Scribing is the operation of marking the boundary and position to be processed on the surface of the part according to the requirements of the drawing or the actual object. The operation is called scribing. The marking can be used to check whether the blank is qualified, determine the machining allowance and make a reasonable allocation, so that the blank with little error can be remedied.

 

Selection of marking basis

 

When marking the workpiece, one or several planes (or lines) must first be selected as the reference for marking other lines. The types of marking datums are:

 

1. Take two mutually perpendicular planes as the reference;

 

2. Based on the two center lines;

 

3. Take a plane and a centerline as the reference.

 

 

cast iron marking platform

 

The general process of marking

 

1. Clean the flash, molding sand and oxide scale on the blank, and blunt the sharp edges of the processed parts;

 

2. Analyze the workpiece according to the drawings and technical requirements, and determine the baseline for marking;

 

3. Coat the surface of the line to be marked with paint, and fill the center of the hole with a plug;

 

4. Draw the reference line and position line first, and then draw the processing line;

 

5. Draw a horizontal line first, then a vertical line, an oblique line, and finally an arc (the same is true for each surface of a three-dimensional workpiece);

 

6. When there is an error in the shape, size and position of the workpiece, it can be solved by borrowing and adjusting;

 

7. After the line is drawn, it should be re-examined and corrected according to the drawing;

 

8. The processing line and the center of the circle should be punched to confirm that it is correct.