Mandrel materials for bending aluminum tube

[EngForm78]

I have an aluminum bending process involving complex extrusion shapes. Currently we use small steel shot to fill the tube before bending to keep it from collapsing. However, some of the extrusions are large and get very heavy when filled with steel. Are there other types of materials or methods that can be used. Aluminum beads? plastics beads? bendable mandrels? foam fill?

Thanks in advance

EngForm78

 

[kenvlach]

Dry sand.

 

[CoryPad]

As Ken states, sand is common. The specific gravity of silica is ~ 2.5, while that of steel is ~ 7.9, so that can be a large mass savings.

Regards,

Cory

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[griffengm]

I've seen pitch (tar) poured into brass tube and then chilled before bending. Only one plug was needed when the tube was filled and it was removed before bending. If I remember correctly, working temp influenced the stretch of the bend. Removal consisted of heating and a wash but it was very effective. I suppose it depends how large your parts are.

Griffy