11 July 2026<\/strong><\/div>\nForce verification to ISO 7500-1<\/strong> proves that a universal testing machine or compression machine indicates true force within class limits \u2014 the foundation of every valid tensile, compression and flexural result a laboratory reports.<\/p>\nWhat the Test Measures<\/h2>\n
The machine’s force readout is compared against a traceable force-proving instrument (load cell or proving ring) at multiple points over each working range. Relative indication error, repeatability, reversibility and zero error determine the machine class (0.5, 1, 2, 3).<\/p>\n
Apparatus Required<\/h2>\n\n- Force-proving instruments to ISO 376, calibrated and traceable to national standards (SAMM\/SST in Malaysia)<\/li>\n
- Adapters and compression platens\/tension grips to load the proving device axially<\/li>\n
- Resolution check tools and temperature monitoring (verification at 10–35 °C, stable to ±2 °C)<\/li>\n<\/ul>\n
Test Procedure<\/h2>\n\n- Exercise the machine to maximum force three times per range.<\/li>\n
- Apply not fewer than five discrete forces (typically 20\/40\/60\/80\/100% of range) in three series, plus a repeatability series.<\/li>\n
- Compute indication error q, repeatability b, reversibility v and zero error f0<\/sub> for each range.<\/li>\n
- Classify each range; affix the verification label and issue the certificate stating class and ranges verified.<\/li>\n<\/ol>\n
Calculation & Reporting<\/h2>\n
Class 1 requires |q| ≤ 1.0%, b ≤ 1.0%, v ≤ 1.5%, zero error ≤ 0.05% of range. The certificate must list each verified range \u2014 a machine may be class 1 over 20–100% but unclassified below 20%.<\/p>\n
Acceptance Criteria<\/h2>\n
Concrete and steel testing standards (EN 12390-4, ISO 6892-1, ASTM E4 equivalent) require class 1 machines verified at least every 12 months<\/strong>, and after relocation, overload or repair. Results from an out-of-verification machine are formally invalid.<\/p>\nFrequently Asked Questions<\/h2>\nWhat usually causes a machine to fail verification?<\/h3>\n
Drifted electronics after years without service, worn spherical seats and platens introducing eccentric loading, hydraulic leak-down at low ranges, and damaged load cells from impact or overload.<\/p>\n
Is a supplier calibration certificate the same as ISO 7500-1 verification?<\/h3>\n
Only if the work was performed to ISO 7500-1 by an accredited (ISO\/IEC 17025) laboratory with ISO 376 proving instruments and the certificate states the class per range \u2014 a generic “calibration” sticker does not satisfy auditors.<\/p>\n
Recommended Apparatus<\/h2>\n
NL Scientific manufactures the ELECTRO-HYDRAULIC Servo Control Universal Testing Machine 2000kN (6KS)<\/a> for this method. Browse the full Steel Testing Equipment<\/a> range or request a quotation<\/a> from our engineers.<\/p>\n
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