Structure of insert molding die

1. The corner around the embedded part of the metal insert should be designed with rounded or chamfered corners. Under normal circumstances, in order to reduce the cracking of the plastic around the insert due to the stress concentration caused by this cooling, it can be designed with a chamfering of not less than 1¡Á45¡ã or an arc with a radius of not less than 0.5mm.

(2) In order to enable the insert to be firmly embedded in the product, without turning or being pulled out when the product is stressed, the outer surface of the insert should be processed into a ring groove or rolled into a prism-shaped pattern or made into other special shapes, so as to ensure that the insert has a firm connection with the plastic.

3. The rod threaded insert should be matched with the mold in the non-threaded part to ensure that the insert is inserted into the mold and can be positioned accurately to prevent overflow.

4. The height of the rod insert shall not exceed twice the diameter of its positioning part. For thin and long inserts, it is necessary to avoid direct impact when the plastic is filled, that is, to prevent the position of the insert from moving. When the insert is too long or in the shape of a slender rod, a pillar can be installed in the mold to prevent the insert from bending, which will leave process holes in the plastic product.

5. The flake type insert of stainless steel sheet should be designed with more incisions and hanging tables embedded in plastic on its surrounding side walls.

Insert molding process

1. Pre-plastic stage

The screw begins to rotate, and then the plastic transported from the hopper is transported to the front end of the screw, the plastic is plasticized uniformly and gradually gathered in the front end of the barrel under the action of high temperature and shear force, with the accumulation of molten plastic, the pressure is increasing, and then the screw is gradually pushed back to overcome the back pressure of the screw, when the plastic in the front of the barrel reaches the required injection volume, the screw stops backing and rotating. The premolding phase is over.

2. Injection molding stage

The screw moves forward under the action of the injection cylinder, pushing forward the plastic stored in the front of the barrel at multiple speeds and pressures, and injecting it into the closed mold cavity through the runner and gate.

3, pressure feeding process

The injection pressure of the pressure holding stage is called the pressure holding pressure. Under this pressure, the melt in the mold cavity is supplemented by cooling, and the product is compressed and densified. In this process, the holding pressure plays a leading role.

The characteristics of the pressure holding stage are: the melt flows slowly under high pressure, the screw has a small feeding displacement, and the material is gradually formed with the cooling and density increase. In the pressure holding stage, the melt flow rate is very small, does not play a leading role, and the pressure is the main factor affecting the process, in the pressure holding stage, the mold pressure and specific volume are constantly changing.

4. Cooling and shaping stage

The plastic passes through the pressure holding in the mold cavity to prevent the plastic backflow until the plastic cures and the pressure in the mold cavity disappears. The proportion of cooling setting time in a production cycle is large.

Insert mold design has some criteria

1, injection molding machine

The insert molding process requires advanced vertical injection molding machines for product development. Vertical injection molding machines have particularly tight tolerances, as this ensures that product accuracy is accurate during the injection molding process. Even a small millimeter deviation can lead to product failure. The combination of vertical injection molding machine and manipulator, insert product line device, etc., insert molding engineering can realize automatic production.

2. Selection of inserts

Different types of plug-ins can be used in the design of molded components. Metal inserts in insert molding are usually made of brass, stainless steel or ordinary steel. These plugins have a threaded surface, so they can be more closely bonded to the product. Inserts are used in various types of processes such as injection molding, compression molding, extrusion blow molding, structural foam, rotary molding, etc.

3. Selection of materials

A variety of polymers are commonly used in the insert molding process to meet customer application needs. Each material contains unique properties and should be selected according to the operating conditions and performance requirements of the finished product.

Insert mold installation precautions

1, high-quality mold inserts will eventually achieve what kind of use effect, and it will be installed structure is related to the shape characteristics of the product and the structure to be highly compatible, which will be difficult to install the product smoothly. The mold frame carrying the product also has certain specifications, the thickness of the template should be moderate, and the rigidity and toughness must meet the standard.

2, the material properties of the mold insert affect the production process and service life of the mold, and the rational material composition can extend the use of the period. High quality steel as the main part of the material, flexibility and rigidity can maintain the optimal level, its chemical composition can not exceed the standard or not enough.

3, the molding of the mold insert is to be forged, can use the cold extrusion process, the mold insert deformation in the overheating environment, the structure will be softened, the cold and hot alternating forging process can ensure the rigidity of the mold insert, improve the level of pressure, extend its usable time.