**2.2. Fabrication of micro circular cup**

By using the developed micro-deep drawing experimental system, a trial test for fabricating the micro-circular cup is carried out. As a first target of the process dimensions for the micro-deep drawing experiment, we aimed to produce the microcups with outer diameter of 500μm from the blank of 1.1 mm in diameter and of 20μm in thickness. Material used is stainless steel (JIS: SUS304-H), phosphor bronze (JIS: C5191-H), and pure titanium (JIS: TR270C-H) ultra-thin metal foils. Redrawing process is adopted to produce a cup of 700μm diameter at the first-stage and 500μm diameter at the second-stage. All microtools are made of sintered WC-Co hard alloy (JIS: V20 tungsten-carbide-cobalt alloy), machined by EDM (Electrical discharged machining) and mechanically fined polishing. By adjusting the clearance between die and punch, die corner radius and punch corner radius, the tool dimensions are determined as shown in Fig. 5.

**Figure 5.** Schematic illustration of tool dimensions for micro-drawing experiment

Fig.6 shows the fabricated microcups on a forefinger and the SEM images of the first-stage and second-stage drawn microcups. The tiny microcups are fabricated successfully by the microforming technology. The micro-deep drawing process is realized by a high-precision blanking-drawing technique, and more than 100 microcups are produced with good reproducibility for every three kinds of materials, as shown in Fig. 7.

Impact of Surface Topography of Tools and Materials in Micro-Sheet Metal Forming 117

**Figure 6.** Appearance of drawn microcups on a forefinger and its SEM image

116 Metal Forming – Process, Tools, Design

would be able to track in the experiment.

**2.2. Fabrication of micro circular cup** 

dimensions are determined as shown in Fig. 5.

=0.654

*Punch*

r21=0.1

D1d=0.69

D1p

> R1d=0.1

*BH*

0.03mm

Fig.6 shows the fabricated microcups on a forefinger and the SEM images of the first-stage and second-stage drawn microcups. The tiny microcups are fabricated successfully by the microforming technology. The micro-deep drawing process is realized by a high-precision blanking-drawing technique, and more than 100 microcups are produced with good

*die*

**Figure 5.** Schematic illustration of tool dimensions for micro-drawing experiment

reproducibility for every three kinds of materials, as shown in Fig. 7.

controlling program, such as linear or S-curve acceleration and deceleration, inching motion

Moreover, the compact feeding device is newly developed for the miniature press machine. By using this device, the coiled material of metal foils can be progressively supplied during the process and the continuous transition of the forming behaviour, such as wear of tools,

By using the developed micro-deep drawing experimental system, a trial test for fabricating the micro-circular cup is carried out. As a first target of the process dimensions for the micro-deep drawing experiment, we aimed to produce the microcups with outer diameter of 500μm from the blank of 1.1 mm in diameter and of 20μm in thickness. Material used is stainless steel (JIS: SUS304-H), phosphor bronze (JIS: C5191-H), and pure titanium (JIS: TR270C-H) ultra-thin metal foils. Redrawing process is adopted to produce a cup of 700μm diameter at the first-stage and 500μm diameter at the second-stage. All microtools are made of sintered WC-Co hard alloy (JIS: V20 tungsten-carbide-cobalt alloy), machined by EDM (Electrical discharged machining) and mechanically fined polishing. By adjusting the clearance between die and punch, die corner radius and punch corner radius, the tool

> R2d=0.3

> > *die*

r2p=0.05

*Punch*

D2p=0.45

> D2d=0.5

at bottom dead point and motion stop at several displacement for input time length.

**Figure 7.** Appearance of drawn microcups with good reproducibility in three different materials, phosphor bronze, stainless steel, and pure titanium
