Fretting Tester
FFT Series

Fretting, Wear, Fretting Loops, 4-Ball
Stroke Control, Voice Coil Control,
Environmental Control

Rtec-Instruments

Fretting with Unmatched Performance

Fretting Tester ConfigurationA

Down Force Control

B

Voice CoilC

High Accuracy Position Control

The fretting test modules cover a wide testing load range. Our technology breakthroughs in voice coilcontrol and high-frequency signal processing algorithms provide fretting wear tests with less than 5 micronstrokes.
The test module comprehensively characterizes fretting wear from micron to macro scale. Ultra-sensitivepiezo-based load cells, with a robust design, high stiffness holders, and low floor noise, provide quantitative
fretting wear characterization of materials, interfaces, thin films, and components.

AETests can be done in controlled environmental conditions to simulate real-life scenarios. Easy to use andintuitive data interpretation make this tester an ideal tool for researchers or quality control engineers.

BF

CD

G

Real-time Stroke Control

We provide the smallest controllable stroke ranging from less than 5 µm to 4 mm,up to 500 Hz. Our stroke control comes with frequency monitoring and correction
using LVDT.

Environmental Control, Surface Electrical Measurement

Replicate real-life simulated environments with variable humidity, temperature,inert gas, and electrical measurements.

Page 2The most accurate and precise displacement
control in the market. Up to 1 nm resolution
and micron level of accuracy. Extremely lownoise. High responsiveness for the dynamic
performance of the system.

Environmental Controller

EUnmatched Waveform

FFriction Measurement and Additional In-line Sensors

GLiquid Containers, Sample Holder

High-Frequency Response Force Sensors

Piezo-based sensors measure friction force with ultra-high accuracy at highfrequency reciprocating tests.

Electromagnetic actuators impart frettingmotion. Dependent on the number of coils andcoil power. The FFT series comes in 3 standard
modules. FFT-M, FFT-1, and FFT-2

D

High Reliability - Flexure Design

With design and manufacturing in-house, Rtec-Instruments provides unequaled
robust platforms with flexural suspension that guide the magnetic assembly
without bearings.

The applied forces can be controlled to gramforce ranges with ease. Real-time correction
account for sample wear and force change. The
force can be constant or dynamically changed
during the test.

The environmental chamber allows for the control and measurement of temperature andhumidity. In addition, a dual high-resolution thermocouple enables independent measurementof the heater temperature and the sample/lubricant temperature.

Without the friction of rolling or bearings, the magnetic flexure-based design provides thecontrol required for the most sensitive tests. The motor controls the smallest of increments ofwaveform and stroke control change.

The tester has advanced piezo sensors to measure high-frequency real-time friction. Ultra-low
noise amplifiers detect minute changes in friction with ease. Acoustic emission sensors detect
the onset of cracks. ECR measures surface resistance change to gain more insight into thematerial interface.

The liquid and sample holder are for standard and non-standard tests. The holders and liquidcontainers are easily customized based on the specific applications needed.
Page 3

Applications

Any Size For Your Needs

Fretting nm to mm• Automotive• Lubricant

FFT-M Bench Top• Aerospace

Includes strokes from 5 µm, high-frequencyoscillation for coatings, lubricants, and materials
across a wide range of testing conditions. Contains
programmable force control (no dead weights).
Combined with piezo sensors to measure realtime friction. The easy-to-use flexure-based
design makes this tester highly reliable andrepeatable.

• Electronics• Power Plants• Coatings• Composite• Polymers• Metals• Components• Biomaterials• Medical

FFT-2
Double the force range with dual high-power coils.
Downforce up to 5000 N. The high-frequency
piezo sensors measure real-time friction. The
magnetic flexure-based design provides sensitive
test control. Customizable liquid and sample
holders make this instrument perfect for standard
and non-standard tests.

Test Data

Page 4

3D Wear Scar Mark4-Ball

Volume Wear

3D Wear Scar MarkHigh Frequency
Data

Fretting Loops

Page 5

Fretting Fundamentals

High Speed Controllers
Software

Fretting

The tester comes with an operation and data analysis package. The test operation is recipe-based
software that allows it to run standard or previously created recipes with a click of a button. Theanalysis package comes with visualization and statistical data analysis. Multiple files can be opened
for easy comparison.

Fretting wear is a test where surface damage occurs
between two contacting surfaces experiencing asmall amplitude oscillatory displacement.

Debris

••••
•••
•
•

Debris formation from asperity contacts
Oxidation at the contacting surface due tohumidity, temperature, or chemicalcomposition change
Oil, lubrication starvation regimes causing wear
Wear due to electric discharge
Repetitive collision between surfaces
Fatigue-related cracks - onset of debris
Polymerization of organic materials at thesurface
Finely powdered debris - highly oxidized
Residual steady stage flow of debris
Diffusive wear
Melting wear

Sample under fretting motion

Wear••StickMixed Stickand Slip

Gross Slip•
••••
•
•

Advanced control algorithms
Intuitive and easy to use software
Fully automatic motions
Compliant with several standards
Fast data reporting
Analyze any kind of sample
Automatic data analysis

Reciprocating
Sliding

Displacement

Regime Schematics

3D profiler wear track image

Fretting Regimes
The tester can work across all fretting regimes: stick, stick-slip regime, and gross slip regimes. Several fretting
parameters control these regimes’ boundaries, including surface finishes and environment.

Slip2500 N, 300 Hz Data

Stick
Stick and Slip

Gross Slip

Reciprocating Sliding

Specification Summary

Fretting Loops
A fretting loop is a hysteresis plot for the coefficient of friction (COF) vs. displacement. As the COF varies
along the direction of motion, the fretting loop given by μ(x,y)=q(x,y)/p(x,y) where q(x,y) is the shear traction
distribution along the interface and p(x,y) is the normal pressure distribution.

Actuators•Displacement 5 µm - 4 mm
•Resolution: 0.1 µm•Oscillation frequency: Up to500 Hz

FxForce
Page 6

FFT-M2 1000 N Down Force
FFT-M1 300 N Down Force

Displacement

Displacement

Displacement

Stick

Stick and Slip

Gross Slip

Environment•Up to -40 °C, 180 °C, 500 °C,1000 °C•Humidity controlled chamberSensors•Potentiostat•Acoustic Emission•Electrical Contact ResistanceCommon standards•ASTM E2789•ISO 19291•ASTM D6425•ASTM D7421•ASTM D5707•ASTM D5706•ASTM D7594•DIN 51834-2•DIN 51834-3•DIN 51834-4
Page 7

Rtec-Instruments IncUSA
1810 Oakland Road, Ste B
San Jose, CA, 95131, USA +1 408 708 9226
info@rtec-instruments.com
Rtec-Instruments Office
Agent / distributor

Rtec-Instruments, CNChina
2nd Floor, Building 3, 69 Olympic St
Jianye District, Nanjing, China, 210019
 +86 25 83210072, +86 18013892749
info@rtec-instruments.cn
Rtec-Instruments, JPJapan
Tokatsu Techno Plaza, Rm 409
5-4-6 Kashiwanoha, Kashiwa-shi, Chiba, Japan, 227-0882
 +81 50 5896 9916
info.jp@rtec-instruments.com

www.rtec-instruments.com

FFT-Series-2023-A-02B-EN

2023 Rtec-Instruments Product Catalogue.
All rights reserved.
All specifications are typical and subject to change without notice.

Rtec-Instruments SAEuropeRue Galilée 6,
1400 Yverdon-les-Bains, Switzerland
 +41 24 552 02 60
info.eu@rtec-instruments.com