Advantages and disadvantages of gate location and structure in the design of MIM injection moulds

The gate, also known as the feed inlet, is the channel connecting the diverging channel with the cavity melt. The choice of the gate is directly related to whether the metal powder injection molding products can be in good condition and of high quality.

Gate design includes：1、Determine the shape and size of gate section；2、Gate location selection.

The location of the gate plays a decisive role in the shape of melt flow front and the effect of pressure retaining. Guangdong dhonghong new material thinks that for the factors that affect the determination of gate location, including product shape, size, wall thickness, dimension accuracy, appearance quality and mechanical properties. In addition, consideration should also be given to gate processing, stripping and cleaning gate difficult degree. The correct gate location can avoid those predictable problems.

According to the characteristics of different metal powder injection moulding products, guangdong dhonghong new material compared the differences of various types of sprue and introduced the advantages and disadvantages of sprue position and structure.

In the design of metal powder injection moulds, according to the structure and characteristics of the sprue, the common sprue forms are as follows:

1、Sprue：That is, the main runner gate, which belongs to the non-restrictive gate.

（1）Advantages：The plastic melt enters the cavity directly from the big end of the main channel, so it has the characteristics of small flow resistance, short flow and long supply time. Such sprue has a good melt flow state, and the melt flows from the center part of the bottom surface of the mold cavity to the fractal surface, which is conducive to exhaust; This gate form makes the metal powder injection molding products and pouring system have the smallest projected area on the parting surface, compact mold structure, metal powder injection molding machine under uniform stress.

（2）Disadvantages：Feed has a larger residual stress, easy to cause the buckling deformation of metal powder injection molding products, gate is larger at the same time, remove the gate mark is difficult and trace is bigger, affect beautiful, so this type of gate metal powder injection molding manufacturers more long used in large and medium-sized injection molding process, deep cavity, cylindrical or shell metal powder injection molding products, particularly suitable for polycarbonate and polysulfone plastic viscosity. In addition, this type of gate is only suitable for single cavity mold. Metal powder injection molding factory in the design of this kind of gate, in order to reduce the contact with the metal powder injection molding products in the gate area and prevent it from shrinkage, deformation defects such as mouth, on the one hand, should try to choose a smaller taper of the mainstream way cone Angle (for 2 ~ 4 °), on the other hand should be reduced as far as possible to determine template and the thickness of the mold base.

2、The side gate：Abroad side gate is called standard gate. The side gate is usually set on the parting surface, and the plastic melt is filled with the mold cavity from the inside or the outside. The section shape is mostly rectangular (flat groove). Changing the gate width and thickness can adjust the shear rate of the melt and the freezing time of the gate. This kind of gate can choose its position according to the shape feature of metal powder injection moulding products, which is convenient for processing and dressing, so it is widely used.

（1）Advantages：The gate section is small, which can reduce the consumption of the molten material in the pouring system. Guangdong dhonghong new material thinks this kind of gate is suitable for all kinds of metal powder injection molding products, but it is not suitable for long and thin barrel metal powder injection molding products.

（2）Disadvantages：Metal powder injection moulding products and sprue can not separate by themselves, there are weld marks, metal powder injection moulding pressure loss, deep cavity metal powder injection moulding products exhaust adverse.

3、The fan gate：Generally, it is set on the parting surface to feed from the external side of the mold cavity. The gate widens gradually along the feeding direction and the thickness decreases gradually. The plastic melt front entering the mold cavity from the gate is relatively flat, which can reduce warping deformation.

4、Thin gate：It is also called flat joint gate. The distribution channel of the gate is parallel to the side of the cavity and the length is usually greater than the width of the plastic product.

（1）Advantages：The plastic melt enters the mold cavity uniformly at a low speed through the thin section gate. Guangdong da-hong new wood believes that its material flow is parallel and can avoid warping and deformation.

（2）Disadvantages：It is difficult to remove the gate, which increases the production cost of metal powder injection moulding products.

5、TAB gate：It is mainly used for injection moulding of high transparent plate metal powder and injection moulding of metal powder with little deformation.

（1）Advantages：The auricle gate is provided on the side of the auricle, and the heat of friction is generated on the side of the auricle by the melt impact through the gate, thus improving the fluidity. After adjusting the direction and speed, the auricle is evenly and smoothly entered into the cavity, which can avoid the jet flow.

（2）Disadvantages：Gate resection is more difficult, gate traces are large.

For more information about powder injection molding technology, please click on guangdong dahong new metal powder injection MIM technology.