with galvanized steel use robotic welding processes, it’s still important to invest in the appropriate level of ventilation or fume extraction.
Advantages of Metal-Cored Wire As use of galvanized steel grows, welding manufactur-
ers are developing more technologies aimed at solving the challenges presented by the material. One way to address the issues presented by welding galvanized steel is switching from solid wire to a metal-cored wire developed specifically for use with the material. Welding galvanized steel with solid wire typically results
in slower travel speeds and hotter temperatures. Tis causes a larger heat-affected zone, which can burn away more of the zinc-oxide coating on the material, potentially resulting in a larger area that is prone to corrosion later. Tis is an important consideration for auto manufacturers, since many of them offer a corrosion warranty that covers against rust for a period of time, which can be 15–25 years in some cases. Travel speeds with metal-cored wire are much faster
than the speeds achieved with solid wire—often double the inches per minute with some metal-cored wires—since one of the greatest advantages of metal-cored wire is its high deposition rate. Metal-cored wire is a type of tubular wire consisting of
a metal sheath filled with metallic powders, alloys and arc stabilizers. As opposed to solid wire, metal-cored wire carries higher current densities (at equivalent amperage settings), making it possible to put more weld metal in a joint in less time during the welding process. Tose faster travel speeds make metal-cored wire a frequent choice for robotic welding applications, like those found in automotive manufacturing. Achieving the same weld quality with solid wire would require much slower welding speeds and, with it, higher heat input and potentially, burn-through. Recent advancements in metal-cored wires, specifically
some carrying the AWS classification E70C-GS, provide sig- nificant advantages for welding galvanized steel. Tese wires feature formulations that allow them to weld with a direct cur- rent electrode negative (DCEN) or straight polarity. Operating in straight polarity offers distinct advantages when welding thin-gage galvanized steel, including: • A soſter arc penetration that prevents burn-through on thinner gaged material.
• An improved penetration profile. • Sufficient arc energy to vaporize the galvanized zinc coat- ing, which minimizes surface and subsurface porosity. Like other metal-cored wires, the wires designed for
welding galvanized steel also feature arc stabilizers that help improve metal transfer from the wire to weld, effectively reducing spatter and the need for post-weld cleaning or slag removal, which could slow down overall throughput.
Pairing a Pulsed MIG welding process with metal- cored wires designed specifically for galvanized steel offers improvements over the speeds and performance of solid wire, since one of the greatest advantages of metal-cored wire is its high deposition rate.
Because of these numerous advantages, switching from
solid wire to metal-cored wire paired with a Pulsed MIG weld- ing process can greatly reduce the amount of necessary rework for manufacturers using galvanized steel. In one case, the manufacturer of a bumper substructure
that required welding high-strength steel to galvanized com- ponents was having issues with gaps, travel speed and spatter. Tis manufacturer needed travel speeds of about 40 ipm or 1016 mm/min to meet production requirements, but they were getting 25–30 ipm (635–762 mm/min) with solid wire. Also, the incomplete fusion and the inability to fill gaps us-
ing the solid wire was resulting in nearly 100% rework—great- ly increasing the manufacturer’s labor and consumables costs. Aſter switching to a metal-cored wire that allowed them
to weld with DCEN, the manufacturer was achieving travel speeds of about 45 ipm (1143 mm\min) and saw rework drop to about 10%, for significant productivity and quality gains.
Increased Productivity While some manufacturers may be hesitant to undertake
a change that could require them to requalify a new process or new wire, the quality and productivity gains that can result make it an investment worth considering for automotive gal- vanized steel applications. Te application and material thickness being welded are
important considerations when choosing the most appropriate filler metal. When welding galvanized steel in automotive ap- plications, weld quality and porosity requirements—and how specific types of filler metals impact those issues—also are important considerations. Recent advancements in filler metal technology are provid-
ing automotive manufacturers with new ways to address the challenges presented when welding galvanized steel, resulting in increased productivity and improved quality.
Motorized Vehicle Manufacturing 61
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72 |
Page 73 |
Page 74 |
Page 75 |
Page 76 |
Page 77 |
Page 78 |
Page 79 |
Page 80 |
Page 81 |
Page 82 |
Page 83 |
Page 84 |
Page 85 |
Page 86 |
Page 87 |
Page 88 |
Page 89 |
Page 90 |
Page 91 |
Page 92 |
Page 93 |
Page 94 |
Page 95 |
Page 96 |
Page 97 |
Page 98 |
Page 99 |
Page 100 |
Page 101 |
Page 102 |
Page 103 |
Page 104 |
Page 105 |
Page 106 |
Page 107 |
Page 108 |
Page 109 |
Page 110 |
Page 111 |
Page 112 |
Page 113 |
Page 114 |
Page 115 |
Page 116 |
Page 117 |
Page 118 |
Page 119 |
Page 120 |
Page 121 |
Page 122 |
Page 123 |
Page 124 |
Page 125 |
Page 126 |
Page 127 |
Page 128 |
Page 129 |
Page 130 |
Page 131 |
Page 132 |
Page 133 |
Page 134 |
Page 135 |
Page 136 |
Page 137 |
Page 138 |
Page 139 |
Page 140 |
Page 141 |
Page 142 |
Page 143 |
Page 144 |
Page 145 |
Page 146 |
Page 147 |
Page 148 |
Page 149 |
Page 150 |
Page 151 |
Page 152 |
Page 153 |
Page 154 |
Page 155 |
Page 156 |
Page 157 |
Page 158 |
Page 159 |
Page 160 |
Page 161 |
Page 162 |
Page 163 |
Page 164 |
Page 165 |
Page 166 |
Page 167 |
Page 168 |
Page 169 |
Page 170 |
Page 171 |
Page 172 |
Page 173 |
Page 174 |
Page 175 |
Page 176 |
Page 177 |
Page 178 |
Page 179 |
Page 180 |
Page 181 |
Page 182 |
Page 183 |
Page 184 |
Page 185 |
Page 186 |
Page 187 |
Page 188 |
Page 189 |
Page 190 |
Page 191 |
Page 192 |
Page 193 |
Page 194 |
Page 195 |
Page 196 |
Page 197 |
Page 198 |
Page 199 |
Page 200 |
Page 201 |
Page 202 |
Page 203 |
Page 204 |
Page 205 |
Page 206 |
Page 207 |
Page 208