Category: Spindle Repair

Chatter Marks — What They Are and How to Avoid Them
Machining chatter. It’s the bane of machinists everywhere, yet everyone will have to deal with it at some point. It can be very difficult to find the root cause, especially without the right tools, and it often goes unnoticed until chatter marks are visible on finished parts.

In this blog, we’ll do a deep dive into machining chatter and chatter marks, what causes them, how to diagnose the cause, and, most importantly, how to best prevent these issues from recurring.

What are Chatter Marks?

Vibration is inherent in industrial processes — many pieces of equipment used in modern machining spaces generate some level of vibration when in use. The equipment manufacturer typically accounts for these vibrations.

Occasionally, however, machinery begins to vibrate in ways that are not intended and have not been accounted for in the design process. These unwanted vibrations are called machine chatter or machining chatter.

Left unchecked, these vibrations will grow and worsen to the point where they become visible in the completed workpieces. These marks are what we call chatter marks — unwanted cutting patterns that are visible on tooled portions of a workpiece.

Aside from resulting in substandard or even completely out-of-spec parts, unattended machining chatter has a number of negative side effects:
- Disproportionate and uneven tool wear
- Damage to machines and machine tools
- Slower work rates, which increases production cost
- Material and energy waste
Types of Machining Chatter & Their Causes

Machining chatter comes in two broad categories: primary and secondary chatter.

Primary chatter includes vibrations that stem from the cutting process itself. They are often, but not always, caused by tools that have worn unevenly. Different types of primary chatter include:
- Friction chatter — caused most often by uneven friction between workpiece and tool
- Thermo-mechanical chatter — caused by temperature and strain rate variations in the plastic deformation zone of a workpiece material
- Mode coupling chatter — caused when one vibration (typically in the thrust force direction) causes a secondary vibration (in the cutting force direction) or vice versa
Secondary chatter primarily includes vibrations that stem from uneven workpiece surfaces. They are known by a few different names — regenerative, resonance, and self-excited chatter — and occur when undulations on the surface of a workpiece cause a vibration in the tool. This vibration then spreads throughout the machine and builds as it goes. In other words, it resonates.

Preventing Chatter and Chatter Marks

Chatter is very difficult to prevent outright. As mentioned, vibrations are innate to the operation of industrial machinery: no tool wears exactly as anticipated, no raw material is completely uniform throughout, no part blank is perfectly proportioned, and so on.

That said, there are some things you can do to minimize the chance that chatter occurs and thereby reduce the rate at which chatter marks appear.

Tooling

There is a right tool for every job, and there are also close-enough tools. It can be tempting, whether for ease or cost, to settle for a close-enough tool for a job, but you’ll be at greater risk of developing chatter and chatter marks. A tool’s substrate, coating, and aspect ratio are just a few considerations. Size and shape are important considerations as well — a longer, thinner tool will vibrate much more readily than a stouter one.

Workholding

The workholding solution you use for a job is also very important, as incorrect position, poor fit, and fixture type will all affect how firmly a workpiece is held and, therefore, how much it vibrates while being machined.

Set Up & Strategy

If a machine is set up correctly — on a flat surface free of imperfections, anchored correctly, and regularly balanced and maintained — you lower your risk of developing chatter and chatter marks. Machining strategy is also important, as workpiece material, RPM, cutting path, degree of cutter engagement, and a host of other workpiece-tool touchpoints can lead to unwanted vibrations.

Vibration Analysis

While the above considerations and strategies can help to reduce the possibility of machining chatter and resultant chatter marks, they cannot completely eliminate it. Despite your best efforts, your machines will encounter unwanted vibrations at times.

That is why the best defense against chatter marks is a good offense — specifically in the form of vibration analysis.

Every machine has a telltale vibration pattern when operating smoothly. In the same way, each type of machining chatter has its own telltale vibration pattern. With a vibration analysis tool like VibePro, you can identify emerging chatter patterns before they worsen to the point of causing chatter marks. Then, rectifying the issue becomes as simple as identifying the type of chatter and alleviating or compensating for the root cause.

Machining chatter remains a headache for manufacturers. While completely eliminating it is rather difficult, savvy manufacturers can fight back by choosing quality tools, optimizing their setup, and using vibration analysis to catch problems before they spiral out of control. This is the key to minimizing chatter marks and other potential part quality issues.
January 23, 2025
The Importance of Winding Down Your Machine Tool Spindles
Previously, we wrote a blog about one of the more common topics that we discuss with our clients – the importance of warming up a spindle properly. Today, we’re covering a related and equally important subject — the importance of properly winding down your machine tool spindles when work is done.

When and Why Does a Spindle Need to be Wound Down?

In the same way that we recommend a spindle be warmed up after any period of idleness, we recommend that you wind your spindle down correctly after every period of use. Whether it’s for a period of extended maintenance, a week or holiday, or just change-of-shift, if you’re shutting down you should wind down the spindle properly.

There are multiple reasons why we are enthusiastic about proper wind down procedures. For example, doing so helps improve a spindle’s health. But the primary reason is to avoid damage and contamination by manufacturing process debris. If a spindle is allowed to cool too quickly, while there are contaminants on the external spindle surfaces, you run the risk of that process debris ingress into your spindle by the process of capillary action like solder into a joint.

How to Wind Down Your Spindle

There are hundreds of spindle manufacturers, and many more spindle models, each of which has unique processes and requirements for winding down. For that reason, we recommend that you always follow OEM instructions. However, there are a few general rules for spindle wind down that should apply to just about any model:
- Reduce spindle speed gradually – run at 50% power for 5 to 10 minutes, and then at 25% power for 5 to 10 more. This helps to control the cooling process, easing the spindle into it.
- During wind down, it’s critical to maintain positive air pressure (air purge) on the machine until the spindle has completely cooled to ambient temperature.
- Periodically wipe down spindle surfaces during wind down, using a soft, clean cloth to keep the spindle both clean and dry. This prevents manufacturing process debris from being drawn into the spindle assembly as mentioned earlier.*
- Clean any coolant residue from the entire work area, including the spindle.
- Ensure that all systems are powered off properly. This includes the coolant system if it’s powered separately.
*Important note: Do not ever use air guns to clean the spindle assembly, especially the face and shaft ID. It may seem like a quicker, lower-touch alternative to using a cloth, but the fact is that you can do serious damage. The pressure of an air gun can easily overpower the positive air pressure (aka air purge) of the spindle, forcing air, contaminated coolant, and machining debris into the critical internal spindle components, such as bearings and others. Using an air gun, you are not blowing debris, chips and coolant off, you are blowing it in.

During and immediately after wind down is also an ideal time to conduct inspections and checks. A few important ones that we recommend performing include:

Inspect and clean toolholders daily, not just during wind down. If tapers have fretting, chip marks or rust, replace them.
- Oil level in the lubricator
- Condition of the tools
- Drawbar retention force using a force gage
- Verify that the coolant system is functioning properly
- Visual inspection of spindle for any signs of wear, damage, or abnormalities
- Listen for any unusual noises
- Documentation – record any observations, issues, or maintenance performed.
What Happens if I Don’t Do It?

If you rush through a wind down, you might get lucky and experience no ill effects for a while. But you risk — or, if you skip the process regularly, you practically guarantee — the buildup of swarf on the spindle surfaces and possible ingress into the spindle assembly. This can lead to diminished performance and bearing life, as well as excessive heat, vibration and finished parts that are out of spec or otherwise of reduced quality. Longer term, you’re looking at inevitable spindle failure which can be costly and cause loss of production.

Our conclusion about the importance of spindle wind down is the same as it was for spindle warmup: it takes a few extra minutes to perform the steps properly, but this a small price to pay when compared to the alternative.
October 18, 2024
Machine Monitoring Systems and Software: An Overview
The heart of any good predictive maintenance program is a robust machine monitoring system. The world of monitoring systems is as vast as the equipment types in use today. They differ in form and function based on machinery type, metrics being monitored, industry, and more. Today, we focus on on the machine monitoring systems and software suitable for use in spindle/machine tool applications.

The Importance of Machine Monitoring Systems

A Machine Tool Monitoring System Could Have Prevented this Spindle from Failing

Boiled down to their core, predictive maintenance programs utilizing machine monitoring systems are important for one primary reason — cost savings.

As we’ve discussed in the past, it’s a relatively common practice to run spindles to the point of failure. The problem is that, though there are some small cost savings in the short term, the costs in the longer term can be significantly higher.

Spindle repairs at the point of failure are typically three or more times more expensive than repairs at the first sign of an issue. And the costs don’t stop there: unplanned downtime is quite a bit more expensive than planned maintenance downtime. Monitoring your machine tools helps you identify issues early, when they’re easier and less expensive to fix.

Machine Monitoring Systems Components and Functions

Machine Tool Monitoring Sensor

Though monitoring systems vary in complexity, they’re focused around two primary components: sensors and machine monitoring software.

Sensors are typically some form of accelerometer. Either permanently affixed to a machine tool or portable, sensors measure a variety of metrics, including:

Vibration

Sound/Ultrasound

Temperature/Thermography

And more

The Role of Machine Monitoring Software

On their own, no matter how powerful or sensitive they are, sensors will not do you very much good. Machine monitoring software is needed to process and generate reports of the collected data. The software is often an app, like the VibePro 10 iPad app.

Machine Tool Software Dashboard

Machine monitoring software takes the raw data from sensors and converts it to a human-understandable form. The software displays the data visually so we can read it, track changes over time, compile both periodic and event reports, sound alarms when key metrics are outside of predefined range, and more.

Machine monitoring systems are powerful tools with many benefits over traditional predictive maintenance methods. They allow for real time machine health data collection, which is presented graphically through robust user-centric dashboards. This critical data allows for improved forecasting accuracy and strategically planned downtime. Their real time alerts and notifications allow operators to resolve issues early, before they grow into much larger headaches. Though machine monitoring systems require some investment upfront, they can pay for themselves quickly thanks to all of the cost-saving advantages they provide.

Want to see if a machine monitoring system can help improve your bottom line?

Click here to learn more about our spindle analysis tools or to reach out to us to address your questions and specific needs.
July 3, 2024
Using Technology on the Factory Floor to Fill Human Gaps
In the manufacturing sector, there’s been a trend toward having fewer people on the floor at any given time. It started with the advent of automation. Reshoring initiatives hastened it, forcing companies to run leaner operations to remain competitive. Finally, skilled labor shortages, due to several factors, have kicked this trend into overdrive in recent years. Now more than ever, companies must do more, with less.
The Future is Tech
Whether you’re frightened or excited by the idea, the future of manufacturing is technology. Staffing needs and abilities are changing, but the task demands haven’t changed. And for just about every task, technology exists that can augment or complement your existing staff.
The Role of Predictive Maintenance in Machining
Many companies still choose to run spindles and other machine tool equipment into the ground before thinking about implementing a preventative maintenance program. This is more prevalent these days, as staffing challenges and leaner budgets have become the new normal.
Here’s the reality. If your spindles are running unchecked for longer periods of time and you’re concerned about failure, and the associated headaches of downtime and unhappy customers — predictive maintenance technologies can help fill the labor gaps.
Humans have pretty good intuition, especially when it comes to how your equipment is running. Seasoned professionals can often hear or sense things that others can’t. But limits exist. We may know a machine is running hot by touching it, but we probably can’t tell why. It can be difficult to determine the source of the heat, what the precise temperature is, or how that increased temperature is impacting other components. Good news. Temperature and other sensors associated with predictive maintenance technologies, on the other hand, can. Also, as we’ve mentioned in the past, remember that if you hear concerning noises coming from your spindle, it’s often too late. The problem is usually severe, and costly repairs or replacements are unavoidable.
It’s also not economically feasible for most manufacturers to keep highly skilled, experienced, intuitive technicians on the floor 24/7, even when we’re running production 24/7. Predictive maintenance technologies empower companies to monitor spindles remotely, from virtually anywhere in the world. It has the power to give you peace of mind that your machinery is being looked after, and gives your staff the flexibility to do it reliably and remotely.
That’s not to mention:
One-time installation of sensors on difficult-to-reach equipment is far preferable to repeatedly struggling to do human checks.
Well-designed predictive analysis systems will warn you of potential issues long before they become serious ones, or even detectable by human senses.
Certain projections estimate that predictive maintenance can reduce a plant’s maintenance fees by 20% and its unplanned downtime by a whopping 50%.
Are You Ready?
Our natural limitations as humans, the constantly shifting workforce landscape, and the relentless march into the future combine to make the case for the implementation of predictive maintenance technologies plain. Almost by the day, it’s becoming more challenging and costly to keep production facilities staffed like we would 20, 10, or even just 5 years ago.
Navigating the future of manufacturing can be overwhelming, especially with buzzwords like Industry 4.0, IIoT, and cloud-based SaaS frequently mentioned. While these concepts are interrelated, they need not be daunting. You don’t have to dive in all at once. Start with one area that can move your production forward—predictive maintenance is an excellent starting point to ensure machinery operates smoothly.
Even in challenging environments, an efficient factory is a profitable factory.
June 11, 2024
Spindle Predictive Analysis
How it Works and Why You Need It

We talk to a lot of people about spindle predictive analysis. In these conversations, we’ve learned that many companies are reluctant to invest in predictive analysis for their spindles. One comment we often hear is that people prefer to use their own “naked ear” to know when their spindles need maintenance or repair.
While listening is a helpful tool, when it comes to spindle maintenance, it’s more of a “last line of defense” tool than a front-line tool. If you can hear something wrong in your machining equipment, you’re often too late to avoid costly spindle repairs or replacement. Why? Most damage was done long before you could hear it happening.
The crux of what is often misunderstood about predictive analysis for spindles is that, yes, you can avoid the upfront cost of a predictive solution by relying on your own ears and waiting until you hear a problem. But your ears are not nearly sensitive enough to detect the early problems.
You not only miss out on the considerable reductions in repair costs, but also have to suffer through the unplanned downtime that a predictive solution helps you avoid. In practice, spindle predictive analysis tools allow you to hear problems in their earliest phases before they grow into much more complex (and expensive) issues.
The Value of Spindle Predictive Analysis Data
The key to developing a full understanding of spindle predictive analysis is recognizing the value of timely and accurate data. After all, the collection and analysis of data is the primary purpose of predictive analysis solutions.
Predictive analysis utilizes a variety of testing methods to collect informative data. These include vibration analysis, thermography, and ultrasound. Let’s focus on the big one: vibration analysis. Not only are vibrations the most common indication of stress in CNC machining processes, but they also can represent the most damaging threats.
Another word for “vibration” is “frequency. As a healthy, well-balanced spindle turns it creates a specific frequency. Predictive tools monitor this frequency and watch for changes. And just as humans make sounds with our larynxes to share information — or data — with each other, your equipment’s vibrations are sharing data with you. Should a bearing start to wear or the spindle become out of balance, the frequency change is obvious, and corrective actions can be taken.
Unfortunately, no matter how finely tuned your ear is, you’re physically limited in regard to the range of vibration that you can perceive. A spindle vibration detection and analysis system, on the other hand, can perceive subtle changes far sooner than humans can — and alert you to the changes before it’s too late.
What Vibration Analysis Does
A vibration analysis system monitors these frequencies (vibrations) and helps you understand what’s vibrating, how it’s vibrating, and even why — and it can give you important clues to the failures that these vibrations can lead to.
Some of the conditions that vibration monitoring can reveal include:
Spindle Bearing health— Bearing failure is a natural phenomenon; vibration monitoring makes tracking bearing lifecycle simple, eliminating surprise failures when done properly.
Imbalance — Often a tooling issue, but could be something else, such as a bad motor brush, for instance.
Misalignment — Shafts that are out of alignment put strain on spindles, resulting in a loss of power transmission as well as damage to, and even failure of, the bearings, couplings, and other associated components.
Looseness — Looseness in your CNC equipment manifests as vibratory sub-harmonic frequencies.
Mechanical wear— Can occur in couplings, bearings, support structures, etc.
Other — These include machine drive issues, lubrication issues, and other failing internal components.
Each of these problems causes different vibrations (frequencies) and, as you use and learn a vibration monitoring system, you’ll learn to spot the signs of each. Over time, the goal is to correlate what you see in the data with what’s specifically happening within the machine.
Understanding the Data
It can seem intimidating to suddenly have access to all this data, especially before you’ve gotten a handle on how to interpret it. If you implement a high-quality spindle predictive analysis system, however, the software will help with the interpretation.
Even if you use a system like this at its most basic level — one measurement taken and recorded periodically — you’re going to see a benefit. After all, as they say, three pieces of data shows a trend, and, “a trend is your friend”. It gives you something to evaluate and compare over time.
The point is that if you are serious about reducing spindle repair and maintenance costs, and about minimizing unplanned downtime, doing the old ear check isn’t going to cut it. You need a robust set of current and accurate data — and spindle predictive analysis is the best way to get it.
May 16, 2024
Precision Matters: The Importance of Quality Spindle Rebuilding
One of the universal truths of business is that not every supplier provides the same commitment to quality and process as others. Some take shortcuts to get through jobs quicker, building their business on throughput. Others, like us at GTI, prefer to do jobs right, from bottom to top, building a business on results and reputation. When it comes to getting your spindles repaired or rebuilt, it’s critical to work with a supplier that provides quality, thorough work.

It’s no secret. Spindles are a cornerstone in manufacturing, with CNC machine tools performing so many functions — boring, drilling, routing, grinding, milling, sawing, cutting, and more. Without a properly functioning spindle, work comes to a halt, leading to a loss of productivity and income. To avoid unplanned downtime, a proficient facility manager will have a preventative maintenance strategy in place. However, a subpar spindle repair job, prone to sudden failures, can disrupt even the most carefully crafted schedules.

Of course, minimizing unplanned downtime isn’t the only benefit of properly rebuilt spindles. The quality of a rebuild also has an impact on the quality of the work you’re producing. Even the slightest imperfections or balance issues, easily missed if the rebuilder isn’t paying careful attention, can directly and negatively impact the precision and quality of your machined components.

A High-Quality Spindle Rebuild

Every spindle repair company and technician will have their own “trade secrets” — we certainly do — but there are a number of steps that are an absolute must for a high-quality spindle rebuild:

Evidence of Improper Lubrication
Cleaning — During disassembly, every surface of every part of a spindle should be carefully cleaned in preparation for inspection.

Inspection — It’s important to identify the primary cause of failure. It takes care and experience to properly conduct a thorough and detailed inspection to shine light on the contributing issues. At GTI, we hand-inspect every single component of every single spindle that comes through our doors.

Measurements and documentation — During inspection, all parts of a spindle, its shaft, and its housing should be measured and documented.

Failure analysis — Every rebuilt spindle should come with a detailed report on what caused the failure. Having this valuable and often actionable information could help prevent future failures, when responded to properly.

Only after these steps are taken should a spindle repair technician then begin the process of repairing and replacing parts.

After the rebuild itself is complete, there are further steps that a shop should take before they return the spindle to its owner:

Testing — A range of tests should be conducted to ensure that the reassembly process was conducted correctly.

Balance adjustments — Spindles are super-precise instruments that need to be balanced on multiple axes to ensure proper operation. At GTI, we dial spindle balance measurements to higher-than-OEM specifications.

What to Look for in a Spindle Rebuilder

Simply put, not every spindle repair job is equal because not every spindle repair shop is equal. But how do you know if the one you’re considering is the right one? Here are a few things that all top-tier spindle repair shops share:

A good shop will have experience, over a long period of time, with a wide range of different OEM brands. Keep in mind, there are spindles from over 350 manufacturers out there!

They will guarantee their repairs and rebuilds meet or exceed original OEM specifications.

They conduct extensive testing and balance adjustments to do so.

And finally, a top-tier shop will offer a top-tier warranty. For instance, all GTI-rebuilt spindles come with a full one-year warranty that kicks in when it’s put back into service, as opposed to when it’s shipped, no matter how far in the future that is.

When it comes to rebuilding your spindle, precision matters. Cutting corners and saving a few dollars will most likely cost you in the long run. Don’t take chances. Choose an experienced shop that has a quality-driven process in place, to ensure a proper and reliable spindle rebuild that will last.

Looking to repair or rebuild a spindle? We can help! Click here to learn more about our spindle repair services.
April 1, 2024
What Is Machine Tool Monitoring?
Machine tool monitoring has become an indispensable asset to machine shops operating in today’s competitive manufacturing landscape. Reactive maintenance strategies are no longer sufficient in an environment where customers will not tolerate unexpected machine tool failures that impact production schedules, delivery dates, and part quality. Implementing monitoring-based predictive maintenance practices allows manufacturers to solve problems early and gain a proactive edge, ensuring efficient operations, happier customers, and cost savings.

A successful up-time strategy boils down to three actions: detect, analyze, and correct. Let’s review each:

Detect

Machine tool monitoring solutions use sensors, like the one shown here, to collect key performance data.

Early detection of equipment issues is the goal for all machine tool monitoring programs. This allows maintenance teams to plan for repairs or changeouts during planned outages to minimize unexpected disruptions. Key technologies for monitoring machine health include vibration analysis and acoustic emission (ultrasound) monitoring. Vibration helps identify problems like imbalance, misalignment, and looseness before they escalate into critical failures. Ultrasound, on the other hand, excels at detecting early-stage bearing faults, often even before vibration anomalies appear. Remember, as we’ve discussed in the past, these earlier issues aren’t audible to the human ear. Therefore, having ultrasonic sensors “listening” becomes crucial.

Vibration and ultrasound technologies work together to help technicians understand what actions may be taken to correct the problem early. They can also predict how much time is left until scheduled maintenance must be planned. Through data trending, an important part of machine tool monitoring, both vibration and ultrasound measurements are watched over time to assess machine health and predict potential issues. This involves comparing collected data to established baseline levels and industry standards like ISO 10816 for vibration alert and alarm levels. Exceeding these thresholds signifies that there are potential problems that require investigation.

Ultrasound is measured in decibels (dB). Ultrasound standards developed by NASA can also be compared to the ultrasound trend. For instance, when compared to the collected baseline, an increase of 8 dB indicates that a machine tool’s bearing is under-lubricated. Lubricating the bearing will lower the ultrasound level back to an acceptable level and a new baseline can be established. An increase of 12 dB means that the bearing has moved into late-stage bearing failure.

Analyze

Data is collected and charted for technicians to analyze and compare against benchmark readings.

Trends are monitored until an alert or alarm sounds. Once the readings exceed acceptable vibration levels, it’s time to analyze the data. This is done by trained analysts, online analysis tools, or remote third-party professionals.
Once an issue arises, its cause must be determined. Analysis can indicate how to mitigate the problem so it can be caught early. Faults like imbalance, misalignment, and looseness cause the majority of machine tool problems, leading to bearing failure, and early intervention can prevent complete failure.

A complete Failure Mode and Effects Analysis (FMEA) should be performed to determine the root cause to eliminate and prevent this fault from occurring in the future.

Correct

Detection and analysis are a big part of any machine tool monitoring program, but correction is where the rubber meets the road. Determining when to intervene can be difficult. Here are some questions to ask:
- Can or should production be interrupted to perform the repairs?
- What is the cost of repair and downtime if we run it to failure?
- When is our next maintenance outage and will it last that long?
Once a fault is found, it needs to be documented. Repair planning and scheduling need to happen. Parts and the proper tools need to be part of the planning and scheduling process, as well as the scheduling of the technicians and millwrights with the training and knowledge to do it right the first time.

Machine Tool Monitoring – It’s Time

Detecting, analyzing, and correcting problems early with machine tool monitoring can reduce maintenance costs by as much as 50% and increase uptime by as much as 30%. Proper training in the use and application of predictive maintenance tools is essential to your success.
Predictive maintenance solutions are becoming less expensive, simpler to use, and readily available. Is this your year to start a machine tool monitoring program?

> Click here to learn more about our industry-leading machine tool monitoring solutions
March 4, 2024
Understanding The Three Approaches to Spindle Maintenance: Reactive, Preventive, and Predictive

This spindle bearing nearly failed due to stress and fatigue.

In machining, there’s no denying that some form of spindle maintenance should be in place to mitigate failures and downtime. While the ultimate goal of any maintenance strategy is to reach net-zero downtime, the method employed will dictate how close manufacturers can come to achieving that goal. Approaches to spindle maintenance fall into three categories: reactive, preventive, and predictive. Understanding these levels will help in determining which strategy is best for you.

They are as follows:

Reactive

Although dated, widely practiced reactive maintenance is just that: racing to remedy spindle failure after a fault has already occurred. With reactive maintenance, you will always experience unplanned downtime. Even if you’re prepared and have a back-up spindle on hand, swapping them out gobbles up time and labor resources. In addition to costly production halts and delayed schedules, the spindles themselves are prone to a shorter life expectancy as they are run closer, if not to a literal breaking point. Since reactive methodologies often result in finding quick solutions, spindle efficiency is greatly reduced. This affects both its health and the organization’s bottom line as additional resources are consumed to keep pace with production timetables. This is especially true when smaller spindle issues are ignored at first. Remember, as we mentioned in the past, if you can hear a spindle issue, chances are it’s in a later stage of failure. The later the stage, the greater the failure, and costlier it is to repair or replace it.

Preventive

Also known as planned maintenance, preventive maintenance is the first tier of machine monitoring that is tailored to reduce occurrences of unplanned downtime. Conducted based on usage or time triggers, spindle maintenance is routine. While this strategy is effective in avoiding unplanned downtime, the cost of servicing machines based on usage as opposed to analytics results in some cases, over-servicing the machines. It also requires exceptional record keeping, and a commitment to sticking with the schedule. It’s easy to put off, especially if the machining center is in the middle of a production run. But kicking this can down the road is risky and could lead to much bigger, yet completely avoidable breakdowns and repairs.

Predictive

A tech monitors the health of a spindle using our VibePro Spindle Monitoring Software.

Driven by the Internet of Things (IoT) and rooted in data collection and analytics, predictive maintenance utilizes spindle condition monitoring to pinpoint at-risk units and identify smaller issues before they get out of hand. This is in stark contrast to reactive and preventive strategies.

Predictive maintenance programs provide floor technicians with the ability to not only identify faults, but also enable informed diagnoses to enhance efficiency and extend a spindle’s life expectancy. In addition to monitoring vibrational and ultrasonic frequencies, many predictive programs utilize thermography technology to identify the slightest decrease in performance so it can be corrected quickly to minimize downtime.

As the most proactive approach to managing machine health, a well-designed predictive maintenance program, employing solutions such as our VibePro spindle monitoring system, can decrease manufacturing costs by reducing downtime and maximizing machine efficiency.

To enjoy the operational benefits and cost savings of predictive strategies, contact us to learn more about our powerful, industry-changing machine tool monitoring solutions.

February 15, 2024
Understanding the Four Stages of Spindle Bearing Failure

Spindle bearing failure due to contamination.
Bearing failure is a leading cause of spindle breakdowns. The truth is, it’s easy to take bearings for granted. Out of sight, out of mind. But bearing systems are at the heart of every spindle and can’t be forgotten. They’re highly engineered and manufactured to hyper-precise tolerances. As such, they require strict maintenance protocols and ignoring these protocols can rapidly lead to otherwise avoidable bearing failure and costly spindle repairs.
In the best-case scenario, bearing failure puts your spindle out of action until it can be swapped out, leading to unproductive downtime and high repair/replacement costs. That’s the best case: in the worst case, failed bearings can do tremendous damage on the way out, potentially ruining the spindle. Repair costs are now in the several thousand-dollar range, deadlines are missed, and everyone gets frustrated – customers, your employees, and management.
Fortunately, the bearings in modern spindles fail in four distinct, identifiable stages. This is good news because — with the right attitude about maintenance and with a good predictive monitoring system in place — you can closely track your bearings’ health and schedule repair or replacement prior to failure.
Stage 1: Normal Operations
Because of the immense physical stresses they’re subjected to, bearings’ first stage of failure typically falls well within normal operations parameters. At this stage, vibrations at ultrasonic frequencies — from 1,200K to 3,600K cycles per minute (CPM), or 20,000 to 60,000 Hertz (Hz) — indicate that lubrication in the bearings is beginning to thin and bearing-to-raceway contact has begun.
Check lubrication levels, increasing or amending as necessary, and continue production.
Stage 2: Micro-Pitting
Left unmitigated, decreased bearing lubrication leads to increased friction, which contributes to the development of micro-pitting on bearings as well as raceways, which in turn further increases friction. Bearings exhibiting advanced micro-pitting will generate resonance detectable in the range of 120k to 480k CPM (2,000 to 8,000 Hz).
Though plant owners and managers are often hesitant to do so, it is at this point that bearings in highly critical machinery should be replaced, ideally at the next reasonable opportunity.
Stage 3: Increased Wear
This spindle bearing failed due to lack of proper lubrication.
Bearings at stage 3 of failure display plainly visible imperfections if disassembled and observed. In terms of vibration, harmonic frequencies appear, as well as sidebands, which are additional modulator frequencies that bracket the primary frequency.
At this point, both critical and non-critical equipment should be shut down for immediate bearing replacement.
Stage 4: End of Life
Evident in the reduction and ultimate loss of standard vibration frequencies, plus the rise of random vibration spikes (particularly in the lower frequencies), stage 4 bearing failure indicates that your bearings have entered the end of their usable life.
At this point, failure is imminent. Ideally, no equipment should ever be pushed to this point.
Vibration Monitoring and Predictive Maintenance
As we’ve alluded to, deciding when to repair or replace bearings in equipment can be a bit of a balancing act.
In reality, it is common to find plant owners and managers who push their equipment right up to the breaking point, thinking (incorrectly) that this is the best way to get the most out of their spindle — their machinery goes down less often, but the repair costs and downtime costs can be immense.
In a perfect world, every plant manager replaces bearings at the first reasonable opportunity after bearings enter stage 2 — this requires equipment to be brought down more often (relatively speaking), but for shorter durations and at dramatically lower costs. A realistic solution is, perhaps, somewhere in the middle.
Whatever your philosophy, it is important to know the status of your bearings’ health at all times. The only way to do this effectively is with a well-designed network of vibration sensors connected to high-quality vibration monitoring and analysis software, such as our VibePro spindle monitoring system. With this type of predictive maintenance program in place, you can easily find a safe, cost-effective balance between production and maintenance.
> Click Here to Learn More about Our Spindle Analysis Tools, Designed to Prevent Costly Failures

February 1, 2024
How Investing in Predictive Maintenance Can Boost the Bottom Line

Equipment maintenance is one of the biggest cost centers for many manufacturers. Machine tool operators are certainly no exception to this rule. Maintenance programs of the past sought to increase the uptime and lifespan of spindles by ensuring they were well cared for on a routine basis, thus minimizing the chance that they would break down at the worst possible time (which they always seem to do), halt production, and negatively impact work order completion rates.
More and more machine shops are now looking to technology to see how investing in sensor systems and data analytics software might further optimize productivity, uptime, and profit. This is achieved by minimizing spindle repair costs and downtime by conducting maintenance before minor issues lead to much costlier ones. This is the key to success with any predictive maintenance program.
Why is Predictive Maintenance Easier Now than Before?
While the concept of predictive maintenance isn’t new, it’s much easier and more affordable today due to technological advancements in sensors, data storage, and AI-driven analytical software. These three key pieces of technology combined, provide the ability to intelligently predict maintenance and service requirements. They yield higher levels of accuracy as they can track and analyze current machine readings and historical data, measured against expected machine performance.
Sensor Accuracy and Lower Data Storage Costs Make Predictive Maintenance Affordable
It’s important to appreciate just how quickly technology has progressed in the previous two decades. Not only have our devices gotten smarter but the cost of accessing high-speed internet and cloud data storage has made accessing “big data” a possibility for almost every business. This combined with the increased accuracy and effectiveness of sensor technology means that many machine shops can invest in a predictive maintenance solution with very low overheads.
However, it’s vital to understand that predictive maintenance programs are only as good as the historical data they use. This is why it’s crucial to start collecting benchmark data from the day your new or repaired spindle is installed, as we discussed in a previous blog. Delaying investment in predictive maintenance prolongs the time it takes for a business to collect the mission-critical data required for these programs to be effective, competitive, and show a return on investment.
What Are You Waiting For?
So, for those of you who haven’t implemented a predictive maintenance program to protect your spindles: what are you waiting for? Now is the time to do it since system costs are relatively lower, while accuracy is up. Having an affordable yet proven solution in place is like having a crystal ball. It will allow you to diagnose and resolve relatively minor spindle problems before they grow into much larger, costlier ones. This adds up to lower repair and replacement expenses over time, less downtime, and happier customers. All of which contributes to a healthier bottom line.
> Click here to learn about our Predictive Maintenance Solutions for Spindles & Machine Tools

January 18, 2024