Wire EDM is a versatile and useful machining process. One of the prerequisites for repeatability, reliability and accurate cutting results is proper machine maintenance. A Wire EDM machine may be one of the most maintenance-intensive pieces of equipment in the shop environment. This is not a reason for concern and does not downplay any of the machine’s capability. It does, however, show the importance of scheduling regular machine maintenance.
Unlike a milling machine that can still operate and produce parts with a dull cutting tool, a Wire EDM machine will not function when not properly maintained. The proper maintenance of a Wire EDM machine is crucial to its performance, and the amount of time required to maintain a Wire EDM will vary by manufacturer and by machine use or application.
Due to the electromechanical nature of the Wire EDM process, there are several machine items that wear and require cleaning under normal operation. The underlying goal and operating strategy for Wire EDM is to maximize machine operating time, and more importantly, to maximize the unattended machine time. Below is a list of the major maintenance items common on today’s Wire EDM machines.
- AWT (Automatic Wire Threading): Performs the automatic wire threading. It is the single most important automated feature on the machine and allows for reliable unattended operation. It requires simple cleaning.
- Power feed contacts (x2): These are sometimes called “energizer plates” and deliver the electrical cutting power to the wire. These contacts, both on the upper and lower machine heads, will erode over time, resulting in a significant decrease of machining speed. They require simple indexing/repositioning.
- Rollers: All rollers and rubber wheels throughout the wire transport system must be cleaned periodically. Accumulation of debris on the rollers from the EDM wire will lead to wire slippage and/or wire tension problems. The clutch, or tension roller, will periodically need to be calibrated for proper wire tensioning.
- Filtration System: (Performed periodically when needed) Requires replacement of the main filters. There may also be a secondary filter element that requires replacement for the AWT system.
- De-ionization resin: (Performed periodically when needed) The DI resin is used to condition and control the conductivity level of the water. The resin will need to be changed and replaced.
- Water reservoir: The water in the main reservoir will need to be monitored and maintained at a certain level due to loss from evaporation.
- General cleaning: Periodic cleaning of the entire work tank and worktable is recommended. The debris generated by the Wire EDM machining process is very abrasive and will accumulate throughout the work tank over time. This debris, if not cleaned regularly, will be difficult to clean if allowed to build up, and will shorten the life of some machine components. Generally, the cleaner the machine is kept, the less likely it is that problems will arise.
- Tank seals: Weekly and/or monthly cleaning of main door seals or sliding seal plates is recommended. Keeping these surfaces clean will prevent the buildup of debris and subsequent seal failure.
- Electrical/generator cabinet: Clean and check the cabinet cooling fans for proper operation periodically.
- Wire: The brass wire is only used once during operation, so the wire spool will need to be replaced once fully consumed. As part of best practices, operators may replace the spool to avoid the machine stopping and losing unattended machining time if the wire spool runs out. The spent wire will also need to be removed and recycled from the collection bin that is typically located in the back of the machine.