1、 Storage and incoming material protection
Thin walled pipes with weak strength in the weld area should be stacked flat. Single point compression, trampling, and heavy weight should be avoided to prevent deformation of flat pipes and micro cracks in the weld seam.
Aluminum tubes, carbon steel parts, and steel fixtures are stored in separate areas to avoid galvanic corrosion caused by iron filings; Use rubber isolation pads during transportation to prevent direct scratching of the oxide film on the inner and outer surfaces by hard tools.
Keep the warehouse dry and ventilated, and avoid long-term outdoor storage; Priority should be given to using pipes with hydrophilic anti-corrosion coatings in coastal and salt spray environments.
Key inspection points for incoming materials: no virtual welding, porosity, or penetration defects in the weld seam; Each batch must undergo airtightness leak detection to eliminate the hidden danger of micro leakage at the factory.
2、 Key points of cutting, bending and other forming processing
Use aluminum specific cutting tools and prohibit hot cutting with grinding wheels; Remove internal and external burrs from the incision to prevent burrs from falling off, blocking the pipeline, and scratching the inner wall.
Bending is strictly prohibited with a small bending radius. The elliptical flat tube weld should be arranged in the neutral layer as much as possible, not in the tensile zone, to prevent weld cracking and pipe wall wrinkling and collapse.
Avoid oil stains and cutting fluid infiltration into the inner cavity of the pipe during the entire molding process; After processing, blow clean the internal debris.
Do not forcefully strike the flat surface of the flat tube, as thin-walled sections are prone to local depressions, which can affect fluid flow and heat transfer area.
3、 Brazing/Welding Assembly Key (Core Process of Heat Sink)
Before welding, it is necessary to thoroughly remove oil stains and oxide films from the pipe mouth and weld area; Weld as soon as possible after cleaning, as the oxide film will quickly regenerate, causing porosity and poor bonding in the brazed joint.
The high-frequency welding of aluminum flat tubes is a weak area, and the brazing in the furnace strictly controls the heating rate and insulation time to prevent overheating from causing a decrease in weld strength and intergranular leakage.
The assembly clearance shall be strictly executed according to the process to avoid the distortion of the pipe caused by forced pressing and the additional stress on the weld seam.
Slowly cool down after brazing to reduce residual stress; Do not induce microcracks through rapid quenching.
4、 System media and water quality control (primary cause of leakage failure)
Cooling medium inside the pipe
Priority should be given to using OAT/HOAT long-lasting antifreeze that is compatible with aluminum alloys as the coolant;
It is strictly prohibited to directly add tap water or well water, as chloride ions in the water can quickly cause pitting and perforation on the inner wall of the aluminum tube; Calcium and magnesium ions scale and block the flow channel, reducing heat dissipation efficiency.
Antifreeze must be mixed with deionized water and regularly monitored for pH and conductivity to prevent acidification and corrosion of the medium.
Prohibit the medium from being in a strongly acidic or alkaline environment for a long time; Avoid mixing corrosive ions such as chloride ions and sulfur ions.
Before the initial operation of the system, thoroughly flush the pipeline, remove welding slag and metal powder, and prevent abrasion of the inner wall.
5、 Limitations on pressure, temperature, and vibration conditions
Strictly operate according to the design pressure, and prohibit overpressure and frequent pressure shocks; Thin walled flat tubes have limited pressure tolerance, and pulsating pressure can easily induce fatigue leakage.
Reserve space for thermal expansion compensation, as the thermal stress generated by cold and hot cycles will gradually damage the weld seam.
Add shock-absorbing fixation under long-term vibration conditions to avoid fatigue cracking of welds under continuous alternating loads; The bracket cannot be rigidly stuck.
Pay attention to the extreme temperature range and avoid exceeding the allowable working temperature of the alloy.
