Tweeter Production Issues

A client needed help with immediate production concerns related to manufacturing yields and reliability of their proprietary tweeter, which had been manufactured worry free for years. Our job was to diagnose and remedy the tweeter manufacturing and reliability issues ASAP as it was affecting sales and the brand’s reputation.

Motor gap varies 0.007" from 0.029" to 0.036"; typically the gap should vary

Motor gap varies 0.007″ (0.18mm) from 0.029″ to 0.036″; typically the gap should vary <0.001″ (0.025mm)

Our analysis of the tweeter samples showed the concentricity of the motor yoke to the front plate was out of spec. Mere fractions of millimeters of error are critical especially with tweeters as it led to manufacturing rejects due to coil rub and buzz.

We also found too much ferrofluid in the gap that splashed onto moving parts during operation. As well as wasting an expensive commodity, the excess fluid degraded performance. The ferrofluid chosen was incompatible with the adhesives used in the tweeter which caused glue joint failure. We identified the correct amount and type of  compatible ferrofluid; and then verified these recommendations with prototypes. Lastly we taught the customer a cost effective way to meter the amount of ferrofluid for consistent production.

The customer was able to implement stringent process controls to ensure concentricity and correct amount of ferrofluid. This improved production yields and reduced field returns.

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