Constrained-layer Arm Dampers are used in hard disk drives to tune resonant frequencies of actuator assemblies for optimum performance. The actuator assembly accurately positions the magnetic recording head over spinning disks which retain the data written and read by the head. The positioning requirement of the head, and its sensitivity to resonant frequency modes require that Arm Dampers be applied to the actuator such that specific modes are either shifted, reduced, or eliminated, depending on the need.

Constrained-layer dampers use out-of-plane deflection of the support member (in this case the actuator arm) to deform a visco-elastic material (VEM) held in place by a constraining material (thin layer of stainless steel). The act of stretching the VEM while it is constrained redistributes energy from the system and changes its resonance signature.

The VEM used in Arm Dampers has very specific characteristics which optimize resonance performance, yet are potentially damaging to the hard drives due to their tendency to contaminate the drive with their own adhesive material, and their ability to carry foreign particles into the drive because of their sticky nature. IntriPlex was the first company to develop a high-volume process to manufacture Arm Dampers with nominally recessed VEM. The VEM edge is placed away from the exposed edge of the Arm Damper such that no adhesive is exposed beyond the stainless steel constraining layer. The recessed adhesive feature has proven to be overwhelmingly successful and is in use inside millions of hard drives throughout the world today.

Hard disk drive design engineers have historically had difficulty placing Arm Dampers over through-holes in the actuator due to the adhesive exposed by the hole, making it extremely difficult to tune frequency modes in certain applications. IntriPlex has remedied the situation by developing a process to produce Arm Dampers with adhesive-free zones (AFZ's) which allow Arm Dampers to be placed over open holes without exposing adhesive to the hard drive, opening the door for much more design flexibility.

Material burrs have always been an issue inside hard disk drives because of the inherent possibility of them breaking loose and destroying data. Because of this, de-burring methods are used on nearly every component within the hard drive, whether it be mechanical (tumbled), chemical, electro-chemical, or by other means. The stainless steel constraining layer used in Arm Dampers is too thin (0.0020 inches or less) to de-burr by conventional methods and required IntriPlex to come up with a unique solution. IntriPlex developed a stamping process which results in near burr-free manufacture which actually produces a smooth roll on both surfaces of the constraining layer, eliminating the need for a de-burring process.

IntriPlex continues to innovate, producing products with features that allow your engineers more design flexibility to achieve their performance goals. How can we help you?