MDI Blog: Importance of Solid Foundation for Rotating Machinery

This blog was created in conjunction with CTC's educational partner, Machinery Diagnostics Institute (MDI)

When it comes to operating rotating machinery, be it large industrial equipment or precision instruments, having a proper foundation is crucial for ensuring optimal performance, longevity, and safety. The foundation on which these machines are installed provides the necessary support and stability, directly influencing their efficiency, accuracy, and overall reliability. 

A solid foundation acts as the anchor for rotating machinery, absorbing vibrations, minimizing dynamic loads, and maintaining alignment. Providing a stable platform prevents excessive movement or shifting during operation, and reduces the risk of misalignment, premature wear, and component failure. Additionally, a well-designed foundation minimizes resonance, which can lead to amplified vibrations, increased noise levels, and compromised machine accuracy.

ISO standards, specifically ISO 10816-3 for industrial machinery, consider a range of variables that influence the choice between a rigid or flexible foundation. These variables include machine size, type, speed, operating conditions, and the criticality of the application. Understanding and adhering to these standards is crucial for engineers, manufacturers, and maintenance professionals to ensure that the foundation aligns with the specific requirements of the rotating machinery. 

Aly Attia at the Machinery Diagnostics Institute provides some helpful insight into the definition of "rigid" and "flexible" foundations:

To consider any foundation to be "rigid," the lowest natural frequency of both machine and foundation must be higher than its main excitation frequency (forcing frequency of rotating machine) by at least 25%.

Another way to look at the definition of "rigid" is the foundation has sufficient stiffness that makes the structure resonance frequencies at least 25% above the resonance frequencies of the rotating equipment attached to it.

For example, large and medium-sized electric motors with low speeds normally have rigid supports.

Turbo-generators and compressors with power of more than 10 MW normally have flexible supports.

Having the right foundation is critical for enhanced performance, extended machine life, and improved safety. Starting with the right foundation for rotating machinery sets the stage for an effective and reliable condition monitoring program. By establishing a stable base, the foundation minimizes unnecessary vibrations and fluctuations, providing a consistent operating environment for monitoring sensors and equipment. This baseline stability allows for accurate data collection and analysis, enabling early detection of potential faults or abnormalities. At CTC, we offer the industry's largest selection of vibration analysis hardware, enabling our customers to create customized condition monitoring solutions for their equipment.