Substantial changes have taken place since the invention of the material. In the 1980's, as
the technology was emerging from the laboratory, drivers of 6-8mm diameter were all that
could be produced in any quantity. The process used to manufacture the materials is
called Free-Stand-Zone-Melting (FSZM), which is a seeded, container-less method for
generating nearly perfect crystals. While the performance of the material was
exceptional, the process was very labor intensive and had a very low mass-yield
(meaning that only 20-30% of the starting mass ended up in the finished rod - the rest of
the material was lost during the process and in machining. Only one rod could be made at a
time, so production lead times for any quantity of material were on the order of months.
The picture on the right shows Mr. Dale McMasters, the inventor of the processes for
Terfenol-D and the FSZM machine.
The first pilot line to manufacture larger diameter drivers of Terfenol-D was established
in 1989. The Bottom-Pour (BP), pictured at left, was capable of producing drivers from
15-50mm in diameter. While the strain performance was much lower than FSZM (25-30%),
BP material was much more cost effective and efficient in its use of materials,
especially for applications requiring a large diameter driver. Designs based on bundles of
FSZM material were and order of magnitude more expensive than a comparable rod from the BP.
To increase the performance of BP materials, a second crystal growth step could be
performed on the cast materials to improve the crystalline alignment of the drivers.
This step was called the Bridgman process (BRDG), and generated very good performance in
the 15-20mm diameter drivers (within 20% of that of FSZM material) but was limited to
diameters below 30mm due to equipment limitations.
Substantial changes have taken place since the invention of the material. In the 1980's, as
the technology was emerging from the laboratory, drivers of 6-8mm diameter were all that
could be produced in any quantity. The process used to manufacture the materials is
called Free-Stand-Zone-Melting (FSZM), which is a seeded, container-less method for
generating nearly perfect crystals. While the performance of the material was
exceptional, the process was very labor intensive and had a very low mass-yield
(meaning that only 20-30% of the starting mass ended up in the finished rod - the rest of
the material was lost during the process and in machining. Only one rod could be made at a
time, so production lead times for any quantity of material were on the order of months.
The picture on the right shows Mr. Dale McMasters, the inventor of the processes for
Terfenol-D and the FSZM machine.
The first pilot line to manufacture larger diameter drivers of Terfenol-D was established
in 1989. The Bottom-Pour (BP), pictured at left, was capable of producing drivers from
15-50mm in diameter. While the strain performance was much lower than FSZM (25-30%),
BP material was much more cost effective and efficient in its use of materials,
especially for applications requiring a large diameter driver. Designs based on bundles of
FSZM material were and order of magnitude more expensive than a comparable rod from the BP.
To increase the performance of BP materials, a second crystal growth step could be
performed on the cast materials to improve the crystalline alignment of the drivers.
This step was called the Bridgman process (BRDG), and generated very good performance in
the 15-20mm diameter drivers (within 20% of that of FSZM material) but was limited to
diameters below 30mm due to equipment limitations.