The working surface of the cast iron square ruler adopts scraping or grinding technology, which is used to measure the straightness and flatness of the workpiece and equipment installation, and the operating temperature is (20 ± 5 ℃).

Cast iron square ruler is used to inspect the flatness of flat plates, long guide rails, etc. by coloring method and indicator table method, and is also commonly used to inspect the straightness of workpiece edges by light gap method. Cast iron square rulers are generally made of cast iron, and rectangular cast iron square rulers are also made of bearing steel or granite.

Cast iron square ruler: The working surface adopts scraping or grinding technology, which is used for checking the unevenness and straightness in machine tool inspection. The two working surfaces are inspected with block gauges, micrometers, level gauges and other instruments. They can be used for different heights, parallel and unconnected levels of the two guide rails, and can be matched with a straight angle ruler. It is a measuring tool for checking the perpendicularity of two parts that cannot be checked by a right angle ruler alone. It is also suitable for equipment installation and inspection.

Support the cast iron square with equal height blocks at the standard support marks 2L/9 from both ends of the cast iron square and place it on the reference plane. Use an indicator or comparator with a scale of 0.001mm to measure the reading in the middle of the working face length; Then move the equal height block to the position of the large support distance (at both ends of the cast iron square ruler), stabilize for 10 minutes, and read it with an indicator or comparator; The difference Y between two readings is the natural deflection of the cast iron square ruler.