Choosing the appropriate manufacturing technique is integral to the success of your manufacturing operation. Sinker (electrical discharge manufacturing) EDM and laser cutting are two exceptional precision manufacturing processes with vast capabilities. Both processes are subtractive, removing parts of a material until the desired shape and structure are formed.
While their processes are distinct, they share some similarities, creating parts with high-precision parts. This article provides you with a comprehensive review of the two methods, including factors that need consideration before selecting one for your next metal part fabrication task. Read ahead!
What is Sinker EDM
Sinker EDM is a nontraditional, subtractive manufacturing process for creating parts from hard, conductive materials. It follows the principles of Electrical Discharge Machining (EDM), where controlled electrical sparks are used to erode materials from a workpiece, creating an intended shape and structure.
The process can achieve high precision, making it ideal for producing intricate shapes, fine details, and sharp corners. Sinker EDM is well suited for thicker materials. Regarding metal hardness, it can work with metals of varying conductive properties, including extremely hard metals like tungsten carbide, titanium, and hardened steels. In addition, it machines these metals, creating excellent surface finishes and tight tolerance specifications.
How It Works
In sinker EDM, the machine uses spark erosion to remove metal components from the workpiece. The electrode – usually graphite or copper – is often submerged in a dielectric fluid, acting as an insulator till sufficient voltage is reached. The machine uses this electrode to create contours of the part, burning away the excesses. The dielectric fluid also acts as a coolant to remove excess heat from the part, preventing excessive thermal expansion.
What is Laser Cutting
Laser cutting is a high-precision manufacturing process that uses focused beams to cut, engrave, or mark a workpiece. The process is versatile and suited to machining various materials, such as metals, plastics, and glass. However, laser cutters are better suited for relatively thinner materials.
For example, they are often used to work metal sheets, not thicker metals. Still, they offer applications in various industries, including automotive, aerospace, and electronics, especially for creating lightweight but durable parts.
How It Works
The laser cutting process involves directing and focusing the high-powered laser beam onto the material to be cut. Afterward, the energy from the lasers heats the material, causing it to melt, burn, or vaporize, leaving an edge with a high-quality surface finish. However, laser cutters are often integrated with CNC functionalities, which is crucial for the process’s precision. Therefore, the process is computer-guided, allowing for accurate cuts, even when working on complex patterns.
Types of Laser Cutting
Lasers for cutting come in different forms, each with unique capabilities. Below, we explore the standard laser options for CNC laser cutting.
Fiber Laser Cutting
Fiber lasers use a solid-state laser source generated by diodes and transmitted through a flexible fiber optic cable. Indeed, laser cutting suits the cutting of thinner materials, but fiber lasers extend the suitability of this machining operation. They are particularly efficient for cutting metals, including steel, stainless steel, aluminum, and brass. They offer high precision and are energy-efficient, making them ideal for high-speed cutting of thin to medium-thickness materials.
CO2 Laser Cutting
As the name indicates, CO2 lasers generate the laser beam using a gas mixture. They are versatile and can cut various materials, including metals, plastics, wood, glass, and ceramics. When people relegate laser CNC cutting services to cutting soft metals, they refer to CO2 lasers. They are mainly used to cut non-metals but provide high-cutting quality and offer extensive applications in various industries.
Nd:YAG Laser Cutting
Like fiber lasers, Nd:YAG (Neodymium-doped Yttrium Aluminum Garnet) are solid-state lasers that use a crystal as the laser medium. Nd:YAG lasers can produce high peak power and are often used in applications requiring high precision and minimal heat-affected zones. They are suitable for cutting and engraving metals and some non-metals. However, they are less efficient than fiber lasers for metal cutting and are more commonly used for marking and engraving. Also, their industrial use is significantly limited because they are expensive.
Sinker EDM vs Laser Cutting for Metal: Which One Should I Choose
Sinker EDM and laser cutting are two unique metal fabrication processes offering distinct advantages to your project. Therefore, several factors must be considered when deciding which best suits your fabrication.
Below, we explore some of these factors.
Material Type and Thickness
Sinker EDM is best suited for cutting hard and electrically conductive materials like hardened steel, titanium, and tungsten carbide. The technique can handle complex shapes and internal cavities, especially in thick and dense materials. On the other hand, laser cutting offers applications to a more extensive range of metals, though more applicable for cutting thin to medium-thickness metal sheets.
Precision and Tolerance
Both subtractive manufacturing processes fabricate parts with excellent precision without compromising tolerance standards. However, sinker EDM is more suitable for higher precision and achieves tighter tolerances. Therefore, it is a better fit for intricate details and sharp corners. Likewise, laser cutting offers high precision, though the precision may vary depending on material thickness and laser type. Fiber lasers are better suited for intricate applications.
Cutting Speed
Laser cutting is known for its high-cutting applications, primarily when cutting thinner materials. This quick cutting speed suits it for high-volume production and quick turnaround times. In contrast, sinker EDM can be time-consuming. It is more tenable for slower cutting speed, as it carefully builds tolerance specifications and work hardened materials.
Surface Finish and Post-Processing
We already discussed the precision quality of both processes. Sinker EDM is known to achieve tighter tolerance specifications, so it is better suited for high-quality surface finishes and consequently requires fewer post-processing needs. Laser cutting also produces smooth edges, particularly after fine-tuning the settings, but it has a higher propensity for oxidation and burring, especially with CO2 lasers. Therefore, there’s often an increased need for post-processing.
Complexity of Design
Sinker EDM is excellent for creating complex, intricate designs, including deep cavities and sharp internal corners. Because of its ability to fabricate complex structures, it is particularly suited for mold-making and die manufacturing. On the other hand, laser cutting is better suited for 2D profiles and flat sheet cutting. Indeed, it can also handle complex patterns but is limited in cutting depth and may struggle with intricate internal features.
Cost and Efficiency
Budget constraints are another important criterion for consideration. Both processes are expensive. However, sinker EDM may be more cost-effective for high-precision, low-volume projects or materials complicated to machine by other methods. Likewise, laser cutting becomes more cost-effective for high-volume production and operations requiring moderate to high cutting speeds.
Conclusion
Sinker EDM and laser cutting are both subtractive manufacturing methods with some similarities. However, they are two distinct operations with unique capabilities. Therefore, selecting between sinker EDM vs laser cutting requires a comprehensive understanding of their processes. Also, you must juxtapose various factors relating to your project to ensure you make an informed decision about the one that best suits your project.
If you are unsure which metal fabrication solution to select, do not hesitate to read this article.
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