Steps to set Injection Pressure скачать в хорошем качестве

Steps to set Injection Pressure

1. Understand Material Requirements Each plastic material (e.g., PP, ABS, Nylon) has a recommended pressure range. Refer to the material data sheet for starting values. Material Typical Pressure Range (MPa/bar) Polypropylene (PP) 80–120 MPa (800–1200 bar) ABS 90–140 MPa (900–1400 bar) Nylon (PA) 100–160 MPa (1000–1600 bar) 2. Start with Manufacturer Guidelines Set the maximum pressure limit based on: o Machine capability (check the max rated injection pressure) o Tooling (mold cavity strength and venting) 3. Use Short Shot Method o Set a low pressure (e.g. 40–60 MPa) and make a short shot (doesn't fill the mold completely). o Gradually increase pressure in small increments (5–10 MPa) until the part is just filled (no flashing or overpacking). 4. Add a Cushion (Pack/Hold Stage) After setting the injection pressure (1st stage), tune the packing pressure (2nd stage) to maintain proper part dimensions and reduce shrinkage. This is typically 50–90% of injection pressure. 5. Monitor V/P Switch Point Set the Velocity to Pressure switch-over point at 95–98% of the mold volume filled. This helps avoid overpacking and flashing. 6. Fine-Tuning Once filled: o Observe part quality (burn marks, sinks, flash). o Check cycle time and consistency. o Use pressure sensors (if available) to refine settings based on real-time cavity pressure. ________________________________________ ✅ Best Practices • Avoid very high pressures unless necessary—can damage mold or cause flash. • Adjust pressure based on viscosity, which is affected by temperature and shear rate. • Use deceleration ramps or stages for multi-stage injection if applicable. • Ensure the mold is well-vented to avoid burn marks from trapped gases. ________________________________________ 🧪 Example: Setting Pressure for PP on 200T Machine 1. Start with 80 MPa. 2. Perform a short shot → check how full. 3. Increase in steps of 10 MPa until just full (e.g., 100 MPa). 4. Set hold pressure at ~70 MPa. 5. Set V/P switch-over at 95% stroke. 6. Check part and adjust ±5 MPa if needed.