Dongguan Precision CastingCast iron has excellent castability and is suitable for manufacturing castings with complex shapes or thin walls. Commonly used cast irons include gray cast iron, malleable cast iron, and ductile cast iron. The carbon in gray cast iron mainly exists in the form of flake graphite, and the fracture surface is gray. Malleable cast iron is made of white cast iron after annealing treatment, and the carbon is distributed in the matrix in the form of graphite in the form of clusters. Malleable cast iron is divided into white heart malleable cast iron and black heart malleable cast iron. Nodular cast iron is made of ordinary gray cast iron molten iron through spheroidization and other processes. The graphite in the cast iron is distributed in the matrix structure in the form of spheroids. Nodular cast iron has higher strength, better plasticity and toughness than ordinary gray cast iron.

1 Scribing during the processing of machine maple has the following effects

(1) Determine the allowance of the workpiece to add L, so that the machining has a clear boundary line

(2) It is convenient for the installation of complex workpieces on the machine tool, and the positioning can be adjusted according to the marking

(3) It can detect and process unqualified blanks in time to avoid losses after processing;

(4) The use of borrowed material to draw lines can remedy the blank with little error, so that the processed parts can still meet the requirements.

2.Dongguan Precision CastingThe accuracy of marking affects the machining accuracy of parts

In addition to the uniform and clear lines to be drawn, the most important thing is to ensure that the size is accurate. When the marking error occurs or the accuracy is too low, it can cause processing errors and make the workpiece scrapped. Since the drawn lines always have a certain thickness, and some errors are inevitable when using tools and measuring dimensions, absolute accuracy cannot be achieved.

Generally, the accuracy required for marking is in the range of 0.25~0.50mm. Therefore, it is usually not possible to rely solely on scribing to directly guarantee the final size of the processing, and it is still necessary to measure during processing to determine whether the size of the part meets the requirements of the drawing.

3 Scribing is divided into two types: plane scribing and three-dimensional scribing

(1) Plane scribing only after scribing on one table of the workpiece, the scribing that can clearly indicate the widening line is called planar scribing. For example, marking on the sheet and strip sheet, drilling and adding a line on the end surface of the plate are all flat markings.

(2) Three-dimensional scribe lines are scribed on several surfaces that are at different angles to each other (usually perpendicular to each other) to clearly indicate the processing boundary line. For example, the processing lines on each surface of the rectangular block and the processing lines on the surface of the bracket and the box are all three-dimensional scribe lines.

4Precision cast steelCommonly used scribing tools when scribing:

Scribing plate: It is used to place the workpiece and the scribing tool, and to perform the scribing work on it.