An experimental investigation of tool wear in electric discharge machining

Abstract

In this study, the variations of geometrical tool wear characteristics -namely, edge and front wear -and machining performance outputs -namely, workpiece removal rate, tool wear rate, relative wear and workpiece surface roughness -were investigated with varying machining parameters. Experiments were conducted using steel workpieces and round copper tools with a kerosene dielectric under different dielectric flushing conditions (injection, suction and static), discharge currents and pulse durations. The experiments have shown that machining parameters and dielectric flushing conditions had a large effect on geometric tool wear characteristics and machining performance outputs. Additionally, published research on tool wear is presented in detail in this study. Symbolsh a Front surface wear height (average) (mm) h a Front surface wear rate (mm/min) i e Discharge current (A) r o Outer edge radius (mm) r i Inner edge radius (mm) t e Discharge duration (µs) t i Pulse duration (µs) t m Machining duration (min) t o Pulse interval time (µs) u e Discharge voltage (V) P s Suction flushing pressure (bar) P i Injection flushing pressure (bar) R 2 Regression constant R a

Micro Eletro Discharge Milling for Microfabrication

“…In EDM of high speed steel and boron carbide (B 4 C), tool wear was found to be proportional to current and inversely proportional to pulse duration (Puertas and Luis, 2004;Lin et al, 2006). It was also found that tool wear showed an optimum peak value while pulse duration had increased (Ozgedik and Cogun, 2006). However, use of shorter pulse ontime was suggested to achieve lower TWR (Son et al, 2007).…”

“…Dielectric flushing system is also responsible for the variation in MRR. The low material removal rate in static condition is mainly due to improper flushing of the molten and evaporated workpiece material from the machining gap (Ozgedik and Cogun, 2006). With the increase in flushing flow rate, MRR increased.…”

Recent Research Trends in Tool Electrode of Electrical Discharge Machining: A Review

“…The variations of geometrical tool wear characteristics such as edge and front wears during EDMed of steel with Copper tool were analyzed by Ozgedik and Cogun [53]. They explain the tool wears phenomena of EDM process as shown in the Fig.…”

“…Fig. 4 Tool wear phenomenon in EDM process [53] Instead of this, Marafona [54] investigated that the migrated carbon from the dielectric fluid during the EDM process are attached to the tool surface and form the black layer, which consist some other elements like iron, chromium, vanadium and molybdenum and known as equivalent carbon as shown in the Fig. 5.…”

Role of Heat Transfer on Process Characteristics During Electrical Discharge Machining

“…In the work of Bulent et al, 2006 andOzgedik &Cogun, 2006 they used Eq. 7 to estimate the energy released due to a single spark.…”