Tribology

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.