A twenty-year-old milling machine often still operates flawlessly from a mechanical standpoint. What’s missing is the connection to a modern monitoring system. This is exactly where a retrofit comes in: external sensors measure vibration, temperature, or current consumption and feed the data into a monitoring system without replacing the machine itself.
A retrofit costs 30 to 50 percent less than building a new facility and often pays for itself in less than 24 months. The overall equipment effectiveness (OEE) rises in the projects observed from around 30 percent to 50 to 60 percent, maintenance costs will drop by 20 to 30 percent. This requires a mechanically sound system with several years of remaining service life.
A retrofit costs less than building the same facility from scratch. For companies with tight investment budgets, this is an argument that a simple new purchase can rarely match.
Starrag and the VDI Center for Resource Efficiency via lion-smart, 2025
Retrofit Machine Digitization in Practice
| metric | Before | Afterward |
|---|---|---|
| Overall equipment effectiveness (OEE) | about 30 percent | 50 to 60 percent |
| Maintenance Costs | Reference | 20 to 30 percent lower |
| Standstill | Reference | 12 percent less in the sample calculation |
| Savings on a daily margin of 4,000 euros | Reference | 480 euros per day, about 120,000 euros per year |
Novo AI has observed these figures in digital transformation projects (Novo AI, 2026). According to estimates by lion-smart the return on investment is often less than 24 months (2025). The order of steps matters here: first the sensors show where wear or inefficiency actually occurs, after which retrofitting or maintenance can be targeted, instead of simply servicing everything more often.
How to Successfully Get Started with a Brownfield Project
A company with an established machine fleet should not attempt to digitize all of its systems at once. The standard approach involves starting with a single pilot line, where sensor technology, data connectivity, and data analysis can be tested before rolling out the system to other areas (allaboutautomation, 08/2026). This phased approach reduces risk and quickly delivers initial, reliable results.
When selecting a pilot line, the machine's age is less important than its significance to production. An older, non-critical auxiliary system provides little insight, even with perfect sensor technology. A critical line with a documented history of failures, on the other hand, quickly yields measurable results.
In practical terms, this also means that those in charge should agree on a reference period in advance. Without comparative figures from the months prior to the retrofit, it will be difficult to demonstrate the benefits later on. A simple before-and-after comparison of downtime is often enough to justify the investment internally.
Where Retrofits Reach Their Limits
Not every existing machine is equally suitable. Machines with heavily worn mechanical components or frequent operator errors provide sensor data that says more about the operator than about the machine’s technical condition. Integration also becomes more complex for machines whose control systems lack any interface and whose manufacturers no longer exist. Furthermore, a retrofit is no substitute for an overdue major overhaul. A machine with structural damage does not become more reliable simply by adding sensors; it merely provides earlier warnings of the next failure.
What a retrofit project typically involves
- Select measurement points. Not every machine requires the same sensor technology; a transmission requires a different type of measurement than a hydraulic pump or a conveyor belt.
- Assembly. With external sensors, this is usually possible without interrupting production, because the sensors are clamped to the housing or bearing location from the outside.
- Calibration. Collect measurement data and compare it with actual operating conditions. Only once it is clear how normal operation differs from the early signs of a malfunction can warning thresholds be set effectively. This phase lasts from a few weeks to a few months and is often underestimated.
- Integration into everyday life. Even the best sensor technology is of little use if no one regularly reviews the data or responds to alerts.
Retrofitting is therefore less of a purely technical project and more of an initiative for which maintenance, production, and often the IT department must share responsibility.
Is your system suitable for a retrofit?Tell us the machine type, year of manufacture, and the most significant malfunctions over the past two years. We’ll let you know if retrofitting is worth it.
Connection to the Control Architecture
A retrofit project rarely stops at the sensors alone. The data has to get out of the machine and into an analysis system, often across heterogeneous networks with older generations of controllers. How this connection can be implemented without interfering with running production lines is described in our article on Integration of OT and IT. The article illustrates the entire chain from the sensor to the key metric From Sensor to Dashboard.
Frequently Asked Questions
Which existing systems are suitable for a retrofit?
The most suitable equipment is that which is in good mechanical condition, plays a key role in production, and has a remaining service life of several years. Equipment that is about to be replaced or has structural defects will derive little benefit from additional sensors.
Is it necessary to modify the existing control system?
In most cases, no. External sensors can be installed on many machines without modifying the control system and operate in parallel with the existing system. This reduces the risk to ongoing operations and avoids disputes regarding the warranty and approval of the original control system.
What happens to the machine's warranty?
External sensors that do not interfere with the control system generally do not affect the warranty. If in doubt, it is advisable to consult with the machine manufacturer in advance, especially if the system is still under warranty or if safety-related components are involved.
The Next Step
torck builds the data chain from the sensor to the dashboard using its own plant monitoring product. Our teams in Maxhütte-Haidhof, Vienna, and Rabat also handle OT-IT integration in existing facilities, drawing on our own experience with established machinery fleets in industry and retail. For dates and further information, please visit our page at Plant Monitoring.
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