The world continues to evolve, and so does technology. The rapid evolution of technology and its constant changes affect how several companies carry out their manufacturing processes. Today, there are various techniques available in industries, with many of them being effective and productive.
Two of the popular methods are CNC machining and wire EDM. Many designers and product developers sometimes find it tricky to decide which one of the two methods to use. This guide aims at helping you to understand the differences between the two processes. You will also learn the various factors to consider while choosing a process.
CNC Machining in Brief
Computer Numerical Control (CNC) machining involves using connected computer systems in the production of components.
After receiving CNC machining quotes, the technology helps businesses to bring out their product ideas and boost productivity. The CNC machine comes with a cutting tool with several dimensions along with finishing workpieces.
Standard machining procedures would generally involve a human operator. However, CNC machining involves computers, so there is limited human error. The technology ensures accuracy of results and general reduction of wastes during manufacturing. Thus, an overall advantage in terms of manufacturing costs and product quality.
Wire EDM in Brief
EDM is an acronym for Electrical Discharge Machining. This process involves creating products using an electrical current. Manufacturers also refer to it as arc or spark machining. The electrical current passes through the workpiece and an electrode.
A liquid usually separates these two components, with a spark being created whenever there is a contact between liquid and the current. The spark erodes the piece. This way, it helps to form the desired shape. Manufacturers and engineers employ EDM whenever there is a need to machine materials into complex configurations. It is also one of the best options to work with delicate and fragile items. The final results from this process are usually precise and come out in the best conditions.
When to Choose Wire EDM Manufacturing Over CNC Machining
The following are some specific situations where wire EDM tend to produce better outcomes than the traditional CNC machining process:
When there is a need for sharp internal corners
Wire EDM is the ideal option in machining sharp internal corners. This is usually hard to achieve with the conventional method because it typically uses round cutting tools. The wire used in EDM is much finer and can create sharper corners with the radius reduced to as low as 0.005 inches.
When there are minimal hole diameters
If your component should have a hole diameter far less than 1mm, then you cannot use the conventional CNC machining method. Wire EDM can accept holes with diameters up to 0.4 – 0.8mm.
More extended cutter tools are often required to machine deep cavities and cuts when using conventional CNC machines. EDM offers adequate solutions whenever there is a need for very deep cuts. This advantage is mainly because wire EDM is not affected by chatter. EDM will comfortably create holes with a 20:1 length:diameter ratio.
When there is a need for tighter tolerances
Using electrical discharge machining makes precision machining a lot easier because it is able to achieve tighter tolerances. Furthermore, EDM does not cause deformation on the workpiece because there is no form of physical contact.
When manufacturing a mold
Sometimes, mold makers prefer to use wire EDM as opposed to CNC machining. This may be since it can conveniently cut through harder metals like steel. Wire EDM helps to ensure details.
Advantages of EDM
Here is a look at the several advantages that come with EDM.
Part Geometry: In EDM, there is no workpiece or tool rotation. Furthermore, the cutting forces are minimal. Since the wire used in wire EDM is typically 0.010 inches in diameter, it is possible to make thin walls and cut holes with very small diameters. Also, cavities and openings can be of non-round shapes.
Hard Materials: The effect of material hardness on the cutting rate of EDM wire is very minimal. EDM can work on tool steel, tungsten carbide, and several other harder metals.
Surface Finish: The surface of an EDM comes with a random texture. This is entirely dissimilar to the conventional CNC milling method. Its advantage comes to play where “lay” or direction may affect the part’s performance. Furthermore, surface finishes with EDM can be as smooth as 4 micro-inches Ra.
Cost Advantages: There is usually no special tooling involved with EDM, which reduces costs and lead time. Also, manufacturers also reuse cut-out slugs. Thus, there is no need to produce chips. The skimming process in this technique eliminates every secondary finishing operation. All of these contribute to cost-saving and faster lead times.
Limitations of EDM
As described earlier, EDM only works on pieces that conduct electricity. That is, it doesn’t work with plastics or wood. Also, wire EDM only cuts 2D profiles in most cases. Also, it is impossible to know the actual size of an electrical spark. Thus, EDM is not usually suitable for some areas that require increased precision.
The most significant disadvantage of EDM, however, is its slowness. The process involves several steps, making it longer than the conventional process. There are multiple electrodes engaged in a single EDM run, and the removal rates are pretty slower than CNC machining.
Factors to Consider When Choosing Between Manufacturing Processes
Selecting the proper manufacturing process for your project is always crucial to successfully completing such a project. Here are some of the essential factors to consider before you decide:
It is crucial to consider the manufacturing costs before making a decision. Many times, the complexity and number of parts influence the final price. The different stages involved in each manufacturing process also play a role in overall cost. Parts with tighter tolerances and more precision requirements will also incur more costs. Therefore, all these should be put into consideration before choosing a procedure.
This factor is usually relative, depending on the speed of manufacture desired. However, every business wants to get its products to market within a short time. That is, every company desires faster lead times. Therefore, you should only choose a process that will not slow down product development.
Tolerances, reliefs, collars, and other design considerations are crucial in choosing the right manufacturing technique. If a particular process is not suitable for your chosen material, you should go for a more suitable one. Likewise, some operations cannot meet some high design demands. Thus, you must select one that best fits.
It is crucial to have an adequate understanding of the two processes before deciding which one is most appropriate for your business needs. Wire EDM has its advantages over CNC machining. Likewise, there are applications where CNC machining is best suited. This guide will help you make informed decisions in choosing the best method.