Welding, Machining and Surface Symbols
≈ 40 minWelding, Machining and Surface Symbols
Grade 12 adds the symbols that tell a workshop how to make and finish a part, not just its size.
Welding symbols sit on a horizontal reference line with an arrow to the joint. The symbol's shape names the weld — a triangle for a fillet weld, a square for a square butt, a V for a single-V butt. Its position matters: below the reference line means the weld is on the arrow side; above means the other side. Size is written to the left of the symbol, length to the right.
Surface texture symbols are a tick-like mark on the surface, with a roughness value in micrometres (Ra). A bar across the top means material removal is required; a circle means it is prohibited — the surface must stay as cast or as rolled.
Machining and treatment notes — case-harden, anodise, zinc-plate — are added as leader notes to the surfaces they apply to.
Worked example. A fillet weld symbol drawn above the reference line instead of below places the weld on the wrong side of the joint. The part is welded, inspected, and rejected — the symbol's position is not stylistic.
Core checkpoint: In a welding symbol the position relative to the reference line is information, not layout.
What does a weld symbol placed below the reference line indicate?
On a surface texture symbol, what does a circle on the symbol mean?
Where are the weld's size and length written relative to the symbol?
A fillet weld symbol is drawn above the reference line when the weld should be on the arrow side. What happens?