ABS Sheet Products And Mold Design
Jul 03, 2021
1. The wall thickness of the product
The wall thickness of ABS plastic products is related to the flow length of the melt, production efficiency, and use requirements. The ratio of the maximum flow length of ABS melt to the wall thickness of the product is about 190:1. This value will vary with different grades. Therefore, the wall thickness of ABS products should not be too thin. For products that require electroplating, the wall thickness The thickness should be slightly thicker to increase the adhesion of the coating to the surface of the product. Therefore, the wall thickness of the product should be selected between 1.5 and 4.5 mm.
When considering the wall thickness of the product, you should also pay attention to the uniformity of the wall thickness. Do not vary too much. The surface of the product that needs to be electroplated should be smooth and free of unevenness, because these parts are easy to adhere to dust and difficult to remove due to static electricity. The fastness of the coating deteriorates. In addition, the existence of sharp corners should be avoided to prevent stress concentration. Therefore, it is advisable to use arcs for transitions at corners and thick and thin joints.
2. Demoulding angle
The mold release slope of the product is directly related to its shrinkage rate. Due to different grades, different product shapes and different molding conditions, the molding shrinkage rate has a certain difference, generally 0.3~0.6%, sometimes up to 0.4~0.8% , So its products have high molding dimensional accuracy. The demolding slope of ABS products is considered as follows: the core part is 31° along the demolding direction, and the cavity part is taken 4(/-1°20' along the demolding direction. For those with complex shapes or with letters and patterns For products, the draft angle should be increased appropriately.
3. Ejection requirements
Because the apparent finish of the product has a great influence on the electroplating performance, any tiny scratches on the surface will be clearly revealed after electroplating. Therefore, in addition to requiring no scratches on the mold cavity, ejection is also required. The effective area should be large, the synchronization of the ejection process with multiple ejector pins should be good, and the ejection force should be uniform.
4. Exhaust
In order to prevent the occurrence of poor exhaust during the filling process, causing melt burns, obvious seam lines and other problems, it is required to open a vent hole or vent groove with a depth of not more than 0.04mm to facilitate the production of the melt. The gas is discharged.
5. Runners and gates
In order to make the ABS melt fill all parts of the cavity as soon as possible, the diameter of the runner is required to be no less than 5mm, the thickness of the gate is more than 30% of the thickness of the product, and the length of the straight part (referring to the part that will enter the cavity) is about It is about 1mm. The location of the gate should be determined according to the requirements of the product and the direction of the material flow. For products that need to be electroplated, it is generally not allowed to exist on the adhesion surface of the coating.
