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The Situation
Correct heat treatment and machining processes are fundamental for the functional behavior and fatigue strength of
stress-imposed components. Until now, the only methods in
common practical use to evaluate surface areas of parts and
components are conventional techniques such as metallurgy, X-ray diffraction, and conventional hardness
testing techniques. However, these techniques cannot easily be integrated into
production processes, as their testing speed is too slow and as some of
these techniques are also destructive. Nevertheless, the
results obtained from these techniques can be used for a statistical process control.
Our Solution
Nondestructive testing techniques, which can be integrated into production processes are
available now. A complete inspection with acceptable testing
speeds can be achieved. Fast evaluation and recording of relevant quality parameters can be
accomplished by combining complementary information obtained
through various microstructure and stress sensitive measuring
parameters simultaneously. Approximation functions to determine the quality
characteristics can be obtained using multiple regression
analysis. The main application areas are the
nondestructive inspection of case-hardened components and
machined surfaces.
The objective
is the nondestructive determination of the following material
characteristics:
Our System
The 3MA-II system (Multi-Parameter Micro-Magnetic Microstructure and Stress
Analyzer) is the adequate instrument for these applications . The
3MA-II system consists of a PC with monitor,
control and evaluation unit, power supply for magnetization, and an
analog part with different potential modules to measure various micro-magnetic
parameters such as:
-
Barkhausen
Noise (BN)
Recording of Barkhausen Noise amplitude vs. magnetic
field strength (H)
Measuring parameters:
- Mmax, maximum of BN
- Hcm, coercivity of BN
- D
Hm,
width of M(H) envelope at distinct M values.
-
Incremental
Permeability (Dm)
Recording of Incremental
Permeability vs. Tangential (magnetic) Field Strength.
Measuring parameters:
- Dmmax, amplitude of
Dm
-
Hcm,
coercivity of Dm
- D Hm,
width of
Dm
-
Tangential (magnetic) Field Strength (Ht(t))
Recording the time signal of tangential magnetic field strength
Measuring parameters:
- K, distortion factor*
- Hco, coercivity*
(* both values are obtained through harmonics analysis of Ht(t))
-
Eddy Current
Impedance
Sensor
System
The sensor is an electromagnetic transmitter/receiver
system. The multi-parameter sensor records different micro-magnetic parameters simultaneously. The sensors can be
designed and built according to the individual requirements of the
customer.
Data Evaluation and
Documentation
When the system is working in a production process, the unit can
be custom-tailored according to the customer's requirements.
The unit can be connected to other commercially available computers for advanced
signal processing and evaluation in scientific applications.
Advantages
-
Fast nondestructive
testing
-
Continuous
inspection and documentation of quality parameters
-
Replacement of
destructive testing
-
Economical
production through reduced rejections
-
Complete process
control through integration of the 3MA-II system into production
processes
-
Modular design
allows for customized configurations and individual adaptation
of the user interface software
-
Standard data
interfaces available
Applications
Nondestructive testing and evaluation of:
-
Surface and subsurface hardness
-
Case depth of case-hardened
parts (induction, flame, laser-hardening,
etc.)
-
Hardness and residual stresses (simultaneously)
-
High-resolution
residual stresses and microstructures (e.g. welded components)
-
Machining processes
(e.g. grinding, turning, etc.)
The 3MA-II test
system consists of the following components:
Magnetizing yoke and transmitter/receiver unit; custom-design to
accommodate individual requirements available upon request
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