Choosing the Right Grinding Tools for the Aerospace Industry
Abrasive technology is an important manufacturing process in many industrial sectors, including aerospace engineering. This technique requires the use of grinding wheels with coated abrasives such as diamond powder, which is extremely abrasive due to diamond's hardness. The best choice of material for bonding the abrasive material to the grinding wheel varies greatly and may need to be customized for a specific application. Diamond grinding creates surfaces with a smoother finish and sharper edges, which is often essential in aerospace research. Superabrasives provide better results in grinding operations that require greater duration, higher speed and cleaner cuts.
The most significant factor in selecting the best abrasive material to use in a particular application is the hardness of the material being ground. The Rockwell hardness scales are the most common method of measuring hardness for these applications, especially the Rockwell C scale. This scale is commonly known as the material's RHC, which uses a 120-degree cone under a force of 150 kilogram-force to make an indention in the test material. The RHC measures hardness as a dimensionless number, with values between 20 and 100 generally considered reliable. Superabrasive grinding wheels typically become cost effective for materials with a hardness greater than 45 RHC.
Speed and Cutting
Grinding wheels have ideal ranges for operating speeds and cutting depth that primarily depend on the abrasive material. Diamond grinding wheels should operate at a surface speed between 3,000 feet and 8,000 feet per minute, such that greater speed is better for applications involving frequent interruptions or small areas of contact between the work piece and the grinding wheel. Operators should minimize the depth of the cut to create the best finish and extend the life of the work wheel. The maximum DOC for each pass depends on the particle size of the abrasive material. Abrasives with a grit size between 80 and 150 micrometers shouldn't cut more than 0.002 inches per pass, and abrasives with a grit size between 180 and 220 micrometers should be limited to 0.001 inches per pass. Grit with a size between 240 and 400 micrometers has a maximum DOC of 0.0005 inches per pass, and a 500 to 600 grit size has a maximum DOC of 0.0003 inches.
The choice of bonding material is more complex than many of the other decisions involved in diamond grinding. The material comprising the work piece is a critical factor, as is the size of the abrasive particles. Aerospace engineers must also consider the operating speed of the grinding wheel and the type of coolant that will be used. Additional factors in selecting a bonding material include the type of bonding material and its hardness. Some grinding applications use electroplating rather than bonding to attach the abrasive material to the grinding wheel.
To find more information on which application is best for your project, contact CDT today.