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. |