Magnetic Induction vs Eddy Current Coating Thickness Gauge Fe vs NFe Explained Malaysia
When buying a coating thickness gauge, you will often see terms such as Fe, NFe, magnetic induction and eddy current. What do they actually mean? The simple answer is: Fe is generally used for suitable coatings on ferrous metals such as steel. NFe is generally used for suitable coatings on conductive non-ferrous metals such as aluminium. Understanding this difference is essential when choosing a coating thickness gauge in Malaysia, because an instrument designed for the wrong substrate may not be suitable for your application. Dual-mode instruments such as the TASI TA521A and TA522A support both magnetic induction and eddy current measurement principles, allowing one gauge to cover many common industrial Fe and NFe applications. What Does Fe Mean on a Coating Thickness Gauge? Fe refers to ferrous substrate measurement. Typical ferrous substrates include: Steel Iron Mild steel Carbon steel Other compatible magnetic ferrous materials For suitable coatings over these substrates, a coating thickness gauge commonly uses the magnetic induction principle. A simple example is: Paint → Steel The coating itself is measured relative to the ferrous metal underneath it. What Does NFe Mean? NFe refers to non-ferrous measurement. A common example is aluminium. For suitable non-conductive coatings over compatible conductive non-ferrous substrates, the gauge can use the eddy current principle. A simple example is: Paint → Aluminium This is why users who need to measure both steel and aluminium should normally consider a gauge with both Fe and NFe capability. Magnetic Induction How Does It Work? Magnetic induction measurement is used for suitable non-magnetic coatings over magnetic ferrous substrates. Typical examples include: Paint → Steel Powder Coating → Steel Protective Coating → Steel The instrument uses the relationship between the probe and the magnetic substrate to determine the coating thickness. Because the method is non-destructive, the coating does not need to be cut or removed. This makes magnetic induction gauges useful for industrial QC and inspection. Where Is Magnetic Induction Used? Common applications include: Structural steel Steel fabrication Machinery Powder-coated steel Painted steel components Steel cabinets Electrical enclosures Automotive steel panels Industrial tanks Pipes Equipment frames Protective coating inspection For Malaysian steel fabricators and coating contractors, Fe measurement is one of the most common coating thickness applications. Eddy Current How Does It Work? Eddy curret measurement is used for suitable non-conductive coatings over compatible conductive non-ferrous substrates. Aluminium is one of the most common examples. The probe generates an electromagnetic field. Interaction with the conductive substrate changes according to the distance between the probe and the substrate, allowing the instrument to determine coating thickness. Again, the measurement is non-destructive. Where Is Eddy Current Measurement Used? Potential applications include: Painted aluminium Powder-coated aluminium Aluminium fabrication Automotive aluminium panels Aluminium enclosures Metal finishing Machinery components Architectural aluminium products Manufacturing QC Companies working with both steel and aluminium can benefit from a gauge that automatically supports both measurement principles. Fe vs NFe Quick Comparison ItemFeNFeMeaningFerrousNon-FerrousCommon SubstrateSteel / IronAluminiumMeasurement PrincipleMagnetic InductionEddy CurrentExamplePaint on SteelPaint on AluminiumPowder CoatingSuitable steel applicationsSuitable aluminium applicationsAutomotiveSteel body panelsCompatible aluminium panels The key point is that Fe and NFe refer to the substrate underneath the coating, not simply the type or colour of paint. Why Do You Need to Know the Substrate? Imagine two components that look identical after painting. Component A: Paint → Steel Component B: Paint → Aluminium Visually, the coating may look similar. But the underlying metals require different measurement principles. This is why the first question when selecting a coating thickness gauge should often be: “What is the substrate underneath the coating?” not simply: “What paint are you measuring?” What Is a Dual Fe/NFe Coating Thickness Gauge? A dual Fe/NFe coating thickness gauge combines both measurement principles in one instrument. This provides greater flexibility for users handling different metal substrates. For example, a factory may manufacture: Powder-coated steel cabinet → Fe and: Powder-coated aluminium panel → NFe Instead of keeping separate instruments for these suitable applications, a dual Fe/NFe gauge can cover both. The TASI TA521A and TA522A are examples of this type of instrument. TASI TA521A / TA522A Fe & NFe Capability Both models provide: Fe magnetic induction measurement NFe eddy current measurement Automatic substrate recognition General measuring range of 02000 μm Stated accuracy of ±(3% + 1 μm) Fe+Zn measurement capability Zero calibration μm / mm / mil measurement units 2 readings per second This allows the instruments to cover a broad range of compatible industrial coating applications. Why Automatic Fe/NFe Recognition Is Useful Automatic recognition simplifies operation when the user moves between different substrate types. For example: Measure steel → Instrument recognizes Fe then: Measure aluminium → Instrument recognizes NFe This can be particularly convenient for: Factory QC Metal fabrication Inspection companies Automotive inspection Powder coating companies The operator can work with different compatible substrates without manually changing between two separate instruments. Why Does TA522A Also Offer Manual Selection? Automatic operation is convenient, but professional users sometimes know exactly what material they are measuring. For example, a production line may manufacture only powder-coated steel parts during an entire shift. The operator already knows that the substrate is Fe. The TASI TA522A provides additional manual measurement mode selection, giving the operator greater control during repetitive work. This is why we generally position: TA521A → General / straightforward use TA522A → Professional / repetitive industrial QC The TA522A does not have higher stated core accuracy than the TA521A. Its advantage is additional operating flexibility. What About Galvanized Steel? Galvanized steel requires additional consideration because a zinc layer is present over the steel. A simplified structure is: Steel → Zinc and a painted galvanized product may be: Steel → Zinc → Paint The TASI TA521A and TA522A include Fe+Zn measurement capability, with TASI specifying an Fe+Zn range of 3500 μm. Users working with galvanized steel should describe the complete layer structure and specify which thickness they need to measure. Do not automatically treat every galvanized application as ordinary Fe measurement. What About Stainless Steel? The term “stainless steel” alone is not enough to determine the correct measurement mode. Different stainless steels can have different magnetic characteristics. Therefore, do not assume: All stainless steel = Fe or: All stainless steel = NFe If stainless steel coating measurement is your main application, provide the exact substrate information and coating system before selecting the instrument. What About Plastic? Standard magnetic induction and eddy current coating thickness principles rely on compatible metal substrates. Plastic is not a ferrous steel substrate and is not a conductive non-ferrous metal substrate suitable for these standard Fe/NFe measurement methods. Therefore, an Fe/NFe gauge should not automatically be assumed to measure paint thickness on: Plastic bumpers Plastic housings Composite panels Fibreglass components Different measurement technologies may be required. Fe/NFe for Automotive Inspection Modern vehicles can contain different panel materials. A vehicle may have predominantly steel panels while selected components use aluminium. A dual Fe/NFe gauge can therefore be more useful for professional vehicle inspection than an Fe-only instrument. However, plastic components remain outside normal Fe/NFe metal measurement. Fe/NFe for Powder Coating Companies owder coating companies are another strong application. A coating company may receive: Steel products → Fe and: Aluminium products → NFe Using a dual-mode coating thickness gauge allows the QC department to inspect both suitable substrate types with one portable instrument. This is one reason Fe/NFe capability is particularly useful for coating contractors and metal finishing companies. Common Buying Mistakes Choosing by Range Only A 2000 μm range is useful only if the instrument is compatible with your substrate. Ignoring the Material Under the Paint Always identify the substrate. Assuming NFe Means Any Non-Steel Material NFe measurement still requires a compatible conductive non-ferrous substrate. Assuming Fe/NFe Can Measure Plastic Standard Fe/NFe measurement principles are intended for compatible metal substrates. Assuming Automatic Detection Is Always Necessary For repetitive professional work on a known substrate, manual mode control may also be useful. FAQ What does Fe mean on a coating thickness gauge? Fe refers to ferrous substrate measurement, typically involving compatible steel or iron substrates. What does NFe mean? NFe refers to non-ferrous measurement. Aluminium is a common example of a compatible NFe substrate. What principle is used for paint on steel? Magnetic induction is commonly used for suitable non-magnetic coatings over ferrous steel. What principle is used for paint on aluminium? Eddy current measurement is commonly used for suitable non-conductive coatings over compatible conductive aluminium. Can one coating thickness gauge measure both? Yes. A dual Fe/NFe instrument such as the TASI TA521A or TA522A supports both measurement principles. Can Fe/NFe gauges measure plastic? Standard Fe/NFe coating thickness measurement requires compatible metal substrates and should not be assumed to work on plastic. Can TA522A automatically detect Fe and NFe? Yes. The TA522A supports automatic substrate recognition and also provides manual measurement mode selection. Is TA522A more accurate than TA521A? Their stated core accuracy is the same at ±(3% + 1 μm). TA522A's advantage is additional measurement mode control. Looking for an Fe/NFe Coating Thickness Gauge in Malaysia? Before choosing a coating thickness gauge, identify: 1. Your substrate steel, aluminium, galvanized steel or something else 2. Your coating paint, powder coating or another coating system 3. Your expected thickness range 4. Your inspection requirement MTM Precision supplies coating thickness gauges for metal fabrication, powder coating, automotive, manufacturing, steel structure and industrial QC applications. For users who need both magnetic induction and eddy current measurement, the TASI TA521A and TA522A provide Fe/NFe capability in one portable instrument. Contact MTM Precision MTM Precision Sdn Bhd No. 29-1 & 29-2, Jalan Bandar 18 Pusat Bandar Puchong 47160 Puchong, Selangor, Malaysia Website: www.mtmpre.com.my WhatsApp: +6016-660 7346 Email: mtmpre@yahoo.com
26 Aug 2026
