Tribologie

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AAC starting with space tribology has focused its test expertise and devices in three domains:

Space tribology: Our aim is to test materials and coatings for use in space applications, from sample level up to semi-components like gears or bearings. Our focus in space applications is combined with expertise in dry lubrication as well as composites or coatings.

Electro-tribology: Our aim is to test materials and coatings for use in electrical sliding contacts, covering slip-rings and potentiometers, on semi-components like brushes. Research and development is running for space and on-ground applications.

Forming tribology: Our aim is to measure friction factors during forming, which can be used for simulation of forming processes (to optimise production).

Survey of all tribological test devices
This is only a short survey of our test devices. But as we developed them ourselves many modifications are available which are not listed herein. Please contact us.

Device Sample Output Specialities
Vacuum Tribometer Pin/Ball – Disc

Slip-Rings

Friction, LinWear, El.Contact-resistance Vacuum, air, CO2

Temp: –100/+300°C

Cold Welding Pin-Disc/fretting Friction, Adhesion Vacuum, air, CO2
Journal Bearing Test Rig (JBT) Bush-Shaft Torque Vacuum, air, CO2

Temp: –100/+300°C

Forming tribometer Shaft-Bush

Ring-Ring/Plate

Reibfactor for Simulation

Torque for bearings

Load up to 200.000N
Torque up to1000NmTemp up to 950°C
SALOTTE 1 Gears, bearings Torque & Life time Vacuum, air, CO2
–150 to +250°CEl.Brake to 50Nm
SALOTTE 2

Milli-Vacuum Tribometer

Pin-Disc/

Brush/Wire-Ring

Friction,
El. Contact-resistance
Vacuum, air, CO2
–100/+300 °C Forces
10–1000 mN
Slip-Ring-Tester Brush/Ring Friction,
El. Contact-resistance
Forces 10–500 mN

Ambient from –20 to +50 °C

Ball bearing test rig Ball bearings

Ring-Ring

Torque, lifetime

Friction

Vacuum, air, CO2
RT to +200°C
vacuum to +700°C
Component testing Components Temperature, Torque,.. Clean room, vacuum –190 to +300 °C

Space Tribology

The Space tribology covers on one hand standardised friction and wear testing on material (sample) level, testing of semi-components (bearings, gears, slip-rings) up to life-testing of full sub-systems (actuators) in a thermal vacuum chamber in clean room.
Testing on material level can be done using a Pin-on-Disc-type Vacuum tribometer, a milli-Vacuum-tribometer (low loads as in slip-rings) but also offers also very specialised and unique equipment which enables to simulate cyclic closed contact, like e.g. in relays, or at end stops, and to measure forces necessary to re-open the contact, i.e. the adhesion forces. This effect is herein referred to as “Cold Welding”, but other terms may be e.g. stiction. Two facilities cover the most dangerous types of contacts: Impact and Fretting.
For testing on semi-component level, several test devices were developed by AAC to test bearings, gears, potentiometers or brushes for slip-rings. A survey of all devices is given in the table above. For detailed descriptions follow the links to the device descriptions. Those devices were developed by us, hence modifications towards your needs are possible.
Finally, test chambers enables testing of (tribo-) components and subsystems under thermal vacuum are available (Examples are given in section “Component Testing” and “Testing of Flight Hardware”). AAC offers setup of support structures and life-time test under thermal vacuum (providing also actuators or brakes). Software can be adopted to modes of movements defined by customers.

Electro-Tribology

A slip ring (in electrical engineering terms) is a method of making an electrical connection through a rotating assembly. Slip rings, also called rotary electrical interfaces, rotating electrical connectors, collectors, swivels, or electrical rotary joints, are commonly found in electric motors, electrical generators for AC systems and generally in all rotary systems with electrical connections of sensors and receptors.

AAC has developed a set of test devices that enables to test components and materials for slip-rings or potentiometers on simple components: e.g. just a wire =brush and a ring with v-groove can be sued to compare different coatings, surface finishes. On the other hand, for potentiometers just the grip and the ring are needed and loads downto 10mN can be realised.

The exact specification of each chamber relevant for electrical sliding contact materials can be found in the facility descriptions. They cover possibilities to select best material candidates for sliding contact applications in space (electro-tribological testing of material pairings in adequate environment, post analysis of sliding surfaces / wear tracks). Usually with best material pairings breadboards and engineering models are manufactured which can also be tested in same environments on their electrical and mechanical behaviour (torque of whole slip-ring or cable wrap stack, arcing resistivity, electrical conductivity). Finally, testing of flight hardware may be performed in a thermal vacuum chamber placed in a clean-room class 10000.

Forming–Tribology

Today, optimisation of forming processes is often supported by simulation like FEM. The success of such simulation may even be improved, if the friction coefficient of the actual process and the related material pairing is known.

This device was developed to determine friction factors as input data for simulation of forming processes (bulk processes like forging, extrusion, …).

It enables the measurement of friction between a plastically deforming ring (work piece) and a rigid plate (tool). Temperature at ring and plate can be controlled separately up to +950°C. The facility enables load forces up to 200kN and torques up to 1000Nm. It enables on-line measurement of friction force during unidirectional sliding. The radial deformation of the ring can be monitored by laser. This provides input data for simulation of forming processes.