What Quality Issues Do Buyers Fear Most in Aluminum Die Casting?
When a buyer receives a shipment of aluminum die cast parts, the first thing they check is surface and structural quality. If defects like porosity or surface swelling show up, it leads to extra costs — whether that’s rework, rejection, or customer complaints downstream. From our two decades of experience supplying parts to industries like automotive, lighting, and medical, we know exactly which defects buyers worry about most, and we’ve built our process to address them before parts leave our factory.
Defect #1: Porosity — Why It Happens and How We Minimize It
Porosity is the most talked-about defect in aluminum die casting. It shows up as tiny air pockets or voids inside the part — which can affect pressure resistance or surface finishes like anodizing. There are two main types: gas porosity and shrink porosity.
Common Causes:
- Poor venting in the mold
- High gas content in the molten metal
- Uncontrolled cooling or mold temperature
How We Prevent It:
- We use ADC12 alloy with good flow and gas control characteristics
- Molds are designed with proper venting and vacuum evacuation (if needed)
- We control mold temperatures and injection speeds to reduce turbulence
Defect #2: Cold Shut — What Causes This Flow Defect?
Cold shut happens when two molten fronts meet but fail to fuse properly. You’ll see it as a visible line or even a crack-like seam in the part. It’s mostly caused by low melt temperatures or overly thin sections.
How We Handle It:
- Our furnace melts ADC12 at a stable 660–680°C range
- We ensure mold preheating before every batch
- Flow paths in the mold are optimized to avoid slow-fusing areas
Parts with cold shut can be structurally weak — especially for components with sealing functions. That’s why we eliminate it during tool design and parameter setup.
Defect #3: Flash — What It Means and How We Control Mold Fit
Flash is excess material that seeps out of mold parting lines or ejector pin holes. It may look harmless, but it leads to unnecessary trimming time and can disrupt downstream assembly if left untreated.
Why Flash Happens:
- Mold wear or improper closure
- Excessive injection pressure
- Misaligned parting lines
Our Prevention:
- Our machines apply locking force up to 250 tons for standard tools
- We routinely inspect and maintain mold closing surfaces
- Injection pressure is adjusted based on each mold design to avoid overfilling
We also integrate flash trimming into post-processing for high-volume orders.
Defect #4: Shrinkage — Understanding Volume Loss During Solidification
Shrinkage occurs as the molten aluminum solidifies and contracts, especially in thick or poorly cooled areas. It results in internal voids or slight warping in structure.
Typical Areas Affected:
- Thick bosses or rib intersections
- Asymmetric wall thickness zones
Our Control Tactics:
- Balanced wall design in the mold
- Controlled cooling rate via water lines and mold steel selection
- Accurate pressure hold time to allow proper feeding during solidification
With ADC12, we monitor mold fill speed and pressure to maintain proper compaction across the cavity.
Defect #5: Surface Blisters — What Causes Bubbling or Swelling?
Surface blisters appear like small bubbles or raised patches after die casting or secondary processes like painting. Buyers often confuse them with porosity, but the cause is usually near-surface gas trapped by overheating.
Possible Causes:
- Mold temperature too high
- Moisture in metal or release agent
- Poor degassing of molten aluminum
How We Avoid It:
- We pre-dry ADC12 ingots and avoid wet release agents
- Mold temperature is kept below 240°C at contact zones
- Degassing units are used for large batches, especially for export products
This step is especially important for visible parts or housing components in electronics and medical fields.
How We Monitor and Control Defects in Real Production
Our process isn’t based on luck — it’s based on routines. Each production batch follows a clear quality workflow:
| Control Step | Frequency | What We Do |
|---|---|---|
| Mold Temperature Check | Every 4 hours | Handheld sensors, thermal probes |
| Metal Composition Test | Every raw batch | Spectrometer test for ADC12 purity |
| Mold Maintenance Review | Daily and weekly | Check vents, runners, ejectors |
| Visual + Dimensional QC | Per production lot | Random checks with calipers, X-ray |
These steps are what allow us to say our scrap rate is kept under 2%, and our defect-related returns from customers are under 0.3%.
What Our Rework and Reject Rate Says About Our Process
We believe that transparency builds trust. In our current projects, we maintain:
- Overall defect rate: < 2%
- Porosity-related defects: ~0.5%
- Flash-related rework: Less than 1.2%
- Customer returns due to defects: < 0.3%
By focusing on early detection and real-time control, we rarely let defects slip past our factory gates.
Most buyers aren’t looking for perfection — they want reliability. They want to know that when they place an order, they won’t be dealing with rejections, delays, or warranty issues. After 20+ years of producing aluminum die castings, we’ve built our reputation on this steady reliability.
Searching for High-Quality for Aluminum Parts?
You’ve come to the right place! Yongzhu Casting is a certified die casting manufacturer with over 20 years of expertise in the industry.
We have successfully completed numerous die casting projects for Aluminum casting parts, particularly in your industry.
Zhejiang Yongzhu Casting Technology Co., Ltd.
Location: Zhejiang, China
Company type: Manufacturers, Producers, Wholesalers
Year Founded: 2004
Main Products: Aluminium die casting, Mold Making, Die Casting, Sand Casting, Gravity Casting
Leading Chinese producer Yongzhu Casting is formerly known as Hangzhou Higer Metal Products Co., Ltd., was established in 2004.
With 20 years of experience in the industry, we are a specialized manufacturer in Aluminum casting and Machining.
Our products are widely used in various applications such as Automotive, Energy, Lighting, Medical, Home Furnishings, Machinery & Equipment etc. Below are our advantages:
Design Review & DFM Support
Our professionals will evaluate your designs and provide suggestions for cost savings. Additionally, we offer Design for Manufacturing (DFM) assistance and conduct mold flow analyses to facilitate efficient production.
State-of-the-Art Manufacturing Equipment
Our facility is equipped with advanced hot-chamber and cold-chamber die casting machinery for aluminum and zinc production.
We also utilize high-precision CNC machines in a temperature-controlled workshop, featuring 3-Axis, 4-Axis and 5-Axis setups to manage any project you have.
Rigorous Quality Control Measures
Our dedicated quality control team ensures that all parts meet the highest standards of quality and consistency. We employ high-accuracy measurement instruments, including CMM, spectrometers, and X-ray detectors.
Comprehensive Surface Treatment Options
We provide a variety of surface finishing techniques for your precision die casting components. Our in-house services include cleaning, polishing, anodizing, shot blasting, and painting.
Flexible Project Acceptance
While larger manufacturers often shy away from low-volume projects, and smaller ones may struggle with quality, Yongzhu Casting stands apart. We prioritize customer satisfaction and willingly accept high-mix, low-volume projects like yours.
