Services
Industrial Furnace Refurbishment & Modernisation
Getting More from Existing Systems
A 15-year-old industrial furnace with a sound shell and outdated electronics is not a liability, but an opportunity. The mechanical structure of industrial furnaces is designed for decades. What ages is the controls, safety relays, thermocouples, insulation and heating elements: all replaceable.
NTH Therm modernises industrial furnaces of all manufacturers and types to current standards: new PLC, touch HMI, up-to-date safety technology, and optionally new process capabilities. The result is a system that in terms of operation, safety and energy consumption is barely distinguishable from a new build, at 30–60% of new-purchase cost.
When Does Modernisation Make Sense?
| Signal | What It Means |
|---|---|
| Ageing PLC (S5, older S7-300) | End of spare-part supply; security risk; no remote access |
| No touch HMI / no data logging | Missing traceability for ISO / IATF / CQI-9 / AMS2750 audits |
| High energy consumption | Outdated control strategy, poor insulation, over-heating |
| Outdated safety technology | Non-compliant with EN ISO 13849; DGUV-3 failed |
| Desire for new processes | New application (protective gas, carburising) requires new sensors/control |
| Frequent faults | Wear in heating elements, thermocouples, control hardware |
What NTH Therm Modernises
Control and Visualisation:
- New PLC (Siemens S7-1200 / S7-1500, TIA Portal)
- Touch HMI with intuitive interface (Siemens, Weintek or equivalent)
- Recipe management with unlimited programme positions
- Data recording and export (USB, network, cloud-ready)
- Secured VPN remote maintenance access
- Optional: OEE integration (Evocon or equivalent) for availability tracking
Safety Technology:
- Safety-rated relays (Pilz, Siemens Safety) per EN ISO 13849 / SIL 2
- New emergency-stop chain, door safety circuit, light-curtain interface
- Over-temperature protection, gas monitoring, pressure monitoring (atmosphere furnaces)
- DGUV-3 inspection and complete CE documentation on completion
Temperature Measurement and Control:
- New thermocouples (Type K, N, S or B to match temperature range)
- PID control with self-optimisation (auto-tuning)
- Multi-zone control for improved temperature uniformity
- Oxygen probe and carbon-potential controller (for carburising / protective gas)
Heating System:
- New heating elements (NiCr wire, Kanthal, SiC or MoSi₂ to match temperature range)
- Power optimisation via modern phase-angle or zero-crossing control
- Thyristor control for wear-free switching
Insulation and Mechanical Components:
- New refractory lining (ceramic fibre, vermiculite, firebrick to match requirements)
- Renewal of door and bogie seals
- Bogie drive and guide-rail overhaul
What You Gain from Modernisation
- 15–30% energy saving through improved control strategy and new insulation
- 15+ additional years of service from the mechanically sound structure
- Audit compliance for ISO 9001, IATF 16949, CQI-9, AMS2750, NADCAP
- New process capabilities without a new purchase (e.g. add protective-gas capability)
- Fewer faults through replacement of worn components
- Remote diagnostics via integrated remote maintenance access
Process-Expanding Modernisations
Modernisation does not have to target the status quo. We also extend existing systems functionally:
Add protective-gas capability: Equip a chamber furnace with N₂ inlet, atmosphere valves, oxygen probe and automatic purge sequence. Result: protective-gas annealing enabled, without a new furnace.
Add carburising capability: Extend an existing hardening furnace with carbon-potential control, endothermic gas supply and exhaust combustion. New application fields: case hardening of gears, shafts, pins.
Add multi-zone temperature control: Uniformity improvement in large chamber and bogie-hearth furnaces through independently controlled heating zones.
Integrate OEE monitoring: Connection to Evocon or comparable OEE software for availability tracking, batch data logging and predictive maintenance planning.
Modernisation Project Sequence
- Initial assessment: condition survey based on technical documentation (remote or on site)
- Quotation and scope of work: clear definition of all components, deliverables and dates
- Dismantling and refurbishment: carried out in our workshop or at the customer’s site
- Commissioning: on-site commissioning, process trials, calibration
- Documentation: DGUV-3 report, CE documentation, PLC source files, wiring diagrams
- Training: operator briefing on new controls and functions
Frequently Asked Questions
Is modernisation worthwhile compared to buying new?
Yes, when the mechanical structure (furnace shell, insulation, bogie hearth, load-bearing framework) is still in good condition. This is often the case, as mechanical components last significantly longer than controls and safety systems. Full modernisation typically costs 30–60% of a comparable new build, with a comparable result.
Which control systems does NTH Therm use for modernisations?
We work preferably with Siemens S7-1200 and S7-1500 (TIA Portal). For simpler applications also with Unitronics, Schneider Electric or other standard market systems, depending on requirements and the customer's existing infrastructure.
Can I unlock new processes through a modernisation?
Yes. A basic chamber furnace can be extended with an N₂/H₂ atmosphere circuit, oxygen probe and automatic purge sequence to enable protective-gas annealing, without buying a new furnace. An existing hardening furnace can be fitted with carbon-potential control for carburising. We assess your system's modernisation potential as part of our initial analysis.
How long does a modernisation project take?
Simple control modernisations (new PLC + HMI) typically take 4–8 weeks. More comprehensive projects including insulation renewal, new heating system and new capabilities (atmosphere, multi-zone control) can take 12–20 weeks, depending on scope and material availability.
Do you modernise furnaces from other manufacturers?
Yes, we are brand-agnostic. We have modernised furnaces from Nabertherm, Linn, Thermconcept, Heraeus, Carbolite and various international manufacturers. Prerequisite: provision of technical documentation or a chargeable condition survey.
What happens to DGUV-3 compliance after modernisation?
After every modernisation we carry out a full DGUV-3 inspection to DIN VDE 0100-600 and issue a new inspection report. The system is then fully standards-compliant, including CE documentation for significant modifications.