Design features of bmc mold


The bmc mold is manufactured according to injection mol […]

The bmc mold is manufactured according to injection molding. In order to better obtain high-quality injection molded products, the manufacturability of the structure must be considered when designing the product, so that the design components can prevent injection shortcomings.
Some design features of the following bmc molds should be paid attention to.
(1) The thickness of the product
Every plastic product has a certain thickness range, and its wall thickness is generally 0.5~4mm. When the wall thickness exceeds 4mm, the refrigeration time will be lengthened during the whole process of injection molding, which is very prone to problems such as shrinking. Therefore, the product structure is improved in the design. The thickness of the product should be symmetrical, otherwise it is very easy to cause vent holes, welding marks and surface gathering marks.
(2) Mold opening position and parting line
At the beginning of the design, it is necessary to clarify the mold opening position and the parting line, try to avoid the core-pulling structure, and eliminate the harm of the parting line to the product appearance. After the mold opening position is clear, the structural design of the protrusions, locks, and structural reinforcement ribs in the product parts are as consistent as possible with the mold opening position. The selection of the parting line is beneficial to improve the appearance and characteristics.
(3) Draft angle of view
The draft angle is beneficial to the ejection of the product. A moderate draft angle can prevent the parts from scratching and the top of the product from scratching. Generally speaking, the draft angle of the shiny surface should exceed 1.5, the draft angle of the soft leather should exceed 1, and the draft angle of the thick soft leather should exceed 1.5. Naturally, the draft angle of view should be adjusted based on the raw material.
(4) Rib plate
In order to better improve the rigidity of the product, structural reinforcement ribs are generally designed inside the parts. The thickness of the structural reinforcement ribs is recommended to be 25 to 70 minutes of the wall thickness, otherwise it is very easy to cause the surface to collapse, and the inclination of the structural reinforcement rib side should exceed 1.5, to prevent excessive top damage.
(5) Arc
Setting an effective arc on the bmc mold can improve the manufacturing process of the mold and prevent low-efficiency metal processing. If the arc is too small, the product stress, and the product and the die are very easy to crack.
(6) Hole
The radial direction of the hole and the mold opening direction should be as consistent as possible to prevent core pulling. The shape of the hole should be designed into a ring as much as possible, which is simple and easy to use. The height diameter of the buried hole should generally not exceed 4. The hole is not suitable to be too close to the edge of the product. The distance between the hole and the edge of the product generally exceeds the size of the diameter.
(7) Insert
The software is generally copper or other metal materials or bmc molds. The parts inserted into the plastic parts should be designed with anti-rotation and pull-out structures such as bending, squeezing, shoulders, extrusion taps, and holes. In the above plot, analyze the tailored volume in the definition design. The plastic around the insert is designed to be as thick as possible to avoid ground stress cracking of the BMC mold.
(8) Deformation of injection molded products
The injection molded product must have a certain rigidity requirement, and the product must not have any allowable deformation. Minimize the floor plan structure as much as possible, but properly and effectively set the opposite side, convex and concave structures, and design effective ribs.

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