and wear rate. Some small-hole drilling EDMs are able to drill through 100 mm of soft or hardened steel in less than 10 seconds, averaging 50% to 80% wear rate. Holes of 0.3 mm to 6.1 mm can be achieved in this drilling operation. Brass electrodes are easier to machine but are not recommended for wire-cut operations due to eroded brass particles causing "brass on brass" wire breakage, therefore copper is recommended. Metal disintegration machining Several manufacturers produce EDM machines for the specific purpose of removing broken cutting tools and fasteners from work pieces. In this application, the process is termed "metal disintegration machining" or MDM. The metal disintegration process removes only the center of the broken tool or fastener, leaving the hole intact and allowing a part to be reclaimed. Closed loop manufacturing Closed loop manufacturing can improve the accuracy and reduce the tool costs Advantages and disadvantages EDM is often compared to Electrochemical Machining. Advantages of EDM include: Ability to machine complex shapes that would otherwise be difficult to produce with conventional cutting tools. Machining of extremely hard material to very close tolerances. Very small work pieces can be machined where conventional cutting tools may damage the part from excess cutting tool pressure. There is no direct contact between tool and work piece. Therefore, delicate sections and weak materials can be machined without perceivable distortion. A good surface finish can be obtained; a very good surface may be obtained by redundant finishing paths. Very fine holes can be attained. Tapered holes may be produced. Pipe or container internal contours and internal corners down to R .001". Disadvantages of EDM include: Difficulty finding expert machinists. The slow rate of material removal. Potential fire hazard associated with use of combustible oil based dielectrics. The additional time and cost used for creating electrodes for ram/sinker EDM. Reproducing sharp corners on the workpiece is difficult due to electrode wear. Specific power consumption is very high. Power consumption is high. "Overcut" is formed. Excessive tool wear occurs during machining. Electrically non-conductive materials can be machined only with specific set-up of the process. See also Electro chemical machining References Bibliography External links New Arc Detection Technology for Highly Efficient Electro-Discharge Machining Engineering Design For Electrical Discharge Machining Electric arcs Machining Metallurgical processes Articles containing video clips Hole making