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OVERMOLDING OF HIGH MODULUS ACTUATOR COMB BY PLASTIC INJECTION MOLDING

IP.com Disclosure Number: IPCOM000014778D
Original Publication Date: 1999-Dec-01
Included in the Prior Art Database: 2003-Jun-20
Document File: 1 page(s) / 27K

Publishing Venue

IBM

Related People

T LINCOLN: AUTHOR [+3]

Abstract

Published is a disk drive actuator comb design that has a low in rotational moment of inertia and high stiffness. The comb is made by injection molding a polymer body around a coil and arms. Multiple arms used in the design can be individual, or instead a machined assembly (sometimes known from its shape as a C-block or E-block). Materials suitable for the arms have high moduli and low densities, such as: beryllium-aluminum alloys, ceramic reinforced metal matrix composites or ceramics. Possible ceramic reinforcements are: silicon carbide, silicon nitrate, boron carbide, and alumina which have four to six times greater specific stiffness than aluminum. Carbon fiber reinforced polymer can be: thermoplastics, liquid crystal polymers (LCP) or thermoset plastics. This design increases servo bandwidth by moving the structural resonances to higher frequencies and increasing the damping of those modes. Use of low density polymer and arm materials results in decreased seek times because of the combs lower rotational moment of inertia. State-of-the-art materials utilized for overmolded comb arms or E-blocks are magnesium. stainless steel or aluminum. Using this design, materials and process a low cost one-piece comb can be manufactured cost effectively. 1

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  OVERMOLDING OF HIGH MODULUS ACTUATOR COMB BY PLASTIC INJECTION MOLDING

     Published is a disk drive actuator comb design that has a low in
rotational moment of inertia and high stiffness. The comb is made by
injection molding a polymer body around a coil and arms. Multiple arms used
in the design can be individual, or instead a machined assembly (sometimes
known from its shape as a C-block or E-block). Materials suitable for the
arms have high moduli and low densities, such as: beryllium-aluminum alloys,
ceramic reinforced metal matrix composites or ceramics. Possible ceramic
reinforcements are: silicon carbide, silicon nitrate, boron carbide, and
alumina which have four to six times greater specific stiffness than aluminum.
Carbon fiber reinforced polymer can be: thermoplastics, liquid crystal
polymers (LCP) or thermoset plastics.

     This design increases servo bandwidth by moving the structural
resonances to higher frequencies and increasing the damping of those modes.
Use of low density polymer and arm materials results in decreased seek times
because of the combs lower rotational moment of inertia.

     State-of-the-art materials utilized for overmolded comb arms or E-blocks
are magnesium. stainless steel or aluminum. Using this design, materials and
process a low cost one-piece comb can be manufactured cost effectively.

1