The aluminum die-casting shell of communication products is prone to damage due to impact, vibration, or improper installation. Repair should be carried out based on the material characteristics, degree of damage, and usage requirements of the shell, and an appropriate process should be selected to ensure structural strength and protective performance while minimizing the impact on communication signals.
The argon arc welding repair process is suitable for damages with large damage areas and structural stress areas, such as shell corner fractures, large holes, etc. Before operation, the damaged area needs to be pre treated by grinding with an angle grinder to remove oxide scale, oil stains, and impurities from the damaged area, exposing fresh metal substrate at the damaged edge. After grinding, clean the surface with anhydrous ethanol. Select the matching aluminum welding wire based on the aluminum die-casting material, such as ER4043, ER5356, etc. Adjust the parameters of the argon arc welding equipment, control the welding current at 80-150A, argon flow rate at 5-10L/min, and use short arc welding to avoid excessive heat concentration and deformation of the shell. During welding, gradually fill from the outside of the damaged edge towards the center. When welding multiple layers, the interlayer temperature should be controlled. After each layer is welded, cool it to room temperature before proceeding to the next layer. After welding, use an angle grinder to polish the weld seam to make it level with the surface of the shell and improve the appearance flatness. This process has high repair strength and a tight bond with the substrate, but requires high operational skills to avoid welding defects.
The brazing repair process is suitable for small area damages in thin-walled areas with high precision requirements, such as small cracks and tiny holes on the surface of the shell. During pre-treatment, use sandpaper to polish the damaged area, remove the oxide layer, and apply brazing agent evenly. Choose aluminum based brazing materials with a melting point lower than that of aluminum die-casting materials, such as BAg45CuZnSn. Fix the shell on the fixture table and heat it using flame brazing or induction brazing. Flame brazing requires controlling the flame temperature to avoid local overheating and burning of the shell; Induction brazing has uniform heating, high efficiency, and is more suitable for repairing precision parts. Heat the brazing material until it melts, evenly fill the damaged gaps, keep it warm for a moment, then cool naturally. After cooling, clean the remaining solder and polish it smooth with fine sandpaper. Brazing repair has small deformation and good appearance effect, but the repair strength is lower than argon arc welding and is not suitable for stressed parts.
The adhesive repair process is suitable for small area damages that require high appearance and are not under stress, such as scratches and small cracks on the surface of the shell. Select specialized aluminum structural adhesives, such as epoxy and acrylic structural adhesives, which have strong adhesion and good aging resistance to aluminum die-casting materials. During pre-treatment, use sandpaper to polish the damaged areas and surrounding areas to increase the bonding area and adhesion. Clean with anhydrous ethanol and air dry. Mix the adhesive in proportion, stir evenly, and apply it to the damaged area to ensure that the adhesive layer covers the damaged area evenly. For crack like damages, apply multiple times along the crack direction, and if necessary, lay fiberglass cloth for reinforcement. After application, fix it with a fixture and control the curing temperature and time according to the characteristics of the adhesive. Room temperature curing adhesive generally takes 24 hours, while heating curing adhesive can cure at 60-80 ℃ for 2-4 hours. After curing, remove excess adhesive layer and use sandpaper to polish step by step until the surface is smooth. Adhesive repair is easy to operate, cost-effective, and has no thermal deformation, but its temperature resistance and long-term reliability are slightly inferior to welding processes.
The cold welding repair process is suitable for repairing damaged parts of shells that require no thermal deformation and high precision, such as those with precision interfaces and communication component installation positions. Using a dedicated cold welding machine, the repair material is fused with the substrate at room temperature through high-frequency pulse current. During pre-treatment, polish and clean the damaged area, select a cold welding repair wire that matches the aluminum die-casting material, adjust the current, pulse frequency and other parameters of the cold welding machine. The current is generally 5-20A, and the pulse frequency is 50-100Hz. When operating, hold the welding gun and let the repair wire contact the damaged area. Gradually fill the damaged area with the repair wire through the pulse current, and the filling amount should not be too much each time to avoid accumulation. After the repair is completed, use fine sandpaper to polish and polish the surface roughness to meet the requirements. Cold welding repair has a small heat affected zone, no deformation, high repair accuracy, but low repair efficiency, suitable for small-scale, high-precision damage repair.
After various repair processes are completed, quality inspections should be carried out on the repaired areas, including appearance flatness, adhesion, sealing, etc., to ensure that they meet the requirements for the use of aluminum die-casting shells for communication products
