Vol. 5, No. 4, April 2021


Case Study Of A Quality Complaint On Aluminum Die Casting Products
- The Importance Of Process Quality Capability Improvement
To Ensure Stable Product Quality (Ⅵ)

(Continued from the last issue)

Customizing blister tray according to each product. Blister tray size should be designed based on the size of the outer box. Placing a certain number of products on each blister tray and placing the blister tray in the packaging box in layers and isolating each layer with cardboard. The advantages of this packaging are that the products can be well protected, there is no collision between them, and the risk of oxidation and blackening is small. The disadvantages are that the packaging cost is high and so is the recycling cost of blister trays after the client receives the goods. This packing method is suitable for customers with small batch or small order quantity but with complex product structure and high appearance requirements.

Placing all the products in an outer box, put a big plastic packing bag inside the outer box, and then place the products in layers in the large plastic packing bag. Separate each layer into several small spaces with slotted partition to place each product, making sure each layer is isolated with cardboard. After the placement, 1-2 small bags of desiccant are put in the top layer, then twist the bag opening in the top layer of the packing and seal the packing box. The cost of this packaging method is higher than that of the first one, but it is the easiest to operate; The disadvantage is that the quantity of each box is reduced. This packing method is suitable for most customers who can accept the slight increase of packing cost, and with large quantity and stable order.

Precautions for packaging process: packing boxes and other chipboard partitions should be kept dry; packing plastic bags should not be too thin; desiccant used for packing should meet the requirements; packers should wear gloves correctly for operation; and parts should be held and put away lightly when packing.

▌The impact of storage and transportation on having black spots on casting surface.

Die castings are highly susceptible to oxidation and erosion under high temperature and humidity. After the surface is oxidized, the color will become gray, even black or moldy. So the die castings that have been cleaned and packed should be delivered as soon as possible to avoid oxidation, blackening and mildew caused with long-term stacking in the humid warehouse. Therefore, it is necessary to have good anti-oxidation measures in place and good warehouse management.

First of all, we should require the warehouse have dehumidification device to keep the warehouse well ventilated. Open the window for ventilation in sunny weather, timely close the window in rainy days or rainy seasons and apply necessary dehumidification treatment.

Secondly, the warehouse should have material storage shelves with appropriate pallets. Die castings should not be placed directly on the ground or at lower levels of the shelves. For the products that are not shipped in time, they should be sealed and dehumidified with desiccant. Special protective measures should be taken in rainy seasons to prevent the castings from moisture and mildew. For example, the products can be put in small plastic bags or stored in plastic bags as large as the outer packaging boxes, and then sealed with desiccant.

Third, cartons, partitions and other packaging materials should be stored at the top of the shelf. Damp cartons, paperboards and circulating boxes should not be used, plastic circulating boxes and plastic boxes should be used instead. After packing, the boxes should be sealed immediately and the top layer should be covered.

Finally, for aluminum die castings with steel and iron inserts, antirust oil must be applied on the inserts, meanwhile, the flow process of die casting parts should be speed up.

For castings with long storage time, it is necessary to open the box for inspection before delivery to make sure everything is fine.

As for the protection in the process of transportation, we should keep the parts protected against rainwater, and pay special attention to the weather conditions of sea and ground transportation as well as during the rainy season transportation. If there is a failure of rain protection measures resulting in the castings being wet, the batch should be immediately isolated and re-washed and dried. Castings can be released for shipment only after being placed for 7 days without rust and blackening.

For castings parts transported by sea and land or delivered in rainy season, plastic bags can be added for packaging, and the castings can be sealed in small plastic bags, or they can be stored in a plastic bag as large as the outer box with sufficient amount of desiccant.

From the above analysis we can see that there are many reasons and possibilities that lead to the blackening of aluminum die-casting. We could only ensure the quality of the final product by monitoring each production process, especially the important ones, and taking corresponding control measures for the quality problems in an effort to continuously meet the customers’ requirements for enduring and stable product quality.

By Felix SS YUAN


Windshield Wiper

Wiper is a simple cleaning tool on the front glass of vehicles to prevent rainwater and other dirt from affecting the sight. Some vehicle are also equipped with wipers on the rear glass to prevent the rear glass from rainwater and other pollutants affecting the driver’s view of the vehicle behind through the rearview mirror.

▌Primary failure modes:
● Failure to clean the rainwater and pollutants on the glass due to damaged mechanical arm, affecting the driver’s view.
● Wiping area insufficient to meet regulatory requirement and causing drivers dissatisfaction.
● Failure to clean the rainwater and pollutants on the glass due to damaged motor.
● Uneven operation speed, leaving parts of windshield uncleaned.
● Poor operation stability and loud noise.

▌Preventive measures:
● Check the coating thickness of surface treatment and the time of salt spray test.
● Check whether the length of wiper arm and wiper strip meet the requirements, and whether the wiper blade matches the glass.
● Check wiper motor, switch and connector, and conduct validity tests.
● Check whether the product speed design and connectors are malfunctioning.
● Check whether the material selection is correct and whether the assembly is wrong.




China National Accreditation Service for Conformity Assessment (CNAS) is the national accreditation body of China that is unitarily responsible for the accreditation of certification bodies, laboratories and inspection bodies in China.

For the accreditation of testing and calibration laboratories, CNAS uses ISO/IEC17025 as the accreditation criteria.

CNAS is a member of the International Laboratory Accreditation Cooperation (ILAC). The accreditation certificates issued by CNAS are also recognized by accreditation bodies in different countries who are also members of ILAC.

For a test report and certificate issued by an ISO/IEC17025-compliant laboratory in China to be recognized by accreditation bodies in other countries, the report and certificate should bear the stamp of CNAS, and the information of the laboratory could also be verified on CNAS’ website.


Cost of raw materials:
Exchange rates:

USD/RMB: 1:6.5256

EUR/RMB: 1:7.7777

RUB/RMB: 1:0.0854

April 2021

The above information is for reference only


China Supply Chain Alert

The increase of raw material costs is still the number one topic among the manufacturing industry and the foreign trade community in China. Expectations of a reverse trend would come and go, and we still have reports that prices for various commodities, especially anything relating to iron ore, keep rising recently. There are also reports that there would be another wave of price increase for steel-related materials after the May 1st Holiday.

The overall trend seems to be that early on small and medium manufacturers were impacted badly while most large manufactured managed to hold their prices stable. But recently the impact has started to force those large manufacturers to also announce price increases. Also, smaller manufacturers tend to increase their prices at significantly higher levels on average.

The issue is so serious that the top policy-setting and regulatory body in China, the National Development and Reform Commission, has also tried to calm the market recently, and there are signs that the situation might start to change.

SHENTOU SUPPLY CHAIN MANAGEMENT CO. LTD. is a Shenzhen, China, based company serving international automotive clients in the implementation of their China strategies and programs. CHINA AUTOMOTIVE SUPPLIER QUALITY MANAGEMENT BRIEFING is a bi-monthly newsletter published by Shentou to address the specific and unique quality challenges and concerns international automotive companies face with suppliers in China. Comments are welcome at Click here to subscribe.

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