Forging Draft Angle Table for Hammer Forge
In forges powered by hammers, the draft angles of forged parts must ensure sound forgings with minimum shrinkage and clean surface finish. As a consequence, a number of components have to be included to ensure accurate forging shapes and tolerances. Designers need to understand the impact of draft angles on the forging process to ensure the best results from their custom forgings.
The angle of a draft angle determines the ways that a forging shape is altered during hammer forging. When a part is heated and subjected to mechanical hammers it becomes stretched. This stretching is related to the draft angle. The greater the draft angle, the more elongation will occur as the bar is stretched into the desired shape. This means that it is possible to achieve more intricate shapes with draft angles than without them.
Draft angles can affect the surface finish of a forged part. When a draft angle is placed in the design, it helps the hammer correctly apply the force needed to achieve the desired shape. The drafts angle helps compress the material on the surface, rather than just pushing it out of the way. This results in a cleaner and smoother finish. In addition, using drafts angles can help reduce the number of flaws that might occur during a forging operation.
When deciding on a draft angle for forging components, several criteria need to be taken into consideration. Primarily, draft angles mustbe large enough to compensate for the contraction of the forging material due to cooling. As a rule of thumb, a minimum 15° draft angle should be included. The design should also take into account whether the part is to be machined or not. If the part is to be subject to further machining, it is important to design a draft angle into the initial forging so that the machined parts fit together easily. Finally, what type of hammer forging will be used should also be considered, as draft angles may need to be adjusted accordingly to compensate for the force orientation of each hammer type.
Forging draft angles are a critical design factor in achieving a good forging result. With the right design, employing such angles can give high quality, dimensional accuracy, and repeatable consistency to forge projects, allowing complex and intricate shapes to be created. The following table provides rough guidelines for the draft angles used in hammer forge operations depending on the type of material being used.
Material
AISI 1020-1045
Carbon Steel
Draft Angle 30°-35° 30°-35°
