Processing characteristics of medical titanium and titanium alloy
Titanium has good biocompatibility and was chosen as the most ideal implantable product. For more than a decade, many scientific research departments, medical schools, hospitals, etc. in international countries and China have also done a lot of fundamental work and clinical research. From the depth and breadth, they recognize titanium as the most ideal human implant product. There are thousands of cases of artificial femoral heads, artificial wrist joints, knee joints, artificially cultivated teeth, skull repairs, and pacemakers. These years of research, stalking, and contrasting, so far reported that titanium is The most ideal product for human implants. The design of the orthopedic device needs to conform to the complex shape of the bones and joints, so the processing of these parts is also complicated. These devices, which are machined from titanium rods, require a large amount of material to be cut, and thus the process index is expensive because of the low cutting performance index of many materials. Therefore, some parts are cast close to the final shape of the part, which often requires complex and expensive fixtures.
Titanium 6AL-4V ELI is a specification for the manufacture of ankle joints, bone screws, knee joints, plate bones or organs, dentures and surgical equipment. However, cobalt-chromium alloys are used more and more often because of their firmness, tighter particle size and cleaner than titanium. The cutting force required to process titanium alloys is only slightly larger than that of machined steel. However, the metallurgical properties of titanium alloys make it more difficult to machine than steels of appropriate hardness. Titanium has a work hardening property that eliminates the consolidated metal (beading) in front of the cutting tool. This helps to increase the shear angle during machining, thus constituting a thin chip that touches the outer surface of the cutting tool over a suitably small area. Because of this work hardening, the feed should not be stopped during the tool and workpiece motion touch. The large supporting force that occurs during processing combines the friction generated by the chips in the touch area, so that heat is greatly added in the portion of the tool. The heat generated by cutting titanium does not dissipate quickly because it is a poor conductor. Therefore, most of the heat is collected on the cutting edge and the tool's appearance. The large bearing capacity and heat form a crescent near the cutting edge, causing the tool to be agile. To make matters worse, titanium alloys have a strong tendency to alloy with or revitalize the chemical in the tool at the operating temperature of the tool. There is also a tendency to cause the tool to appear when the chips are bonded to the cutting edge of the tool. damage. These difficulties are doubled when the tool begins to break. Therefore, the tool used to machine titanium and its alloys should be carefully supervised to ensure that the blade is sharp and replaced before it is blunt. The experience with titanium and titanium alloys is that if any changes are seen during processing, the tool should be changed immediately, as the change means that the tool is dull. Another reason for sticking to the sharpness of the tool is that titanium can cause a fire when cutting with a damaged or damaged tool. When incinerated, the metal generates oxygen, so the fire will spontaneously ignite. Therefore, many workshops that process titanium do not report fires, and they are equipped with a rescue system on the machine.
Titanium has a suitably low modulus of elasticity and is more elastic than steel and therefore tends to violate cutting tools during machining unless it is to be robustly cut or used as a suitable support. Slender parts tend to deflect under tool pressure, causing problems with knives, tool friction and workmanship. Through the processing experience, it is considered that the rigidity of the entire system of the tool is very important, and it is necessary to use a sharp and accurate shape of the tool. Due to these pressures, new technologies have been introduced to help the manufacturing of medical parts in the workshop to cope with competition, processing performance to produce these complex parts, the precision is very high; many innovations in EDM, making the production of high-quality parts faster, eliminating many old processing techniques The problem inherent in it.
As a new type of product, titanium has been developed and used in China's pharmaceutical industry, medical equipment, human implants, etc., but it has been a history of nearly two decades. However, it has achieved great success and achieved remarkable social and economic benefits, shortening the gap between China and international advanced countries. Since the 1970s, the Northeast Pharmaceutical General Factory, Shandong Xinhua Pharmaceutical Factory, and Wuhan Pharmaceutical Factory have taken the lead in the use of titanium equipment in the production of aspirin, analgin, caffeine and other commodities, not only dealing with the serious troubles of the company's production and development. The equipment is corroded and the quality of the medicine is greatly improved.