|
A New Instrument for Measuring the
Magnetic Parameters of Cemented Carbides
The 5800 Hard Metal Magnetometer (HMM) from Walker Scientific is a new instrument designed to measure both the magnetic saturation and coercivity of cemented carbides. This instrument uses a new technique employing inductive sensors and high magnetic fields, which provides highly repeatable and accurate magnetic saturation (Ms) and coercivity (Hc) measurements. The 5800 features automatic entry of sample mass, and simultaneous measurement of both coercive force and magnetic saturation. Measurement results are displayed on a CRT screen in spreadsheet format in less than one minute. A personal computer running Windows XP integrated with a digital mass balance acquires, displays and logs the data.
The 5800 clearly offers significant advantages over competitive measurement techniques and equipment.
System Components
The 5800 Hard Magnetometer consists of the following components:
- Digital balance to measure sample mass
- PC with Windows XP Professional
- System control console
- Electromagnet
- Inductive sensor assembly with sample holder
Measurement Process
- The sample is weighed on a digital mass balance.
- The sample mass is entered directly into the PC with the click of a mouse. No thumbwheels or push buttons are
required to enter the mass.
- The sample is placed in the measurement chamber and inserted into the inductive sensor assembly in the system
electromagnet.
- An electromagnet sweeps the field to measure the sample.
- Magnetic saturation and coercivity of the sample are acquired and displayed on the PC Monitor.
Total test time is less than one minute from the time the sample is inserted into the inductive sensor assembly.
Since the mass of a sample can be obtained during the measurement of another sample, a series of samples can be measured at a rate of about one sample per minute.
Specialized Customer Applications
Walker LDJ Scientifics’
Test Development Language (TDL) software is especially designed for easy modification to specific customer applications and programs. For example, bar code readers to facilitate faster transfer of data can be integrated into
the 5800. Additionally, data logging can be customized to analyze specific quality issues such as individual furnace performance. The instrument adapts to the needs of all quality assurance programs.
Advantages over Other Measurement Techniques & Equipment
- High magnetic field for complete magnetic saturation
- Inductive sensors producing very high accuracy and repeatable magnetic saturation measurements
- Measures both coercivity and magnetic saturation at the same time
- Measurements are not affected by changing magnetic environment i.e. metal file cabinet door opening and closing
- Combining magnetic saturation and coercivity measurement reduces test time.
- Data logs Grade, Batch #, Furnace, Volume, Weight, Hc and Ms identifying each measured parameter as “pass” or
“fail”
- Is lower in cost and requires less space than competitive systems.
Features
- Fast measurement time. Most tests require less than 1 minute
- Measures both magnetic saturation and coercivity at the same time
- Performs QC pass/fail on every measurement
- Displays Grade, Batch #, Furnace, Volume, Weight, Hc and Ms of last 20 measurements.
- Measurement operation and weighing initiated by a single keystroke
- Controlled by PC with Windows XP Professional
- Fully network capable
- Three levels of security Engineering, Setup and Operator
- Measurement is highly accurate and repeatable
- Produces 11,000 oersteds magnetizing field
- Traceable to NIST for ISO quality programs
The Advantage of High Fields
The 5800 Hard Metal Magnetometer uses magnetic fields with a strength of 11,000 Oersteds (equivalent in A/m) or greater. This magnetically saturates the
carbide sample in any orientation during the measurement process. Previously available equipment to measure cemented carbides used fields under 10,000 Oersteds. These lower fields do not guarantee that the sample is
magnetically saturated in all orientations, and lead to sample geometry and orientation effects on both magnetic saturation and coercivity measurements. This can negatively affect the accuracy and repeatability of the
measurements by as much as 3 to 5%. The higher magnetic fields of the 5800 permit much more precise and repeatable magnetic measurements.
The Advantage of Inductive Sensors
Inductive sensors have a number of advantages over fluxgate sensors
commonly used in some commercial coercimeters. Fluxgate sensors can be prone to drift, and can be influenced by metal objects moving around the instrument (such as belt buckles!). Inductive sensors have far greater stability
over a wide range of conditions, and permit measurement of larger samples.
Traceable to National Standards Laboratories
The Hard Metal Magnetometer is calibrated using standards traceable to the National Institute of Standards and Technology
(NIST). Walker LDJ provides the only instrumentation to magnetically measure carbide samples traceable to a National Standards Laboratory. This is often essential for ISO and QS quality programs and certification.
Specifications
|
