Manual force test stands are mechanical devices that hold a force gauge and allow tensile and compression tests to be carried out with the load applied by hand, ensuring the correct direction, better repeatability than free-hand testing and greater convenience for the operator. They come in vertical models (for axial tensile and compression tests) and horizontal ones (for tests where a horizontal layout of the specimen is preferable, such as fabrics, cables and wires). They are used in laboratory and workshop quality control where motorisation is not needed or where the budget is limited.
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Design
A typical manual test stand comprises: a solid base (in aluminium or steel), a rigid vertical column (on vertical models) or a horizontal bed, a force gauge mounted on the moving carriage or on the fixed end, and a manual drive mechanism (leadscrew and nut, lever or handwheel) that moves the carriage and applies the load to the specimen. The system can be graduated to read the mechanical displacement in mm or fractions. The stiffness of the stand is critical to accurate measurement: elastic deformation of the structure produces errors in the force measurement on less compliant specimens.
Loads and applications
Manual stands typically cover loads up to 500-2500 N. Manual operation requires operator effort proportional to the load, so above 1 kN it becomes physically demanding. The rate at which the load is applied varies (it depends on the operator) and is not controlled: this limits the ability to run tests to standards that require a specific test speed (such as ISO 6892 for the tensile testing of metals). Manual stands are therefore suited to qualitative, comparative and pre-screening tests, not to formal material certification.
Types of test
Manual stands are used for: tensile tests on springs, elastic bands and elastics; compression tests on springs and rubber; pull-off tests on electrical crimps (with dedicated accessories); opening and closing tests on caps and capsules (with cap testers); ergonomic tests on buttons and operating levers; extraction tests on press-fitted components; delamination tests on laminates; and seal strength tests on seals. Dedicated accessories exist for each application: clamps, hooks, grips, mandrels and horizontal supports for cables and wires.
Displacement measurement
The more complete stands incorporate a displacement measuring system (optical encoder, magnetic scale, micrometer screw with dial), which allows force (from the gauge) and displacement (from the stand) to be recorded at the same time. The combined force-displacement data make it possible to plot test curves useful for advanced analysis (elastic modulus, deformation at yield, energy absorbed). Models with a PC software interface display the curve in real time and generate test reports.
Selection criteria
The choice of manual stand depends on the maximum load required, the test direction (vertical or horizontal), the useful travel needed (for long specimens), the mechanical stiffness (to obtain accurate measurements on rigid specimens), compatibility with the force gauge used, the availability of an integrated displacement measuring system, and the availability of accessories for the specific application. For repetitive testing on large numbers of specimens, it is worth considering the investment in a motorized stand, which reduces operator fatigue and guarantees a constant speed.
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