Titanium Alloy Characteristics
The types of titanium alloys are roughly divided into three categories, α titanium alloy, β titanium alloy, α + β titanium alloy. The titanium alloy specification with the largest dosage at present is TC4 (Ti-6AI-4V), i.e. titanium alloy with α+β phase structure.
Titanium alloy has high strength, good thermal stability, high temperature strength, chemical activity, low thermal conductivity and other characteristics, the higher the temperature, the higher the hardness, belonging to one of the most difficult to process materials, grinding up very difficult, grinding performance is very poor. The grinding of titanium alloy usually adopts 36#-80# grain size.
Problems in grinding
1. The bonding problem of the grinding wheel is serious and the knot problem is serious.
In the grinding process, the surface of the titanium alloy falls off, adhering to the grinding wheel, and the bonded surface layer in the subsequent grinding will be accompanied by the abrasive particles on the grinding wheel together, the damage to the grinding wheel is very serious.
2. The workpiece is easy to burn, deformation and cracking
Due to the characteristics of titanium alloy, the higher the temperature, the higher the hardness, the required grinding force is larger, the resulting temperature is too high, and the heat transmitted into the workpiece is difficult to export, it is hot will destroy the titanium alloy, easy to lead to workpiece burns, deformation, and even cracks.
Suitable abrasives
Because titanium alloy is a non-ferrous metal, it is more suitable for grinding with silicon carbide (SiC) or green silicon carbide (GreenSiC), or super-hard diamond abrasives (Diamond). The use of GreenSiC and SiC grinding wheels results in lighter adhesion and fewer burns and cracks. Therefore, green silicon carbide grinding wheels are generally used.
Solutions to Grinding Problems
Titanium alloys are prone to bonding of grinding wheels during the grinding process as well as easy burning, deformation and cracking of workpieces due to high grinding temperatures. Higher grinding temperatures lead to severe plastic deformation, which causes damage to the surface of the workpiece, and the bonding effect between the abrasive and the metal occurs through physical or chemical adsorption.
The fundamental solution is to solve the heat dissipation problem. A common practice is to increase the grinding ratio in order to achieve as much removal as possible with as little wear on the grinding wheel as possible.
Conventional practice
Traditional practice; slowing down the speed of the grinding wheel, the grinding temperature will be reduced, than in the case of high-speed rotation, will achieve a better grinding effect; however, in this case, due to the slowing down of the speed of the grinding wheel consumption will be accelerated, the more time and frequency of dressing, the slower the machining efficiency will be, invariably also affects the cost of processing, but also has a certain effect on the workpiece plane precision / dimensional accuracy; therefore this is not the best way. an optimal approach.
Ideal practice; the rotational speed is the same condition, to achieve good heat dissipation. In the grinding wheel or grinder, the highest speed allowed to do grinding, the use of grinding wheels or grinding fluid or processing conditions, etc., to achieve better heat dissipation, as far as possible, do not lose the rotary speed of the grinding wheel, so as not to consume the cost of the grinding wheel.
However, the requirements of the titanium alloy grinding fluid, in addition to cooling and flushing effect, more importantly, to inhibit the adhesion of titanium and abrasive particles and chemical effects. It is appropriate to use water-soluble grinding fluid containing a variety of extreme pressure additives.
Titanium alloy grinding fluid has excellent biostability and antirust properties. The longest service life can be more than two years; good anti-rust performance, reducing the consumption of cutting fluid. At the same time, titanium alloy grinding fluid does not contain chlorine, nitrite, phenol and other harmful substances, belongs to the environmental protection grinding fluid, will not irritate the skin, to protect the health of the operator. If you want to use the existing grinding wheel to improve efficiency, you can try to reduce the speed of the grinding wheel to see if it achieves the effect, if so, it proves that the grinding temperature caused by the problem, you can start from this condition to see how other conditions should be set.
In general, it is the use of grinding wheel heat dissipation, coupled with other methods of heat dissipation with each other, such as cutting fluid, etc. is not a good match; so that it provides better heat dissipation.
