Final inspection in hypodermic needle manufacturing
Each needle is imaged as a silhouette against a backlight; cannula straightness and bevel angle are measured in the image and the tip is checked for burrs. A needle outside tolerance is blown into the reject bin at the next position.
Tip deflection and bevel angle of every needle are written to the lot record; a needle outside tolerance is blown into the reject bin by the air jets at the next drum position, and the counters go to the machine controller.
- 01 Index
- 02 Acquire
- 03 Axis
- 04 Tip check
- 05 Decide
The drum indexes one step; the nest sensor detects the needle and brings it into the gauging position.
- Tip deflection
- —
- Bevel angle
- —
Scenes are illustrative simulations; they are not customer references or performance guarantees.
Need
The cannula is under a millimetre across and its shiny stainless surface gives no usable edge under direct light; a tenth of a millimetre of tip deflection or a few degrees of bevel angle only show in a sharp silhouette. As the needle can shift in the drum, the measurement is referenced to the hub.
Solution approach
The indexing drum brings the needle in front of the backlight once the nest sensor confirms it is present; a long focal-length camera captures a sharp silhouette with the strobe. The cannula centre line is extracted and tip deflection is computed against the hub axis; at the tip the angle between the lower edge and the cut face is measured and the edge profile is checked for burrs.
Process steps
- 01
Index
The drum indexes one step; the nest sensor detects the needle and brings it into the gauging position.
- 02
Acquire
The backlight strobes and the needle silhouette is captured.
- 03
Axis
The cannula centre line is extracted and the tip deflection from the nominal axis is measured.
- 04
Tip check
The bevel angle is measured and the tip is checked for burrs.
- 05
Decide
The measurements are compared with the tolerance limits.
Related applications
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