The charges to Work in Process-Assembly Department for a period, together with information concerning production, are as follows. All direct materials process at the beginning of production. c. Assuming that the direct materials cost per unit did not change from the preceding period, did the canversion costs per equivaient unit increase, decre temain the same for the current period? The charges to Work in Process-Assembly Department for a period, together with information concerning production, are as follows. All direct materials process at the beginning of production. c. Assuming that the direct materials cost per unit did not change from the preceding period, did the canversion costs per equivaient unit increase, decre temain the same for the current period