Contact Thickness Gauges
Alloy-Independent Strip Thickness Measurement with ±0.5 µm Accuracy
Contact thickness gauges are the most direct way to measure strip thickness. Two diamond-tipped transducers touch the upper and lower surface of the strip simultaneously. The distance between them is the true, absolute thickness — no calibration models, no alloy compensation, no assumptions about material properties.
Vollmer has manufactured contact thickness gauges since 1963. Nearly 2,500 systems have been put into operation worldwide, and the number grows every year. Many of the original installations are still in daily use, forming the measurement backbone in mills that have been modernised multiple times around them.
Our contact gauges — the VBM, VBK and VBF series — cover strip thicknesses from 0.005 mm (ultra-thin foil) to 19 mm (heavy plate), with accuracy down to ±0.5 µm. They are the industry reference standard for absolute thickness measurement.
How Contact Thickness Measurement Works
The measurement principle is elegant in its simplicity. Two transducers are positioned above and below the strip path. Each transducer has a diamond-tipped sensor that makes contact with the strip surface. The upper transducer measures its distance from a fixed reference point to the top of the strip. The lower transducer measures its distance to the bottom. The sum of these two measurements is the absolute strip thickness.
Because the measurement is physical — the sensors touch the actual surfaces — the result is independent of the strip's alloy composition, density, magnetic properties, surface finish, temperature, or the presence of rolling oil. A 0.5 mm strip of carbon steel gives the same reading as a 0.5 mm strip of stainless steel, copper, aluminium, or titanium. No alloy tables, no compensation algorithms, no recalibration when changing material.
The diamond tips are extremely hard-wearing and resist degradation even on abrasive strip surfaces. They maintain their geometry over extended service, which is one reason why Vollmer contact gauges remain in specification for decades of continuous use.
Auto-zeroing
When the gauge moves to its parking position during a coil change, the upper and lower transducers touch each other. The system registers this zero point and corrects for any drift. This automatic zeroing cycle runs at every coil change, maintaining measurement accuracy without operator intervention.
On the VBM XX65, an additional auto-calibration plate can be used: the gauge measures a plate of known thickness and corrects itself against this reference. This is useful in heavy-duty environments where thermal expansion or mechanical wear may affect the zero point.
VBF 1018
Application
Foil lines, copper or stainless-steel thin strip, laboratories and R&D facilities.
Why choose VBF 1018?
- Maximum resolution 0.1 µm
- Line speed 800 m/min without pre-press rolls
- Accuracy ±0.0005 mm
Selected specifications
- Thickness range 0.005 – 2.5 mm
- Gap 100 mm
- Sampling 1 kHz
- Averaging filter 1 – 2000 ms
VBM 1063
Application
Annealing, cold-rolling and skin-pass lines that require quick recipe changes.
Why choose VBM 1063?
- Motorised positioning ±1 mm, PLC recipe-controlled
- Accepts ±5 mm pass-line variation without support rolls
Selected specifications
- Thickness range 0.1 – 4 mm
- Max speed 500 m/min
- Accuracy ±0.001 mm
VBM XX65
Application
Heavy-duty cold mills, service centres and high-temperature strip lines.
Why choose VBM 1063?
- Measures up to 9 mm strip
- Auto-calibration plate swings in automatically at recipe change
- Maintains ±0.001 mm accuracy at 800 m/min
Selected specifications
- Modular gap 50 – 200 mm
- Optional head heater for strip temperatures > 40 °C
VBK 512
Application
Foil lines, copper or stainless-steel thin strip, laboratories and R&D facilities.
Why choose VBK 512?
- Simultaneous thickness 0.01 – 9 mm and width 1 – 18 mm measurement
- Accuracy ±0.001 mm (thickness) and ±0.002 mm (width)
- Operates at 600 m/min without loss of precision
Selected specifications
- Gap 100 / 165 mm (thickness vs. thickness + width)
- Sampling 1 kHz
Where Contact Gauges Are Installed
Contact thickness gauges are installed at every stage of the strip production process. Their alloy independence, absolute measurement principle, and long-term stability make them the default choice wherever physical contact with the strip is acceptable.
Cold rolling mills
The primary application. Contact gauges at the entry and exit of the mill provide the AGC system with the most accurate thickness signal available. The alloy-independent measurement means no recalibration when changing from one steel grade to another — the gauge measures the true physical thickness regardless of material.
Annealing lines
After heat treatment, strip thickness must be verified. Contact gauges provide the absolute reference that confirms the strip has not deformed during annealing. The VBM 1063's motorised positioning handles the different pass-line heights that occur with varying strip thicknesses on the same line.
Skin-Pass and Temper Mills
Final thickness verification after the skin pass. The elongation applied during skin-pass rolling changes the strip thickness slightly — the contact gauge confirms the final dimension is within specification.
Finishing Lines
Before the strip is approved for delivery, contact gauges verify that thickness meets the customer specification. This measurement becomes part of the quality certificate — the data logged by VRecoS provides traceable documentation for every coil.
Slitting Lines
At slitting operations, contact gauges verify the thickness of both the incoming master coil and the outgoing slit strip. For narrow strip and flat wire, the VBK 512's combined thickness and width measurement is particularly valuable.
Steel service centres
Service centres process material from many different suppliers and in many different alloys. Contact gauges are ideal for this environment because they measure any material without alloy-specific calibration. The incoming material is verified, and the outgoing product is measured and documented — all with the same gauge, regardless of alloy.
Metrology Laboratories and R&D
The VBF 1018, with its ±0.5 µm accuracy, is used as a reference standard in metrology labs. It provides the traceable thickness measurement against which other systems are calibrated.
Request a quotation for our contact thickness gauges
Contact us today for expert advice, a personalized quote, or a product demonstration. Let our experience and technical expertise guide you to the measurement solution that will elevate your quality assurance processes and drive operational excellence.