Precision requirements of plastic and stamping molds structure

- Dec 11, 2019-

Mold accuracy is for product accuracy. High-precision products must be guaranteed by a higher-precision mold. 

The mold accuracy must generally be 2 or more than the precision of the part.

Method 1 to improve mold accuracy. Guaranteed accuracy of mold processing facilities 

2. Precision requirements for parts manufactured by mold ①. Mould data accuracy requirements

Mold steel processing tolerance control Standard template size Fine plate thickness Flatness within 300X300 + 0.005-0 ± 0.005300X500 within + 0.01-0 ± 0.01500X800 within + 0.01-0.01 ± 0.015800X1200 within + 0.02-0.02 ± 0.02② . Precision requirements of mold parts a. The guiding parts that affect the precision of the mold adopt MISUMI guide post and guide bush series, and the ultra-fine tolerance can be controlled within 0.002mm.

b. Cutting edge forming punch adopts MISUMI standard material: 

SKD-11 / 1.2379 tool steel hardness: 60-62HRC cutting edge shapes include: DREGTH punching needle is usually used to form the inner hole or cylindrical shape on the product. 

The precision of punching can be controlled within ± 0.01mm. Special requirements can be achieved about 2um, and the mirror surface can be maintained.

3. The size of the mold gap is an important basis for mold design and manufacturing accuracy. In order to ensure the dimensional accuracy and shape and position accuracy of the products produced by the mold, as well as the product quality (such as the cross-section quality of the punched part and the height of the burr), it is necessary to ensure the distance between the mold concave and convex molds. Clearance.

4. Structural accuracy requirements of the mold ①. The guarantee of the accuracy of the mold base Luo Baihui said that from the perspective of processing and assembly, the accuracy of the mold base includes the following aspects: a. Consistency of the plane size of the upper and lower template and the position of the guide hole; b. The flatness and parallelism of the large plane of the template; c. The perpendicularity of the guide hole to the large plane; d. Verticality between adjacent sides of the template; e. The precision of the fitting between the guide post and the guide sleeve.

The important methods to ensure the accuracy of the mold base are: a. The one-time processing method is to finish the large plane processing of the template, and then the upper and lower templates are clamped together, and the planar dimensions and guide holes of the two templates are processed at one time.

b. Offset one of the four guide holes from the symmetrical position to ensure the assembly orientation of the mold.

c. Processing datum (Datum), used for calibration processing.

d. Use high precision guide post and guide sleeve.

e. Improve the machining accuracy of parts.

②. Guarantee of the accuracy of the punch Luo Baihui believes that from the perspective of processing and assembly, the accuracy of the punch includes: a. Shape and size accuracy of the punch; b. The verticality between adjacent sides of the punch.

③. Accuracy guarantee of the die From the perspective of processing and assembly, the precision of the die is important including: a. Shape and size accuracy of the die; b. Perpendicularity between adjacent sides of the die; c. The verticality of the side of the die to the large plane; d. Position of the die.


5. Accuracy of forming process When CNC machining the forming structure, whether it is computer gong, electric spark, wire cutting or ordinary CNC milling machine, the coordinate processing method is used. The guarantee of this accuracy depends on the accuracy of the machine tool and the accuracy of the calibration and division of the operator. 

As with the establishment of corporate product quality assurance and management system guidelines, guiding concepts, the concept of mold accuracy should also be consistent throughout the mold design and manufacturing process. 

In order to ensure the accuracy requirements of the closed loop of the dimensional chain of the mold assembly, all processes involving mold manufacturing, outsourcing (including data, standard parts) and the entire process of mold assembly, mold testing, acceptance, packaging and transportation will affect the mold The critical links and factors of precision must be strictly controlled and managed.


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