Red Seal Machinist Practice Exam

Which type of grinding wheel is best for sharpening high-speed steel tools?

1. Resin-bonded grinding wheel

2. Diamond grinding wheel

3. Vitrified grinding wheel

4. Alumina grinding wheel

The correct answer is: Vitrified grinding wheel

The most suitable type of grinding wheel for sharpening high-speed steel tools is the vitrified grinding wheel. Vitrified wheels are made from a ceramic bond that offers superior strength and wear resistance. This type of wheel can withstand high temperatures generated during the grinding process due to its excellent thermal stability. High-speed steel (HSS) is tough and often used for cutting tools. When sharpening HSS, it is essential to maintain the tool's characteristics without altering its temper. The vitrified structure allows for efficient cutting action and helps create a fine edge, which is critical for metalworking tools. In comparison to other types of grinding wheels, a resin-bonded wheel might not withstand the same level of heat as effectively as a vitrified wheel, which can lead to problems such as clogging or burning the tool. A diamond grinding wheel excels in grinding very hard materials but is not typically necessary for HSS, as the hardness and abrasiveness of vitrified wheels are usually sufficient. An alumina grinding wheel is also effective but generally does not provide the same durability and precision as vitrified wheels for sharpening HSS tools. Thus, the vitrified grinding wheel stands out as the ideal choice for efficiently sharpening high-speed steel tools, ensuring a precise edge