Precision Rotor Balancing for Turbomolecular Pumps
- May 16, 2023
- 4 min read
Updated: Dec 5, 2025
Ultra-high vacuum equipment manufacturer developed high-precision rotor balancing system in five weeks using the NI USB-9234 DSA, LabVIEW, and the NI Sound and Vibration Measurement Suite.
*As Featured on NI.com
Original Author: Gerard Johns, Edwards
Edited by: Cyth Systems
Project Summary
Ultra-high vacuum equipment manufacturer developed high-precision rotor balancing system in five weeks using the NI USB-9234 DSA, LabVIEW, and the NI Sound and Vibration Measurement Suite.
System Features & Components
Integrated IEPE signal conditioning of NI USB-9234 enabled direct accelerometer connection without external amplification
NI sound and vibration measurement software included signal reconstruction and analysis functions that facilitated quick implementation of custom processing algorithms
LabVIEW software enabled rapid prototyping, automated code generation, and implementation of parallel processing architecture
Parallel processing architecture balancing of two pumps simultaneously per station enhanced balancing operation throughput capability through
Interactive operator guidance tools translating phase angle and magnitude calculations into correction mass assembly instructions
Outcomes
Complete system development from concept to production deployment in under five weeks
Dynamic input range exceeding all commercially available balancing systems
Parallel balancing and correction operations per NI USB-9234 increased production throughput at a fraction of the cost of a typical commercial system
Class-leading vibration measurement performance enabled successful product launch
Technology at-a-glance
Hardware:
NI USB-9234 Dynamic Signal Analyzer (obsolete – comparable NI C Series module NI-9234)
Accelerometers
Digital photo sensor for rotor position detection
Software:
NI Sound and Vibration Measurement Suite (obsolete – replaced by LabVIEW Sound and Vibration Toolkit)
Ultra-High Vacuum Pumps
Laboratory mass spectrometers and electron microscopes require ultra-high vacuum environments where even minimal vibration compromises measurement accuracy. Edwards, a leading manufacturer of vacuum equipment serving semiconductor and pharmaceutical industries, faced a critical challenge when developing their nEXT Turbo Molecular Vacuum Pump. They wanted to achieve world-class vibration performance, which required rotor balancing tolerances that were impossible to measure with existing solutions available on the market.
Edwards needed a custom balancing system that could measure vibration with unprecedented precision for rotors spinning at high velocities.
Measurement & Data Analysis Challenges
The nEXT Turbo Molecular Vacuum Pump utilized a turbine rotor spinning at 60,000 rpm, with blade-tip velocities approaching 90% of the speed of sound.
These unparalleled capabilities of this technology presented a few critical manufacturing challenges for Edwards.
Inaccessible measurement location: Rotor assembly contained within sealed pump housing prevented direct vibration measurement at the source, deviating from standard balancing methodology
Manual calculatios: Off-the-shelf balancing solutions required operators to perform manual calculations and balancing compensation, which greatly slowed production and increased the potential for human error
Compressed timeline: Product launch was weeks; Edwards needed to take their concept through validation to production deployment relying only on their internal teams for development
Measurement precision: Dynamic input range required for the detection of minute vibrations and high rotor speeds exceeded all commercially available rotor balancing solutions
Due to technical and timeline constraints, Edwards knew they could not rely on the conventional balancing solutions commercially available. They decided to leverage an NI-based technology stack to accelerate development while staying within budget.
Left: OEM vacuum pumps by Edwards, Right: the inside fan blades of a turbomolecular pump.
High Measurement Accuracy
Edwards' engineering team selected the a few key pieces of NI platform to prototype and deploy a custom balancing solution.
Core Platform Selection:
NI LabVIEW software: Graphical programming environment enabled rapid prototyping and robust application development into production environments
NI Sound and Vibration Measurement Suite: Domain-specific libraries with signal reconstruction functions and vibration analysis algorithms
NI USB-9234 dynamic signal analyzer: Precision measurement hardware with 51.2 kS/s sample rate per channel, 24-bit resolution, and 102 dB dynamic input range
Integrated IEPE signal conditioning: Direct connection from USB-9234 to the accelerometer simplified system architecture and reduced potential signal degradation points
This development approach enabled Edwards to accelerate prototyping and application development without sacrificing the high measurement accuracy critical for this application.
Rapid Prototyping Through Production
The NI Sound and Vibration Measurement Suite signal reconstruction functions enabled interfacing a digital photo sensor with analog inputs for rotor position detection. An accelerometer attached to the pump body captured vibration data.
The Sound and Vibration Assistant automatically generated LabVIEW code from the prototype configuration, eliminating weeks of manual coding and providing a validated foundation for production application development.
Edwards built production-ready features on the LabVIEW foundation:
Automated calibration functions to maintain measurement accuracy across multiple balancing rigs
Proprietary calculation algorithms for measuring pump imbalance through the housing rather than directly at the tip of the rotor
Interactive operator guidance tools to translate phase angle and magnitude calculations into straightforward instructions for rotor balancing
Using LabVIEW's parallel processing architecture, Edwards configured the USB-9234's remaining channels to balance two pumps simultaneously. This effectively doubled production capacity from a single hardware platform at a fraction of the cost of purchasing two commercial systems.
In less than five weeks, Edwards took their proof of concept through validation and into production deployment.
Increased Production & Enhanced Sustainability
Edwards’ augmented technical capabilities far exceeded commercially available balancing equipment. The key technical features enabled by the NI USB-9234 included:
Detection and correct of vibrations in rotors spinning at 60,000 rpm
102 dB dynamic input range enhanced measurement flexibility and enabled quick accommodation for variations in pump models and rotor configurations
Leveraging the NI technology stack, Edwards increased their rotor balancing operation efficiency:
Cost Savings: Parallel, dual-pump rotor balancing capability delivered two complete balancing rigs at fraction of the price for a single commercial system
Improved cycle time: Automated imbalance calculations and operator guidance tools reduced balancing cycle time and training requirements
Operational control: Internal solution support eliminated vendor dependencies and enabled direct implementation of system enhancements as product line expanded
Platform standardization: LabVIEW and NI hardware as accepted standards across Edwards’ production test, global service centers, and R&D laboratories, resulting in reduced training complexity and enhanced knowledge transfer
In five weeks, Edwards used LabVIEW, the USB-9234, and the Sound and Vibration Measurement Suite to rapidly develop a custom solution for high-speed rotor balancing that outperformed commercial alternatives.
Original Author: Gerard Johns, Edwards
Edited by: Cyth Systems
