1. Silver problem
Silver bad is the most common PC / ABS material problems, silver, also known as silver, water, flowers, etc., is in the product surface along the flow of silver whitish filamentous phenomenon.
The main reason is because of gas interference, which produces gas is divided into three main components:
Air: Molten and entrained air in the injection stage;
Moisture: moisture contained in the material itself;
Pyrolysis gas: gas generated by pyrolysis / pyrolysis.
Solution : First, check whether the material is dry enough, after confirming the material is fully dried, and then by adjusting the injection molding process to improve the silver defects. At the same time, poor injection of silver is also related to mold exhaust.
2. Flow marks problem
Flow marks are generated when the material is injected, because the material flow is not good, flow marks and silver lines are different, it is not caused by water or material decomposition, the appearance is not the same.
Solution : You can improve the liquidity by increasing the material temperature to avoid, the appropriate increase in mold problems to increase material flow in the mold and reduce the injection speed can be solved.
3. Shrinkage and dent problem
Shrinkage is due to insufficient material in the mold cavity filling caused.
Solution : Appropriate increase in mold temperature and material temperature to improve material flow, injection time to increase dwell, increase injection pressure, increase the injection speed to improve moldability, but also can increase the size of the gate, the gate to heat the runner to Reduce and eliminate shrinkage products;
Dent is due to improper material temperature and improper product design, the material temperature is too low, not only will have shrinkage, but also the problem of dent, the material temperature is too high, the mold temperature is too high, will melt in cooling When excessive contraction, resulting in dents.
Solution : Use of appropriate processing problems to increase injection speed and measures.
4. Warpage problems
Plastic parts warpage is due to unreasonable parts design, improper gate position and injection molding conditions unreasonable, resulting in the internal stress, uneven or excessive shrinkage due to mold temperature is too high or uneven mold temperature, Caused by the workpiece mucosa and mold release difficulties, or uneven cooling, the same will have warping deformation;
Solution:
Processing: Lengthening the injection molding cycle, reducing the injection temperature, appropriate injection pressure and injection speed adjustment, while slowing the ejection speed, increase the ejection area, to maintain a balance of ejection force;
Product design: increase the wall thickness, additional reinforcement and fillet reinforcement can reduce warping deformation;
5. Streaks problem
Usually due to high-speed injection, the expansion of the melt into the cavity caused by 'melt fracture' due.
Solution:
Molding process: take to increase the material temperature, increase the nozzle temperature, slow down the injection speed to reduce the appearance of stripes;
Mold: increase the mold temperature, additional overflow tank, increase the gate size, modify the gate shape.
6. Pitting problems
Solution:
Poor dispersion, add dispersant or oil, increase the temperature, plus back pressure.
Pay attention to whether mold problems. Try with other materials.
Baking temperature time is sufficient.
Mold temperature adjustment.
7. Products 'peeling' problem
The peeling problem of plastic products is closely related to the fluid rupture caused by high shear stress. At low shear stress or rate, small perturbations caused by various factors are suppressed by the melt. In high shear At stress or rate, disturbances in the fluid are difficult to suppress and develop into unstable flows; when a critical shear force is reached, the fluid will rupture.
Solution:
Material: PC and ABS between the two components are partially compatible, so in the modification process must add appropriate compatibilizers to improve its compatibility.Of course, because of mixing caused by peeling bad We need to be the first step to exclude;
Mold: the principle of mold design to follow to minimize the direction of shear In general, dense striae products more prone to peeling phenomenon (high-speed filling in the cavity with cavity friction wall shear Cut caused); the same time, the gate design, the gate size is too small, will lead to melt over the gate resulting in excessive shear, which led to the product surface peeling;
Injection molding process: the main direction to avoid over-shear in the product filling difficulties, you can use high-speed high-pressure way to improve, so in the actual injection process, you can also consider increasing the injection temperature / mold temperature, and to improve material flow way To reduce the flow resistance of the actual filling process, so as to avoid excessive shear caused by high speed and high pressure.