-1-21 - fibre optic cables

EN 60794-1-21 specifies mechanical test methods for optical fibre cables, including short span compression tests. The method simulates compressive loads encountered during installation, storage, and service. In this test, the cable is placed between two flat plates, and a defined load is applied to replicate operational mechanical stresses. Results confirm that the cable can withstand expected service conditions without impacting optical performance.

SCT is widely applied in quality assurance, R&D, and material qualification:

• Packaging: Measuring the short span compressive strength of carton board to predict box compression strength and ensure protection during pallet stacking.
• Fibre optics: Testing cable sheath and buffer tube resistance to crushing, minimising signal loss and extending service life.
• Specialty materials: Evaluating thin laminates, films, and protective coatings for industrial and consumer applications.

For example, kraft linerboard tested at 0.70 mm span often shows compressive strengths in the range of 5 to 15 kN/m, correlating directly to box compression performance in transit simulations.

SCT testing equipment and tools

Accurate SCT testing requires equipment that can apply controlled and repeatable loads:

• Mecmesin OmniTest and MultiTest-dV - universal test frames capable of precise load application and movement control, available in a range of capacities.
• VectorPro software - for automated control, load-displacement data capture, and customised reporting in line with ISO and EN standards.
• Specialised short span fixtures - designed to hold the specimen securely with minimal deformation outside the compression zone.

These systems are engineered to meet relevant international standards, ensuring reliable and repeatable results.

Step-by-step testing guide

• Specimen preparation - Cut samples to standard dimensions as specified by the relevant standard.
• Fixture setup - Place the specimen into the short span fixture, ensuring correct alignment and clamping pressure.
• Load application - Apply a steadily increasing compressive load at the specified rate.
• Data capture - Record the peak force at failure, then calculate the compressive strength.
• Analysis - Compare results against specification limits or historical benchmarks to assess compliance.

Mecmesin provides complete solutions for short span compression testing, combining precision-engineered test frames, purpose-designed fixtures, and advanced control and analysis software. With decades of expertise in packaging and fibre optic testing, Mecmesin ensures that test results meet the requirements of ISO 9895 and EN 60794-1-21.

Engineers and manufacturers choose Mecmesin systems for their ability to deliver repeatable, standards-compliant data that reflects real-world performance.

Speak to one of our technical specialists today to discuss your short span compression testing requirements and discover how Mecmesin can help you achieve accurate, compliant, and reliable results.