alumunium 2.5mm aluminium plate spot welding sampel Sampel pengelasan titik tulangan paduan aluminium Sampel pengelasan titik paduan aluminium Sampel Pengelasan Proyeksi Ring Aluminium Silinder Sampel pengelasan titik plat dekoratif aluminium Aluminium heat pipe bracket spot welding sampel Aluminium heat sink spot welding sampel Aluminium pin spot welding sampel Sampel pengelasan multi-titik aluminium plat Sampel pengelasan titik pengelasan plat aluminium Sampel pengelasan titik lembaran tabung aluminium Aluminium wire mesh spot welding sampel Sampel pengelasan titik aluminium plat Ketebalan dinding 1.2 sampel pengelasan titik dukungan tabung aluminium