Automated End-of-Line Testing System for Hearing Aid Components
Challenge
A manufacturer of hearing aid components required a fully automated end-of-line testing solution for miniature loudspeakers measuring only 3×2 mm.
The system needed to automatically handle products supplied in trays containing 100 parts, perform electro-acoustic testing, classify products according to measurement results, and communicate with the factory MES system. Due to the extremely small dimensions of the components, the machine required very high positioning accuracy while maintaining demanding production throughput targets.
In addition to reliable product handling, the solution had to coordinate multiple robots, testing fixtures, machine vision systems, and measurement equipment operating simultaneously within a single machine.
Solution
The machine was controlled by a Beckhoff CX5140 Industrial PC running TwinCAT 3 and integrated multiple automation technologies into a single coordinated platform.
Products entered the machine through a servo-driven tray feeding system. Trays containing hearing aid speakers were stacked at the machine infeed and automatically transported into the working area. A Cognex vision system identified the precise position of each component and provided coordinate data to the PLC.
Two Mitsubishi SCARA robots were integrated into the machine in a mirrored configuration. Each robot serviced four independent electro-acoustic test fixtures equipped with reference microphones and pneumatic actuators.
The TwinCAT application coordinated tray handling, vision processing, robot movements, testing operations, and product sorting. Intelligent scheduling logic was implemented to maximize machine throughput by ensuring that robots and test fixtures operated in parallel whenever possible while avoiding process bottlenecks and collision risks.
The machine communicated with electro-acoustic measurement equipment via TCP/IP and exchanged production data with the manufacturing execution system (MES) through OPC UA. Product recipes were automatically loaded from MES and production results were reported back to higher-level systems.
Machine safety functions were implemented using TwinSAFE technology and a dedicated HMI was developed to provide operators with machine control, diagnostics, alarm handling, and production monitoring capabilities.
System Architecture
conveyor_belt
Product Handling
Servo-driven tray feeder
Automated tray exchange
Position-controlled indexing of product rows
Handling of trays containing 100 components
camera
Machine Vision
Cognex vision system
Automatic product localization
Position correction for robotic handling
precision_manufacturing
Robotics
2 Mitsubishi SCARA robots
EtherCAT communication with TwinCAT
Dynamic task scheduling
Parallel operation across multiple fixtures
checklist
Test Stations
8 electro-acoustic testing fixtures
Reference microphone integration
Pneumatic fixture actuation
Automated measurement execution
storage
Industrial Connectivity
OPC UA communication with MES
TCP/IP communication with electro-acoustic measurement equipment
Automated recipe management
Production data reporting
web
Safety and HMI
TwinSAFE safety system
Operator HMI
Alarm management
Diagnostics and production monitoring
Key Responsibilities
TwinCAT 3 PLC software development
Mitsubishi SCARA robot integration
Cognex vision integration
Development of machine coordination logic
Throughput optimization and process synchronization
TwinSAFE implementation
HMI development
OPC UA MES integration
TCP/IP communication with measurement equipment
Machine commissioning and optimization
Results
The completed machine provided a fully automated testing and sorting process for miniature hearing aid speakers while maintaining exceptional accuracy and throughput.
Automatic classification into OK and 10 NOK categories
Seamless MES integration through OPC UA
Automated recipe loading and production reporting
Stable and reliable operation in a high-volume manufacturing environment
Optimized robot and fixture utilization through parallel process execution
Most importantly, the machine achieved a production cycle time of:
1 tested component every 2 seconds
while maintaining the precision required for one of the smallest products handled within the manufacturing process.
Technologies
Beckhoff CX5140
TwinCAT 3
EtherCAT
TwinSAFE
Mitsubishi SCARA Robots
Cognex Vision
OPC UA
TCP/IP Communication
MES Integration
Electro-Acoustic Test Equipment
Industrial HMI
Servo Motion Control
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