When choosing an expression plan, you should pay attention to the following two points: 1.The number of views should be appropriate You should consider reducing the dotted lines in the view as much as possible and using a small number of dotted lines properly. On the premise that the shape of each part of the part is clearly expressed, strive to express concisely, the number of views is just right, and avoid repeated expressions as much as possible.A part sketch is a part drawing drawn by hand. It is an important basis for drawing assembly drawings when drawing part drawings and parts. When drawing a part sketch, it is required to visually check the size of the part, determine the drawing scale, and draw freehand. The general steps are as follows:2.the expression method should be appropriate According to the shape of the internal and external parts of the part, the expression of each view should have its focus and purpose, and the expression of the main structure and the local structure should be clear. At the same time, it is necessary to consider the reasonable layout of the graphics, such as configuring the basic view in a prescribed manner.1. Understand the analysis parts and determine the expression scheme According to the size, complexity and expression of the part, determine the appropriate drawing scale and width. It is best to use graph paper for sketching. 2. Draw the drawing frame line and title bar Determine the position line of the main view, such as the main axis, centerline, and drawing reference line. 3. Visually inspect the hand drawing. Draw the outline of the primary structure first, then the outline of the secondary structure. Relevant views of each structure should be drawn to match the projection characteristics. At the combination of adjacent structures, the increase or decrease of the graph line should be considered (such as the intersection line at the intersection, wireless at the tangent, etc.). Finally complete all graphics.4. Check and correct the whole picture and erase unnecessary lines Determine the size reference in three directions, draw the extension lines, size lines and size arrows of all sizes; draw section lines. 5. Measure and determine all dimensions. For the dimensions of standard structures (such as keyways, chamfers, etc.), you should consult the relevant manuals or perform calculations before filling in. 6. Annotate the necessary technical requirements Fill in the title bar, and complete the part sketch.Based on the completed part sketch, combined with the actual production conditions and machining technology experience, a comprehensive check of the part sketch is performed before drawing the part drawing. When checking the sketch, usually pay attention to several issues, such as: whether the expression scheme is reasonable and complete, whether the dimension is clear and complete, correct and reasonable, and whether the proposed technical requirements can meet the process requirements and the performance requirements of the parts.After checking and correcting the sketch, start drawing the part work drawing. The drawing steps of the part work drawing are as follows: 1. Analyze parts and select expression schemes. 2. Determine the drawing scale and width, draw the frame line, and locate the main view. 3. Draw the base map. 4. Check and correct the manuscript, deepen all the graphics, and draw the section lines without errors. 5. Draw extension lines, size lines and size arrows, and note the size values and technical requirements. 6. Fill in the title bar, check, and complete the work drawing of the part.