Content Menu
● What is Tungsten Carbide?
● The Tungsten Carbide Machining Process
● Machining Methods for Tungsten Carbide
>> Electrical Discharge Machining (EDM)
>> Grinding
>> Turning and Milling
>> Ultrasonic Machining
● Key Considerations for Machining Tungsten Carbide
● Applications of Tungsten Carbide
● Advantages and Disadvantages of Tungsten Carbide
● Conclusion
● FAQ About Machining Tungsten Carbide
>> 1. What is the best method for cutting tungsten carbide?
>> 2. What type of tools should be used for drilling tungsten carbide?
>> 3. Is coolant necessary when machining tungsten carbide?
>> 4. Can tungsten carbide be welded?
>> 5. What are some common applications of tungsten carbide?
● Citations:
Tungsten carbide is a composite material renowned for its exceptional hardness, wear resistance, and toughness[3][7]. These properties make it highly desirable for a wide range of applications, from cutting tools and wear parts to jewelry and medical instruments[3]. However, they also present significant challenges when it comes to machining[2]. This article explores the various techniques and considerations involved in machining tungsten carbide, providing a comprehensive guide for engineers, machinists, and designers.
What is Tungsten Carbide?
Tungsten carbide (WC), often referred to as cemented carbide, is a composite material created through powder metallurgy[10]. It consists of tungsten carbide particles bound together by a metallic binder, typically cobalt or nickel[10]. The proportion of tungsten carbide usually ranges from 70% to 97% of the total weight[10]. This combination results in a material with a unique blend of hardness, strength, and wear resistance[3].
Properties of Tungsten Carbide
- High Hardness: Tungsten carbide is exceptionally hard, allowing it to cut and shape other materials effectively[3].
- Wear Resistance: It resists abrasion and erosion, making it ideal for applications involving friction and wear[3].
- High Strength: Tungsten carbide can withstand significant compressive forces[7].
- High-Temperature Resistance: It maintains its hardness and strength at elevated temperatures[3].
- Good Density: Its high density contributes to its stability and performance in demanding applications[3].
The Tungsten Carbide Machining Process
Machining tungsten carbide is a complex process that requires careful control at every stage to ensure the quality and performance of the final product[1]. The general process involves several key steps:
1. Smelting Process (If Applicable):
This step is skipped if using pre-made rods or plates[1].
- Batching and Mixing: Tungsten carbide and cobalt powders are selected and mixed to specific ratios[1][9].
- Crushing and Drying: The mixture is crushed and dried to achieve uniformity and optimal flowability[1][9].
- Binder Addition and Granulation: Binders are added, followed by drying and sieving to create a granulated mixture ready for pressing[1][9].
2. Sintering and Inspection:
- Sintering: The pressed tungsten carbide is sintered in a vacuum low-pressure sintering furnace to form solid blanks[1].
- Quality Inspection: Blanks undergo inspections, including ultrasonic testing and dimensional checks[1].
3. Molding and Machining:
- Molding: Sintered blanks are molded into the desired shapes and sizes[1].
- Machining: This includes various high-precision mechanical operations[1]:
- Wire EDM (Electrical Discharge Machining)[1][2]
- CNC lathe machining[1]
- Turning, milling, and drilling[1]
- Grinding (surface, contour, internal, and external)[1][5]
- EDM machining[1]
4. Heat Treatment:
-Heat treatment may be applied to eliminate internal stresses and achieve specific hardness tolerances[1].
5. Surface Treatment:
Surface treatments enhance wear resistance and achieve fine surface finishes[1]:
- Mirror Polishing: Achieves extremely fine surface roughness[1].
- PVD Coating: Enhances wear resistance and hardness[1].
6. Quality Testing:
Stringent quality testing after each step ensures adherence to specifications[1]:
- Dimensional accuracy[1]
- Surface quality[1]
- Hardness[1]
- Mechanical properties[1]
Machining Methods for Tungsten Carbide
Due to its hardness and brittleness, machining tungsten carbide requires specialized techniques[2]. Here are some common methods:
Electrical Discharge Machining (EDM)
EDM is a widely used method for machining tungsten carbide, especially for creating complex shapes and intricate details[1][2]. It involves removing material using electrical discharges between an electrode and the workpiece[1][4].
- Wire EDM: A thin wire is used as the electrode to cut through the material[1][2]. This is ideal for simple cuts, drilling, and shaping carbide[2].
- Sinker EDM: An electrode with a specific shape is used to create cavities or complex geometries[4]. EDM surfaces may experience hydrogen embrittlement and grain removal[4].
Grinding
Grinding is a common precision machining method for tungsten carbide, particularly when high accuracy and surface finish are required[1][5].
- Surface Grinding: For creating flat surfaces[1].
- Cylindrical Grinding: For creating cylindrical shapes[1].
- Internal Grinding: For grinding internal diameters[1].
Proper abrasive and tool selection is critical, along with controlling grinding speed, depth, and coolant usage[5]. The high hardness of tungsten carbide can lead to wear and thermal deformation, hence the need to control grinding temperature and depth[5]. Aluminum oxide or silicon carbide wheels with a coolant are recommended[4].
Turning and Milling
Turning and milling are common methods for machining tungsten carbide, requiring the use of special carbide tools[1][2]. These processes involve removing material using rotating cutting tools[1].
- Turning: The workpiece is rotated while a cutting tool removes material[1].
- Milling: A rotating cutting tool removes material from a stationary workpiece[1].
Speeds and feeds should follow recommendations for gray cast iron[4]. Carbide inserted cutters are suggested for turning and boring[4].
Ultrasonic Machining
Ultrasonic machining is another method used for machining tungsten carbide, especially for achieving high precision and surface quality[6].
Key Considerations for Machining Tungsten Carbide
Machining tungsten carbide requires careful attention to several key factors:
- Tool Selection: Use carbide tools for drilling, milling, and turning tungsten alloys[2][4].
- Cutting Parameters: Carefully choose cutting parameters such as speed, feed rate, and depth to avoid material fracture[5].
- Coolant Usage: Use coolant or lubricant to reduce heat and friction[4][5]. Chlorinated oil can be used as a coolant[4].
- Stress Relief: Heat treatment can be used to eliminate internal stresses[1].
- Finishing: Surface treatments like mirror polishing and PVD coating can enhance wear resistance and surface finish[1].
- Joining: Brazing, mechanical joining, shrink fitting, and silver soldering can be used to join tungsten carbide to itself or other materials[4].
Applications of Tungsten Carbide
Tungsten carbide is used in a wide array of applications due to its superior properties[3]:
- Cutting Tools: Carbide inserts, end mills, drills, and reamers[3][7].
- Mining and Drilling Tools: Drill bits and milling tools[3].
- Medical Tools: Surgical tools and instruments[3].
- Wear Parts: Balls for ball-point pens and hot rolls for rolling mills[3].
- Jewelry: Rings, pendants, and earrings[3].
- Mold Industry: Inserts and core pins for injection molds[7].
Advantages and Disadvantages of Tungsten Carbide
Advantages:
- Exceptional hardness and wear resistance[3][7]
- High strength and toughness[3][7]
- Resistance to high temperatures[3]
- Versatile applications[3]
Disadvantages:
- High cost[3]
- Difficult to machine[2]
- Brittleness[2]
- Susceptibility to thermal shock
Conclusion
Machining tungsten carbide is a challenging but essential process for producing high-performance components across various industries[1]. By understanding the material's properties and employing appropriate machining techniques, engineers and machinists can effectively shape and refine tungsten carbide to meet specific application requirements. The continuous development of new machining methods and technologies promises to further enhance the capabilities and efficiency of tungsten carbide machining.
FAQ About Machining Tungsten Carbide
1. What is the best method for cutting tungsten carbide?
Wire EDM (Electrical Discharge Machining) is often preferred for simple cuts due to its precision and minimal mechanical stress[2].
2. What type of tools should be used for drilling tungsten carbide?
Carbide tipped or solid carbide drills are recommended because of the material's hardness[4][8].
3. Is coolant necessary when machining tungsten carbide?
Yes, the use of a coolant or lubricant is highly recommended to reduce heat and friction[4][5]. Chlorinated oil can be used as a coolant[4].
4. Can tungsten carbide be welded?
Brazing is a good method for joining tungsten alloy material to itself and other materials, but it should be done in a controlled atmosphere to prevent oxidation[4].
5. What are some common applications of tungsten carbide?
Tungsten carbide is commonly used in cutting tools, mining and drilling tools, medical tools, wear parts, and jewelry[3][7].
Citations:
[1] https://www.carbide-products.com/blog/tungsten-carbide-machining-process/
[2] https://www.carbide-products.com/blog/how-to-machine-tungsten-carbide/
[3] https://www.linkedin.com/pulse/applications-tungsten-carbide-zzbettercarbide
[4] https://www.eaglealloys.com/tungsten-alloy/machining-tungsten-alloys/
[5] https://www.carbide-part.com/blog/how-to-machine-tungsten-carbide/
[6] https://www.hit-tw.com/advantagedetails.aspx?id=48
[7] https://pistentool.fr/what-is-tungsten-carbide-and-its-applications/
[8] https://www.cnccookbook.com/machining-tungsten-alloys-feeds-speeds-guide/
[9] https://www.carbide-part.com/blog/tungsten-carbide-machining-process/
[10] https://cdn.thomasnet.com/kc/1741/doc/0000100974_70_54661.pdf
