What is the default tolerance zone shape for a position tolerance?
If the tolerance is preceded by a diameter symbol (⌀), the tolerance is a diameter or cylindrical shaped zone, as in the position of a hole. If there is no symbol preceding the tolerance, the default tolerance zone shape is parallel planes or a total wide zone, as in the position of a slot or profile of a surface.
What type of geometric tolerance is the parallelism tolerance?
The normal form or Surface Parallelism is a tolerance that controls parallelism between two surfaces or features. The surface form is controlled similar to flatness with two parallel planes acting as its tolerance zone.
What is the shape of the tolerance zone for perpendicularity as it applies to a single surface?
Tolerance Zone for Surface Perpendicularity is defined by two planes (dotted red) perpendicular to the datum (dotted red)… The Tolerance Zone for Axis Perpendicularity is an ideal cylinder surrounding the axis.
What is tolerance zone in GD?
The projected tolerance zone applies to a feature’s protrusion. In most cases, the zone to which geometric tolerance is applied is limited to the range of the feature specified in the drawing.
What does Gd and t mean?
Geometric Dimensioning and Tolerancing
What is the use of GD and T?
Geometric Dimensioning and Tolerancing (GD) is a structured language of symbols, rules and definitions that allows the geometrical features of mechanical parts to be defined according to functional limits of imperfection.
What is runout and total runout?
While total runout takes the surface of the entire part in a 3D tolerance zone, runout or circular runout only captures the cross-section of the part.
What is the runout symbol?
It is a characteristic that is generally called out when you have a part that must rotate around a central axis and have all points on the entire surface of the part be in spec. In GD, the total runout symbol is a double arrow.
What is TIR runout?
Total indicator runout, or TIR, is a term often used in manufacturing, especially when dealing with rotating parts. TIR is simply the difference between the maximum and minimum values measured across an entire rotating surface about a reference axis.
What causes runout?
Run-out or runout is an inaccuracy of rotating mechanical systems, specifically that the tool or shaft does not rotate exactly in line with the main axis. Radial run-out is caused by the tool or component being rotated off centre, i.e. the tool or component axis does not correspond with the main axis.
What is a runout tolerance?
Run-out tolerance is a geometric tolerance that specifies the run-out fluctuation of a target’s feature when the target (part) is rotated on an axis (specified straight line). A datum is always necessary to indicate run-out tolerance; as such, it is a geometric tolerance for features related to datums.
How can I control my runout?
Runout is how much one given reference feature or features vary with respect to another datum when the part is rotated 360° around the datum axis. It is essentially a control of a circular feature, and how much variation it has with the rotational axis.
What is difference between runout and concentricity?
Both are notoriously difficult to measure. Runout is a combination of concentricity and circularity. If a part is perfectly round, the runout will equal the concentricity. Concentricity is also a 3D form of 2-Dimensional True Position when applied to a circular feature.
How do you check CMM runout?
The typical, non-CMM way to measure runout is to put a small dial indicator on the surface of the cylinder, zero-out the indicator, and then spin the cylinder. This indicator measures any difference along that circle as the cylinder rotates. A CMM essentially does the same thing.
What is base alignment in CMM?
To define a part alignment, the operator must constraint, or lock, all three axes of the coordinate system to the part. This is done via the CMM software and requires establishing the direction of X, Y and Z, as well as their intersection point-origin or XYZ zero point.
How do you control concentricity?
Unlike with coaxiality, you measure the circle of the plane. Put the stylus on the measurement point on the datum circle, and then put the stylus on the measurement point on the target circle to measure the concentricity. The stylus only comes into light contact with the surface and does not scratch the target.
How do you calculate Coaxiality?
Hold the target in place and put the dial gauge on the vertex of the circumference for which tolerance is indicated. Rotate the target and measure the maximum and minimum run-out values using the dial gauge. Repeat measurements on the specified axis. The greatest maximum-minimum difference is used as the coaxiality.
How is runout of shaft measured?
To measure coupling or shaft runout, it is common to use a dial indicator with a standard magnetic base. Simply mount the magnetic base on a stationary surface. Then mount the dial indicator on the surface to be checked.
How much runout is acceptable on a drive shaft?
Tube run-out is a direct contributor to driveshaft balance. If you have too high run-out (bent tube), your driveshaft will not balance without welding excessive weight on one side. Dynotech recommends tube run-outs at 0.020 inch or less over the entire length of the tube.
How do you check gear runout?
Runout of a gear can be measured with a dial indicator over a pin or ball placed in successive tooth spaces. On modern CNC gear measuring machines this inspection can be provided in a fully automatic cycle. Runout measurement is used to assure correct backlash and minimum variation of rotary motion.
What is flank of tooth?
Flank of Tooth is that part of the tooth surface which is below the pitch surface.
What is the effect of improper alignment of each tooth?
Statement 1: Improper alignment of each teeth will cause high bearing stresses.
Which of the following is incorrect about tolerances?
6. Which of the following is incorrect about tolerances? Explanation: Loose tolerance results in increase in cost, assembly problems and poor performance of the product. Tight tolerance results in unnecessary machining and inspection time.
What precise movement does CMM have?
What precise movement does CMM have? Explanation: Co-ordinate measuring machines are useful for three dimensional measurements. These machines have precise movements in x,y and z coordinates which can be easily measured and controlled. 2.
How accurate is a CMM?
The accuracy of coordinate measurement machines are typically given as an uncertainty factor as a function over distance. For a CMM using a touch probe, this relates to the repeatability of the probe and the accuracy of the linear scales. 00005 inch (half a tenth) over the entire measurement volume.
What does CMM stand for?
CMM
| Acronym | Definition |
|---|---|
| CMM | Capability Maturity Model (Software Engineering Institute) |
| CMM | Coordinate Measuring Machine (laser tracker) |
| CMM | Computerized Maintenance Management (job) |
| CMM | Certification in Meeting Management (Meeting Professionals International) |