Laser Shaft Alignment vs Traditional Alignment: Key Differences Explained

Just 0.5 mm off-center can halve bearing life, increase vibrations and create tens of thousands of dollars in additional energy and repair expenses. Studies indicate that misaligned equipment accounts for at least fifty percent of all rotating machinery failures.

Most of the time, problems develop as equipment continues to run, and only become apparent due to excessive wear, abnormal noises, or unscheduled downtime.

As such, when it's time to properly align connected shafts, maintenance personnel will choose between tried and true conventional methods and contemporary laser Shaft Alignment systems.

Although both types of methods will ultimately achieve the same objective—positioning connected shafts on the exact same centerline so that there are no obstacles to smooth, efficient transmission of power—the primary difference lies in how precise measurements are made, how rapidly, and the ability to document and replicate those measurements for future reference.

What Is Shaft Alignment and Why Is It Important?

Shaft Alignment refers to positioning two or more connected pieces of machinery (such as a motor turning a pump, gearbox, fan or compressor) so that their respective shafts run on the same centerline under normal operational conditions (i.e., including thermal expansion).

Correct alignment minimizes unwanted stresses on bearings, seals and couplings allowing them to operate within their respective design specifications. 

Proper alignment provides several Benefits to users, including lower energy consumption, longer equipment lifespan, less unanticipated downtime and reduced overall vibration. Therefore, maintaining reliable equipment is a key element of successful preventative maintenance for reliability-oriented companies.

Common Causes of Misalignment

Equipment becomes misaligned for a variety of reasons. Some common causes of misalignment are:

• Improper assembly of equipment during original installation.

• Thermal growth resulting from heating of equipment.

• Soft-foot (distortion of the base due to uneven tightening of mounting bolts.)

• Foundation settlement or other forms of foundation movement over time.

• Pipe pull due to piping attached to the equipment.

• Vibration causing periodic looseness of mounts.

• Wear in bearings, couplings or other hardware.

• Recent maintenance activities or relocation of equipment.

What is Laser Shaft Alignment?

Laser shaft alignment utilizes precise laser emitting devices along with position sensitive sensor devices and electronic display devices to measure and adjust shaft positions instantaneously.

Devices are mounted on each machine, and turn the shafts (specialized modes can also be employed), then immediately compute the amount of misalignment between the two shafts.

Some modern devices allow the user to view real time feed back during adjustment, thus eliminating guess work. Technicians view exact amounts of correction needed for each shaft via a hand held device or tablet display. Thus, completion of laser-based shaft alignment projects are generally quicker and more repeatable compared to traditional techniques.

Benefits of Laser Shaft Alignment

• Precision Measurement: Measurements can be achieved to 0.0001 inches (microns) better than traditional methods.

• Time: Most laser-based systems complete set-up and corrections in a fraction of the time required using traditional techniques.

• Real-Time Guidance: Users receive immediate readouts providing users with instantaneous correction values reducing the need for "trial-and-error".

• Documented Records: Automatically generated digital reports containing before-after data for audit trail purposes, tracking and trending.

• Repeatability: Regardless of operator experience, results obtained using laser-based systems are consistent.

• Return-on-Investment: Many facility owners report recovery of the capital expense incurred for laser-based systems within nine months based on energy savings alone.

Traditional Shaft Alignment Methods

Prior to lasers being developed, technicians utilized various manual tools and calculations for determining Shaft Alignment. Although these older methods are still viable for less complex applications or when laser-based solutions are unavailable, they do require significantly more time, expertise and patience.

• Straight edge & feeler gauges: a straight edge spanned the coupling while Feeler Gauges measured the gap. Simple to utilize for Quick checks however low in terms of accuracy.

• Dial indicator alignment: one dial indicator was mounted to one shaft while another was attached to the opposite shaft. The first dial indicated movement on the second shaft while it rotated. This method is considered to be the "gold standard" for manually based precision alignment.

• Rim & face method: two dial indicators were used to measure both rim (amount of offset) and face (angle) movement relative to the coupling.

• Reverse dial method: movement on both sides of the shaft were recorded simultaneously. More accurate than rim-and-face if performed properly although still requires calculation and/or use of an alignment chart along with correct Setup.

Process Used with Older Manual Methods

Technicians would attach dial indicators to each shaft, rotate the shafts at predetermined intervals (commonly 0°, 90°, 180°, 270°), read the dial indications, calculate (use tables/charts) and apply shims to achieve desired Shaft Alignment.

Effective but susceptible to sagging brackets, parallax error, and human variability when reading dial indications.

Comparison: Laser Shaft Alignment vs Traditional Shaft Alignment

Feature	Laser Shaft Alignment	Traditional Shaft Alignment
Method of Measuring Position	Digital laser sensors and real-time software	Manual dial indicators, straightedge, or feeler gauges
Measurement Accuracy	High precision with excellent repeatability	Lower precision, more dependent on setup and operator skill
Setup Time	Typically faster	Often slower due to manual adjustments
Process for Adjustment	Real-time correction guidance	Manual calculations and trial-and-error
Operator Skill Level	Moderate	High
Consistency Between Operators	High	Varies by technician experience
Documentation	Automated digital reports	Handwritten notes or none

Best Use Cases for Laser Alignment

Select laser-based systems when high accuracy, rapid completion times and documented records are essential:

• Production Equipment Where Downtime Costs Thousands Per Hour

• Equipment That Requires High-Speed Operation With Tight Tolerances

• Multiple Alignments During Scheduled Shutdown Periods

• Maintenance Documentation Requirements (i.e. Reliability Programs)

• Alignment Of Large Or Difficult-To-Reach Machines

• Reliability Focused Maintenance Programs To Reduce Repeat Failures

Best Use Cases for Traditional Alignment

There are valid situations where traditional methods can still be applied effectively:

• Non-Critical Smaller Equipment

• Basic/Rough Alignment Checks/Verification Only

• Limited Budget And No Access To Laser-Based Systems

• Infrequent Jobs On Simple Machinery

• Operators Who Possess Significant Experience With Dial Indicators

Conclusion

Proper Shaft Alignment provides some of the best ways to improve equipment reliability, efficiency and service life. Even small errors in Shaft Alignment can lead to unnecessary vibration which will accelerate wear on your equipment, resulting in long-term maintenance costs.

Traditional methods still have value for smaller or non-critical equipment checks or basic checks by experienced technicians working without laser-based tooling. However, many modern facilities prefer use of a laser based shaft alignment system as it offers greater speed, precision, repeatability and documented results.

The right method depends on the machine specifically, demands for operation and required tolerances. Selecting the proper approach will help reduce maintenance costs over time, extend equipment life and keep operations running as intended.