Tribotesting Equipment

The tribomaterials group has a wide range of tribotesting machines at their disposal, covering many contact situations and mimicking the conditions of numerous applications. Some are tailored to suit specific applications, and some are intentionally given a more generic design.  Most machines have been designed and built within the group, and appropriate test procedures have been developed.

Several of the rigs are unique:

  • In-situ sliding / scratching in SEM
  • Two more rigs for testing in vacuum environment, one with high temperature possibilities
  • Load scanner
  • ”Performance scanner”, designed for efficient evaluation of gradient materials
  • Rig for realistic testing of combustion engine valves
  • Miniature rig for detailed studies of the tool/wood interaction in mechanical pulping
  • Small scale sliding contact rig for sliding on snow or ice

Overview of rigs:

Pin-on-disc rig – Pinne-skiva maskinen

Contact situation Sliding contact, ball on flat or pin on flat
Varied parameters  Load, speed, lubrication, temperature, atmosphere
Studied parameters Friction, wear and surface damage
Typical specimen size 5 mm pin or ball against 50 mm disc
Notes Wide range of disc shapes and sizes allowed. Heating stage (max 500°C) may be mounted.

Sliding contact rig – Stor-Svarven

Contact situation Sliding contact, crossed cylinders, pin on cylinder
Circular track around the cylinder or – more often – a helical track, which allows continuous feed of fresh countersurface to the stationary contact. This is more relevant for tool like situations, where the tool continuously meets new work material.
Varied parameters  Load, speed, "counter material", continuous or intermittent contact (pneumatic actuator). Often used for testing tool materials for metal cutting or rock drilling.
Studied parameters Friction, wear and surface damage
Typical specimen size Stationary pin: ø 5 mm, l 20 mm
Rotating cylinder: ø 150 mm, 500 mm
Notes Many configurations available, wide load and speed spans, stationary/intermittent contact, etc. Rig designed by modification of large turning lathe.

Sliding contact rig – Lill-Svarven

Contact situation Sliding contact, crossed cylinder, flat on cylinder, etc. load constant or automatically increasing up to seizure limit.
Varied parameters  Load, speed, lubrication
Studied parameters Friction, wear, seizure, and surface damage
Typical specimen size Stationary pin:14 mm thick, 7 mm*20 mm area
Rotating cylinder: 40 mm diameter, 500 mm length
Notes Rig designed by modification of small turning lathe. Continuous load increasing mode ideal for finding critical load/ seizure limit in continuous sliding. Adaptable also for lubricated cam/follower type contact.

Sliding on ice and snow rig – Lill Vasan

Contact situation Sliding contact between e.g miniature ski and snow or ice.
Varied parameters  Load, speed (up to 3.5 m/s), temperature (down to -14°C)
Studied parameters Friction
Typical specimen size Ski: 20 mm* 40 mm glide area
Snow or ice covered disc ø 500 mm
Notes Essentially a pin-on-disc rig placed in a top-opening refrigerator. Ice sheet easily formed by freezing directly on the disc. Snow formed by spraying water with an air brush.

Reciprocating sliding contact rig – Elvis

Contact situation Reciprocating sliding contact, ball on flat, cylinder on flat
Varied parameters  Load, stroke, frequency, temperature (lower flat specimen heated). System for intermittent spray lubrication.
Studied parameters Friction, wear and surface damage
Typical specimen size Flat: 15 x 15 x 100 mm
Stationary cylinder: ø 10 mm, l 10 mm
Notes Rig designed primarily to mimic the cylinder liner/piston ring contact.
The rig has a double crank mechanism, and two holder arms for the stationary cylindrical specimens, allowing two simultaneous tests.

Reciprocating sliding contact rig – Rock Olga

Contact situation Reciprocating sliding contact, ball on flat (cylinder on flat)
Varied parameters  Load, stroke, frequency, temperature (lower flat specimen heated)
Studied parameters Friction, wear and surface damage
Typical specimen size Flat: 15 x 5 x 40 mm
Stationary ball: ø 10 mm
Notes Basically a smaller, single sided version of Elvis, with shorter maximum stroke and lower maximum load.

Tribological load scanner – Saxriggen

Contact situation Sliding contact (single stroke or reciprocating)
Varied parameters  Load range, speed, lubricant, number of strokes (from 1/2 to several 100 000)
Studied parameters Friction (unique possibility to map µ vs load and no. of strokes withi one single test), wear, galling, and surface damage
Typical specimen size 100 mm ø 10 mm, cylindrical bars
Notes Wide load interval (e.g. 50–2400 N) covered by single test. Unique by resulting in that each point along the contact pass has only met one single point on the counterbody, and only experience one specific load, also in a test with numerous cycles. The resulting surface damage can thus be coupled to specific load and a specific position on the counterbody. The specimens can be preheated for short tests at elevated temperatures.

Fretting and reciprocating rig – Skak-Nisse

Contact situation Fretting or reciprocating sliding
Varied parameters  Load, stroke, frequency, speed, lubrication, current load, atmosphere (including flowing gas corrosion test)
Studied parameters Friction, seizure, contact resistance, contact area growth, surface damage and wear
Typical specimen size ø 10 mm, l 20 mm cylinders, alternatively ball on flat
Notes Initially developed for testing electrical contacts, but very versatile. Several optional specimen shapes and sizes.

Rolling contact rigs – Rullrika och Rolle

Contact situation Rolling (or rolling/sliding) contact
Varied parameters  Load, speed, dry/drip lubricated, (degree of sliding)
Studied parameters Wear, surface damage and subsurface fatigue
Typical specimen size Max ø 10 mm, 50–100 mm long cylindrical bar
Notes Two very similar rigs. The central specimen is changed or repositioned each test, while the counter surface discs are reground after a number of tests.

Particle erosion rig – Erofugen

Contact situation Particle erosion, particles accelerated during passage through channels in the spinning disc.
Varied parameters  Particle size, type, speed and impact angle
Studied parameters Erosion rate and damage mechanism
Typical specimen size 10 x10 mm, 20 x 20 mm, thickness 3-10 mm
Notes Up to 18 specimens can be tested simultaneously.

Micro abrasive wear test – Kraterslipen

Contact situation Abrasion (grinding) of small spherical crater on flat surface. Diamond particles slurry.
Varied parameters  Specified set of load, speed and abrasive particles
Studied parameters Volume loss (and surface damage mechanism)
Typical specimen size 15 x 15 x 3 mm, ø 20 mm grinding wheel
Notes Primarily a well specified test for the quality of thin hard coatings. Unique by being capable of giving a measure of the coating without influence from coating thickness or substrate material.

In-situ scratcher – In-situ reparen

Contact situation Scratching by abrasive tips (e.g. spherical diamond) or soft tips (e.g. aluminium) in the SEM
Varied parameters  Load (≈ 0.1–3 N), tip shape
Studied parameters Deformation and chip formation mechanisms in abrasion and grinding, failure mechanism of thin coatings. With soft metal tips on harder flats, primarily surface damage, material transfer, friction.
Typical specimen size 15 x 10 x 4 mm
Notes Direct high resolution observation in the SEM.

Flat-on-flat rig – Stora blå

Contact situation Reciprocating sliding, self-adjusting flat-on-flat
Varied parameters  Load (2– 20 kN, corresponding to nominal pressures 22– 220 MPa). Speed (up to 4 mm/s). Temperature. Presence of water or lubricant.
Studied parameters Friction, deformation, galling and wear
Typical specimen size Upper: 20 x 4,6 x 4,6 mm (all +0, -0.1) mm
Lower: 75 (±0.1) x 15 (±0.1) x 15 (+0, -0.1) mm

Slip-ring rig – Släpringsriggen

Contact situation Sliding, wire against cylinder
Varied parameters  Mechanical load, electrical load, speed
Studied parameters Contact resistance, electrical noise, wear
Typical specimen size Cylinder: ø 100 mm. Wire: ø 0.5 mm, l 50 mm, up to 5 wires simultaneously in separate tracks
Notes Initially developed to investigate a very specific contact situation. The stationary wires are individually pressed against the rotating cylinder.

Engine valve rig

Contact situation Engine valve against valve seat insert, opening and closing motion resulting in impact and microscopic sliding.
Varied parameters  Mechanical load, frequency, temperature, number of cycles, feed of heated air with ppm levels of vaporised motor oil
Studied parameters Wear, formation and break down of protective tribofilm
Typical specimen size Valve head: ø 40 mm, stem length: 170 mm

Scratch tester

Contact situation Hard stylus scratching over a flat surface, typically a conical diamond stylus with rounded tip (the Rockwell shape), r = 200 µm
Varied parameters  The normal load is linearly ramped along the scratch, e. g. from 0-100 N
Studied parameters Scratch deformation, fracture, adhesion of coatings
Typical specimen size 20 x20 x 5 mm
Notes Mostly used to study scratch resistance and adhesive behaviour of hard ceramic coatings on metallic substrates, but useful for many types of studies.