Controllable errors are also know as a Systematic errors. These errors are controllable in there magnitude as well as sense which can be determined and reduced.
Controllable errors either have a constant value or changing value according to a definite law.
The Controllable errors are.
- Calibration errors
- Avoidable errors
- Ambient Condition
- Stylus pressure
Calibration errors are The actual length of standard device such as slip gauges and engraved scales are differ from nominal value by a small amount. These are called Calibration errors.
In electrical process Calibration errors are in signal transmission such as drop in voltage along the wires between the electric meter and transducer occur.
The avoidable errors occurs due to parallel and the effect of misalignment of the work piece centers. While in measuring air temperature by placing a thermometer in sunlight is avoidable errors.
Ambient Condition of the deviation from standards. These standards gives rise to errors in the measured size of the component.
The standard values are barometric pressure 760 mm of Hg and 10 mm of mercury, Vapour pressure at 20°C.
In this process any component is evaluated under a stylus pressure the deflection of the work piece shape and deformation of the work piece surface both will occur at a in this process.