CUSTOM FIXTURES

CUSTOM FIXTURES

The production of fixtures for environmental tests, mainly vibration tests, is one of the historical milestones of Centrotecnica's activities.
We employ FEM analysis and the most advanced technologies for the design, production and validation of each fixture, and commit significant resources to research into new technologies and new materials that increase performance.


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Agusta Westland, Ferrari, Leonardo, Thales Alenia Space, ABB, FCA, Airbus… The companies that turn to us for the supply of these sophisticated test equipment are present in all production sectors, with a prevalence of requests in the automotive, avionics, defence and rail sectors.



The FIXTURE function

Fixtures are the interface tools between the sample and the machine that produces vibrations or shocks, and must perform the function of transferring the resulting stresses to the sample.


The FIXTURE function


Kinds of FIXTURES

Single-axis fixtures: these are by far the most common: they transmit stresses exclusively along the axis of vibration. They are the simplest and cheapest to make.

Triaxial fixtures: much more complex to design. The sample is placed on an inclined plane that distributes the solicitations on the three axes simultaneously. Triaxial fixtures produce the closest to real test conditions.

Resonance fixtures: they amplify the stresses by allowing very high acceleration levels, even much higher than those provided by the machine, to be reached with minimum effort. Ideal for shocks.


Kinds of FIXTURES


Special fixtures, CENTROTECNICA exclusives

Fixtures with 3D-printed elements (additive manufacturing) with plastic, metal or composite materials: they have the advantage of being able to replicate exceptionally faithfully the type of fixturing of the specimen in real use, and thus provide even more accurate answers on their reliability.


Special fixtures, CENTROTECNICA exclusives

RT Fixtures: these are equipped with skids and mounted directly on the guides of the slip table, bypassing the table. This feature allows great weight savings, resulting in improved shaker performance and efficiency. RT Fixtures can only be used in conjunction with our RT slip tables.


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Inspections and certifications

The most important technical feature of a fixture is the amount of resonance frequencies in the range of use for which it is intended. All our fixtures are delivered with documentation certifying their high production standards:

Dimensional validation: the extremely low dimensional tolerances with which our fixtures are produced are guaranteed by measurements made with a 7-axis 3D measuring arm. Inaccurate dimensions may lead to difficulties or impossibility of sample assembly.

Resonance search: fixtures are tested on a shaker table to identify resonance frequencies and the best control strategies, which are reported in the test report.


Inspections and certifications


The skills of a vibration test fixture

Centrotecnica's environmental test laboratory makes regular use of our fixtures made for customers from all sectors. Consequently, our designers are clear about the qualities of a good fixture:

General qualities:

  • optimal dynamic behaviour in the test frequency range.
  • ease of set-up: mounting of sample, accelerometers and test axis change operations must be easy.
  • longevity: no cracks, breaks or deformations should occur even after very long use.
  • lightness: saving weight leads to greater efficiency and optimises shaker performance. To reach this goal, we have acquired the necessary know-how for the production of magnesium fixtures.

Optional qualities:

  • modularity: possibility of varying configurations to adapt to different samples.
  • possibility of assembling many samples at once: a feature in great demand in the automotive sector that allows considerable savings in time and resources.

The skills of a vibration test fixture


Complementary fixture accessories

CENTROTECNICA produces very effective and in some cases exclusive complementary fixture elements:

Cubes and prisms: for testing on multiple axes and/or multiple samples with a minimum of setup changes.


Complementary fixture accessories

Interface plates: for adapting fixtures to the drilling template of shakers, slip tables and expanders. Our LAB has many plates that are available to customers to make the necessary drilling templates for their fixture.


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Instant Clamp: patent-pending product of great added value in economic and practical terms. It makes simple and ultra-rapid (less than 30 seconds) the fastening or axis changing of the fixture to the shaker or slip table.


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Static test fixtures

This kind of fixture does not require dynamic behaviour control, but very precise specific arrangements:

Rain test fixtures: these are used to test the watertightness of automotive headlamps. They make use of resin components in order to replicate body profiles with the highest fidelity and achieve the best possible adherence of the sample.


Static test fixtures

Salt spray test fixtures: made of acrylic material for salt spray testing. They must be non-deformable and unaffected even after months of testing in a highly corrosive environment.


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Photometric fixtures: for beam analysis tests of automotive lighting units, they are anodised black so as not to interfere with the beam characteristics.


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Delivery

Fixtures ordered from Centrotecnica are delivered worldwide carefully packaged, equipped with the assembly kit and provided with reports certifying compliance with construction dimensions and dynamic behaviour profile.

Contact us for any request of further information