Author: info@echeloncomm.com

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
Critical Spindle Installation Steps: Balance Correction & Vibration Baselining

Previously, we discussed the importance of proper spindle installation. In particular, we reviewed important basic steps — pre-installation inspection, mounting, lubrication hookup, post-installation inspection, and start up/run in.

But there are two steps that we left out of that blog. Not because they’re important, but because they’re the most important. Those steps are balance correction and vibration baselining.

Balance Correction

Spindles are super-precision components with incredibly precise operating parameters. Testing the balance of a spindle is a good way to help ensure a new spindle is installed and will perform correctly.

While spindles are shipped from manufacturers and repair facilities already carefully balanced, that balance can easily be thrown off by rough handling during shipment or, more commonly, the installation of mounting accessories. Every different mounting accessory you include during a spindle installation will have an impact on the standard balance.

For that reason, you should check the balance of a newly installed spindle as soon as it is properly warmed up. Use a solution such as BalancePro. We developed BalancePro years ago as an iOS app for testing the balance of both one- and two-plane rotating machinery, like spindles. It’s a powerful tool for not only helping you to balance spindles, but for collecting and storing data for a variety of metrics (popover, amplitude, polar plot, and more).

Vibration Baselining

After your spindle is in balance, the next step is to gather baseline vibration measurements. Vibration measurements are less common but arguably as important, if not more so, as balance correction.

As high-velocity instruments, spindles vibrate as a natural part of operation. If you get measurements of your spindle’s standard vibrations immediately after installation, when it’s at its cleanest and most perfectly balanced, you have incredibly valuable baseline numbers to measure future data against.

As you continue to run your CNC and spindle in daily operations, you can take vibration measurements and compare them to your baselines. High-quality vibration measurement equipment can detect minuscule changes in vibration that an unaided human operator could never notice.

This gives you astounding insight into the inner workings of your spindles, providing warnings about developing issues long before they become catastrophic failures. You can save tremendous amounts of money in unexpected repair or replacement costs, all thanks to getting a vibration baseline measurement during installation.

Be sure to use a field-proven solution, such as our VibePro, to collect and record accurate vibration measurements. VibePro is an expansive turnkey spindle monitoring system consisting of discreet three-axis omnidirectional vibration sensors and an expansive iOS app for collecting, storing, analyzing, and sharing vibration data.

Conclusion

While all the steps of a spindle installation are important, balance correction and vibration baselining stand out as particularly so. All of the care you take during mounting is for nothing if you don’t ensure that your spindle is properly balanced at the end. And you’ll be operating virtually in the dark, in regards to your spindle’s health, without baseline vibration measurements.

In short, it’s imperative that you carefully follow all of the steps while installing your spindles — otherwise, you’ll be in for a world of hurt somewhere along the line.

November 20, 2023
Spindle Installation: Getting it Right the First Time
We understand the impulse to get a new spindle installed, and up and running, as quickly as possible. Time is money, after all — especially in fiercely competitive manufacturing spaces.

The fact is, though, that in their desire to minimize costly downtime, many CNC operators rush the spindle installation process. This simply sets the stage for bigger and more expensive issues down the road.

It pays to do it right, so here’s a refresher.

Why take the time to install a spindle properly?

Most maintenance questions relating to spindles boil down to one simple equation: pay now or pay more later.

That might seem reductive, but it’s the truth. You can periodically pull spindles for regularly scheduled maintenance, costing a few hours of downtime to do the swap; or you can wait for a catastrophic failure, costing tens of thousands in repair or replacement costs, plus many more in unplanned downtime.

The same holds true for new spindle installations. It may take a couple more hours than you’d like in order to do a good, thorough, by-the-books installation of a new spindle, but you’ll be saving yourself untold thousands of dollars in expenses later on.

Proper spindle installation

Spindles are super-precision instruments that require the highest degree of care, handling, and calibration. This means that installation can be rather a complex process.

Every CNC machine and every spindle is unique. As such, they each have unique installation processes. The steps detailed below should be considered general guidelines — always follow manufacturer-provided process when installing a new spindle.

Safety

Do not perform any maintenance on any machinery without first disconnecting the equipment from power.

Pre-installation Spindle & Machine Inspection

Before installing a spindle, be sure to inspect both the spindle itself and the machine in which it is to be installed. Check the following:

Use caution to avoid impacts, which can damage spindle bearings

Clean all mounting surfaces, both on the CNC and the spindle itself

Mounting

Mounting a super high-precision component like a spindle is a delicate job, as even small mistakes can have notable impacts. While mounting:

Use chains or straps with enough lift capacity to minimize risk of drops

Do not force a spindle into position under any circumstance; if a spindle will not fit, stop and ensure that you’re attempting to mount it in the correct way

Back off immediately in the event of binding

Secure the spindle to standard torque values, unless other values are specifically called out in the manufacturer’s mounting instructions

Overtightened bolts will distort the spindle housing, which can result in instant spindle failure

Never use pipe dope, tape, or other compounds on the threads of lubrication fittings

Ensure that all mounting accessories — rotary unions, draw bars, pulleys, toolways, etc. — are clean, new (when recommended, like for rotary unions), and installed properly

Lubrication System Connection

After physically mounting a spindle, the lubrication system must be connected. Ensuring cleanliness of the system is of utmost importance, as there is no filter between the lubricator and the spindle. When connecting a mounted spindle to the lubrication system, consider the following:

Keep all hoses and fittings clean, inside and out

Ensure hoses are free from kinks

Never use any sort of fitting aid (pipe dope or PTFE tape)

Where possible, blow air through lines for at least 5 seconds to dislodge contaminants

After all connections are made, test the system:

On drip systems, calibrate air pressure

Test lubrication pressure

Test flow

Post-installation Spindle & Machine Inspection

There are a variety of tests and inspections that you should make before attempting to start up and run in your newly installed spindle. A few of these checks include:

Air purge/blow out

Direction of rotation

Distention

Encoder feedback

Runout

Taper blast

Tool knockout, changer alignment, and retention

Start Up & Run In

Starting up and running in your newly installed spindle is a critical phase in the installation process — if not performed correctly, all of the careful work you’ve done so far can be undone in seconds. You should always carefully follow the manufacturer-specified procedures, but you can see our blog post on spindle start up and run in for a helpful overview.

Conclusion

Spindles are delicate, super-precision components, which makes every stage of installation incredibly important. That’s why we put so much emphasis on following manufacturers’ instructions whenever available.

When installing a new spindle, make sure that you carefully follow all installation steps. This includes two extremely important considerations: balancing and gathering vibration reading baselines, which we’ll talk about next month — stay tuned.
October 24, 2023
Southtec 2023
Are you heading to Southtec? If so, come visit us at booth #1334, say hi, and sign up for a free on-site Spindle Health Analysis at your facility. Here’s why you need one:

Learn about potential issues in your system before they lead to much bigger ones

Avoid unplanned downtime, and all of the headaches associated with it, such as missed delivery deadlines and unhappy customers

Keep spindle repair costs in check by learning about and fixing potential problems before they become much costlier ones

If you haven’t registered yet, we’d love to have you as our guest. Click the button below to register. We hope to see you there!

Not going to Southtec?
You can still get an analysis through the month of October 2023. Simply submit a contact form, and include “Show Special” in the “How can we help you?” box. We’ll reach out to you to schedule a time. The service is free, but some restrictions apply, we’ll discuss those when we talk.

Register as our Guest
October 20, 2023
The Importance of Warming Up Your Machine Tool Spindle
Over the past three decades, we’ve had a lot of conversations with countless clients and prospects. As you can imagine, they tend to revolve around spindles and spindle care.

One topic that comes up regularly is the idea of doing a warmup cycle on your spindles. Responses have always been mixed — some do, some don’t, and some operate 24/7 and think they don’t have to but they do (when, for example, they replace a spindle).

We thought we’d take some time today to talk about the importance of warming up your spindles.

When and Why Does a Spindle Need a Warmup?

We recommend that you do a warmup cycle after your CNC machine has been idle — whether just overnight, after a weekend, or when a spindle is installed, whether it’s new, repaired, or just pulled from storage.

This is our recommendation for one major reason: lubrication distribution. If you crank a cold machine straight up to operating speed without taking the time to properly warm it up, you’re not giving the lubrication system time to distribute oil or grease evenly. This causes unnecessary friction, rapid temperature spikes, hastened lubrication breakdown, and damage that can be quite severe, and costly.

How to Warmup Your Spindle

There’s no universal way to warm up a spindle. Every machine has different runup and warmup procedures. For that reason, we always recommend that you follow the OEM’s instructions. If you don’t know them, reach out — they’re usually happy to help.

That said, there are a few general guidelines that you should be following:

Warm up your spindles at every start-up. Do it incrementally, monitoring temperature as you go.

For oil-lubricated spindles, wait until you see oil draining before ramping up to full speed, this tells you that oil has moved through the entire system, lubricating all the parts in its path.

Closely monitor temperature to be certain that the spindle isn’t running too hot. If the temp creeps out of the acceptable range, dial it back, and bring it back up more gradually.

Monitor vibration levels as well — if you have the right equipment, like VibePro, you can monitor your machine’s vibrations and glean a huge amount of real-time performance information.

The warmup cycle is especially important on a brand-new spindle. The process is typically referred to as “break-in”. Just like with an everyday warmup, a break-in cycle will vary by machine and maker, but here’s the general process:

Start the spindle at a fraction of its maximum speed

Run it for a while

Monitor temperature and vibration closely

If temperature and vibration remain steady, increase the speed by small increments

Repeat steps 2 to 4 until:

Maximum RPM is reached, and

Temperature remains stable and within spec, and

Vibration remains stable and in-spec

If at any time the temperature or vibration levels spike:

Stop the spindle

Return it to ambient temperature

Begin the process again, starting at a speed just slower than when you stopped

What Happens if I Don’t Do It?

Once or twice, if not severe, probably nothing (if you’re lucky).

But if you skip it habitually? Well, in short… eventually, you’re in for a world of hurt.

We’ve written at length about all the bad — and expensive — damage that a poorly cared for spindle can sustain. Overheating leads to premature bearing wear and aging. Wear and aging in the bearings of a spindle leads to inaccuracies and/or defects in your work product. They also, of course, lead to spindle failure and expensive repairs on a schedule that far outstrips maintenance expectations.

All of that without even factoring in the costs and frustrations caused by ever-looming unplanned downtime.

In short: putting your spindles through a warmup cycle may cost you some time here and there, but that’s nothing compared to the cost of shutting down your production line and rebuilding or replacing a damaged-beyond-repair spindle.
September 13, 2023