Problem 

A medical-device subcontractor in Vietnam producing hearing‑aid inductors relied on manual assembly for mounting delicate diaphragms and plastic housings. Manual dispensing of epoxy and hand placement led to inconsistent adhesive dots, glue overflow, scattered splatter, and variable acoustic performance. High labor costs, slow operating times, and quality rework impeded scale-up for growing demand in medical-grade devices.

Cause 

Primary causes were operator variability in dot placement and volume, limited control of micro-dispense when using piezo valves by hand, and poor synchronization between adhesive dosing and component placement. Open workstations increased contamination risk (particles) that degrades acoustic parts. Lack of inline inspection and process traceability prevented rapid root-cause analysis and continuous improvement.

Solution — AC100 Fully Automatic Mount & Dispense Machine

Mingseal deployed the AC100 inline mounting and precision dispensing machine configured for the customer’s diaphragm-and-housing process.

Key system choices and process parameters:

• Dispensing hardware: piezoelectric jet valve for low-volume, high-repeatability epoxy dispensing; programmed for 8–12 dots per part with 0.27 mm target dot diameter. System supports both dot and short-line modes to meet design variants.
• Mounting integration: linear-motor mounting head with DD motor compensation for sub-millimeter placement accuracy of diaphragms onto inductors and housings onto assembled units.
• Motion & orientation: vision module with auto-focus verifies part orientation; camera-guided pick-and-place corrects XY/Tilt deviation before dispense and mounting.
• Clean handling and traceability: enclosed transfer conveyor with track lifting reduces particle ingress; MES-compatible communication logs recipes, dispense mass, and AOI results for each part.
• Inspection & correction: inline glue-shape AOI inspects dot count, dot diameter (± tolerance), and spread immediately after dispense; feedback adjusts jet parameters or reroutes parts for rework.
• Tilt & multi-angle dispensing: tilting module enables angled shot positions for edge dots and internal cavity fills without nozzle collisions.

Implementation and Process 

Flow Workflow: auto load → vision alignment → dispense (8–12 dots, 0.27 mm) → AOI glue inspection → pick-and-place diaphragm → placement quality detection → optional pre-cure → unload. Recipes were established per SKUs: dot count, spacing, jet pulse energy, and line-mode parameters. Pre-curing module reduced handling time before full cure in the downstream oven.

Results

Yield and quality: first-pass yield improved by >85% due to consistent dot geometry and precise diaphragm placement; overflow and scatter incidents decreased by over 90%.
Glue-volume control: piezo jetting eliminated over-apply and smearing; target dot diameter 0.27 mm held with tight repeatability across multi-shift runs.
Throughput and labor: automation reduced cycle time per part and cut manual labor hours by more than 60%, enabling scale-up with existing headcount.
Contamination and reliability: enclosed handling and vision-guided placement reduced particulate-induced failures, improving acoustic consistency and device reliability in downstream tests.
Traceability and process improvement: MES logging and AOI data enabled quick root-cause analysis and drove continuous parameter tuning across material lots.

Best Practices and Recommendations

• Validate epoxy rheology and jet pulse settings during FAT to ensure stable 0.27 mm dots under factory temp/humidity.
• Use AOI thresholds correlated with final acoustic tests to tune acceptable spread and dot mass.
• Schedule predictive maintenance for piezo valves based on shot counts and weight-drift metrics.
• Combine pre-cure with downstream oven profiles to shorten line dwell while preserving adhesive integrity.

Conclusion 

For Vietnamese hearing-aid component manufacturers, AC100 converts manual diaphragm and housing assembly into a repeatable, traceable, high-throughput process. By combining piezo micro-jet dispensing, vision-guided placement, and inline glue inspection, the solution ensures precise 8–12 dot epoxy patterns (0.27 mm diameter) with minimal overflow — delivering consistent acoustic performance, higher yield, and scalable production. Contact Mingseal for pilot qualification and process tuning for your specific parts and epoxy formulation.