The Basics of Electrical Discharge Machining (EDM)
Have you ever wondered how the latest styles of automobiles came to be?
The next time you drive or ride in a car, you’ll notice much of the interior consists of plastic. The molding around the entertainment center, the steering wheel, and more all consist of plastic.
Take a look at the exterior. The headlights and bumpers? In many models, they consist of, you guessed it, plastic.
But plastic
automotive molding is relatively new.
Automobiles before the 1970s used metal for everything. This made them heavy and clunky.
It wasn’t until the 1940s and 1950s when the plastics started booming. By the 1970s, vehicles started using lightweight plastic for decorative elements. It wasn’t until the 1980s that some exterior elements started to use plastics.
The 2000s welcomed the use of plastics for structural parts making vehicles lighter and more fuel-efficient.
Today, automotive molding is an efficient way to manufacture plastic components for vehicles. Here are the types and advantages of
auto molding.
How Automotive Molding Works
Injection molding is one of the most popular processes of automotive
electronic molding. Its uses range from forming car parts and cell phones to toys and storage containers.
Injecting molding uses an injection machine to create a foam or
plastic molding. To use it, you feed plastic powder or granular into the machine which heats it into molten plastic.
Once melted, the plastic enters an injector which pushes it into a shaped cavity. It fills the cavity and sits until it cools and hardens. After it hardens, you can remove it from the metal cavity and use it for its intended purpose.
A similar process works with most polymers, resins, foams, and silicone rubber. The process and machine used will change a little depending on the size of the part you’re molding and material used.
Structural automotive foam, which you can find inside the door and side panels, uses a foam mold. Resin is the primary material, but other plastics can work as well. It’s even lighter than most plastics and can be just as durable.
Sometimes when you’re choosing what manufacturing method to use, the requirements for dimensions, materials, and specifications make conventional production processes too expensive. Milling, turning and drilling to machine a block with openings and chamfers that will hold bearings or other components is complex and difficult. Of course, you can cast parts, but the up-front cast molding investment only makes sense when fabricating parts in high volumes.
What if you’re working on a prototype in its early design stages and you only need to fabricate only one or two parts? Milling and turning take a lot of time and waste a lot of material, but electrical discharge machining services (EDM) can be a more efficient solution. EDM is a manufacturing process where material is removed from a workpiece by applying a series of current discharges between two electrodes separated by a dielectric bath liquid.
Why would you use
EDM machine manufacturing as opposed to traditional methods? Read on to learn about the different types of electrical discharge machining and find out.
Types of EDM Manufacturing
Wire Cutting Electrical Discharge Machining: For this type of EDM, a wire is used as an electrode, and is continuously and automatically fed with a spool during the process. Typically, the fluid is ionized water and the wire is brass or copper. Checking the workpiece material and wire electrode materials to determine best electrical discharge machining process parameters is highly recommended to guarantee compatibility and to prevent corrosion. Because a wire electrode is used to cut the workpiece, only cuts through the whole thickness of the workpiece are possible.
Sinker Discharge Machining: This process is known as die, traditional, or Ram EDM. It can produce complex geometries not possible with Wire EDM. The
high speed electrode machine material is typically graphite or copper machined into a specific shape that’s the inverse of the intended final geometry of the part. Once the electrode is shaped, a process called “electrode wear” damages the workpiece by the sparks to form the correct geometry. Unlike Wire EDM, Sinker EDM can do both partial cuts and cuts completely through the workpiece.
Hole Drilling Electric Discharge Machining: The third type of EDM is used for drilling. Hole drilling EDM is able to machine very small, deep holes, which is difficult or even impossible with conventional drilling methods. Additionally, hole drilling EDM is super clean, and doesn’t require any deburring. In this process, the electrodes are tubular and the dielectric fluid is fed through them. Similar to the other EDM types, the electrode cuts/erodes the workpiece, but due to the discharged gap, the electrode doesn’t actually contact the workpiece. This minimizes deflection of the tube electrode as compared to drill bit deflection in conventional
drilling machine processes.