班級：碩研機械一甲姓名：田正雨學號：M9810213

Micro-EDM of sintered diamond

• excellent hardness and very low frictional wear

• machine SD(Sintered diamond) with high precision by conventional methods such as cutting and grinding

Introduction(1/2)

• Since SD contains metal as binder, it is electrically conductive

• Micro-EDM, its ability to machine regardless of the hardness of the workpiece

• four types of SD, composed of 1, 3, 10 and 20 μm diamond particles

Introduction(2/2)

• Panasonic MG-ED72 micro-EDM machine, WEDG, 50μm-diameter cylindrical electrodes(tungsten)

• Binder (cobalt) , approximately 5%

• Tungsten carbide alloy was also tested for comparison

Experiments(1/3)

• Hole machining：

• Discharge capacitance was 100 pF, and the open-circuit voltages were 100, 80, and 60 V

• measured the machining time, the electrode wear, and the side gap

Experiments(2/3)

• Trench machining：

• The size of the trenches ： 50 μ m (width) × 4 mm (length) × 30 μm (depth)

• 100v, 3300 pF(rough), 100 pF(medium) and stray capacitance(10pF, finish machining)

• surface roughness at the bottom of the trenches

Experiments(3/3)

• Shape of machined holes：

• There is no significant difference of size and roundness among all holes

• This fact suggests that precision and micro EDM of SD is practical

Results and discussion _ Hole machining(1)

Ø 50μ m, 100 V and 100 pF

• Machining speed：

• 20 μ m at 60 V and 80 V could not be machined ：electrode wear was so large

• Machining speed, SD and tungsten carbide alloy ： No significant difference

Results and discussion _ Hole machining(2)

Volmetric machining speed

• Machining speed：

• 100V 、 80V, machining speed apparently decreases ： debris

• The same phenomenon ：3 μ m , BUT, 10 μ m and 20 μ m appears to be constant

Results and discussion _ Hole machining(3)

diamond particle：Debris influence ：

• Electrode wear

• The wear ratio：tungsten carbide < SD

• Machining speed：

Electrode wear：

Results and discussion _ Hole machining(4)

• Side gap

• There is no apparent correlation between diamond particle size and side gap

Results and discussion _ Hole machining(5)

• Surface roughness：

discharge capacitance ：

the surface roughness ：

Results and discussion _ Trench machining(1)

• Observation of machined surface(By SEM)

Results and discussion _ Trench machining(2)

Same craters craters

diamond particles are small：can be removed

diamond particles are largea part of particles

• Round Ø 50 μ m micro holes were proved, 1–20 μ m

• Electrode wear ratio appeared to have a strong correlation with machining speed

• Side gap not have apparent correlation with diamond particle size.

Conclusions(1/2)

• There is no significant difference in machining speed between SD and tungsten carbide

• A surface roughness of approximately 0.13 μ m Ra was achieved for trench machining.

Conclusions(2/2)