The main purpose of using Go and No Go gauge is to use it as _____?
limit gauge
Understanding Go and No Go Gauges
Go and No Go gauges are essential tools used in manufacturing and quality control to quickly check if a manufactured part falls within specified dimensional tolerances. The main purpose of these gauges is to implement a system of inspection based on the concept of limits.
What are Limits and Tolerances?
In engineering, it's impossible to manufacture every part to an exact nominal dimension. Therefore, a range of acceptable variation is specified. This range is defined by an upper limit and a lower limit. The difference between the upper limit and the lower limit is called the tolerance.
- Upper Limit: The maximum permissible size of a feature.
- Lower Limit: The minimum permissible size of a feature.
- Tolerance: The total permissible variation in the size of a feature, calculated as Upper Limit - Lower Limit.
How Go and No Go Gauges Work
A Go gauge is designed to check the maximum material condition (MMC) of a feature (e.g., the largest shaft or the smallest hole). If the Go gauge fits into or onto the part, it means the part's dimension is within the acceptable limit towards the MMC.
A No Go gauge (or Not Go gauge) is designed to check the minimum material condition (MMC) for external features (like shafts) and maximum material condition (MMC) for internal features (like holes), effectively checking the dimension closer to the opposite limit of tolerance. If the No Go gauge *does not* fit into or onto the part, it means the part's dimension is also within the acceptable range at that limit. If the No Go gauge *does* fit, the part is oversized (for external features) or undersized (for internal features) and thus outside the tolerance.
For a part to be considered acceptable, the Go gauge must fit, and the No Go gauge must not fit.
| Gauge Type | Purpose | Condition for Acceptance |
|---|---|---|
| Go Gauge | Checks if the part is not larger than the upper limit (for holes) or not smaller than the lower limit (for shafts). Checks the MMC (Maximum Material Condition). | Must fit/enter the part. |
| No Go Gauge | Checks if the part is not smaller than the lower limit (for holes) or not larger than the upper limit (for shafts). Checks the LMC (Least Material Condition) according to Taylor's principle, but primarily checks the non-MMC limit. | Must NOT fit/enter the part. |
Go and No Go Gauges as Limit Gauges
Based on their function, Go and No Go gauges directly inspect whether a part's dimension falls within the specified upper and lower limits. They do not measure the exact size of the part, but rather determine if the size is within the acceptable range defined by these limits. This is precisely the definition and purpose of a limit gauge.
Why Other Options are Incorrect
- Radius Gauge: Used to check the radius of a curve or fillet. Not related to checking linear dimensions against tolerance limits.
- Pitch Gauge: Used to measure the pitch of screw threads or gears. Specific to thread/gear geometry, not general linear dimensions.
- Slip Gauge: Precision length standards used to calibrate other measuring instruments or set up specific dimensions. They are reference standards, not inspection tools for checking production part tolerances.
Therefore, the primary purpose of using Go and No Go gauges is to serve as limit gauges, ensuring that manufactured parts are within the specified dimensional tolerances.
Revision Table: Go and No Go Gauge Purpose
| Concept | Description |
|---|---|
| Go Gauge | Checks minimum acceptable size (for shafts) or maximum acceptable size (for holes). Verifies one limit. |
| No Go Gauge | Checks maximum acceptable size (for shafts) or minimum acceptable size (for holes). Verifies the other limit. |
| Limit Gauge | A gauge used to check if a dimension is within its specified upper and lower limits. |
| Purpose of Go/No Go | To quickly and effectively check if a part dimension is within the tolerance defined by the limits. They function as limit gauges. |
Additional Information on Limit Gauges
Limit gauges like Go and No Go gauges are widely used because they are:
- Fast: Inspection is quick, just a matter of fitting or not fitting the gauge.
- Simple: Requires minimal skill to use.
- Reliable: Provides a clear pass/fail result based on tolerance limits.
- Economical: Relatively inexpensive compared to measuring instruments that provide an exact dimension.
They are particularly useful for mass production where many parts need to be inspected quickly. Different types of limit gauges exist for various features, such as plug gauges for holes and ring gauges for shafts, all operating on the Go/No Go principle to check against dimensional limits.
Important Questions from Gauges
A screw ring gauge is used for checking _______.
Which type of gauge typically features the 'GO' and 'NO GO' measuring members on separate ends of the gauge body?
The measuring faces of the slip gauges are finished by ______.
Bevel protractor is used for
The minimum material condition for hole in NOGO gauge is ______ .
