Market for Spindle Motors
for 2.5-Inch or Smaller HDDs |
We will strategically cultivate demand for spindle motors for 2.5-inch or smaller HDDs by entering markets that offer high potential in terms of profitability and growth. We will also take advantage of rising demand for 2.5-inch or smaller HDDs for use in notebook PCs and cellular phones and other handheld information terminals.
|
 |
| HMF-Type FDB Unit (Patents Pending) |
While 2.5-inch or smaller HDDs currently account for only approximately 20% of the global HDD market, demand for use in such applications as notebook PCs, digital music players, digital cameras, cellular phones and car navigation systems is rising rapidly. The HMF-type FDB unit, developed in collaboration with Hitachi Powdered Metals, has positioned us to enter the market for FDB spindle motors for 2.5-inch or smaller HDDs. Delivering outstanding performance and cost-competitiveness, this unit uses sintered metal for the bearing and a multiple-lobed shape for the inner surface of the bearing to generate hydrodynamic force in the radial direction, which makes it highly appropriate for use in compact and thin motors. Proprietary precision sizing technologies facilitate the simultaneous forming of radial and thrust bearings, significantly reducing production costs.
| Structure of HMF-Type FDB Unit |
|
|
 |
• Herringbone-Groove FDB (Conventional FDB)
FDBs with herringbone grooves on the inner surface of the sleeve are commonly used in spindle motors for HDDs. A thin layer of oil is injected between the shaft and sleeve. The rotating shaft causes the oil to collect in the herringbone grooves, triggering a pumping action that generates hydrodynamic force that ensures the rotational accuracy of the shaft is maintained.
• Multiple-Lobed FDB (HMF-Type FDB)
FDBs featuring an inner surface with three lobes have been used to date in such applications as motors for laser scanners and spindle motors for CD-ROM drives. The HMF-type FDB was developed specially for use in spindle motors for HDDs by introducing a number of key technical improvements. Key among these is the use of five lobes instead of three. The wedge action of the oil in the bearing clearance generates hydrodynamic force that ensures the rotational accuracy of the shaft is maintained.
Bearing stiffness and bearing loss are shown as percentages. As these graphs indicate, while bearing stiffness varies little between FDBs with multiple-lobed inner surfaces and those with herringbone-groove inner surfaces at all temperatures, bearing loss is close to 20% less for FDBs with multiple-lobed inner surfaces.
|
|
