1. the surface of the mold is rough or fouled 2. volatile substances in raw materials 3. poor exhaust 4. mold temperature is too low 5. improper injection molding process
1. improve mold finish and clean surface 2. fully dry raw materials 3. additional exhaust passage 4. increase mold temperature 5. adjust injection speed, pressure and extended dwell time
cause analysis
Where the weld seam is formed is where the fine flow of the melt branches and is joined together, most typically a melt flow around the core or a multi-gate product. Where the trickle meets again, the surface will form weld seams and flow lines. The larger the core around the melt or the longer the flow path between the gates, the more pronounced the weld seam is formed. Fine weld seams do not affect the strength of the product.
However, where the process is long or the temperature and pressure are insufficient, filling the mold will cause significant grooves. The main reason is that the front end of the fluid is not uniformly fused to produce a weak spot. Spots may be generated where the pigment is added to the polymer due to significant differences in orientation. The number and location of the gates determine the number and location of the weld seams. The smaller the angle at which the fluid front meets, the more pronounced the weld seam.
In most cases, it is not possible to completely avoid weld seams or flow lines in process commissioning. All you can do is reduce their brightness or move them to places that are inconspicuous or completely invisible.
problem handling
1. injection speed is too low, increase injection speed 2. melt temperature is too low, increase barrel temperature 3. mold surface temperature is too low, increasing mold temperature 4. keep the pressure too low, increase the pressure, and pressurize the switch as soon as possible.
Some plastics such as PA, ABS, PMMA, SAN, and PBT are easily absorbed. If the plastic is not stored properly, moisture will enter the granules or attach to the surface. When the particles melt, moisture turns into steam to form bubbles. During the injection, these bubbles are exposed to the surface of the fluid front, bursting and then creating irregular lines.
The residual moisture in the granules is too high; the storage conditions of the granules are checked, the time of the granules in the hopper is shortened, and the material is provided with sufficient pre-drying;
1. the surface of the mold is rough or fouled 2. volatile substances in raw materials 3. poor exhaust 4. mold temperature is too low 5. improper injection molding process
1. improve mold finish and clean surface 2. fully dry raw materials 3. additional exhaust passage 4. increase mold temperature 5. adjust injection speed, pressure and extended dwell time
1. the surface of the mold is rough or fouled 2. volatile substances in raw materials 3. poor exhaust 4. mold temperature is too low 5. improper injection molding process
1. improve mold finish and clean surface 2. fully dry raw materials 3. additional exhaust passage 4. increase mold temperature 5. adjust injection speed, pressure and extended dwell time
1. the surface of the mold is rough or fouled 2. volatile substances in raw materials 3. poor exhaust 4. mold temperature is too low 5. improper injection molding process
1. improve mold finish and clean surface 2. fully dry raw materials 3. additional exhaust passage 4. increase mold temperature 5. adjust injection speed, pressure and extended dwell time
