In our last entry, we focused on the various nozzles and wear parts that are specifically designed for Makino’s Split V-Guide system. In part two of our response, we’re going to be looking at the part list associated with PICO (Round Guide) systems.
Q: What are the main types of flush cup nozzles and consumable wear parts for Makino wire EDMs?
A: Even simple questions sometimes require detailed answers. In this situation, the answer actually requires two responses as the part numbers vary between the Split V-Guide and PICO (Round Guide) systems that are available. Part one of this response covers the Split V-Guide system.
When consulting EDM shops on work holding solutions, one question that we frequently receive is whether you can use standard magnetic chucks for EDM applications. Unfortunately, this is not the case. Magnetic chucks used in EDM machines are typically specialized for EDM applications. These chucks are sealed differently than magnetic chucks that are used for grinding machines, as the oil and debris from the EDM process can damage and seize-up the typical ON/OFF magnet levers. Several magnetic chuck manufacturers (such as Walker Magnetics, Suburban, Hermann Schmidt) offer EDM specific chucks that have fine pole divisions for improved work holding, magnetic poles that reach to the very edge of the chuck, and a more compact, thinner design to preserve the usable Z-axis stroke of the machine. Be sure that the magnetic chuck you purchase is designed and compatible for use on EDM machines.
Q: Is there a way to perform discharge dressing of the electrode on a Makino EDAF3 machine?
A: Yes, the Hyper-i control does have a dedicated macro program for discharge dressing of electrodes, but the machine should be equipped with the high-speed C-axis spindle (MA C-Axis) and discharge dress macro. The discharge dressing process uses the machine to create its own electrode through the EDM erosion process. Creating small diameter electrodes is the most commonly performed function of EDM dressing, but this process can also be used to create shaped electrodes or remove worn sections of an electrode.
Discharge dressing starts with a larger diameter electrode that is then EDM’ed down to whatever diameter is needed using a dressing block that is setup within the work tank. Depending on the required electrode size, multiple steps can be dressed on the electrode to provide the best possible rigidity for the final diameter. Once an electrode diameter is dressed to size, it is then used to EDM the workpiece feature.
The dressing block can be made from pure tungsten, tungsten carbide, copper tungsten (CuW), or silver tungsten (AgW). The CuW and AgW materials typically provide the best results. The electrode material can be made from copper, tungsten carbide, pure tungsten, copper tungsten, or silver tungsten. Each electrode material type has slightly different characteristics that determine the amount of time that is required to discharge dress. Additionally, each material type provides varying degrees of rigidity for extremely small diameters, but AgW electrode materials are typically recommended for best results.
On the Hyper-i control, there is a dedicated Model Plan and G-Code function associated with the discharge dressing process.
For first time visitors, this blog entry is part three of a three-part series discussing considerations for selecting coated EDM wires. To get up to speed on previous entries in this series, please check out part one and part two.
Not all coated EDM wires are created equal, making it critical for EDM shops to know and understand the physical and performance-based differences of each coated wire type. In this series, we’ve covered initial planning considerations, impacts on speed, and accuracy capabilities for coated EDM wire. In this final entry, we will look at additional considerations related to surface finish, speed and limitations, that can impact your selection of coated EDM wire.
SURFACE FINSH: If surface finish requirements are priority, it is advised to avoid coated wires that are designed for speed. Coated wires designed for speed may result in the degradation of surface finish, resulting in a rougher surface. Depending on the type of coated EDM wire, 1- or 2-pass skim cut finishing is all that might be achievable, as some high-speed coatings do not work with low power settings. If an incompatible coated EDM wire is used for fine finishing, wire shorting can occur, causing visible wire lines on the final part.
For finer surface finishes, plain zinc-coated wires, the same types used for improved accuracy, will the deliver the required results. The degree to which surface finishes are improved will depend on the make and model of the machine and the machining processes used, but improvements of up to 15% over Plain Brass wire are achievable.
WIRE BREAKS: If your current processes are challenged by wire breaks, the use of any type of coated EDM wire should provide a higher level of wire break prevention compared to plain brass wire. The outer layer of a coated wire is designed to erode off during machining, preserving the integrity of the inner wire core and making wire breaks less frequent. The outer layer thickness and metallurgical make-up vary between the different types of coated wire, which explains the differences in price and performance characteristic that exist among the available coated EDM wires.
LIMITATIONS: It is important to understand the advantages and disadvantages, as well as the unique performance and capability attributes of each coated wire type compared to traditional plain brass wire. Each coated EDM wire is designed for a specific application, characteristic and price point, so it is important to understand how and when to apply the different types of wire.
The bulk of coated EDM wires are marketed for achieving greater speed, so it is critical to establish specific part requirements for accuracy and surface finish before rushing to apply coated wire to a job. Based on the part requirements and machine being used, some simple test cuts may help to verify a coated wire’s capability and performance gains within a specific application. This may lead to further process optimization, which can also help to justify the higher consumable price paid when using coated wire. Additionally, the use of coated EDM wires may increase the need for machine maintenance, including the cleaning of rollers or more frequent indexing of power contacts, so it is important to take this into consideration when switching to coated wire.
We hope this series has been helpful to you. If you are interested in learning more about coated EDM wire, please check out our free webinar, “The Selection of EDM Coated Wires”. Thank you for your readership, and happy EDMing!