Fig. 1 Flowchart of the parallelism evolution model More

Fig. 2 Schematic of upper plate inclinations with different workpieces: ( a ) different thickness, ( b ) various shapes, ( c ) slanted workpieces with same thickness, and ( d ) various shapes with same thickness More

Fig. 3 Schematic of upper plate inclinations with one or two slanted workpieces More

Fig. 4 Schematic of DSL with five workpieces: ( a ) DSL with floating upper plate and ( b ) contact situations of the lapping plates and workpieces More

Fig. 5 Schematic of workpiece force analysis: ( a ) contacts situation of the workpieces and lapping plates and ( b ) force analysis on three workpieces More

Fig. 6 The pressure with different lapping plate profiles More

Fig. 7 Force analysis of workpieces during DSL process: ( a ) contact situation of the workpieces and lapping plates and ( b ) force analysis on five workpieces More

Fig. 8 DSL Setups More

Fig. 9 Parallelism measurement instrument More

Fig. 10 Calculation results of slanted workpiece parallelism evolution More

Fig. 11 Calculation results of a parallel workpiece parallelism evolution More

Fig. 12 Experimental results of slanted workpiece parallelism evolution More

Fig. 13 Experimental results of a parallel workpiece parallelism evolution More

Fig. 14 The flatness and parallelism of the workpieces: ( a ) before optimization and ( b ) after optimization More