In order to ensure the rationality and consistency of the mold making and processing technology, optimize the processing technology, and improve the progress of the mold making, each mold factory generally formulates the process standards suitable for the factory.
1. The craftsperson compiles craft card
When the craftsperson compiles the craft card, the machining reserve, the orientation of the reserve, the roughness requirements and the matters needing attention should be specified in the craft card in detail.
The principle of writing process card: On the premise of ensuring accuracy and quality, priority is given to using equipment with high processing efficiency. The processing efficiency of milling machines, CNCs, and grinders is faster than that of wire cutting and electric pulses, especially the slowest processing efficiency of electric pulses. The size on the drawing cannot be changed at will (only a technician can change it).
2. Principle of processing reserve
For workpieces that need heat treatment, add 0.25mm grinder allowance on one side of the shape preparation size before heat treatment. For mold cores and inserts that require CNC rough machining, a allowance of 0.2mm is reserved on one side. Leave a margin of 0.3-0.5mm. For workpieces that need to be processed by a grinder after wire cutting, reserve 0.05mm on one side of the forming part, and reserve a grinding margin of 0.1mm on one side of the rough shape; CNC finishing and electric pulse should be mirrored Polishing, leaving a polishing margin of 0.03mm on one side.
3. Machining accuracy requirements
The manufacturing precision of the mold size should be within the range of 0.005～0.02mm; the perpendicularity should be within the range of 0.01～0.02mm; the coaxiality should be within the range of 0.01～0.03mm; the upper and lower planes of the parting surface of the movable and fixed molds The parallelism requirement is within the range of 0.01～0.03mm.
After closing the mold, the gap between the parting surfaces is less than the overflow value of the molded plastic. The parallelism of the other template mating surfaces is required to be in the range of 0.01～0.02mm; the matching accuracy of the fixed part is generally within the range of 0.01～0.02mm; if the small core does not have the requirement for insertion or has little effect on the size, the bilateral 0.01～0.02mm can be used. The clearance fit of the sliding part is generally selected as H7/e6, H7/f7, H7/g6.
Note: If there are inserts with hanging steps on the mirror surface, the fit should not be too tight. Otherwise, when the inserts are knocked back from the front, the tool used for knocking is easy to damage the mirror surface. If it does not affect the product size, you can choose between 0.01~ 0.02mm clearance fit.
4. The principle of CNC electrode removal
Mold cavity cores should first disassemble the main body electrode, then disassemble other main electrodes, and finally disassemble the partial electrodes; the fixed-mold appearance electrode should be processed as a whole, and for the places where the CNC can not clean the corners, use wire cutting to clean the corners to facilitate the fixed mold The appearance surface is complete and there is no joint mark; the reinforcing ribs, ribs, and pillars with the same dynamic mold depth can be processed together on one electrode as much as possible; the deeper ribs are to be used as inserts, and the electrode side is to be punched separately. To prevent carbon accumulation during electrical pulses; try not to wire-cut the corners of the movable mold electrode after CNC milling. If necessary, disassemble the electrode or directly use wire-cutting; the ribs and ribs of the movable mold or the column If the interval exceeds 35mm, it should be done separately to save copper.
The rough machining spark position of the large electrode is 0.3mm on one side, the fine machining spark position is 0.15mm on one side; the rough machining spark position of the general electrode is 0.2mm unilateral, and the fine machining spark position is 0.1mm unilateral; the spark position of small electrode rough machining The single side is 0.15mm, and the finishing spark position is 0.07mm on the single side.
Post time: Nov-16-2021