Tungsten Carbide Milling Cutter

   There is a type of cutting tool that is very powerful, whether it is a carrier on the water or a fighter jet in the sky, or the recently launched Webb Space Telescope costing $10 billion, all need to be processed by it. It is a tungsten steel milling cutter. Tungsten steel is very hard and is the hardest type of steel produced by manual mass production. It can process almost all steels except carbon. Non steel, also known as hard alloy, is mainly composed of carbides and cobalt sintered. Tungsten carbide powder is smelted from tungsten ore. China is the world's largest tungsten mining country, accounting for 58% of the proven tungsten reserves.

    How to produce tungsten steel milling cutters? Nowadays, powder metallurgy technology is commonly used. Firstly, tungsten ore is made into tungsten powder, and then the powder is pressed into a designed mold by a machine. A grinding machine weighing nearly 1000 tons is used for pressing. Tungsten powder is usually formed by advanced equal immersion molding method. The friction between the powder and the mold wall is small, and the billet is subjected to uniform force and density distribution. The product performance is greatly improved.

  The tungsten steel milling cutter is cylindrical, so the pressed tungsten steel is a cylinder. At this time, the tungsten steel is just a powder block stuck together by plasticizers, and then it needs to be sintered.

  This is a large sintering furnace that charges compressed tungsten powder rods and pushes them together to heat them to the melting point of the main components, transforming the aggregates of powder particles into the disintegration of grains.

  To be more specific, firstly, after low-temperature pre firing, the molding agent is removed and the crystallization is fired at medium temperature to complete the sintering process at high temperature. The density of the sintered body increases, and during cooling, energy is gathered to obtain the required physical and mechanical properties of the material. Sintering is the most important process in powder metallurgy.

Remove the tungsten steel alloy that has been cooled to room temperature and proceed to the next step of centerless grinding. Heartless grinding is a process of polishing, where the surface of tungsten steel is very rough and hard. Therefore, the diamond that can be ground is the continuous grinding of the material surface by two diamond brush wheels. This process generates a large amount of heat and requires continuous surface treatment of the coolant. After completion, it is the finished product of tungsten steel rod material. The production of rod material may seem simple, but in fact, it has a high technical content from the initial preparation of tungsten powder to the formation of high-quality grains through controlled sintering.

  At this time, the workers will inspect the tungsten steel bars to see if there are any missing corners or damages, and if there are any deviations in length or stains before packaging and selling them. The density of tungsten steel is very high, and a box like this weighs the weight of an adult man. It can be loaded onto a truck and transported to a tool processing plant to further process tungsten steel bars into milling cutters.

  When the tool factory receives tungsten steel rod material, taking my Zhuzhou Watt as an example, the first step is to expose the tungsten steel and check for any defective products. All defective products will be eliminated and returned to the manufacturer. There are many types of tungsten steel milling cutters, corresponding to different processing environments, so the tool factory is also responsible for tool research and development.

  Based on the processing conditions and materials provided by the customer, the engineer will design the corresponding tool shape to meet the customer's needs. In order to facilitate the clamping of the milling cutter, we will chamfer the tail of the material, and it can be clearly seen that the chamfered tail presents a trapezoidal shape. The tool holder is a bridge connecting the CNC machine tool, which can be easily installed into the tool holder. After chamfering, we will cut and insert the bar material, which is professionally referred to as a level difference only in the vertical direction of the high and low planes.

  Here, a rough outline of the bar material is machined using a method similar to turning, and the cutting process also requires continuous cooling with coolant.

  Cutting edge is the main process in the production of milling cutters, and the cutting machine is a grinder, which is the main equipment in tool processing factories. An imported five axis CNC grinder is very expensive, usually costing millions per machine. The number of grinders determines the output of cutting tools, and the performance of the grinders also affects the quality of the cutting tools

  For example, if the rigidity of the grinder is strong, the vibration during processing is small, and the milling cutter produced has high precision, so precision is very important for the grinder. Grinding machines have multiple functions, which can significantly improve work efficiency. They have a complete range of machining tools, can automatically adjust cableway pressure, load and unload materials, and enable one person to supervise multiple machine tools, even without supervision.

  During use, the first step is to check the jumping of the rod. After passing the jumping test, the brush wheel is used to grind the discharge groove, cutting edge, and various parts of the milling cutter cutting edge on the rod body, which are all processed by the grinder. Similarly, diamond grinding wheels are also used, accompanied by a large amount of cutting coolant. A tungsten steel milling cutter with a diameter of 4 millimeters usually takes 5-6 minutes to complete. But this is also determined by the grinding machine. Some grinding machines have multiple axes and high efficiency, and can process multiple tungsten steel milling cutters at the same time. It can be seen that after processing, a tungsten steel rod has transformed into a milling cutter, and the milling cutter is still a semi-finished product. According to the customer's order, the cutting tools are palletized and sent to the ultrasonic cleaning room. After cutting, the cutting tools are first cleaned to remove the cutting fluid and oil residue on the blade for easy passivation.

  If not cleaned, it will have an impact on the subsequent processes. Next, we need to carry out a passivation treatment for it. Passivation, literally translated as passivation, aims to remove burrs on the cutting edge. Burrs on the cutting edge can cause tool wear and rough the surface of the processed workpiece. Sandblasting passivation like this uses compressed air as power and high-speed jet material to spray onto the surface of the tool. After passivation treatment, the cutting edge becomes very smooth, greatly reducing the risk of chipping. The surface smoothness of the workpiece will also be improved, especially for coated tools, which must undergo passivation treatment on the cutting edge before coating to make the coating more firmly attached to the tool surface. 

  After passivation, it also needs to be cleaned again, This time, the purpose is to clean the residual particles on the tool body. After this repeated process, the lubrication, durability, and service life of the tool have been improved. Some tool factories do not have this process. Next, the tool will be sent to the coating. Coating is also a very important link. First, install the tool to the pendant and expose the edge to be coated. We use PVD physical vapor deposition, which vaporizes the coated materials by physical methods, and then deposits them on the tool surface. Specifically, first vacuumize, bake and heat the milling cutter to the required temperature, bombard the voltage of 200V to 1000V with ions, and leave the machine with negative high voltage for five to 30 minutes. Then adjust the current to make the plating material fusible so that a large number of atoms and molecules can be vaporized and left the liquid plating material or the solid plating material surface or sublimated and finally deposited on the body surface. Adjust the evaporation current as required until the end of the deposition time, wait for cooling and then exit the furnace. A proper coating can increase the tool life by several times and improve the surface quality of the workpiece to be processed.

  After the tool coating is completed, basically all the main processes have been completed. At this time, the tungsten steel milling cutter can be installed on the machine tool. We pull the newly coated milling cutter into the packaging room, and the packaging room will carefully check the milling cutter again. Through the anime microscope, check whether the cutting edge is broken and whether the accuracy meets the requirements, and then send it to mark, use the laser to engrave the tool specification on the handle, and then box the tungsten steel milling cutter. Our milling cutter shipments are generally in thousands, sometimes tens of thousands of tons, so the automatic packaging machine is not allowed A small amount can save a lot of manpower and financial resources. Intelligent unmanned factory is the trend in the future. 

  It involves many processes to prevent tungsten steel milling cutter from growing from scratch, In recent years, with the rapid development of the tool industry, many tool companies have started independent research and development of technology points that have not yet been fully controlled domestically, such as coating technology and five axis precision grinding machines, and have gradually shown a trend of replacing imports.