Why is it necessary to monitor OHT vehicle vibration during operation?

OHT vehicles are responsible for transporting wafers inside semiconductor cleanrooms. If excessive vibration occurs during operation, it may affect wafer transportation stability and even cause wafer damage or transportation system abnormalities. Vibration monitoring helps detect problems early and reduce process risks.

How can you determine whether the abnormality comes from the vehicle body or the rail?

Vibration sensors can be installed on the OHT vehicle body and analyzed together with rail position information. The system compares vibration data with track position to determine whether the abnormality comes from a specific vehicle or a specific rail section.

What is OHT scout mode?

OHT scout mode can be used after equipment overhaul or for full-factory rail inspection. By continuously recording traveling vibration data, the system automatically creates alarm events and uploads related data when long-term vibration exceeds the threshold or vibration spikes occur.

What information is reported when an OHT vibration alarm occurs?

When abnormal OHT vibration occurs, the system can report alarm status, g/RMS vibration data, and current OHT position information. The data is mainly transmitted through Wi-Fi and can also be supported by low-frequency backup communication to ensure reliable alarm delivery.

Case

Application

FAQ

Support

Excessive Vibration Occurred During OHT Rail Car Operation?

Q: What problems can excessive OHT vibration cause?

Excessive OHT vibration may lead to unstable wafer transportation, impact on FOUPs or carriers, accelerated vehicle mechanism wear, worsening rail abnormalities, reduced transportation efficiency, system downtime, and production loss.

Q: What are the benefits of implementing OHT vibration quality monitoring?

After implementing OHT vibration quality monitoring, users can grasp vehicle vibration status, rail health, and vehicle position information in real time. When an abnormality occurs, the system issues immediate alarms and supports fast troubleshooting. Long-term trend analysis also improves wafer transportation stability, reduces unexpected downtime, and increases semiconductor production line reliability.

Case ｜ Excessive Vibration Occurred During OHT Rail Car Operation?

OHT plays a critical role in wafer transportation. Abnormal vibrations and insufficient transport stability can lead to product quality issues. How can such issues be predicted in advance?

OHT Overhead Transport System

The primary object transported by OHT is wafers. With the advancement of the semiconductor industry, cleanroom automation has improved significantly. In highly regulated environments, unmanned automated transport systems like OHT are widely adopted.

OHT functions like a transportation network in a small city, ensuring smooth movement within the facility while adhering to designated paths and schedules.

OHT is also known by various names such as overhead transport vehicle, crane system, and aerial transport system. The primary "passenger" of OHT is the wafer, and the vehicles follow predefined routes. Encounters with other OHT vehicles are common, and any instability in traffic speed or movement could indicate excessive vibration, anomalies, or collisions. Severe cases can result in wafer damage or system disruptions.

How to monitor OHT rail car vibration quality?

Monitoring Overview

IIoT Unlimited: Industrial IoT
OHT is an unmanned transport vehicle, and ensuring transportation quality is crucial to preventing unnecessary losses and enhancing semiconductor production efficiency and reliability.

It is essential to equip OHT vehicles with monitoring instruments or sensors. Through a central monitoring dashboard, real-time monitoring, alerts, and maintenance actions such as component replacements can be carried out to ensure smooth transport operations.

Measurement Status

OHT Rail Car Vibration Quality Monitoring

1. Detection Target: Excessive vibration during rail car operation
2. Confirm if the abnormal vibration is caused by rail car motion
3. Perform self-diagnosis to verify track health and ensure the issue originates from the rail car
4. Issue alerts for abnormal vibration of individual rail cars

Scout Mode:
1. Detection Target: Abnormal track conditions
2. Usage Scenario: Full track inspection after periodic maintenance, with monitoring modules tracking OHT vibration conditions in real-time (prolonged excessive vibration and sudden vibration spikes are considered alert events).
• The module simultaneously synchronizes position information with the OHT.
• If an alert event occurs (vibration signal exceeds internal threshold), an over-limit alert is triggered.

To the Main System:
• Alert Information: Alert notifications, real-time vibration data (g/RMS), current OHT position information.
• Alerts and data are primarily transmitted via WiFi.
• In case of WiFi signal failure, a secondary backup (low-frequency transmission) ensures reliable alert delivery.
• If vehicle communication is lost, the backup system can still report excessive vibration events with OHT identification but without location details.

Measurement Conclusion

By installing sensors on the OHT vehicle, it is possible to detect abnormal vibrations, assess track conditions, and track real-time vehicle positions. When an anomaly occurs, immediate alerts can be issued.

Gain control of production lines and perform real-time anomaly detection. Utilizing Industrial IoT solutions for continuous monitoring ensures unexpected failures are avoided.

IIoT Solutions

Comprehensive data monitoring for real-time production insights

FAQ

Why do OHT vehicles need travel vibration monitoring?
OHT (Overhead Hoist Transport) vehicles are responsible for transporting wafers in semiconductor cleanrooms. If excessive vibration occurs during travel, it may affect the stability of wafer transport, or even cause wafer damage or transport system anomalies. Therefore, monitoring vehicle travel vibration through sensors can detect anomalies in advance and reduce process risks.

What problems can excessive OHT vibration cause?
Excessive OHT vibration may cause unstable wafer transport, impact to the FOUP or carrier, vehicle mechanism wear, abnormal track widening, transport delays, and system downtime. If not detected promptly, it may also affect the production efficiency and reliability of the semiconductor production line.

How to determine if an OHT anomaly comes from the vehicle or the track?
Vibration sensors can be installed on the OHT vehicle, paired with self-detection to test track health. The system can compare the vehicle's travel vibration with track position information to confirm whether the anomaly is caused by an individual vehicle or originates from a specific track section, thereby assisting engineers in rapid troubleshooting.

What is the OHT Scout Mode?
The OHT Scout Mode can be used for track inspection after annual maintenance or across the entire plant. Through the monitoring module, it monitors the OHT travel vibration status in real-time. When continuous vibration exceeds the standard or sudden vibration surges occur, the system treats it as an alarm event and transmits the vibration data along with the OHT location information.

What information is transmitted in an OHT vibration alarm?
When OHT vibration exceeds the standard, the system can transmit the alarm status, current vibration data (such as g/RMS), and the current OHT position information. Alarm data is primarily transmitted via Wi-Fi but can also be paired with a secondary backup low-frequency band transmission to prevent alarms from failing to be sent when the Wi-Fi is down.

What are the benefits of implementing OHT vibration quality monitoring?
After implementing OHT vibration quality monitoring, vehicle vibration, track status, and OHT position information can be grasped in real-time. When an anomaly occurs, it alarms immediately to assist in rapid on-site troubleshooting. Through long-term monitoring, it also improves wafer transport stability, reduces the risk of unexpected anomalies, and enhances the reliability of the semiconductor production line.