naturally occurring quartz crystals of extremely high purity, necessary for the crucibles and other equipment used for growing silicon wafers in the semiconductor industry, are expensive and rare. a major mining location for high purity quartz is the spruce pine gem mine in spruce pine, north carolina , united states . 27
zircon sand. zircon sand is a compound of approximately two-thirds zirconium oxide zr 2 o and one-third silica. it has the highest fusion point of all the base sands at 2,600 c 4,710 f , a very low thermal expansion, and a high thermal conductivity. because of these good properties it is commonly used when casting alloy steels and other .
equipment. milling is performed with a milling cutter in various forms, held in a collett or similar which, in turn, is held in the spindle of a milling machine. types and nomenclature. mill orientation is the primary classification for milling machines. the two basic configurations are vertical and horizontal. however, there are alternative .
the popularity of hydraulic machinery is due to the very large amount of power that can be transferred through small tubes and flexible hoses, and the high power density and wide array of actuators that can make use of this power. force and torque multiplication
threading is the process of creating a screw thread. more screw threads are produced each year than any other machine element. there are many methods of generating threads, including subtractive methods many kinds of thread cutting and grinding, as detailed below ; deformative or transformative methods rolling and forming; molding and casting .
a quest, or mission, is a task in video games that a player-controlled character, party, or group of characters may complete in order to gain a reward.quests are most commonly seen in role-playing games and massively multiplayer online games. rewards may include loot such as items or in-game currency, access to new level locations or areas, an increase in the character's experience in order to .
6525: imaging equipment and supplies: medical, dental, veterinary 6530: hospital furniture, equipment, utensils, and supplies 6532: hospital and surgical clothing and related special purpose items
the field of statistics, where the interpretation of measurements plays a central role, prefers to use the terms bias and variability instead of accuracy and precision: bias is the amount of inaccuracy and variability is the amount of imprecision. a measurement system can be accurate but not precise, precise but not accurate, neither, or both.