circularity callout<\/a>?<\/p>\nThe circularity callout does check the circularity of a feature, but it does not do so in reference to a datum axis.<\/p>\n
So, a surface that is perfectly round would meet the circularity callout even if it is off-centred. This could, however, cause the part to wobble when it rotates during service.<\/p>\n
Circular products that require close tolerances or rotate at high speeds must rotate around the central axis besides being as circular as possible to prevent errors in operation. Even a small wobble can significantly affect the functionality and reduce service life.<\/p>\n
Circular runout helps us control and measure this wobble to ensure it is within permissible limits.<\/p>\n
The datum axis acts as an anchor for the tolerance zone in circular runout. The callout creates a 2D circular tolerance zone around the specified datum axis. The ideal surface of the feature lies in this tolerance zone. In order to meet this callout, all points on the actual surface must lie in this zone.<\/p>\n
Runout manages to specify everything necessary to avoid the wobbling effect without putting many different and too tight tolerances<\/strong> on the part.<\/p>\nFeature Control Frame of Circular Runout<\/h2>\n
<\/p>\n
The feature control frame follows the same rules as it does with other GD&T symbols. The circular runout frame consists of three sections.<\/p>\n
Circular Runout Symbol<\/h3>\n
Circular runout symbol<\/figcaption><\/figure>\nThe runout symbol is a diagonal arrow pointing northeast (\u2197<\/strong>). It is a reference to how we measure the runout of a feature. We use a dial or height gauge to measure runout so the symbol actually represents the pointer in a dial gauge.<\/p>\nThe runout symbol is placed in the first compartment of the feature control frame.<\/p>\n
Tolerance limit<\/h3>\n
<\/p>\n
The tolerance limit makes up the feature tolerance compartment (2nd block) of the feature control frame. Note that the circular runout callout does not need the diameter symbol in the feature tolerance block.<\/p>\n
The total variation on the dial gauge must be less than the stated limit.<\/p>\n
Datum axis<\/h3>\n
<\/p>\n
As is often the case with GD&T, this is the most important part of runout\u2019s FCF. Usually, we choose the central axis as the primary datum and mention it in the third block. But there are cases where we may choose a different axis as our datum.<\/p>\n
Sometimes, the primary datum is the surface of the circular feature. Other times, it may be the plane perpendicular to the central axis.<\/p>\n
In rare cases, two datums may be combined and used as a primary datum instead of one being primary and the other being the secondary datum.<\/p>\n
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Scale Your Manufacturing from Prototyping to Series<\/span>\n\n \n - \n
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