Services
TUS & Flow Simulation for Industrial Furnaces
Verified Temperature Uniformity and Flow Optimisation – From Measurement to Process Release
Reproducible heat treatment results require that the furnace can actually maintain the required temperature uniformity. The Temperature Uniformity Survey (TUS) is the central measurement instrument for this qualification — and is normatively required in aerospace, automotive supply chains and many other industries.
NTH Therm performs TUS measurements to AMS2750, CQI-9 and customer-specific requirements, and produces audit-ready documentation. We also offer numerical flow simulations (CFD) for temperature distribution analysis and loading configuration optimisation.
Temperature Uniformity Survey (TUS)
What is measured:
- Temperature uniformity across the entire working chamber (multi-point, up to 40 measurement positions)
- Heat-up behaviour and soak times at defined process temperatures
- Deviation from setpoint at each measurement point — the basis for furnace classification
Standards and norms:
- AMS2750 (NADCAP pyrometry, aerospace): Class 1–6
- CQI-9 (AIAG, automotive suppliers): Heat treatment classes A–D
- CQI-11 (induction hardening) and customer-specific requirements on request
Documentation delivered after TUS:
- TUS measurement report with temperature trace curves for all measurement points
- Furnace classification (system accuracy class) with validity period
- DAkkS-traceable calibration certificates for all thermocouples used
- Recommendations where deviations are found (control adjustment, heating circuit correction)
System Accuracy Test (SAT)
In addition to the TUS, we carry out the System Accuracy Test (SAT): a comparison between the furnace’s display thermocouple and a calibrated reference thermocouple. The SAT demonstrates that the furnace measurement system is within the required tolerance — a standalone verification requirement under AMS2750 and CQI-9.
Flow Simulation (CFD Analysis)
Application areas:
- Development of new furnace types: pre-validation of temperature distribution before the first prototype
- Loading optimisation: simulation of different charge configurations to minimise temperature gradients
- Fault analysis: localisation of cold or hot zones without an extensive measurement campaign
- Refurbishment planning: assessment of the thermal impact of planned modifications
Typical analysis parameters:
- Hot-gas flow and recirculated-air distribution
- Thermal radiation and convective heat transfer to the charge
- Temperature gradients within the charge (surface vs. core temperature)
- Influence of charge carrier configurations
When is a TUS required?
| Situation | Action required |
|---|---|
| Initial commissioning | TUS + SAT before production release |
| After repairs to heating or control system | TUS repeat required |
| After defined time intervals | Per AMS2750 / CQI-9 depending on class |
| Preparation for NADCAP audit | Complete TUS documentation mandatory |
| Temperature anomalies in production | TUS for root-cause analysis |
TUS for Third-Party Furnaces
We carry out TUS and SAT independently of furnace manufacturer. Prerequisites are accessible measurement ports (feed-throughs or openable measurement positions) and specification of the applicable standard and required temperature class. For furnaces without complete specification documentation, we assess qualifiability as part of a preliminary analysis.
Frequently Asked Questions
What is a TUS and when is it required?
A Temperature Uniformity Survey (TUS) is a multi-point temperature measurement throughout the working chamber of an industrial furnace. It is required by AMS2750 (aerospace / NADCAP), CQI-9 (automotive suppliers), CQI-11 and other quality systems. Measurement intervals depend on the furnace class: Class 1 furnaces (tightest tolerance) require more frequent TUS cycles than Class 6.
How many thermocouples are used in a TUS?
The number is governed by AMS2750 or the applicable standard and by the chamber volume. Typically 9 measurement points (corners plus centre) are used for standard chambers. Larger systems or tighter accuracy classes may require up to 40 measurement points. NTH Therm uses calibrated Type-K/Type-N measurement cables with DAkkS-traceable certificates.
How long does a TUS take and what does it cost?
Duration: 4–8 hours depending on furnace size, number of measurement points and the required heat-up cycles. Testing is carried out on site at the customer's premises. Results and report are typically available within 3 working days. Prices on request — they depend on furnace size, applicable standard and number of measurement points.
What is flow simulation used for?
Flow simulation (CFD – Computational Fluid Dynamics) models the hot-gas or recirculated-air flow inside the furnace chamber. It is used to analyse temperature distribution during furnace development, to optimise charge carriers and loading configurations, and to identify root causes of temperature non-uniformities without an extensive measurement campaign.
Can you carry out a TUS on third-party furnaces?
Yes. We perform TUS, SAT and temperature qualification for industrial furnaces from all manufacturers. Prerequisites: accessible measurement ports and provision of technical documentation for classification purposes.