Experiment on metal powder compaction by differential speed rolling

When differential speed rolling is applied to powder roll compaction, the state of stress in the powder or strip between the rolls may be different from that found in conventional powder rolling. Differential speed rolling of electrolytic copper powder is conducted under the condition of carefully controlled powder feed rate. Roll speed ratios are changed in the range 1.00–1.33 by choosing combinations of the number of roll revolutions. The rolling load increases on increasing the ratio of powder feed volume to strip speed and is slightly smaller compared with that of conventional rolling. The decrease in the rolling load is about 25% of what is found in conventional rolling, when the roll speed ratio is 1.33. The relative density of the strip is about 15% larger than that of conventional rolling under the same rolling load. The strip thickness increases with an increase in the rolling load for each roll gap, regardless of the roll speed ratio.