EDM or Electrical Discharge Machining boasts as the solution for demanding machining applications that require optimum accuracy while traditional metal removal proves challenging, if not impossible. The process goes by many ‘aliases’ like arc machining or spark machining. Still, the fundamentals are relatively simple in concept, whereas an electrical current pass between a work piece and an electrode for which there is a dielectric liquid separating them.
This fluid becomes an ‘electrical insulator’ provided there is not too much voltage created to where it reaches the ionization level. If it comes to that point, it acts as a conductor. The sparks that discharge erode the working material to create what is a final shape.
The Various Types Of EDM Machines
Electrical Discharge Machining or EDM falls into various specialized classes, but the industrial arm generally offers three distinct categories: 1) ‘Ram’ or Die Sinker 2) ‘Cheese Cutter’ or Wire 3) ‘Hole Popper’ or Hole Drilling.
The three variations run on the same type of principle, as discovered in 1770 by Joseph Priestley, which involved erosion through electrical discharge. That’s the only aspect that the three share.
- Die Sinker or ‘Ram’: This is also referred to as the ‘vacuum-tube’ EDM infamous for elevating spark frequency to over 1,000 from the standard of merely 60. The system is responsible for developing complex shapes in the form of ‘cavities’ for tool and die as with plastic injection molds or metal stamping dies.
The first step in the phase involves forming a ‘positive’ from a graphite electrode for the desired cavity. It is then driven gently into the work material, creating a spark throughout the platform. At the same time, features maneuver the closing of the sparking gap.
- The Wire or ‘Cheese Cutter’ EDM: The claim is that this technique was gradually developed over the span of approximately a decade. It is merely a way of creating dyes out of hard steel. In this method, the electrode is a thin wire manipulated in a controlled, thoughtful pattern, reminiscent of a woodworker maneuvering his scroll saw. This movement generates a spark between the work material and the wire.
With wire EDM, there is an entire spool of wire used so it can continuously move, presenting a clean discharge throughout the cut. The restriction with this method is the fact that the wire needs to completely pass through the material, making what deems a two-dimensional cut into what is a three-dimensional part.
- The Hole Drilling or ‘Hole Popper’ EDM: Fast hole drilling or ‘hole popper’ EDM implements a rotating conductor tube as the electrode along with a continuous flow of, typically, deionized water serving as the dielectric fluid as a means to flush out the cut. This method is also used in making the necessary pilot holes required for wire threading.
Being able to create precise, accurately sized holes regardless of the consistency of the material notes as key in many technological advances, including EDM-manufactured cooling holes for higher temperature turbine blades of alloy. These allow ‘film cooling’ so jet engines can function at advanced temperatures creating a greater sense of durability and efficiency.
The use of EDM has practicality in terms of the fact it can cut hardened materials as well as exotic alloys, saving time and cost, not to mention risks for any kind of alterations in the finished dimensions. The process also allows for an exceptional surface finish, generally not requiring any treatments or post-processing. It’s pretty accurate, very predictable, and can be repeated. These are usually reserved for parts with higher accuracy needs and smaller feature sizes.
The claim is that the machines require a bit more maintenance and upkeep, but they allow a business to do far more than just what the standard necessary manufacturing equipment can achieve. Read how EDM is superior to traditional methods.
These will also save a considerable amount of time and money given that they can work with any variety of hard material or exotic alloy without difficulty, resulting in an ideal finish that doesn’t require additional workup. It’s the perfect setup if you need a process that’s precise and generally stress-free.