Q NET Engineering GmbH
3MA
Electromagnetic Microstructure Tester
Situation
The near-surface residual stress state and the case depth are the most important quality characteristics of case-hardened components. Residual tensile stress in the surface layer caused by faulty heat treatment often leads to failures of these highly stressed parts. Quality control which determines the residual stress of heat-treated parts is partly destructive or in the case of X-ray testing limited to the determination of surface layer residual stress.
- Figure 1: 3MA II - Microstructure tester
Solution
The 3MA tester enables process-integrated, non-destructive testing at a considerably high testing speed. The relevant quality parameters can be determined and stored very fast. You obtain information about different parameters of the microstructure and stress conditions at the same time. The 3MA method is mainly used for testing heat-treated parts and treated surfaces.
The overall aim is the non-destructive testing of the following parameters:
- Hardness
- Residual stress
- Case depth
- Stress defects
Advantages
- Fast and non-destructive testing
- Continuous testing and documentation of quality parameters
- Replaces destructive testing
- More economical production due to less downtime
- Complete production control by integrating the 3MA system into all production processes
- Modular design can be adjusted to customers' needs
3MA Testing System
The 3MA device comprises of a computer plus monitor, a control and evaluation unit, a power unit for the magnetisation and an analogue interface for different modules for the determination of different micromagnetic parameters such as:
Barkhausen Noise (BN)
Recording of Barkhausen noise amplitudes versus magnetic field strength (H).
Measurement parameters:
- Mmax: maximum BN
- Hcm: coercivity of BN
- ΔHm: width of M(H) at different M values
Incremental Permeability
Measuring incremental permeability versus tangential magnetic field strength.
Measurement parameters:
- µmax : amplitude of µΔ
- Hcµ: coercivity µΔ
- Hµ width of µΔ
Time Signal of Magnetic Field Strength (Ht (t))
Recording time signal of tangential magnetic field strength.
Measurement parameters:
- HD: harmonic distortion factor
- Hco: coercivity
Multi-Frequency Eddy Current
Measurement parameters:
- Coil impedance
- Determination of the real and the imaginary part of the impedance at 3 frequencies
Example 1
The following example shows the comparison between reference data and the results of non-destructive yield stress testing of tin sheet metal.
- Figure 2: Comparison of reference- and test data
Example 2
The following example shows yield stress measurement at moving strip
- Figure 3: yield stress measurement
Sensor System
The sensor is an electromagnetic transmitter/receiver. The multi-parameter sensor records several micro-magnetic parameters simultaneously. The probe can be adjusted to the customers' individual needs.
- Figure 4: 3MA sensor
Data Collection and Documentation
The use of databases throughout the whole process enables your company to access and organise the planning and testing of data via a connected company network.
Technical Data
Non-destructive testing and data collection of:
- Hardness
- Case depth
- Residual stress
- Stress defects
Build-up of the 3MA Testing Device
- Computer with integrated monitor (Windows)
- Magnetizing yoke
- Output power: 300 W harmonic distortion factor: less than 0.1%
- Bandwidth: 5Hz-120kHz
- Amplification 26dB
- Electromagnetic transmitter/receiver, tailored to the client's needs
- Function generator with sine wave outlet: (frequency range: 1-250 Hz) interface for analogue unit
- Front-end unit
- AD converter
- Signal processing of the tangential field strength, eddy current, Barkhausen noise, harmonic analysis, incremental permeability
- Software
- Signal processing and display on Windows
- Multiple regression analysis for determining the quality parameters
Contact
Yvan LejeunePhone: +49 (0) 6 81/9 76 71 53
Fax: +49 (0) 6 81/9 76 71 58