The surface quality varies depending on the alloy, the condition of the tool, the shape of the extrusion and process parameters used.
High surface requirements place greater demands on the tool, control of process parameters and the handling of extrusions during production. Lower productivity and a risk of increased scrap means that a high surface requirement results in a more costly product.
It is important that surface requirements and any visible surfaces are indicated on the production drawings. The markings to be used for this are:
|Double-dotted and dashed line||— – – — – – — – – —|
|Dashed line||— — — — — — — —|
|Dotted line||– – – – – – – – – – – –|
Even unmarked surfaces can have a surface requirement.
- The markings are used to describe surface requirements and/or visible surfaces for a specified surface section.
- Unmarked surfaces can, unless otherwise defined, be given a surface requirement 1 step lower than the lowest indicated surface requirement.
- Unmarked surfaces are in most cases not visible.