Last updated on Apr 6, 2025

What are some best practices and tips for performing runout inspection efficiently and accurately?

Runout is a geometric tolerance that controls the variation of a circular or cylindrical feature as it rotates around an axis. It is often used to ensure the smoothness, balance, and concentricity of parts such as shafts, gears, and bearings. However, measuring runout can be challenging and time-consuming, especially for complex or large parts. In this article, you will learn some best practices and tips for performing runout inspection efficiently and accurately.

1 Understand the runout specifications

Before you start the inspection, you need to understand the runout specifications for your part. These include the datum reference frame, the tolerance zone, the modifier, and the material condition. The datum reference frame defines the axis of rotation and the reference surfaces for the runout measurement. The tolerance zone is the cylindrical or conical zone within which the feature must lie. The modifier indicates whether the runout is total, circular, or radial. The material condition specifies whether the tolerance applies at maximum or minimum material condition. You should also check the drawing notes and symbols for any additional information or requirements.

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2 Choose the appropriate inspection method

Depending on the size, shape, and complexity of your part, you may need to choose between different inspection methods for runout. A dial indicator and fixture can be used to measure the deviation of the feature from the tolerance zone. This method is simple, fast, and accurate, but requires a suitable fixture and a calibrated dial indicator. An alternative is to use a coordinate measuring machine (CMM) to scan the part and generate a 3D model of the feature. This method is more flexible, precise, and comprehensive, but requires a CMM and a skilled operator. The most advanced option is to use a laser scanner or vision system to capture the image of the part and measure the runout using software algorithms. This method is automated and versatile, but requires a high-resolution scanner or camera and a powerful computer.

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Wahyudin P. Syam

Technical project manager
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Runout is shape or geometrical variation when a part is in rotation. Since run out is a variation measure when a cylindrical feature is in operation, we need to measure it while it is rotating. There are several run out measurements: radial or axial runout. The basic method to measure 2D profile run out, let's say the radial run out is by placing a cylinder whose runout to be measured in a rotating spindle at the speed where the cylinder will operate. Then, touch the surface profile with the tip of a dial gauge and set the dial gauge to be zero. Then, rotate the part several rotation an observe the movement of the dial gauge reading. The movement (maximum-minimum range of the reading vairation) should be within the runout tolerance.

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3 Follow the inspection procedure

Once you have chosen the inspection method, you must follow the inspection procedure carefully and consistently. This includes preparing the part by cleaning it and removing any dirt, grease, or burrs that may affect the runout measurement, as well as marking the feature and datum axis clearly and accurately. Additionally, you need to calibrate the equipment and adjust the settings according to the runout specifications, then align the part and equipment properly and securely. Once you have done this, measure the runout at multiple points along the feature and record the results. Furthermore, check the repeatability and reliability of the measurement by performing it several times or using different equipment. Finally, compare the results with the runout specifications to determine whether the part meets tolerance or not, then identify any sources of error or variation and take corrective actions if needed.

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4 Document and report the results

The final step of the runout inspection is to document and report the results, adhering to the standards and formats for documenting geometric tolerances. This should include the part number, name, and description, as well as the runout specifications and symbols. Additionally, you need to provide information about the inspection method and equipment, the measurement data and calculations, the pass or fail status and any deviations or nonconformities, the date, time, and operator of the inspection, and any comments or recommendations. After compiling this information, you must report the results to the relevant stakeholders such as the customer, engineer, or quality manager, in order to communicate any issues or feedback.

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5 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?

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Wahyudin P. Syam

Technical project manager
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some aspects to consider are as follows: - We must assure all fixtures are set up properly minimizing over- and under-constraints. Also, the force to tight the fixture should be enough not too much and not too low. these unproperly setup could cause few micrometer error on the measurement. - We must perform the measurement process carefully and patiently. void rushing to perform the measurement as this can cause misreading or any other unwanted error. - We must assure that all datums are selected properly. - We must assure that all measurement strategy follow a best practice. - We must assure that all part surface and probe tip or dial gauge tip are clean properly.

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What are some best practices and tips for performing runout inspection efficiently and accurately?

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1 Understand the runout specifications

2 Choose the appropriate inspection method

3 Follow the inspection procedure

4 Document and report the results

5 Here’s what else to consider

Geometric Dimensioning & Tolerancing

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