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Tooling
Each of our methods of extrusion curving has its own type and requirements for tooling. In brake forming there is little cost or complexity in the tooling. Simple hand tools, radius gauges and arbor blocks are about all that is needed. Mainly, a lot of skill, material, time and talent is involved. Compression bending requires a wipe shoe that fits the part, a follower block and some lathe and mill work that fits the inside of the part to follow the profile and desired contour. In roll forming one would be using a three- or four-roll forming machine in conjunction with some lathe finishing of rolls. Stretch wrap forming requires more tooling. A large form block is normally needed. This block fits to the inside radius of the part to be curved. Many types of tooling can be successfully used in creating form blocks. Plastic, wood, aluminum and steel all can be used with good results. The size of the part, tolerances needed and quantities all must considered together in determining what is the best material to use for tooling. A job which requires large a small quantity job may make it cost prohibitive to use metal and therefore plastic or wood may be the best. To keep the extrusion from collapsing while being curved, a filler material must be used inside the part. In roll forming, sand, Cerro bend or plastic is put into the part and then taken out. In compression bending, plastic or Cerro bend can be used, but normally a mandrel with an extractor is used. Stretch wrap forming uses the same basic filler as used in roll forming. |
