Machine Tools, Materials, and Gears

• The process of uniformly heating steel above hardening temperatures, followed by air cooling, is normalizing.

Machine Tools

• A shaper is a machine tool that machines flat or plane surfaces using a single-point cutting tool.
• A planer is a machine tool used for producing flat surfaces on large or heavy workpieces that are difficult to hold on a shaper.
• A milling machine uses a revolving cutter with multiple teeth to remove stock from a workpiece, creating various surfaces.
• A tool grinder sharpens tools using an abrasive wheel.

Materials

• An abrasive is a material capable of wearing away a softer substance.
• Brass is an alloy of copper and zinc.
• Bronze is an alloy of copper and tin, often with a small amount of phosphorus.
• Galvanized iron is iron coated with zinc.

Gears

• The pitch circle is an imaginary circle where meshing gear teeth make contact.
• A gear rack is used to change rotary motion into reciprocating motion.
• Worm gears are used for heavy-duty applications requiring a large speed ratio, commonly found in speed reducers.
• Bevel gears transmit motion between shafts at an angle to each other.
• In spur gearing, tooth outlines are usually involute curves.
• Addendum: The portion of a gear tooth that projects above or outside the pitch circle is the addendum.
• Dedendum: The portion of gear tooth space that is cut below the pitch circle and is equal to addendum plus the clearance
• The circular pitch is the distance from the center of one tooth to the center of the next, measured on the pitch circle.
• The diametral pitch represents the number of teeth per inch of pitch diameter, indicates the size of the gear teeth.
• Module: The gear teeth to each mm pitch diameter.
• The dedendum is the depth of the tooth space below the pitch circle.
• The full depth, also known as whole depth, of the tooth space is equal to the addendum plus dedendum.
• Backlash is the clearance between the tooth profiles of gear teeth.
• The root circle coincides with a tangent at the bottom of the tooth space.

Measuring Tools and Techniques

• A dial indicator is used to align machine tools, inspect workpieces, and compare measurements.
• A feeler gauge is a set of thin metal strips of varying thicknesses for measuring clearances.
• A micrometer is used for accurately measuring diameters.
• A torque wrench measures tension on bolts.

Heat Treatment

• Tempering involves reheating metal to a temperature below the transformation range to achieve desired properties.
• Quenching is rapidly cooling a heated workpiece by immersion in water, brine, or oil.
• Hardening involves heating above the transformation temperature and quenching, typically in oil, to increase hardness.
• Annealing is a method for softening metal, involving slow heating above the usual hardening temperature, maintaining the heat, and then cooling slowly.
• Stress relieving is heating to a subcritical temperature (1100°F to 1300°F) to reduce internal residual stresses.
• Normalizing involves heating to approximately 100°F above the transformation range, followed by cooling in still air to produce a uniform metal structure.

Fasteners and Tools

• A tap is a cylindrical steel bar with threads and flutes used to cut internal threads.
• Stud bolts are bolts without heads, threaded on both ends.
• Carriage bolts are designed for bolting wood parts together, featuring a round head and a short shank that secures into the wood.

Fits

• Tanking is not a common term relating to the classification of fits. Common terms include snug, medium force fit, and bound.

Machine Elements

• A chuck is a gripping device with adjustable jaws set radially.
• A dividing head is a mechanism that usually does the indexing in a machine tool.
• Mandrel: A tool which when pressed into a finished hole in a piece of work, provides centers on which the piece may be turned or otherwise machined

Hole Creation and Enlargement

• Reaming is sizing and finishing a hole with a multi-edged cutting tool.
• Boring enlarges a hole using an adjustable cutting tool with a single cutting edge.
• Countersinking creates a cone-shaped enlargement of a hole, such as for a flat head screw.

Welding

• Brazing is a welding operation using a non-ferrous filler metal that melts below the base metal's temperature but above 450°C.
• Resistance welding joins metal using high current at low voltage, with pressure from electrodes producing a forge weld.
• Internal stresses in a welded connection may be relieved when the weld is peened.
• Gas welding: Fusion process in which the metal is heated into a state of fusion permitting it to flow together into a solid joint

Machining Operations

• Forging forms metal parts using dies after heating the metal to its plastic range.
• Knurling creates a checkered pattern on a surface by rolling checkered depressions into it.
• Laying out includes marking center points, circles, arcs, or lines on metal surfaces as a guide for the work.
• Squaring squares the end of a workpiece with its axis.

Steel Properties

• Ductility is the ability of a metal to deform considerably without rupture.
• Abrasive: a material that can wear away a substance softer than itself

Machine Components and Features

• Headstock: In lathe, it comprises the main spindle, the necessary mechanism for obtaining various spindles speed and also certain gears which are used to operate the quick-change gear mechanism.
• Live Center: If fits into the main spindle of a lathe and is called because it acts as a bearing surface on which the work rests.

Steel Alloying

• Chromium is used in stainless steel.
• SAE 1320 is a manganese steel containing approximately 0.20% carbon.

Machine Tools

• Slotter: A machine tool which is very similar to a shaper except that ram is reciprocates vertically rather than horizontally.

Geometry

• The moment of inertia of rectangle whose base is b and height h about its base is bh3/3.

Fits

• Tolerance: The total permissible variation in the size of dimension, the difference between the limits of sizes.

Gear Types

• Hearing bone gears: Consist of two-handed helical gears.

Chucks

• Independent Chuck: A kind of chuck which has reversible jaws which could be adjusted separately.
• Universal Chuck: A kind of chuck which should not be used when extreme accuracy is required.