Six years. $180,000 in tracked sensor and instrument purchases. One clear conclusion: SICK wire draw absolute encoders—the SICK encoder ATM60 in particular—outperform cheaper alternatives on total cost of ownership in nearly every application we've put them in. Not because SICK gives the best quotes. They don't. But because the failure-rate gap and the downtime math make a budget encoder anything but a budget decision.
I'm the procurement manager at a 140-person industrial automation company. I've managed our measurement and sensor budget (roughly $45,000 per year) since 2019, compared quotes from 40+ vendors, and documented every order in our own cost-tracking spreadsheet. I don't sell sensors and I don't get commission from any manufacturer. What I get is an earful from the maintenance team when a cheap purchase fails on the plant floor.
If you've ever signed a purchase order for the "value option" and watched it fail three months later, you know exactly where this is going.
The ATM60 Isn't the Cheapest Encoder. It Is the Least Expensive One.
Here's what our procurement records show. Between Q1 2023 and Q4 2024, we collected quotes for absolute encoders across three production projects: a SICK ATM60 with a wire draw attachment (also called a wire-actuated or draw-wire encoder—it measures linear travel with a spooled cable assembly) landed at $1,150–$1,450 depending on interface. PROFIBUS DP, CANopen, and SSI were the three we weighed. Comparable absolute encoders from lesser-known import brands came in at $700–$900 complete, meaning with wire draw mechanism included.
The tempting math, if you calculate nothing else: save $500 per unit, get nearly two spares for the price of three SICK units. I understand why purchase orders like that get signed.
But our data also shows that 6 of the 10 budget-class encoders we installed between 2021 and 2023 either lost accuracy or failed outright within the first 18 months of duty. That failure triggers a service call, a replacement, and—the figure that actually matters—production downtime.
Run the numbers: a line hour at our facility costs about $400 in labor and lost throughput. One encoder failure normally burns 3–4 hours of electrical and mechanical troubleshooting plus re-installation. That's $1,200–$1,600 of productive time, gone. The $500 saving evaporates the first time the cheap unit dies. (Surprise, surprise.)
On the reliability side, we've sent exactly two ATM60 units out for repair in six years. SICK isn't perfect—I'm not going to pretend we've never had a warranty claim. But the failure rate per operating hour is in a completely different league from the budget class.
The ATM60 also streamlined our spare-part storage. By standardizing on the ATM60 family across two lines, we reduced our encoder spare count from six distinct part numbers to two. Which means less capital tied up in spare inventory, fewer expired units on the shelf, and less confusion for the maintenance technicians who have to find the right spare at 2 a.m. That last one is hard to quantify, but anyone who's done plant maintenance knows it's a real cost.
Do You Actually Need a Wire Draw Absolute Encoder?
Quick reality check: if your machine runs a homing cycle at every startup, and position retention across a power loss doesn't matter, a wire draw absolute encoder is overkill. A good incremental encoder will do fine, and it'll cost less. We use wire draw absolute encoders for vertical-axis positioning, where gravity means a machine can shift position while powered down—and where the machine has to know its exact position the moment the control system wakes up.
In August 2023, we lost a full week of production because a budget absolute encoder on a vertical axis lost its zero reference after a short power dip. The machine homed to a wrong position and drove a tool head into a stop. The repairs cost more than our entire annual SICK encoder budget. (Ugh. That incident is burned into my memory.)
The Same TCO Lesson, Two Other Instruments
Encoders aren't the only category where I've watched cheap initial quotes create expensive follow-up costs. Two more stand out because they follow the exact same pattern.
Precision Balance: The $400 Saving That Cost Us $800
In 2021, I approved a budget precision balance for our calibration lab to save $400 against the lab manager's requested unit. The spec sheet looked fine—same readability, similar repeatability. But the unit drifted noticeably with temperature changes in the lab, and two calibration batches had to be redone at a cost of roughly $600 in labor. I ended up buying the unit we should have bought the first time. Net result: a "saving" that produced a loss.
Since then, our procurement policy requires that any measurement instrument used for validation decisions gets reviewed against the application, not just the price tag. (Not that the lab manager has let me forget the original mistake.)
True RMS Multimeter: Pays for Itself in One Fault Diagnosis
Here's the thing about true rms multimeters: they're priced maybe 2–3 times higher than an averaging multimeter with the same basic voltage range. But if you're troubleshooting variable frequency drives, switched-mode power supplies, or anything with non-sinusoidal waveforms, an averaging meter can be off by 20–40%. I've personally seen a 25% reading discrepancy on our VFD output in this facility.
That misreading creates a classic loop: the technician sees a voltage that looks wrong, swaps out a perfectly good drive, and sends the "faulty" drive to the repair bench for a $150–$300 assessment fee. One avoided misdiagnosis pays for the price difference between a budget averaging meter and a true RMS instrument. Our maintenance team now gets true RMS meters as standard-issue equipment. The first avoided service call after that policy paid for the price difference of the whole team's meters.
How to Install IFM Inductive Sensors Step by Step (Learned From a Failure Log)
I'm not a maintenance engineer, so I'm not the ultimate authority on sensing-distance derating curves or inductive-load suppression. What I can tell you, from the procurement side, is that between Q2 and Q3 2023 we replaced seven inductive sensors that failed in under a year—including a batch of IFM units installed by an external contractor. Every failure traced back to an installation error, not a product defect. After we standardized installation practice, the failure rate dropped by roughly 90%.
Here's the step-by-step approach that stopped the bleeding (it applies not just to IFM inductive sensors but to any brand we put on the wall):
- Confirm the output type before wiring. PNP vs. NPN and normally-open vs. normally-closed. Mismatching output logic against the PLC input card is one of the fastest ways to kill an inductive sensor.
- Check the supply voltage. Most industrial sensors, IFM's efector series included, run on 10–30 VDC per their datasheets. A sagging or noisy supply causes erratic switching and premature failure.
- Set the gap at 70% of the rated sensing distance. The spec sheet distance is the maximum in ideal conditions. Flush-mounted sensors inside metal deserve a further derate per the datasheet.
- Torque the mounting hardware to spec. Hand-tightened sensors drift. Over-tightened sensors stress the housing. Use a torque wrench and thread locker if the facility standard says so.
- Wire it correctly, then verify. Brown to L+, blue to L−, black to the input. Reversed polarity is fatal for most sensors. A quick continuity check with a multimeter costs 30 seconds and pays for itself in avoided replacements.
- Test with the real target before finalizing the mount. Confirm the output changes state with the actual metal target, in both directions. This catches wiring errors and gap mistakes in one pass.
- Protect the cable. A sensor mounted perfectly but with a cable rubbing against a moving part will fail within a year. Strain relief and cable routing matter as much as the mounting itself.
To be fair, none of these steps are a secret. IFM's installation documentation covers most of them, and so does SICK's. The gap between having documentation and having a checklist that gets enforced is exactly where our $1,500 failure log came from.
When the SICK ATM60 Isn't the Right Answer
Before you take this article to your procurement team and demand SICK everywhere, here's the counter-case: the ATM60 is overkill for simple, slow position sensing where a homing cycle runs at every startup. It's the wrong choice if the application demands a protection rating beyond what it offers, or if the mounting envelope simply won't accept a wire-draw mechanism. And if your budget is genuinely tight, buy a high-quality incremental encoder rather than a suspiciously cheap absolute encoder—the incremental one is at least being honest about what it is.
Also, prices quoted above are from quotes we collected in 2024 and early 2025; they will shift. Verify current numbers with your SICK distributor before building your budget around them.
One more honesty note: we're not a single-brand facility. We run IFM sensors on some machines, we use measurement equipment from multiple vendors, and our normal product mix is a lot messier than any brand campaign would suggest. The point isn't that SICK is the only reliable manufacturer out there—it's that the decision framework has to sit on total cost over the equipment's working life, not on whichever quote lands lowest in Q1.
This article reflects purchasing and operating experience at our facility as of April 2025. Product specifications, prices, and market conditions change—verify details against official sources such as SICK's website and current vendor quotes before making decisions.
