The Japanese Industrial Standards (JIS) organisation developed the JIS standard for machine accuracy to ensure consistent quality and performance of machines used in manufacturing and other industries.
Machine accuracy standards included in the JIS standard include spindle rotation accuracy, positioning accuracy, and straightness accuracy. These requirements describe each component's permitted variation from ideal shape and performance.
In the context of spindle rotation accuracy, for example, the JIS standard specifies the spindle's maximum permitted deviation from its ideal axis of rotation. This variation is measured in micrometres and is proportional to the machine's size and intended application. The JIS standard also specifies the permissible deviation of spindle radial and axial runout, which might impact machined part precision and surface smoothness.
Similarly, the JIS standard specifies the permitted variation of machine positioning accuracy, which relates to the machine's ability to move and stop precisely in a given location. The JIS standard also specifies the permitted variation of straightness precision, which refers to the machine's movement along a linear axis.
The JIS machine accuracy standard is essential for maintaining the quality and operation of machines used in manufacturing and other industries. Machine makers and suppliers use the JIS standard to develop and build machines that meet or exceed accuracy and performance standards. The JIS standard can also be used by machine users to guarantee that their machines are performing within acceptable limitations.
How To Check Machine Bed Plate Parallelism JIS Standard
To examine machine bed plate parallelism in accordance with JIS requirements, perform the following steps:
1. Determine the machine's accuracy class: The JIS standard divides machine accuracy into groups based on their intended purpose and size. The maximum permitted deviation from parallel for the machine bed plate is determined by the accuracy class.
2. Remove the machine bed plate: Before taking any measurements, the bed plate should be completely cleaned and any debris or dust removed.
3. Setup measurement points: The JIS standard specifies the number and location of measurement points on the bed plate. The standard suggests taking at least three measurements along the length and three measurements along the breadth of the bed plate.
4. Adjust the dial indicators: Dial indicators are commonly used to measure the bed plate's displacement from parallel. The dial indicators should be put on each measurement point with care to ensure that they are stable and accurate.
5. Zero the dial indications: Before taking any measurements, zero the dial indicators to account for any differences in their own readings.
6. Take the measurements: The measurements can be done with the dial indications in place and zeroed. To measure any deviations from parallel, move the dial indicators along the bed plate.
7. Determine the average deviation: Following the completion of all measurements, the average deviation from parallel can be calculated using the following formula:
Average deviation = (sum of all deviations) /
(number of measurements)
8. Analyse the results in relation to the JIS standard: For each accuracy class, the JIS standard specifies the maximum permitted deviation from parallel. Compare the average deviation calculated in step 7 to the JIS standard for the accuracy class of the machine. According to JIS standard values, the maximum permitted deviation for machine bed plate parallelism is 0.02 mm for accuracy class A, 0.03 mm for class B, and 0.05 mm for class C.
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