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CNC GLOSSARY 5

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anandengg's version from 2018-03-23 08:55

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SAE Steel– Steel manufactured under the specifications by the Society of Automotive Engineers.
Sandblasting– A process of blowing sand by compressed air with considerable force through a hose against an object.
Scale– The rough surface on hot. finished steel and castings. Also, a shop term for steel rules.
Scraper– A hardened steel hand tool used to scrape surfaces very smooth by removing minute amounts of metal.
Scribe (scribe; scratch awl)– A steel rod 8 to 12 inches long and about 3/16 inches in diameter. It has a long, slender, hardened steel point on one or both ends.
Sector– A device that has two radial, beveled arms which can be set to include any number of holes on the indexing plate of a dividing head to eliminate recounting the holes for each setting.
Set– The bend or offset of a saw tooth to provide a clearance for the blade while cutting. Also, the permanent change in the form of metal as the result of repeated or excessive strain.
Set Screw– A plain screw used principally for locking adjustable parts in position.
Setup– The preparation of a machine tool to complete a specific operation. It includes mounting the workpiece and necessary tools and fixtures, and selecting the proper speeds. feeds, depth of cut and coolants.
Shank– That part of a tool or similar object which connects the principal operating part to the handle, socket’, or chuck by which it is held or moved.
Shims– Very thin sheets of metal made in precise thickness and used between parts to obtain desired fits. Sometimes they are laminated, to be pulled off to the desired depth.
Shoulder– A term for the step made between two machined surfaces.
Shrink Fit– A class of fit made when the outer member is expanded by heating to fit over a shaft, and then contracts or shrinks tightly to the shaft when cooled.
Side Cutter – A milling cutter that has cutting teeth on the side as well as on the periphery or circumference.
Side Rake– That surface which slopes to the side of the cutting edge. It may be positive or negative and is combined with the back rake. See rake.
Sine Bar– A precision instrument for laying out, setting, testing, and otherwise dealing with angular work.
Slabbing Cutter– A wide, plain milling cutter having helical teeth. Used for producing large, flat surfaces.
Slitting Saw– A narrow milling cutter designed for cutoff operations or for cutting narrow slots.
Slotter– An attachment which operates with a reciprocating motion. Used for machining internal slots and surfaces.
Soft Hammer– A hammer made of brass, copper, lead’. or plastic to a, non-marring finished surfaces on machines or workpieces.
Spherodizing– A process of heat treating steel to produce a grain structure that is relatively soft and machinable.
Spindle– A rotating device widely used in machine tools. such as lathes., milling machines, drill presses, and so forth, to hold the cutting tools or the work, and to give them their rotation.
Spindle Speed– The RPM at which a machine is set. See cutting speed.
Spot Facing– Finishing a bearing surface around the top of a hole.
Spur Gear– A gear having teeth parallel to the axis of the shaft on which it is mounted.
Square, Solid (toolmaker’s tri square)– A very accurate try square in which a . steel blade is set firmly into a solid, rectangular-shaped handle so that each edge of the blade makes an angle of exactly 90″ with the inner face (side) of the handle.
Square Surface– A surface at a right angle with another surface.
Square Threads– A thread hating a depth. width. and space between threads that are equal. It is used on heavy jack screws. vise screws. and other similar items.
Steady Rest– A support that is clamped to the bed of a lathe used when machining a long workpiece. Sometimes called a center rest.
Stellite– A cast alloy of chromium, cobalt. and sometimes tungsten, used to make lathe cutter bits that will stand exceptionally fast speeds and heavy cuts.
Step Block– A fixture designed like a series step to provide support at various heights required for setups.
Stock– A term for the materials used to make parts in a machine tool. Also, the die stock used for threading dies.
Stop– A device attached to a machine tool to limit the travel of the worktable and sometimes the work head.
Straddle Milling– A milling setup where two side milling cutters are spaced on an arbor to machine two parallel surfaces with a single cut.
Stress– The internal force or resistance developed in steel which was hardened, extensively machined, or cold worked.
Surface Grinding– The process of grinding flat surfaces on a surface grinding machine. With special setups, angular and form surfaces may also be ground.
Surface Plate– An accurately machined and scraped flat metal piece (usually of cast iron) used to check the flatness of surfaces.
Swing– The dimension of a lathe determined by the maximum diameter of the work that can be rotated over the ways of the bed.
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Question Answer
Tailstock– That part of a machine tool. such as a lathe or cylindrical grinder which supports the end of a workpiece with a center. It may be positioned at any point along the way of the bed, and may be offset from center to machine tapers.
Tang– The flat on the shank of a cutting tool, such as a drill, reamer or end mill, that fits a slot in -the spindle of a machine to keep the tool from slipping. Also, the part of a file that fits into a handle.
Tap– A tool used to cut threads on the inside of a round hole.
Taper– A uniform increase or decrease in the size or diameter of a workpiece.
Tapping– The process of cutting screw threads in a round hole with a tap (an internal thread cutting tool).
T-bolt– Term for the bolts inserted in the T-slots of a worktable to fasten the workpiece or work-holding device to the table.
Tempering– A heat-treating process to relieve the stresses produced when hardening and to impart certain qualities’, such as toughness-, sometimes called “drawing.”
Template– A pattern or a guide for laying out or machining to a specific shape or form.
Tensile Strength– The property of a metal which resists force applied to pull it apart.
Thread– A helical projection of uniform section on the internal or external surface of cylinder or cone. Also, the operation of cutting a screw thread.
Thread Angle– The angle formed by the two sides of the thread (or their projections) with each other.
Thread Axis– A line running lengthwise through the center of the screw.
Thread Crest– The top surface joining the two sides of a thread.
Thread Depth – The distance between the crest and the root of a thread.
Thread Pitch – The distance from a point on one screw thread to a corresponding point on the next thread.
Thread Pitch Diameter– The diameter of a screw thread measured from the thread pitch line on one side to the thread pitch line on the opposite side.
Thread Root– The bottom surface joining the sides of two adjacent threads.
Throw– The crankpin on a crankshaft. Also, the length of the radius of a crank, an eccentric, or a cam.
Tolerance– The allowable deviation from a standard size.
Tool Steel – A general classification for high-carbon steel that can be heat treated to a hardness required for metal cutting tools such as punches, dies. drills. taps’, reamers, and so forth.
Traverse– One movement across the surface of the work being machined.
Truing– The act of centering or aligning a workpiece or cutting tool so that an operation may be performed accurately. Also, correcting the eccentricity or out of round condition when dressing a grinding wheel.
T-Slot– The slots made in the tables of machine tools for the square-head bolts used to clamp the workpiece,, attachments, or work-holding fixtures in position for performing the machining operations.
Tumbler Gears– A pair of small lever-mounted gears on a lathe used to engage or to change the direction of the lead screw.
Two-Lip End Mill– An end milling cutter designed with teeth that cut to the center so that it may be used to feed into the work like a drill.
Universal Grinder– A versatile grinding machine designed to perform both internal and external grinding operations. including straight and tapered surfaces on tools and cutters.
Universal Milling Machine– A milling machine with a worktable that can be swiveled for milling helical work. It is always supplied with attachments, including an indexing fixture.
Universal Vise– A vise designed for holding work at a double or compound angle. Also, a toolmaker’s vise.
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