the sneaky saboteurs of shaft alignment

Ensuring precise shaft alignment is important for the performance and longevity of rotating machinery. Even minor misalignments can lead to increased wear and tear, vibration, and premature failure of machine components. Cupped washers are often an overlooked challenge. Understanding the problems associated with cupped washers is crucial for maintenance professionals aiming to achieve accurate and reliable shaft alignment.

Cupped Washer

Cupped washers result from using washers that are not thick enough to properly support the foot bolt when torqued. They are typically found on machines where the feet have been drilled out to correct a bolt-bound condition. When the bolt is tightened, it causes the center of the washer to bend and “cup.”

The Problems with Cupped Washers in Shaft Alignment

1. Non-Repeatable Readings: During the alignment process, the flexibility of cupped washers can lead to false readings. The washers might temporarily conform to the alignment adjustments but move back under operational loads, causing misalignment.

2. Difficulty in Achieving Precise Alignment: Shaft alignment requires high precision, often within thousandths of an inch. The unpredictable nature of cupped washers makes it difficult to achieve and maintain such precise alignment. The washers’ tendency to shift and settle under load compromises the stability of the alignment, making it challenging to achieve accuracy.

Best Practices for Addressing Cupped Washer Issues

To reduce the problems associated with cupped washers in shaft alignment, maintenance professionals should consider the following best practices:

– Use Thick Washers or Spacers: Opt for flat washers instead of cupped washers for shaft alignment tasks. Flat washers provide consistent thickness and stable support, ensuring more reliable alignment.
– Avoid Drilling Feet if Possible: Conduct regular inspections of aligned machinery to identify any shifts or changes in alignment that may be caused by washer deformation or other factors. Early detection of misalignment can prevent more significant issues down the line.
– Proper Torquing: Ensure that bolts are torqued to the manufacturer’s specifications to minimize the risk of loosening. Proper torquing helps maintain the stability of the alignment over time.
– Alignment Tools: Utilize advanced alignment tools, such as laser alignment systems, to achieve high precision. These tools can help detect and compensate for any minor discrepancies introduced by cupped washers.
– Monitor Alignment Corrections “Live”: Monitor the alignment with the laser tool as the bolts are tightened following horizontal and vertical corrections to ensure accuracy.


By understanding cupped washers and adopting best practices, maintenance professionals can overcome the challenges, ensuring more accurate and reliable shaft alignment.

Hamar Laser X Series for accurate and reliable shaft alignments!



Leave a Reply

Your email address will not be published. Required fields are marked *

You may use these HTML tags and attributes:

<a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <s> <strike> <strong>