Determination of springback gradient in the die on compacted polymer powders during high-velocity compaction
2006 (English)In: Polymer testing, ISSN 0142-9418, E-ISSN 1873-2348, Vol. 25, no 1, 114-123 p.Article in journal (Refereed) Published
A uniaxial high-velocity compaction process for polymer powder using a cylindrical, hardened steel die and a new technique with relaxation assist was tested with various heights. The influences of the relaxation assist device on the process characteristics are discussed. Two bonded strain gauges and a high-speed video camera system were used to investigate the springback phenomenon during the compaction process. It was found that the relaxation assist improves the compaction of the polymer powder by locking the powder bed in the compacted form. It is shown that the high-velocity compaction process is an interruption process and that the delay times between the pressure waves can be reduced by increasing the height of the relaxation assist device. The delay times between the pressure waves are also strongly dependent on the strain rate. If the height of the relaxation assist device is increased, the first gross instantaneous springback, and the total elastic springback, are reduced. In addition, the density of the powder bed is increased. The relative times of the compacting stage, decompacting stage and the reorganisation of the particles can be also controlled by altering the height of the relaxation assist.
Place, publisher, year, edition, pages
2006. Vol. 25, no 1, 114-123 p.
high-velocity compaction; powder polymers; polyamide-11; relaxation assist; strain rates; relative green density; morphology; springback gradient
IdentifiersURN: urn:nbn:se:kth:diva-6227DOI: 10.1016/j.polymertesting.2005.09.002ISI: 000235262700017ScopusID: 2-s2.0-31444445807OAI: oai:DiVA.org:kth-6227DiVA: diva2:10876
QC 201005062006-10-062006-10-062016-05-18Bibliographically approved