Minimizing Spindle Downtime: Preventative Maintenance & More

The goal of any service program should be to achieve and maintain the highest possible level of equipment performance across the board. Spindle service can be divided into the following categories, depending on the circumstances.

• The scheduled maintenance program: Spindles should receive routine maintenance check ups that are scheduled according to previous maintenance records. The goal of this type of service is to ensure the spindle is in good working order and catch any potential issues. One possible downside of standardized scheduled maintenance is that it does not account for anomalies like environmental factors, inconsistent hours of operation, or even whether a spindle needs to be serviced.
• The spindle “hotel” program: Some shops will keep two or more of the same spindle in stock so they can replace one in a hurry if it crashes or malfunctions in some way. The spare spindles are kept either onsite or at a spindle repair facility. However, these backup spindles can take up valuable storage space or risk getting damaged if not stored properly.
• The emergency program: Though emergencies are unpredictable, having an emergency spindle service plan at least identifies a procedure for unplanned downtime. In addition to routine maintenance, all facilities with spindles should have a plan in place for where to send a spindle at short notice, their available budget, and their allowable lead time for a repair.
• The “first in, first out” program: The least practical of all the service programs, this is equivalent to having no plan at all for spindle malfunctions. Damaged spindles are repaired on an as-needed basis, leading to extended downtime and lost productivity, not to mention unexpected costs.

Out of these programs, the scheduled maintenance program is the most critical to implement, since it can help prevent any of the more urgent service requests. Different production schedules may affect a facility’s choice of service program, but the goal should never be to rely solely on the “emergency” or “first in, first out” strategies.

As an experienced spindle repair facility that’s trusted across industries, Northland Tool has the capacity to evaluate and repair almost any spindle. Though repairs are a normal part of any spindle’s lifespan, the goal should be to keep your spindle operable and in good shape for as long as possible. We’ve compiled a list of steps you can take to maximize uptime and avoid costly repairs.

1. Perform Regular Preventative Maintenance 

Elements of spindle maintenance may look different depending on the facility and application, but we recommend the following for nearly every spindle owner or operator:

• Create a regular maintenance schedule for each piece of equipment, then document and analyze the resulting trends.
• Use prior documentation to inform predictive maintenance tasks and scheduling.
• If TTC is utilized, make sure the union and seals are healthy (otherwise contamination is imminent).
• Avoid contamination by cleaning your filters and skimming any tramp oil out of your spindle coolant.
• Clean the water trap on compressed air regulators to prevent particulate contaminants from being released and impacting spindle bearings and other critical components.
• Always ensure your spindle bearings are properly lubricated to avoid excessive vibration, unusual noise, or overheating.

The frequency of maintenance checks depends on the application. Here is a general guide:

• 100,000 rpm grinding spindle: Weekly
• 12,000 rpm milling spindle: Monthly
• 700 rpm lathe: Quarterly

Consult with a spindle repair technician to determine your specific maintenance schedule, as it can vary depending on application, production volume, scheduling, and more.

2. Avoid Spindle Crashes

A spindle crash occurs when the spindle collides with a workpiece or machine tool components, and can be caused by a misaligned tool, an error in programming, or human error during operation. Spindle crashes can result in damaged workpieces, broken tooling, other damaged machine components, and a costly repair.

No spindle is entirely immune to crashes, but with the right precautions, you can reduce the likelihood of a crash by doing the following:

• Stay within the recommended parameters for each individual operation as they pertain to load, speed, and feed.
• Any time you adjust the parameters, perform a trial run before starting the job.
• Utilize “safe start” blocks of code in your programming; these prevent the operator from restarting a program with the tooling in the wrong position.
• Recognize that any crash can be severe, even if it doesn’t seem like it at first.

On this last point, the visible damage of a serious crash is obvious, but even a minor crash can cause dents or other signs of wear on the bearing surfaces. If left unchecked, minor damage can impact spindle performance, degrade parts quality, and shorten the spindle’s lifespan.

3. Prevent Tool Imbalance

Ensure your tools are properly balanced by avoiding using corroded, rusty, damaged, or overly worn tool holders. Any imbalance or distortion in the tool itself is transferred to the spindle.

Quality tool holders will protect against high total indicator runout (TIR), which can shorten tool life and impact parts finish. If a toolholder is damaged, it needs to be replaced immediately.

4. Listen to Your Machines

Sound is one of the most valuable tools when it comes to assessing spindle health. A change in pitch, vibration, volume, or noise frequency can indicate a serious or impending issue.

Spindles, toolholders, and associated components vibrate naturally as part of their operation, so if you’re familiar with what their baseline vibration sounds like, you’ll be able to detect changes. Listen for chattering or whining, and keep an eye out for changes in the surface finish, since that will confirm there is a problem.

Most machines come with a manual that clearly lists the recommended intervals and procedures for maintaining the machine and spindle — this is your best resource to keep your spindles healthy. Since each machine and application is different, the recommendations in this post should be considered general guidance.

To be on the safe side, any spindle that emits unusual noises or vibrations should be assessed by an expert technician with a working understanding of pneumatics, hydraulics, physics, vibration, thermal dynamics, lubrication, tooling, their process, and machine capabilities.

For expert spindle evaluations, repairs, and maintenance recommendations that can prevent unplanned downtime, contact the technicians at Northland Tool and Electronics today.