What are the common defects in die cast motor parts？

Common Defects in Die Casting Motor Parts
1. Porosity (Internal or Surface)
During the solidification process of the molten metal, the gas fails to be exhausted in time, resulting in round or irregular cavities. They often appear in thick walled areas, near the gates, or in areas where the flow is obstructed.

2. Shrinkage Cavities and Shrinkage Porosity
Local cavities or loose structures are caused by metal shrinkage or uneven cooling, especially in areas with uneven wall thickness.

3. Cracks
Cracks are caused by high stress concentration or rapid cooling. They may penetrate the entire casting or appear locally, affecting the structural strength.

4. Cold Shut (Cold Lamination)
It is a delamination defect formed by insufficient temperature or poor exhaust during the flow of molten metal. It is often accompanied by surface dents or internal inclusions.

5. Surface Defects (Patterns, Flow Marks, Protrusions)
Surface defects are caused by unreasonable runner design, excessive gate specific pressure, or rough mold surfaces, which affect the appearance and subsequent processing.

How to Quickly Locate Defects and Reduce the Scrap Rate?
A Systematic Method for Quickly Locating Defects
1. Defect Classification and Image Collection
Take photos, X rays, or CT scans of defective parts and establish an image library according to defect types (porosity, shrinkage cavities, cracks, etc.) for quick comparison later.

2. Fishbone Diagram (Cause and Effect Analysis)
Attribute the defects to six major factors: "materials, equipment, processes, personnel, environment, and management", and trace the root causes layer by layer to form a visual cause and effect chain.

3. Monitoring of Key Process Parameters
Collect key parameters such as pouring temperature, mold temperature, injection pressure, and flow velocity in real time. Use a big data platform for abnormal alarm to quickly identify the abnormal production section.

4. Numerical Simulation and Hot Spot Prediction
Use software such as ProCAST and MAGMA to simulate the flow field, temperature field, and stress field of new molds or improved processes. Predict possible defect locations in advance and adjust the process accordingly.

Systematic Improvement Measures to Reduce the Scrap Rate
1. Optimization of Process Parameters
Increase the pouring temperature and mold pre heating temperature to ensure complete filling of the molten metal. Appropriately increase the gate capacity and improve the exhaust system to reduce the probability of porosity and cold shut.

2. Improvement of Mold Structure
Use adjustable structures such as limit rods and limit grooves to compensate for mold wear, ensure tight mold clamping, and significantly reduce the scrap rate caused by poor mold clamping.

3. Continuous Improvement Process (PDCA)
Plan: Develop a defect analysis plan.
Do: Implement targeted improvements (such as replacing the gate or adjusting the injection speed).
Check: Randomly inspect the improved products and statistically analyze the change in the scrap rate.
Act: Solidify successful experiences into work instructions and inspection standards to form a closed loop.
4. Quality Archive and Traceability System
Establish a defect archive library to record the time, batch, process parameters, and rectification measures of each defect occurrence, enabling full process traceability and preventing the recurrence of similar defects.