Analysis of Wire Breakage in Slow Wire EDM
Electrical discharge machining (EDM) is a manufacturing technology that uses electrical sparks as a heat source to erode workpieces of hard, electrically conductive materials like metals, stones, and ceramics. The technology has been long established as a cost-effective way to work hard and precision-controlled products like engine components, turbine blades, and watch and jewelry parts. Wire EDM, in particular, is the process of using electrical discharges to remove material from a conductive wire. By controlling the electricity’s flow, the wire is effectively cut and shaped into components of any intricate design.
However, this technology can be extremely vulnerable to faults such as wire breakage. But what exactly is causing this, and how can it be prevented? Let’s explore the underlying causes and solutions related to wire breakage in slow wire EDM.
The Components Involved in Electric Discharge Machining
The primary components used in EDM machines include the following:
• Workpiece: This is the material being machined. This could be a metal, stone, ceramic, or any other electrically conductive material.
• Power supply: This is the energy source used to create the electrical spark used to erode the workpiece.
• Controlling Unit: This is the software used to control and adjust the power supply output. This will also monitor and maintain other components like the spark amplitude and pulse duration.
• Guide: This is the guide which keeps the wire either submerged in the dielectric fluid (or die) or away from it. The position and speed of the guide affects the cut quality and material removal rate (MRR).
• Dielectric Fluid: This is the fluid used during the EDM process. It provides electrical insulating properties, cooling properties, and lubrication for the wire.
Causes of Wire Breakage in Slow Wire EDM
Due to its complexity, it can be difficult to identify the exact cause of wire breakage in slow wire EDM. The most common causes are due to:
• Poor Workpiece Condition: The workpiece must be of suitable material type and hardness for EDM to be successful. If the material is too hard, the wire may not be able to cut it and break.
• Poor Wire Cut Quality: If the wire is not cutting properly, it can cause stress and overheating, leading to breakage. Poor cut quality can be due to incorrect voltage, wire contacts, or improper dielectric fluid.
• Incorrect Guide Movement or Wire Position: If the guide moves too rapidly, it can cause the wire to bend and break due to excessive tension. Additionally, if the wire is inappropriately positioned or too close to the workpiece, it can cause it to break prematurely.
Preventing Wire Breakage in Slow Wire EDM
There are several tips and measures one can take to prevent wire breakage in slow wire EDM. First, it is important to be mindful of the workpiece material and hardness, and that the workpiece is not too hard for the wire. In addition, one should check the wire for any damage or wear and tear before use, such as kinks, knots, and corrosion.
Next, the cutting speed must be adjusted to ensure the optimum output power necessary for the cut quality. Additionally, it is important to check the guide movement is correct, as this can cause stress and tension on the wire if it is not. The guide should move at a steady pace along with the wire, and the wire should be well-positioned away from the workpiece.
Finally, it is important to use the appropriate dielectric fluid for the job. This should be a dielectric fluid specifically made for EDM and one that is capable of providing sufficient cooling for the wire.
Conclusion
Wire breakage can be a major issue when machining through metal and intricate parts in slow wire EDM. Ultimately, it is important to take the necessary precautions to prevent this from happening, such as proper use of the dielectric fluid, monitoring the wire wear and tear, and controlling the guide movement. By doing so, it is possible to safely and successfully use the slow wire EDM technology to produce components with accurate and precise cuts.
