Metalworking Glossary "S"

S Is for Swarf

Metalworking Glossary for the Letter S

See the index to the Glossaries here:

https://www.libertymachineworks.com/blog/150-metalworking-glossary

• Saddle. On a lathe, a saddle is part of the carriage and is located at the top of a lathe. It supports cross-slide movements. On a mill, a saddle is the part of the mill between the table and the knee. It slides in and out (Y-axis) on the mill base. The mill table moves left and right (X-axis) on top of the saddle.
• SAE. Abbreviation for Society of Automotive Engineers.
• SAE Steel. Steel that is manufactured under the specifications set by the Society of Automotive Engineers.
• Safety Laser. A laser-based safety device that immediately stops a machine tool like a press brake or shear in place if an object like the operator’s hand interrupts the beam.
• Sandblasting. A finishing process that blows sand at high pressure against a workpiece using compressed air.
• Sanding. A finishing function that involves using an abrasive material such as sandpaper—either by hand or attached to a machine or piece of tooling—and moving it rapidly against a workpiece to create a smooth and uniform surface.
• Saw Guides. The devices on a bandsaw that secure the blade from either side to align it for a straight cut. They consist of rollers and/or carbide blocks.
• Scale. In metallurgy, scale is a layer or crust of oxidation that forms on steel when it’s heated, such as mill scale.
• Screw Gauge. A screw gauge is used to measure the diameter of a thin wire or the width of a metal sheet.
• Screw Machine. A screw machine is a small capacity multi-spindle lathe.
• Section Roll. Another name for a profile roll, a section roll has three or four rolls used for curving a section or profile of metal, like angle iron. Other names for the machine include angle roll and section bending machine.
• Set. The term set can refer to several concepts. In metalworking it can mean a collection of things (a tooling set), being made secure (a set screw), or the offsetting of teeth on a bandsaw blade to provide side clearance (a saw set).
• Set Screw. A screw used to anchor a tool or part in position.
• Setup. The preparation of a machine to complete a specific operation, including fixturing the workpiece, mounting the tools, and setting all the variables into the controls, such as speed and depth of cut.
• Shank. Below the functional end of a piece of tooling is a long, narrow part called a shank that is held in place by a tool holder on a machine tool. Different types of shanks can be secured in different ways, such as a cylindrical shank that is held in place by the friction of a closed collet, or a Weldon shank with a flat area that that is fastened in position with a set screw.
• Shaper. Shapers are adaptations of metal planers, though much smaller, and instead of a workpiece moving on a large table under a stationary tool, the shaper applies a moving cutting tool to a stationary workpiece. Primarily used for creating a flat surface, a shaper can also be used to machine irregular shapes that weren’t able to be readily produced using other machines from its era. With the workpiece clamped securely to the table or in a vise, a reciprocating ram moves a non-rotary cutter called a single point cutting tool back and forth across its surface. The cutting usually takes place during the outward stroke, with a quick return mechanism bringing the ram back. During the ram return, a ratchet gear and pawl mechanism advances the workpiece laterally to the next cutting position.
• Sheet Support Arm. An extension that is mounted to the front of a sheet or plate metal working machine like a shear or press brake and supports (and possibly gauges) a workpiece that is being fed into the machine.
• Shim. A very thin sheet of metal machined to a precise thickness and used between parts to achieve a desired fit. Other materials besides metals are sometimes used for temporary shims on a machine.
• Shoulder. A step that is created between two machined surfaces.
• Side Grinder. Another term for an angle grinder.
• Side Milling. A type of peripheral milling where the cutter machines the side of the workpiece.
• Simplex Milling Machine. A mill that has a spindle that can only travel in a single direction, usually vertically.
• Sinking. The operation where an impression is machined into die blocks for a specific forging.
• Slack Tub. Usually consisting of a large water-filled container, a slack tub is used by a blacksmith to quench hot metal.
• Slag. Any unwanted byproduct of smelting ore. Also called dross or tailings.
• Slot Milling. A type of milling used to produce a slot (channel) in a workpiece, usually with an end mill or a disk mill.
• Slotter. A machine or attachment that operates with a reciprocating motion in order to cut a slot.
• Slug. In forging, a slug is a piece of raw stock material. Also called a blank, a multiple or just forging stock.
• Slugging. Cutting blanks (slugs) for subsequent metalworking operations.
• Smelting. The process of heating and melting ore to extract metal.
• Smith Forging. The type of forging commonly performed by blacksmiths. It is a forging worked between flat or simple contour dies by repeated strokes and manipulation of the workpiece. Also called hand forging, flat die forging, or open die forging.
• Snap gauge. A type of go/no-go gauge.
• Spheroidizing. A form of annealing so named because it causes the graphite in an iron base alloy to assume a spheroid shape. The process consists of prolonged heating of the alloy slightly below the critical range temperature, followed by relatively slow cooling.
• Spindle. A rotating device in a machine like a lathe, mill or drill press that holds either the cutter or the workpiece for a machining operation.
• Spindle Bar. Commonly called a “Tommy bar,” it is a round steel bar used to tighten and loosen spindle accessories such as chucks.
• Spindle Speed. Measured in rotations per minute (RPM), spindle speed is the rate at which a spinning tool like an endmill revolves when in operation.
• Splines. Splines are teeth on the end of a drive shaft that look like a gear when viewed end-on.
• Spot Facing. The process of finishing a bearing surface around the top of a hole.
• Springback. The tendency of a bent or shaped piece of metal to return to its original shape or contour after undergoing a forming operation.
• Sprockets. A spoked wheel that engages with a chain (like on a bicycle).
• Spur Gear. The most common type of gear, also known as a straight-cut gear. Two kinds of spur gears are involute gears and cycloidal gears, each of which have teeth with a specific type of rounded curve to them.
• Square. A shortened term for the precision machinist square used in metalworking to confirm right angles.
• Square Shoulder Face Milling. A type of milling that does the functions of both an end mill and a face mill.
• Square Shoulder Mill Cutter. A cutter with a 90° lead angle that used for square shoulder milling.
• Stainless Steels. Steels that contain a minimum of 10% to 12% chromium, making them corrosion and heat resistant.
• Standard Shaper. A shaper that has a table that moves horizontally and vertically.
• Steady rest. On a lathe, a steady rest is a bracing tool that will often be used with long workpieces to support them in the middle, halfway between the main spindle and the tailstock. It helps keep the workpiece centered with the axis of the spindle despite the pressure from the cutting tools pushing against it.
• Steel Scale. A steel scale is a precise metal ruler, usually with inches and millimeters measured out on opposite sides.
• Step Block. A fixture designed like a series of steps to provide support during setups at different heights.
• Step Turning. Step turning is a lathe function that creates two surfaces with an abrupt change in diameters between them that resembles a step.
• Stock. The material that is machined, forged, or otherwise worked on to make a part. Raw stock is usually cut down to make a blank, which is a piece of stock that is slightly bigger than the finished part and can be easily worked with.
• Stop. A device that is attached to or built into a machine tool or metal fabrication machine and can be set to limit the travel of a section of the machine during an operation, such as the descent of a press brake ram or the horizontal movement of a worktable.
• Stress. In metalworking, the term stress refers to the internal resistance a metal has to the distorting effects of an externally applied force. The six types of stresses that affect metal are bending, compression, fatigue, shear, tension, and torsion. Some metals are ductile and will yield under stress before breaking (such as stainless steel), while others are brittle and will fracture and break rapidly under stress (like high-carbon steels).
• Stroke Length. The maximum distance that the tool holders in a metalworking machine can advance in relation to a potential workpiece. For example, the stroke length of a press brake, also known as daylight or open height, is the distance between the top and lower beams without tooling when the brake is fully open.
• Straightedge. Another name for a steel scale.
• Straightening. A finishing operation for correcting misalignment in a forging or between different sections of a forging. Straightening may be done by hand, with simple tools, or using a die with forging equipment.
• Strain Rate. The rate at which metal is deformed.
• Strain-rate Sensitive Alloys. Those alloys that can be forged only at low rates of deformation.
• Stress Relieving. A process that reduces residual stresses in a piece of metal created by machining, welding, quenching, or other operations. The metal is heated to a specific temperature and held there for a set amount of time.
• Structural Shape. The design or profile of a piece of metal in a recognized metal industry standard, such as angle iron, channel, "H" beam, "I" beam, tubing, etc.
• Surface Finish Pattern. The surface characteristics, such as roughness, of workpiece.
• Surface Grinder. Like its name implies, it grinds the surface of a workpiece, usually for material removal rather than finishing work. One of the most common types of grinders, its adjustable head can be lowered to bring the grinding wheel into contact with a workpiece which is mounted to either a horizontally moving table or a rotary table.
• Surface Plate. A surface plate or surface table is a smooth, flat surface used to check flatness and squareness of objects and as a reference point for vertical measurements. While they were originally created out of metal—and cast-iron surface plates are still in use today—granite surface plates came into widespread use during World War II due to metal shortages and remain a popular style today. Many metalworkers prefer granite surface plates because they don’t rust or corrode, have a non-glaring surface, and aren’t magnetic.
• Surface Roughness Tester. A surface roughness tester physically probes or digitally scans the surface of an object to determine its roughness. The measurements are given as one of two units, either Ra, the average roughness of a surface based on a measurement of all “peaks” and “valleys,” or Rz, the difference between the tallest and deepest points on the surface. One type of surface roughness tester is a profilometer, which can determine specifications such as curvature, flatness, and step by analyzing the topography of the part’s surface.
• Surface Speed. A measurement indicating how fast a tool moves over a workpiece while it cuts. It can also be referred to as cutting speed and is measured in SFM (surface feet per minute).
• Swing. A key dimension of a lathe referencing the maximum workpiece diameter that it can hold and rotate over the ways of the bed.
• Swarf. Also called “chips,” swarf is the byproduct material that is cut off a workpiece while it is being machined.
• Swing-frame Grinder. A powered rotating grinding wheel mounted into a framework that can be moved to different positions over a stationary workpiece.
• Swiss-style Lathe. A Swiss-style lathe is a very precise lathe used for extreme accuracy.