Photochemical machining (etching), microstamping, and micromachining are all used to make small, precision components. Each process has its own advantages and limitations. Sometimes, combining their capabilities for development and high-volume production can give designers and manufacturers the flexibility to meet performance, time to market, and cost goals.
For example, consider a suspension assembly for positioning a read-write head in a hard-disk drive. The assembly must maintain the height of the head 8 nm above the spinning disk as it seeks or writes data across the approximately 300,000 tracks/in. Deviations could cause catastrophic drive failure and result in the loss of data. Manufacturing the highly precise device requires assembling several small mechanical components as well as integrating an electrical circuit
One company that uses several microtechniques for manufacturing suspensions is Hutchinson Technology Inc. (HTI), Hutchinson, Minn.. According to the company, using different methods can provide design and fabrication options that lower front-end and high-volume production costs.
The job entailed less than four-week lead times on iterations; production- quality performance on first iterations; full product definition, including modeled and empirical results, before design lock; fast time to ramp with lowest total manufacturing costs; and millions of units per week during production.
HTI etched the component prototypes. Photochemical machining and micromachining both provide production-quality tolerances for precisionprototypes at relatively low set-up and tooling costs and with short lead times. But etching lends itself well to running multiple design of experiments (DOEs) on design features. This flexibility lets designers quickly assess different concepts.
Next, the company used low-cost microforming (a type of microstamping) to generate complex 3D features. Lastly, the prototypes underwent metal finishing and final performance adjustments before going to the customer. At this point, the customer had fully functioning prototypes with minimal hard-tool costs.
HTI designers then locked-in final product features and specs while process engineers provided feedback on the high-volume manufacturing techniques. Etching and micromachining have significant front-end cost advantages over microstamping, but microstamping can reduce high production-volume costs.