Customer was launching a new printer for printing labels for marking wires and fiber optics cables. The feed mechanism of the printer consisted of a clutch composed of an o-ring, a sintered cylindrical busing and a shaft. The o-ring is placed over the shaft on a grove and the shaft/o-ring assembly is inserted into the sintered cylinder. As the shaft turns, the o-ring turns; and because of the friction created by the o-ring against the cylinder wall, it turns the cylinder which advances the label.
If the o-ring is above or below tolerances, the friction of the clutch will be too high -- where it rips the label; or if it is too low -- it will not advance the label at all. Customer was using off-the-shelf standard o-rings and was having problems with tolerances from lot-to-lot and from part-to-part.
We were able to help the customer because we were able to hold tighter tolerances than most other molders. In addition, we were able to work with them to re-design the o-ring to make it more reliable and consistent. We moved the parting line of the part off the center of the part, allowing us to hold the OD of the part at a tighter tolerance, and making the de-flashing operation less critical.