What is eccentricity in metrology?

Article by: Dr. Arnau Parra | Last update: April 10, 2022
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Eccentricity. Eccentricity is the difference between measurements of the same mass made at different positions on the plate. This serves to compensate for the fact that in most weighings what you want to weigh is not exactly in the center.


How to do the eccentricity test?

In the eccentricity test, the reference load is placed at a few different specified locations on the load receptor. First, the load is placed in the center of the load receptor and the result is observed. The load is then placed in four different sectors of the load receptor.

What is eccentricity test?

For a weighing instrument with multiple ranges, the eccentricity test should be performed with the highest range. Since the eccentricity test is about finding the difference caused by the location of the load, it is not necessary to have a highly accurate calibrated mass.

What is roundness in metrology?

Roundness: Any inside or outside diameter. Concentricity: Any ID or OD with any other ID, OD or axis.

How are weights calibrated?

The Calibration of a Weight consists of the comparison of the value measured by a Standard and that of the Weight by means of a method that guarantees metrological traceability to a Standard formally recognized by the «International Bureau of Weights and Measures» (BIPM).

28 related questions found

How is calibration done?

The process consists of choosing a standard that meets the aforementioned norm on measurement uncertainty and making it serve to compare its measurement with that of the calibrated device. After choosing a standard with a tighter degree of uncertainty and repeating the previous operation.

What is a set of calibration weights and what is it used for?

Calibrated test weights or scale calibration weights are used to calibrate scales. This is a process that ensures the accuracy of the scales.

What is angularity?

Angularity. The angularity requirement specifies how precise an angle is, relative to the reference (reference plane or line), when the specified line or plane is not 90 degrees. Instead of degrees, the millimeter is used as the unit for the angularity indication value.

How to measure the roundness of a piece?

The determination of roundness is made from the evaluation of characteristic irregularities (distance and peak-valley undulations) and lobes (evenly spaced undulations, in a small number) that arise as a result of machining operations.

What is roundness tolerance?

Roundness Tolerance is used to control the roundness of circular parts or features. Circular features can be defined by cylinders, spheres, and cones. Roundness Tolerance controls each circular element of a cylinder independent of each other.

What is the weighing instrument?

Weighing Instrument: A measuring instrument used to determine the mass of a body by using the action of gravity on that body.

What is the calibration of an instrument?

Calibration of process instruments consists of comparing and documenting the measurement of a device against a traceable reference standard.

How is a balance calibrated?

Calibration must be carried out at a number of points on the balance scale that is between 5 and 10, and between 6 and 10 measurements must be made at each point. These points must be distributed in such a way that the measurement field is divided into approximately equal intervals.

How is the class of a balance determined?

In order to determine the appropriate standard for any balance, it is necessary to know the maximum permissible error of the instrument and ensure that the maximum permissible error of the standard is at least three times less than the maximum permissible error of the balance ( Eq.

How do you verify that the position of the analytical balance is correct?

The main points that must be considered for its correct position are: Characteristics of the measurement room: Have only one entrance. Have the minimum number of windows possible, to avoid direct sunlight and drafts.

How to measure the roundness of a cylindrical part?

To measure the roundness it is necessary to perform a rotation, either of the piece or of the probe by using a small deformation sensor (LVDT) that detects the defect.

How is the perpendicularity of a piece measured?

To measure squareness, first record two measurement values ​​from a single object; this way you will have a reference for the angle. Then use the integrated prism in the D22 laser transmitter, which deflects the laser beam by 90°, and record two new measurement values ​​on the second object.

How to measure a cylindrical piece?

To obtain it, we will measure the diameter of the piece with the gauge and the height with the micrometer. its diameter is between the clamps of the gauge and write down the corresponding length.

What is Angularity Tolerance?

An angularity tolerance is the amount that a surface, plane center, or axis can vary from a specific angle. Angularity establishes a zone of tolerance for the surface, plane center, or axis that is at a specified basic angle (other than 90°) for a datum plane or axis.

What is squareness tolerance?

Perpendicular Tolerance is a three-dimensional geometric tolerance that controls how much a surface, axis, or plane can deviate from a 90 degree angle or can be defined as a condition of a surface, the midplane, or at the 90 degree axis in a plane of reference or axis.

What is a set of lab weights?

Laboratory weights are small parts that are used in digital balances to accurately weigh different substances.

What are control weights?

Weightlifting past and present

Weight units are currently used almost exclusively for adjustments and checks = calibration of electronic balances. Due to this use they are called “control weights”.

How are standard weights classified?

F1 and F2 classes

Standard weights F1 and F2 are intended for calibration of weights of lower accuracy class and for use in balances and scales of accuracy class I and II. They can also be used as test weights and are usually accompanied by a calibration certificate.

How is equipment calibrated?

The calibration of an instrument requires having a pattern, that is, another instrument with greater precision. In this way the value provided will be verifiable, and will be compared with the value indicated on the instrument being calibrated.

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