How to prevent deformation and cracking in the subsequent processing of zinc alloy die-casting hardware bag accessories?
Release Time : 2025-09-04
Preventing deformation and cracking during subsequent processing of zinc alloy die-cast hardware bag accessories requires comprehensive measures, including raw material control, mold design, process optimization, and standardized operating procedures. Zinc alloy's compositional characteristics make it extremely sensitive to impurities. Excessive levels of harmful elements such as lead, tin, iron, and cadmium in the raw materials can form low-melting-point eutectics at grain boundaries, causing cracking along these grain boundaries during cooling or stress. Therefore, it is crucial to strictly select zinc alloy raw materials that meet standards, control the content of harmful impurities, and avoid the influx of impurities from scrap to mitigate the risk of cracking at the source.
The rationality of mold design directly impacts the molding quality of bag accessories. Complex mold structures, improper parting surfaces, or inappropriate runner design can lead to uneven metal filling, localized turbulence or air entrainment, and the formation of defects such as pores and shrinkage. These defects can easily become stress concentration points during subsequent processing, causing deformation and cracking. Therefore, mold design should adhere to the principles of "simplicity, rationality, and feasibility." Optimize runner and gate design to ensure smooth filling of the molten metal. Properly design overflow and vent grooves to promptly discharge gas and residue, minimizing internal defects.
Precise control of die-casting process parameters is key to preventing deformation and cracking. Excessively high mold temperatures exacerbate molten metal shrinkage, leading to tensile stress within the bag accessories. Excessively low mold temperatures can cause premature solidification of the molten metal, preventing it from fully filling the cavity and causing cold shut or water marks.
Furthermore, injection pressure and speed must be precisely matched to avoid incomplete filling due to insufficient pressure or turbulence and air entrainment due to excessive speed. Therefore, mold temperature, injection pressure, and speed must be optimally set based on the bag accessory's structure and alloy properties to ensure molding quality.
Performing the demolding process with proper procedures is crucial to the quality of bag accessories. A deflected ejector plate can result in uneven stress on the casting, with excessive force on one side and insufficient force on the other, leading to deformation and cracking. Therefore, it's necessary to increase the number of ejector pins and adjust their distribution to ensure balanced force during bag accessories ejection. Careful selection and application of release agents are also crucial. Water-based release agents should be used to avoid residual oil-based release agents, which can cause plating blistering or reduced coating adhesion.
Mechanical stress control is also crucial during subsequent processing of bag accessories. Improper operation during drilling, tapping, and polishing, such as excessive force, excessive feed speeds, or inappropriate tool selection, can easily cause microcracks or stress concentrations on the accessory surface. Therefore, appropriate tools and process parameters should be selected based on the accessory material and processing requirements. For example, polishing with low speeds and high feed rates can reduce the impact of mechanical stress on the accessory.
Optimizing the heat treatment process can also effectively improve the bag accessories' resistance to deformation and cracking. Annealing or aging treatments can eliminate residual stress within the accessory, stabilize the microstructure, and reduce deformation during subsequent processing. However, careful control of heating rates and holding times is crucial to avoid coarsening grains or performance degradation caused by improper heat treatment.
Quality inspection and process monitoring are the final line of defense for ensuring the quality of bag accessories. Each batch of accessories must be inspected for dimensions, appearance, and performance to promptly identify and address potential defects. Furthermore, a comprehensive production record and traceability system is established, enabling real-time monitoring of key processes.
This ensures that problems can be traced and addressed. The combined application of these measures effectively prevents deformation and cracking in zinc alloy die-cast hardware bag accessories during subsequent processing, improving product quality and market competitiveness.