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Diameter, Eccentricity, concentricity

The diameter of an object can be established in different ways. If the centre of the object is known, a single sensor is sufficient for the measurement whose result is evaluated with the position of the centre point or the axis. If the position of the centre point is not known, the diameter is measured directly using two sensors. The distance information here is also evaluated together. In particular cases, if the opaqueness of the object allows this, the determination of the diameter can also be made directly using a confocal sensor.

3D measurement of coil springs

Qsigma designed the Spring Measurement System (SMS) for precise 3D measurement of coil springs and other components. It is used, among other things, in the development of prototypes and 100% inspection of series parts. The SMS automatically identifies the spring, evaluates the wire contour and determines the wire diameter, even if it is subject to strong fluctuations. 

The scanCONTROL 2950 sensor has a large measuring field in both the Z and X directions. This enables extremely fast scanning of springs up to a height of 70 cm and radially up to 30 cm. The wide range combined with high point density enables precise evaluation of the wire diameter


Automatic diameter testing of shafts

The Vertical Gauging Unit (VGU) is a measuring system for the precise and non-contact measurement of shafts and axes. The system is equipped with four optical micrometers and a laser distance sensor. The system enables measurements of axial lengths, diameters, concentricity and splines – achieving cycle times and accuracies that could never be achieved with manual measurement techniques.


Bore hole depth

It is essential to measure in bore holes for some applications. In doing so, the depth or the wall structure of a bore hole can usually be measured. Only confocal axial or radial miniature sensors with 4 mm external diameter are suitable for this. Triangulation sensors would not provide any measurement results due to the shadowing of the laser in bore holes. 


Brake disc concentricity

Brake discs are subject to the highest loads in use and are responsible for the safety of vehicles. For this reason alone, brake discs are thoroughly inspected on test benches. Brake discs are checked for various characteristics at a speed of approx. 2000 rpm on special testers. Capacitive sensors are used for checking the geometric characteristics such as concentricity, thickness and wear. As the deformations only occur in the range of hundredths of micrometers, only very precise sensors can be considered for this. The thermoMETER infrared sensors are used for examining the thermal characteristics of the brake disc. The absolute temperature can be monitored with these so that the thermal drift over a long period can be established.


Coil unwinding

Rolled strips in the metal industry are wound on coils for transport. For the later processing when the coils are unwound, it is important to know how much material has already been unrolled. This task is simple to solve by using an optoNCDT ILR optical length sensor. It continuously measures the distance from the surface of the coil to the centre. The thickness of the coil reduces due to the unwinding which is measured using the increase in distance from the coil surface to the sensor. Using the coil thickness, the material length can be recalculated using specific algorithms.


Coil diameter

Rolled strips in the metal industry are wound on coils for transport. For the later processing when the coils are unwound, it is important to know how much material has already been unrolled. This task is simple to solve by using an optoNCDT ILR optical length sensor. It continuously measures onto the surface of the coil and thus records the diameter. The diameter of the coil reduces due to the unwinding which is measured using the increase in distance from the coil surface to the sensor. Using the coil thickness, the material length can be recalculated using specific algorithms.


Stainless steel tubes for catalyst production

Various shapes of catalysts require that the stainless steel casing has a precise dimensional stability. For round catalysts, stainless steel tubes are therefore subjected to a diameter check in a special measuring system. A confocal sensor measures the distance to the tube, which is rotated through 360°. The outer diameter, the minimum circumscribed circle, and the maximum inscribed circle are directly determined by software calculations. The sensor moves in a horizontal direction, depending on the size of the catalyst.


Extruder bore diameter

The idiamCONTROL system has been developed for checking the wear of extruder bores. The measuring cylinder is inserted in the case bore and pushed as far as the upper end. During retraction of the cylinder, several capacitive sensors measure the case diameter on several tracks. Specially for double worm extruders, the measuring cylinder has two metal pins which run along the saddle of both bores and in this way prevent rotation of the cylinder.


Laser sensors support cable banding

Banding machines are used during the manufacture of cables in order to provide cables with a protective sheath. The wire runs centrally through a roll on which the banding material is coiled. The diameter of the roll must be measured constantly so that the tension of the material always remains constant. The challenges here are the metal bars which continuously cross the measuring range and the different materials for banding which can be matt or shiny.


Bearing shell detection in automotive manufacturing

The presence of the bearing shells is checked automatically for all bearing caps before the assembly of the engines at the Swedish automotive manufacturer, Volvo. The bearing caps are kept in the light band of an optical micrometer by robots. As the bearing shells and the bearing caps cover a part of the light band, a reliable OK/NOK inspection can be performed.



Measuring oscillation is a frequently occurring measuring task. Oscillations occur in research and development, in machines and plant construction as well as production control and are measured using sensors.

Oscillations as measured values are usually distinguished by high frequency and alternating amplitudes. Therefore the measuring instruments for oscillation measurement must also show high measuring speeds with high accuracy in order to achieve precise measurement results. Laser sensors, capacitive and eddy current sensors are particularly suitable for oscillating objects.


Diameter of a pulley

Diameter and concentricity are crucial factors for a long service life, due to the high rotational speeds achieved by pulleys. These parameters are evaluated on a special test bed, using four optoCONTROL digital micrometers. Two sensors on each level detect the outside diameter of the disc.


Acquisition of the internal diameter of tubes

An important criterion for the quality or the wear of tubes in industrial applications is the dimensional conformance of the internal diameter over the complete length. Where high demands are made on accuracy, a quick and reliable recording of the data must be ensured, because, for example, wear measurements must be carried out in the chemical

industry on pipes which are already installed, i.e. with the plant shut down. Two pairs of sensors record two tracks offset by 90° in one measurement step.


Quality control of medical tablet stamps and dies

According to ISO 18084:2011, the press tools for the tablet production are subject to a continuous quality control. Due to complex geometry and a strongly reflecting surface, automatic inspection of stamps and dies has been difficult. Only the use of a confocal sensor (confocalDT 2451) and an optical micrometer (optoCONTROL 2600) together with a precise movement with 5 degrees of freedom enabled the development of "Ti-1". Ti-1 is a complex measurement system equipped with a USB interface and special software for the geometric and visual inspection of tools.


Measurement of metal stampings

Cylindrical, ground stainless steel metal stampings are precisely measured in a fully automatic measurement installation. Two optical optoCONTROL micrometers are applied in order to measure roundness, concentricity and diameter.


Measurement of flat washers

These days, flat washers are an auxiliary material used in almost every industry. In most cases, the washers consist of different alloys and are required in all sizes and thicknesses, which means the demands on the manufacturers are particularly high. In order to supply the customer with a correctly sorted, high quality product, the thickness and diameter are inspected before the washers are packed. This inspection is carried out using a scanCONTROL 2910-50 laser scanner.


Non-contacting roundness measurement for rollers

In the production of tapes and foils the high speeds of up to 2700 m/min that are used today lead to an increased vibration tendency in the roller stands. Even smallest μm-range irregularities in the rolling contour lead to cross-grooves on the rolled material and thus clearly reduce the quality of the product. For quality assurance a highprecision

roundness measuring system for rollers is required, in which an eddy-current sensor measures the surface contour of the roller. Ambient conditions like dust or oil must not affect the measurements. With computer support the angular position of roundness errors and the accumulation and periodicity of circularity errors can be documented.


Roller runout

The runout of the roller is a crucial criterion for rolling processes of metals, plastics or other materials. An imbalance is even dangerous for rollers which have to rotate at high speeds. Therefore, the roundness of the roller must be measured before and also during the application. For all the following processes, a sensor measures the roller directly and establishes the ovality. The non-contact eddy current method is used for rollers made of polished metal. Capacitive or laser triangulation sensors are used for rollers made of other materials.