Multi-feature neck and thread geometry measured in under 12 seconds per preform. 24 SKUs in one system. GD&T audit compliance achieved. Rejects reduced from 3.2% to 0.4%.
A major PET preform and bottle manufacturer in Maharashtra — supplying to FMCG, food & beverage, and agrochemical brands across India — produces over 2 million preforms per day across 24 active SKUs. Each SKU has specific neck finish geometry: thread pitch, thread height, neck OD, neck finish height, and support ledge diameter — all with tolerances of ±0.05 to ±0.15 mm driven by customer cap-fit specifications. Manual inspection with ring gauges and vernier calipers was taking 8–12 minutes per 10-piece sample per SKU — a total of 3–4 hours per shift just for dimensional sampling. With 24 SKUs running across 3 shifts, changeover verification (confirming correct mould dimensions after SKU change) was a major bottleneck — often 45 minutes or more. Customer rejections due to cap-fitting issues were running at 3.2% of outgoing shipments — generating costly field returns and credit notes.
Optomech installed the Opto QMM Series with a custom rotary stage, enabling automatic measurement of the complete neck finish geometry in a single 12-second inspection cycle. The rotary stage presents the preform to the telecentric camera at 8 angular positions, automatically measuring 14 features per preform: thread pitch, thread height, 3× OD readings (with ovality), neck finish height, support ledge diameter, gate height, and thread root radius. All 24 SKU programs were pre-loaded at the factory and delivered ready to use. Changeover between SKUs takes under 30 seconds — the operator selects the SKU program, loads the preform, and runs. Measurement data feeds to a live SPC dashboard and exports to Excel for batch reporting. Customer-specific inspection reports are auto-generated at batch close.
| Metric | Result |
|---|---|
| SKU changeover verification time | 45+ min → under 7 min (85% reduction) |
| Inspection time per preform | 8–12 min manual → 12 seconds QMM (98% reduction) |
| Features measured per preform | 14 dimensional features in one automated pass |
| Customer rejection rate | Reduced from 3.2% to 0.4% in first 3 months |
| SKUs managed | 24 active SKU programs — switchover in under 30 seconds |
| Measurement accuracy | ±5 µm — confirmed against NABL-calibrated ring gauge masters |
| SPC trending | Live CPK for all 14 features — alerts operator when trending towards limit |
| Customer audit records | Auto-generated batch report per SKU — accepted by FMCG customers |
"We were losing business because of cap-fit rejections. Customers were sending back entire shipments. The QMM with the rotary stage completely changed our outgoing quality. The 12-second cycle time means we sample 10× more parts than we could before — and changeover verification that used to take 45 minutes now takes 7. We have not had a single cap-fit rejection since installation."
Contact our packaging metrology specialists to discuss how the Opto QMM with rotary stage can solve your SKU changeover and quality compliance challenges.
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