Laser melting inside cavity

• Applicant: Dr.-Ing. Tim Radel, since 10/2021
• Subject Area: Primary Shaping and Reshaping Technology, Additive Manufacturing
• Term: from 2020 to 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 449377606

Forming of micro parts is challenging because of size effects. Therefore, new forming processes are necessary to overcome these problems. Thus, laser rod end melting is used to overcome the bad upset ratio of < 2 using conventional upsetting in micro range and elongates it using the thermal upset ratio to more than 500. During this process the end of a rod is molten by absorbed laser energy to achieve a material agglomeration. Afterwards, a final forming step is necessary to reach the final geometry. In previous work, always cold forming was applied. Anyhow, for materials with a limited formability, as for example NiTi shape memory alloys, a single step cold forming is generally not sufficient to reach the desired final geometry, instead the material would have to be subjected to multiple additional annealing steps. To realize high shape changes also for this kind of materials, while at the same time minimizing the heat input to the base material, the new method laser melting inside the die is presented as a solution. It combines the advantages of hot forming as well as the advantages of cold forming in one step. Here, the shaping begins before the solidification starts, thus it is initially a casting process which becomes by further cooling a forming of mushy or solid material. Via control of the cooling rate the share of casting versus the share of forming on the shaping process shall be varied and examined systematically. At the end of the project the shaping of a joint for a positive-locking connection on a NiTi actuator wire shall be demonstrated.

• DFG Programme: Research Grants
• Ehemaliger Antragsteller: Professor Dr.-Ing. Frank Vollertsen, until 10/2021