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Tungsten carbide blades are a big deal in the manufacturing industry. They’re known for being hard and durable. Understanding how they’re made can help you understand why they’re so good at cutting things. This article will break down the steps for you, so you can understand what you’re buying or just be a more informed carbide blade enthusiast.
Tungsten carbide blades are made through a series of precise steps, going through batching, pressing, sintering, linear cutting, grinding, polishing, and edge opening.
Now, let’s dig into each step a little more so you can understand why these blades are so awesome.
What Are The Raw Materials For Tungsten Carbide Blades?
The main ingredients in tungsten carbide blades are tungsten carbide powder and cobalt. Tungsten carbide is used because it’s super strong and it doesn’t wear out very easily. Cobalt is used as a binder to hold the tungsten carbide particles together and make the blade tougher. The raw materials are chosen carefully and prepared to make sure they’re the best quality.
Tungsten Carbide Powder: This is the main cutting material used because it’s hard and it doesn’t wear out very easily. It stays sharp even when you’re cutting something really tough.
Cobalt: Cobalt is used as a binder to hold the tungsten carbide particles together. It makes the blade tougher so it doesn’t chip or break when you’re using it.
How Is Tungsten Carbide Blades Manufactured?
The following is a detailed description of the manufacturing process for each step of the tungsten carbide blades.
Mix Materials According To Directions
The first step is to mix the tungsten carbide particles and cobalt powder together from a powder proportioning according to the grade requirements. The goal is to produce a consistent mixture throughout the blade. Allow the cobalt to be evenly distributed throughout the tungsten carbide. This step is very important as it affects the performance of the blade. Solvents such as ethanol and water are then added and wet ball milled in a ball mill to ensure a uniform mixture, particle refinement, and the formation of good sintering activity. After ball milling, the wet material is vacuum spray dried to produce a well-flowing powder, which is then sieved to remove oversized or undersized particles and to ensure a consistent pressing density. The above process usually takes about 5 working days.
Molding and Compacting
According to the grade requirements, type, unit weight, size requirements, etc. to prepare the pressing process list, the dry powder mixture filled into the mold, through the hydraulic press for cold press molding, pressing out the knife blank. This process determines the basic shape and initial dimensions of the tool. It is compacted under very high pressure so that the particles are very tightly packed together. This makes the blade denser and stronger.
Sintering Process And Heat Treatment
After the blades are molded, they go through a heat treatment, which is a really important part of making the blades. This process is called sintering. The blades are heated to a temperature of about 1500 degrees Celsius. The whole process takes about 15 hours and does a few things:
Makes the Particles Stick Together: At this high temperature, the cobalt melts and acts like a liquid glue that holds the tungsten carbide particles together. This makes the blade really solid and dense.
Makes the Blade Harder: Sintering makes the carbide blade a lot harder. The high temperature makes the particles stick together tighter, so the blade can handle a lot of stress when you’re cutting with it.
Makes the Blade Less Porous: Sintering gets rid of the little gaps between the particles, which makes the blade stronger and more resistant to wear.
Once the blanks have passed inspection, they are sent to the finishing shop where they are machined according to the drawings.
For more information on heat treatment of blades, you can browse this article “The Detailed Guide To The Heat Treatment Process For Industrial Blades”.
Linear Cutting
The core purpose of linear cutting in the manufacture of tungsten carbide blades is to realize high-precision cutting of complex shapes by means of electric spark discharge. Due to the extremely high hardness of tungsten carbide, it is difficult for traditional machining to deal with complex contours or tiny structures. As a non-contact machining, wire EDM can cut complex surfaces that cannot be processed by grinding wheels (e.g., precision mold cavities, tiny bushings), with a precision of ±0.004mm, and with a cutting seam of only 0.1~0.2mm to ensure the fit gap of convex and concave molds. Its non-contact characteristic reduces internal stress and avoids cracks; thermal influence is controlled by adjusting parameters such as pulse width (<12ms) and current (<2A), and the special emulsion effectively cools and removes the products of galvanic corrosion, thus enhancing processing stability. In addition, wire EDM is also used for scientific research and testing (such as residual stress analysis by contour method) and multiple cutting and trimming to optimize the surface quality, which is an indispensable technology in the precision machining of cemented carbide.
In the manufacturing process of tungsten carbide blades, wire cutting is a very critical process, the main purpose of which is to carry out high-precision contour cutting of sintered tungsten carbide blanks in order to realize complex shapes or non-standard geometries of contour machining. In addition, wire cutting has the advantages of small machining heat-affected zone, small deformation, good surface quality, etc. It can be used to fine-tune the profile before the final cutting edge of the blade to ensure that the edge dimensions are in accordance with the design requirements. For some customized blades or high-end mold blades, wire EDM is an almost irreplaceable machining method, and is one of the basic processes for achieving high consistency and high performance industrial blades.
Grinding
Tungsten carbide knives must be sharpened in multiple steps to achieve their final shape and finish. Start with rough grinding to remove excess material and get the basic shape, pass through grinding surfaces to establish a machining datum and control thickness and flatness. Then do finer grinding steps to get the right size and polish for a better surface finish. Each step uses a different wheel and grind to get the right thing.
Rough Grinding
Rough grinding is the initial machining of the outer contour or surface of the blade after sintering and wire cutting have been completed. Due to the dimensional expansion or surface irregularities that occur during the sintering process, rough grinding quickly removes excess material through the use of diamond grinding wheels to bring the blade close to its design dimensions and to eliminate surface oxidation or minute cracks. This stage pursues efficiency and does not emphasize high precision, leaving mainly machining allowances and structural foundations for subsequent machining.
Surface Grinding
Surface Grinding is the plane grinding of both sides of the blade after rough grinding, usually referring to the upper and lower main planes. The key of this step is to form a precise datum surface to provide accurate positioning reference for subsequent processes such as edge opening, fine grinding and wire cutting. At the same time, the large surface can realize the strict control of the thickness dimension and improve the consistency and assembly precision of the product.
Finish Grinding
The function of fine grinding focuses on achieving precise geometries, angles, chamfers and edge finishes. The use of finer grit diamond wheels results in extremely high surface quality (Ra ≤ 0.2 μm) and sharp edges, while correcting small errors left by the previous process. Precision grinding has a direct impact on tool life, cutting efficiency and finished product quality.
Polishing
Polishing is an optional but commonly used fine process for high-end tools, especially for carbide blades with high surface quality requirements. By polishing the face, edge or specific parts of the tool with diamond paste or ultra-fine abrasives, surface roughness can be significantly reduced (Ra up to 0.05μm), cutting resistance can be reduced, material adhesion and wear can be prevented, and tool stability can be improved in hot, humid or corrosive environments.
Tungsten carbide blades become hard and durable after the above steps. Sharpening is a critical step in the manufacturing process to ensure that each blade is the right size and shape for good cutting. Below are the considerations involved in sharpening:
Tight Tolerances: When you grind, you have to make sure you hold tight tolerances. That means you have to make sure each blade is the right size within a really small amount. That’s important because even a little bit off can mess up how the blade works. It can make the part you’re machining have a bad surface finish or make the tool wear out faster.
Quality Control: After sharpening a blade, you must check its quality to make sure it is acceptable. This means you check the size, edge quality and surface finish. If it’s not up to par, you need to fix it or discard it. This way, you can ensure that only the best blades are sent to your customers.
Coolant: When you grind, you make a lot of heat because the grinding wheel rubs against the carbide. To keep the blades from getting too hot and to make the grinding go smoothly, you use coolant. The coolant helps keep the blade from getting too hot and cracking or changing size.
Opening Edge Of Blade
In the manufacturing process of tungsten carbide blades, cutting edge opening is one of the key steps in determining the cutting performance of the blade. Although the sintered blade already has a complete structure and high hardness, its edge is still in the unprocessed state, the so-called “blunt edge”, which is unable to perform high-efficiency, high-precision cutting tasks. Therefore, the primary purpose of opening the edge is to turn this “dull edge” into a sharp, regular cutting edge through fine grinding, so that the blade has a real cutting function. The main purpose is to form a sharp, precise cutting edge between the large side and the side of the blade, in order to meet the cutting, shearing or scraping needs in actual use.
Open edge is not only for sharpness, but also through a reasonable angle design to control the front angle, back angle, main deflection angle and other geometric parameters, so that the blade in actual use can realize smooth cutting into the workpiece, reduce cutting resistance, improve the chip removal effect, reduce the heat build-up, thus significantly improving machining efficiency and extend the life of the tool. At the same time, the open edge can also correct the edge micro-defects that may arise in the previous process, improve the continuity and integrity of the edge line, to avoid chipping, cracking and other problems in use. For mass production, standardized open edge process can also ensure that each piece of tool edge shape is consistent, to ensure product stability.
In the specific process, the edge opening is usually done with high-precision diamond grinding wheels or special equipment, and the edge shape is realized through high speed grinding. For different purposes of the blade (such as paper cutting, metal shearing, rubber slitting, etc.) using different opening angle and way (single-edged, double-edged, obtuse angle, acute angle, etc.). Some of the high-end or complex structure of the blade will use the CNC grinding machine, with programmed control to achieve accurate and uniform edge angle. For customized tools or shaped edges, it is still necessary to rely on experienced craftsmen to make manual adjustments and micro-grinding to ensure the quality of open edges for their special structures. In addition, the uniformity and consistency of the cutting edge is directly related to the stability of the performance of the whole batch of tools, which is a key aspect of quality control.
Final Shaping And Coating
After the grinding is done, the blade may go through more finishing work to get it just right. Depending on what you are doing, you can apply coatings to the blade to make it last longer. Some common coatings are titanium nitride (TiN) and diamond-like carbon (DLC). These coatings make the blade cut better, and you can read more about coatings in this article “The Ultimate Guide To Blade Coating”.
Understanding the manufacturing process of tungsten carbide blades shows you how much care and precision goes into making these important tools. Each step, from picking the right raw materials to sintering, grinding, and opening edge, makes sure the final product is tough, reliable, and perfect for cutting with precision. By paying attention to all the little details of the manufacturing process, manufacturers can make sure they make really good, reliable products that do what they’re supposed to do in the real world.
