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General Engineering - Capability Statements

Compression testing small coil springs

Cost-effective small spring testing

With a sensitive digital force gauge, such as the Mecmesin Advanced Force Gauge, a manually-operated test stand can be sufficient for small spring testing in compression or tension. For the lightest springs, very fine control is needed, and the standard gearing may be inadequate for fully-repeatable conditions.

With a sensitive digital force gauge, such as the Mecmesin Advanced Force Gauge, a manually-operated test stand can be sufficient for small spring testing in compression or tension. For the lightest springs, very fine control is needed, and the standard gearing may be inadequate for fully-repeatable conditions.

 
Custom fixture to stabliise a compression spring for axial testing

Stabilised spring testing

Our client needed to test a number of small, lightweight springs under compression. To avoid buckling and sideways movement in the springs, a supporting spindle or spigot was required, to the dimensions of the springs under test.

Mecmesin designed and supplied compression probes with supporting pins, for operation on one of our regular MultiTest stands. These enabled rapid insertion and repeatable testing.

 
Custom mandrel required for torque testing of springs

Torsion spring testing

Unlike most compression and tension springs, torsion springs require a central support or core for testing, and custom mandrels to hold and turn the tails, which themselves are designed to purpose. Ensuring axial alignment, our custom solutions for torsion springs of all kinds are meticulously engineered, either for our Vortex range of torque testers, or for the Helixa precision torque tester.
Steering rack force testing

Automotive steering components

Sometimes the dimensions of a component make force testing difficult to achieve. Our client needed to test the sliding force of a bearing along a steering rack rod end, requiring accurate axial alignment of the bearing grip with that holding the rack end of the rod. In this way they could measure manufacturing quality of the assembly. The test required both height capacity of a test stand, and custom fixtures.

Mecmesin supplied a twin-column universal tester and designed the required fixtures for both push and pull testing of the bearing. Coupled with Emperor data acquisition and analysis software, engineers were then able to measure the frictional forces and smoothness of action over distance of travel, in a reliable and repeatable way.

 
Smoke grenade integrity testing

Smoke grenade canister integrity

A manufacturer of smoke grenades required a means of testing the cap pull-off strength, especially gripping the smooth metal cylinder for up to 5 kN of pulling force. An annular clamp would be needed with penetrating pins to hold the cannister, and in alignment with the applied load.

A four-way grip was designed and manufactured by Mecmesin engineers, with pins penetrating the canister base. This provided a secure and symmetrical grip, whilst pulling the rigid cap off with hooks applied to the two cap holes to measure the peak force applied.

Plastic weld strength testing solution

Injection moulded assembly integrity

Plastic injection-moulded subassemblies can be clipped or welded, and the integrity of the whole must be tested at several points. However, their shape can make them very difficult to hold, and places to grip for pulling hard to identify. Our client needed a complete custom fixturing solution.

Mecmesin engineers designed profiled nests and retaining plates, an X-Y table for positioning the test sample, and a range of hooks to pass through apertures and engage edges in the assembly. This enabled a defined sequence of pull-off tests to be made consistently across a number of samples for batch testing.

 
CD004 Transport engineering springs 220

Transport and engineering industry spring testing

Coil springs as used in the transport industry or other general engineering applications may be elements of safety critical components, particularly in public transport (suspension system) or aviation (brake unit) implementations. To evaluate the performance of helical springs under load, the compression test equipment must ensure that the axis of compression remains constant. A coil spring will tend to lean and become out of square under load. Self-levelling compression plates and fixtures custom-designed to constrain and locate the spring must be used. Safety guarding should be a feature of the test system for large powerful springs.

Mecmesin Systems: MultiTest computer-controlled and console operated compression testers

Case Studies: Aircraft brake unit spring testing, railcar spring testing, bespoke spring design and manufacture

 

 

Torsion spring testing

Helical torsion spring running torque

The helical torsion spring comes in a wide variety of sizes and finds use in a diverse range of industries. Spring loaded componentry in home and consumer goods: clothes pegs, clips and old-fashioned mousetraps; small doors and flaps on cameras or hi-fi equipment; large doors and closures such as those on garages or gates and in transport applications like vehicle luggage compartments. Calibrating the torque to turn (running torque) of the torsion spring is required to achieve the desired levels of effort for the user to open/close the component and provide the optimum levels of resistance or snap. The ability to test a range of products requires a set of custom fixtures to match the spring design, for example spiral. A lower rod-shaped mandrel holds the spring and the upper fixture incorporates a drive peg – directly connected to the torque cell – which locates into the outer arm of the spring to load and unload the sample. Computer control with a suite of test programs can rotate the spring to a pre-defined angle and collect the torque and rotational displacement data continuously. The software ensures repeatable testing of clockwise or anti-clockwise turn (approaching the design load point from below and above, then averaging, minimises the effect of friction and hysteresis on the results) and can guard against permanent set in the spring material. The requirement to meet specific torque range limits – within the linear response range of the spring - can also trigger immediate PASS/FAIL indication as the results are recorded and displayed.    

Mecmesin Systems: Vortex computer-controlled torque testers, Emperor™ (Torque)

Video: Testing Torsion Springs with Vortex

Testing a small light torsion spring

Precision helical torsion spring torque to turn

The helical torsion spring comes in a wide range of designs and varying sizes to cover almost every engineering application. Despite being termed ‘torsion’, the spring itself is subjected to a bending stress when the ends rotate about its central axis, driven by the components attached to either arm. The elements which are required to rotate in service depend upon the spring’s stiffness rating in order to be fit for purpose and also exhibit the correct level of resistance for ease of operation and quality feel. The smallest examples, used in precision applications, need to employ a test system which can not only ensure that the spring’s axis remains aligned to within tight tolerances but that can accurately measure the resulting very light torque values.  In these implementations, the frictional forces experienced by the coils may have significance. A spring design with pitch between the coils, rather than close-wound, will counter this issue and allow for even lighter torque to turn efforts, increasing the need for a torque test system capable of measuring these values. Exacting alignment of the fixture (hence spring) and torque cell axes for concentricity should be a capability of the test stand to guarantee the most accurate data.  

Mecmesin Systems: Vortex computer-controlled torque testers, Emperor™ (Torque)

Video: Helixa Precision Torque Measurement Systems

CD017 Marine al frame in grips 220Marine vessel aluminium frame fastener shear and pull-out strength

The marine industrial construction and engineering sector requires stringent testing of the integrity of the fastening systems employed in sea-going vessels. The materials utilised may also be particularly specialised and light weight, thus needing rigorous evaluation to ensure confidence in the strength of the assembly. A bolted aluminium structural element may be tested to accurately simulate its loading in the complex operational environment in order to measure the critical strength of the entire bolted assembly. The weakest element could be the fastener itself, suffering shear failure, or pull-out, or the hole in which the bolt is located could undergo deformation due to the tensile forces and compromise the structure. This testing is thus able to evaluate the lap joint’s performance and provide objective data as to the quality of the batch of supplied fastenings or any modifications to the frame’s cross-section, design or material specifications. Typical shear forces up to 10 kN are able to be handled with appropriately rated wedge grips and a suitably cut-down sample.

Mecmesin Systems: MultiTest motorised test system, 10 kN wedge grip