△═ Surfacing / hardfacing weld
Surfacing / hardfacing weld · Soldadura en plano · ISO 1101 + ASME Y14.5
Example in plan
How to interpret it
On the drawing, “Hardfacing on tool flank” states a surfacing / hardfacing weld requirement.
What controls
Material deposited on a surface to give it properties the base material lacks (wear, corrosion or abrasion resistance) or to restore dimensions on a worn part. It does not join two parts: there is no joint and no throat. The symbol is accompanied by the required layer thickness and, where applicable, the area to be surfaced and the number of layers. The thickness to be guaranteed is the useful, finished material, not the as-deposited build-up.
How to verify
Layer thickness with a caliper or micrometer compared against the original dimension, or with an ultrasonic thickness gauge when there is no access from both sides. Surface hardness of the overlay is checked with a portable hardness tester on the already machined layer, which is where it matters. Bonding and freedom from cracks are checked by visual inspection and penetrant testing on the finished surface.
Workshop guideline values
- General
- Layers of 2–5 mm per pass for wear surfacing on large parts.
- Accuracy
- Layers of 0.5–2 mm when machining to size with a tight tolerance follows.
- High precision
- Tenths of a millimeter in fine surfacing with controlled filler and subsequent grinding.
Guidance only: the drawing's value always wins.
Common mistakes when interpreting it
- Measuring thickness on the as-welded bead and miscalculating the material to be machined off: what counts is the layer that remains at final size.
- Checking hardness on the diluted first layer instead of on the final surface.
- Treating surfacing as a structural weld and applying joint criteria that do not apply to it.
How to get it in the workshop / if it comes out of tolerance
Plan the whole process: surface, leave stock, and machine or grind to size. The first layer is diluted with the base material and does not have the full properties of the filler, which is why many surfacing jobs require two or more layers. Surfacing distorts the part and introduces stresses: on long parts, alternate areas and control the interpass temperature.
Cracks in the surfaced layer are common with hard fillers: review preheat and cooling rate and, if the drawing allows, add a tougher buffer layer. Hardness below the requirement is usually dilution with the base material: increase the number of layers or reduce penetration. If the part distorts, surface in alternating sections and let it cool; straightening a surfaced part afterward usually cracks the layer.
Related symbols
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