Iron metallurgy is the main marker of the African past but its temporality is poorly known because of the low number of dates per site and of the dependence on radiocarbon. The main objective of the TIMA - Time of Iron Metallurgy in Africa – is to better understand the life of iron smelting sites (duration and production rate) through the mobilization of several dating methods (archaeomagnetism, 14C on charcoals and ferrous objects) on a common field site. For this purpose, three field missions have been organized in Benin and Togo in 2021-2022. In Benin, the field is located in the Aplahoué region in the south of the country, where we have started excavations on two smelting sites (Doloumey and Kpeta), preliminarily dated between 800 and 1400 AD. In order to obtain a detailed chronology of the sites, dozens of charcoal samples were collected from different layers of slag heaps and settlements. No blast furnaces have still been discovered. Because of this absence, archaeomagnetism focuses for the moment on the study of the archaeointensity of the geomagnetic field with displaced materials (ceramics, tuyeres, fragments of furnace walls). The scientific context of the mission in the Bandjeli region in central Togo is different: the sites had already been mapped and the furnaces located. They were dated by 14C in the plateau of the last four centuries. This imprecision prevents understanding the chronological relationships between two smelting techniques (one with tapped slag, the other with pit slag), possibly related to two different populations. In order to clarify the chronology, 18 furnaces belonging to the two techniques were collected for archaeomagnetic dating with the archaeodirection and the archaeointensity of the geomagnetic field. This communication will present our methodological approach and the main results already obtained in the TIMA project.