Reasons and detection methods for accuracy errors in cast iron platforms

Reasons and detection methods for accuracy errors in cast iron platforms

As a basic platform for measurement and inspection, it is normal for small accuracy deviations to occur in cast iron platforms. The reasons for this error are not only natural factors, but also human caused deviations: 1. Reference error. As a benchmark measuring tool, there are inevitably errors. The error of the benchmark directly affects the measurement value, such as the manufacturing error of the level. The error of general reference components should not exceed 1/3 to 1/5 of the total measurement error. 2. Method error. Improper selection of testing methods and measuring tools for cast iron platforms, errors caused by simplified measurement principles and calculation formulas, and errors caused by measuring instruments, workpiece positioning fixtures, and stress deformation. 3. Environmental error. The working environment deviates too much from the standard temperature (20 ℃), or its changes over time and space are too significant; Large vibration and shock fluctuations; Errors caused by inadequate air pressure, humidity, and cleanliness. 4. Human error. The operator's sense of responsibility, technical level, emotional and physiological factors (such as vision) may cause improper operation, or errors in reading, recording, or calculation. 5. Deformation error caused by measuring force. The deformation error caused by measurement force refers to the measurement error caused by the small deformation of the part and the measurement contact part due to the measurement force when using a detection instrument for contact measurement. There is usually a device on the measuring device that maintains a constant force. There are two commonly used methods for detecting the flatness of cast iron platforms: one is the coloring method, and the other is the marking method. 1、 The use of coloring method is quite common. When checking whether the cast iron platform is an ideal plane, you can apply a layer of red lead powder on the cast iron plane, and then see if the surface can be fully adhered by the red lead powder. After back and forth research, remove the plane and carefully observe the condition of the red lead powder attached to it. Use a standard coloring point count of 25 * 25 to test the qualification. When conducting inspections, one can use their own flatness error value to make judgments, and also determine it with a standard three to five times higher than the flatness error. Coloring is a relatively simple way of testing and is very easy to operate. 2、 The marking method usually involves placing the tested workpiece and indicator on a reference screen. Simply put, the reference platform is used as the ideal plane. During the inspection, the indicator must be tightly attached to the reference screen and then move point by point or in a straight line to detect the error value. How to use a cast iron platform to extend its service life? In the case where the precision is not easily deformed for a long time, the following main points should be kept in mind: 1. To avoid deformation of the cast iron platform, the support should be supported at the main pivot point when installing the flat plate. When supporting, try to adjust the working surface of the flat plate to the degree plane as much as possible. To avoid deformation of the cast iron platform, after inspection or marking, the workpiece should be lifted down and not placed on the cast iron flat plate for a long time. After use, the working surface of the cast iron platform should be wiped clean in a timely manner, and then coated with a layer of rust proof oil. If not used for a long time, apply a layer of rust proof oil and then lay a layer of rust proof paper. 4. Create a cover on the cast iron platform, and when not using a flat plate, cover the plate with a cover. It is strictly prohibited to drop water on the cast iron flat plate. 5. The cast iron platform flat plate should undergo periodic inspection, and the inspection period should be determined based on the detailed conditions of use, usually 1 year.