Clamping Basics 131

air compressor

A device that pressurizes ambient air by placing the air under force. Air compressors can be used to run vacuum clamping systems by creating an area of greater air pressure compared to the ambient atmosphere.

air pressure

The force created by air at a specific location and in a specific amount of space. Air pressure can change through compression of air or a temperature change.

aluminum

A nonferrous, silvery-white metal that is lightweight, highly conductive, and non-magnetic. Aluminum is often used to make clamping pads.

arm

The metal strip on a screw clamp that connects the post and clamp screw. Arm length can vary to provide more clearance between the post and workpiece or to provide more stable gripping.

assembly

A manufacturing process in which two or more components are joined together to create a finished part. During assembly a workholding device holds components in the proper location for accurate joining.

bolt

A cylindrical fastener with exterior threads that mates with a nut. Bolts fit in holes on fixtures to allow operators to attach supporting, locating, and clamping components.

brass

An alloy of copper and zinc. Brass clamps help prevent marring.

cam clamp

A clamp with a semi-circular head that is moved into place with a lever to provide clamping force. Cam clamps are easy to engage and disengage but provide limited clamping force.

cam head

The semi-circular portion of the cam clamp. The cam head is the component of the cam clamp that rotates into place to provide gripping force.

C-clamps

A type of clamp with an adjustable screw that serves as the clamping arm set in a C-shaped frame. C-clamps are simple to operate but provide limited clamping force.

changeover

The amount of time needed to switch workpieces or change workholding or other setups. Changeover is more efficient when workholding is designed for ease of unloading and loading and to be quickly reconfigured for other operations.

chips

A piece of material that is removed from a workpiece during cutting, grinding, or other manufacturing operations. Chips are tiny curls, shards, fragments, or particles of material that can damage the face, eyes, or skin if ejected toward the operator.

clamp

A workholding device component that tightens to hold a workpiece in place when it is exposed to the cutting forces of manufacturing. Clamps include strap clamps, screw clamps, and toggle clamps.

clamping

Securely holding a workpiece against locators. Clamping a workpiece helps it resist the cutting forces that occur during machining and can also help locate the workpiece.

clamping arm

The component of a clamp that makes contact with and grips the workpiece. Clamping arms may have heads or contact pads to reduce potentially damaging force they exert on the workpiece.

clamping forces

The compressive force that a clamp exerts on a workpiece surface. Clamping forces create pressure on the workpiece surface and friction between the clamp and the workpiece to keep the workpiece still.

clamping pads

A circular component made of a flexible material such as plastic or rubber. Contact pads, or pressure pads, are placed on the end of some clamps to spread out the clamping force and prevent workpiece deformation or surface finish damage.

clamping range

The measurement span between a clamp's most open position and its closed position. Clamping range determines the minimum and maximum workpiece size a clamp can fit.

clamping screw

The threaded component of a screw clamp that makes contact with and grips the workpiece. Clamping screws are tightened and loosened through the use of rotational force or torque.

clearance

An intentional amount of space left between two components. Clearance is often required to prevent undesirable contact between clamps and a cutting or other manufacturing tool.

contact points

The precise location where two objects physically touch each other. Contact points between a clamp and workpiece occur where the clamping arm makes contact with the workpiece.

cutting forces

The various stresses involved in a machining process. Cutting forces include pressure that a tool places on a workpiece when they come into contact.

cutting tool

A device with one or more edges used to create chips and remove material. Cutting tools include mills, drills, and cutting inserts.

cycle time

The time it takes to perform a task and move forward to the next step in a manufacturing process. Cycle time decreases when workholding devices, like clamps, conduct work effectively to allow higher cutting speeds and feeds and reduce required rework.

cylinder

The component of a swing clamp that holds and facilitates movement for the piston. The cylinder can either be a metal rod or a hollow cylindrical component, depending on the piston type.

debris

Small particles or pieces of material, often in the form of chips or swarf. Debris is produced by most manufacturing operations and can cause injury if the correct safety measures, such as wearing personal protective equipment (PPE), are not in use when debris may be ejected by the manufacturing process.

drilling

A machining operation in which a multi-point tool is fed into a workpiece to create a round hole. Drilling is often used as the first step in a hole-making process, followed by more precise procedures such as boring and reaming.

effort

The energy provided to a machine to perform work. Effort for clamps often comes in the form of tightening it or otherwise pressing it firmly against the workpiece.

electric current

The flow of electrons. Electric current can be used to activate some magnets.

feed

The rate at which a cutting tool moves along a workpiece in turning, milling, and grinding or into a workpiece in drilling. Feed is often measured in inches per minute (ipm), or millimeters per minute (mm/min), or in inches per revolution (ipr), or millimeters per revolution (mm/rev).

ferrous

A metal containing iron, generally as a primary ingredient. Ferrous metals are usually magnetic.

finger strap clamp

A strap clamp with a tapered clamping arm or a clamping arm that ends in a pin. Finger strap clamps can fit inside a hole or interior surface to grip a workpiece.

finishing

A final process performed to complete a part. Finishing operations surface, condition, edge, and clean parts and are usually the last steps in the machining process, occurring before inspection and testing.

fixture

A customizable, modular workholding device created by configuring locators, supports, and clamps on a body fixture. Fixtures are useful when holding irregularly shaped workpieces or when holding multiple workpieces for a single operation.

fixture body

A component that provides the base for the other elements of a fixture. Fixture bodies include faceplates for lathes and base plates, angle plates, and tombstones for milling and drilling.

flat jaw

A level surface that makes contact with and grips a workpiece. Flat jaws spread clamping force over a large portion of the workpiece.

force

An influence, like a push or a pull, that produces a change in an object's motion or state of rest. Forces have specific directions and magnitudes.

friction

A force that resists motion between two components that are in contact with one another. Friction helps clamps secure workpieces.

fulcrum

The point around which an object turns, swings, or pivots. Fulcrums in levers allow operators to gain a mechanical advantage over the load.

goggles

A type of tight-fitting eye protection that completely covers the eyes, the sockets, and the surrounding facial area. Goggles offer protection from impact, debris, and splashes.

heel pin

A threaded fastener screwed into a fixture in order to serve as the fulcrum for a strap clamp. Heel pins are less adjustable but more stable than other strap clamp fulcrums, such as step blocks.

hydraulic

A system that creates power and motion through the controlled movement of compressed liquid. Hydraulic systems are the preferred power source for power clamping because they take up less space than pneumatic systems.

inclined plane

A simple machine consisting of a flat, angled surface used to raise objects. An inclined plane's mechanical advantage increases with its length if height remains the same.

inspection

The examination of a part to determine if it conforms to necessary specifications and measurements. Inspection traditionally follows the completion of a part or there may be inspection of the components of a part prior to and after assembly.

lateral

Moving toward or away from the side of an object. Lateral pressure occurs when a clamp grips the workpiece from the side and lateral cutting forces occur as the cutting tool travels through the workpiece.

layout

A manufacturing process during which a workpiece is marked with lines, centers, or circles to show how it should be machined or during which the components of a part are arranged for assembly. Layout occurs prior to the actual machining and assembly processes.

levers

A type of simple machine consisting of a rigid bar that pivots on a fulcrum. Levers are used to transmit motion and alter mechanical advantage.

load

The object or force that a mechanical system must move, hold, or overcome. Loads for most clamps are the workpiece.

locating

Establishing a workpiece in a set position. Locating a workpiece correctly ensures it will be machined or otherwise manufactured to the correct specifications and tolerance.

locators

A fixture component that positions the workpiece and restricts its movement. Locators include locating pins, locating cylinders, and locating screws.

machining

The process of removing material to form, shape, or finish a part. Machining processes include turning, drilling, and milling.

magnetic chucks

A workholding device that holds ferrous, or iron-containing, workpieces using magnetic forces. Magnetic chucks, or magnetic clamps, are used with metallic workpieces.

magnetic clamps

A workholding device that holds ferrous, or iron-containing, workpieces using magnetic forces. Magnetic clamps, or magnetic chucks, are used with metallic workpieces.

magnetism

The power of attraction and repulsion that exists in ferrous, or iron-containing, materials. Magnetism most often occurs between metals.

manual clamps

A clamp that requires an operator to physically move it into place and engage it. Manual clamps are commonly used when machining parts with looser tolerance.

marring

Causing damage and imperfections. Marring can occur on workpiece surfaces if clamps are not tightened and placed properly.

mechanical

Relating to the use of physical force. Mechanical interactions with parts include rotating, pressing, and pushing.

metal cutting

A machining process that uses a tool to create chips and remove metal from a workpiece. Metal cutting operations include milling, drilling, and turning.

milling

A machining operation in which a multi-point horizontal or vertical cutter is used to remove material from a workpiece. Milling is often used to create flat surfaces or to create grooves or pockets in a flat surface.

modular

Consisting of interchangeable and discrete parts. Modular clamps, such as strap clamps, have individual pieces that can be replaced more easily than if the whole clamp had to be replaced.

nut

A fastener with a hole and internal threads that mates with a bolt or screw. Nuts, when tightened, exert clamping force through a clamping arm.

operators

A person responsible for running a machine properly, safely, and efficiently. Operators are often responsible for, among other duties, correctly securing the workpiece in a workholding device.

part run

A series of identically shaped finished products. Part runs require accurate and repeatable workholding to ensure consistency.

personal protective equipment

PPE. Various safety equipment that employees wear or use to prevent injury in the workplace. Common personal protective equipment includes safety glasses, gloves, masks, gowns, and earplugs.

pin

A narrow, cylindrical component. Pins at the end of clamping arms allow clamps to grip holes and other interior surfaces.

piston

The component of a swing clamp that moves around and up and down a fixed axis. Pistons are rods or cylindrical components that fit in or around a cylinder.

pitch

The distance between a point from an individual thread and the corresponding point on the next thread as measured in millimeters. Pitches range from coarse, with few teeth, to fine, with many teeth.

pivot pin

The point on a toggle clamp around which the clamping arm rotates. The pivot pin locks the clamping arm in place when operators pull down a lever to lock the pivot pin.

pivots

Turns around a fixed point. The rigid bar of a lever pivots on the fulcrum.

plugs

A solid component with a tapered conical shape. Plugs are sometimes placed at the end of clamping arms to serve as pressure pads.

pneumatic

A system that creates power and motion through the controlled movement of compressed gas, usually air. Pneumatic power sources are used with some power clamping systems.

post

A threaded screw clamp component that provides the base for the clamp. The post is fixed or mounted to support the screw clamp and allow it to grip a workpiece.

power clamps

A clamp powered by hydraulic or pneumatic means that operators can move into place and engage without making physical contact with the clamp. Power clamps are commonly used in machining operations that require high repeatability.

pressure

The exertion of mechanical force on an object. Pressure in fixtures occurs when a clamp is tightened against a workpiece.

pressure gauge

A mechanical instrument that measures the internal pressure of a vessel or system. Pressure gauges are inserted into a small cylinder of material which is then clamped in order to measure clamping force.

pressure pad

A circular component made of a flexible material such as plastic or rubber. Pressure pads, or clamping pads, are placed on the end of some clamps to spread out the clamping force and prevent workpiece deformation or surface finish damage.

remote control

A device used to direct the movements of a component or machine at a distance. Remote controls can be used to control clamps in power clamping systems.

repeatability

The ability of a workholding device to position a workpiece in the same place, part after part, for a part run. Repeatability is crucial for the efficient, quality production of identical parts.

resistance

The opposition to a force. Resistance occurs when two objects come into contact with one another and create friction and other forces.

rigidity

The quality of a workpiece, machine, or machine setup characterized by being stiff and inflexible. Improved rigidity reduces vibration which reduces surface imperfections on a workpiece.

rise

The height of an inclined plane. Rises that are larger tend to increase the effort required to raise a load up an inclined plane.

rotational

Moving in a circular path around an axis. Rotational movement occurs in cutting tools in milling and drilling and in the workpiece in turning.

rubber

An elastic material made from the latex sap of the rubber tree. Rubber is a soft material, compared to metal, and will not damage metal surfaces when they come in contact.

rusted

Coated in iron oxide. Rusted clamps do not provide a firm, stable grip for workpieces.

screw clamp

A type of clamp that creates clamping force through the turning of a threaded device that contacts and grips a workpiece. Screw clamps have longer setup times but provide secure workholding.

screws

A simple machine that features spiraling grooves or ridges around a cylindrical body. Screws translate rotational force to linear force and are often used as fasteners.

serrated

A surface notched with a series of ridges or grooves. Serrated surfaces improve gripping ability.

setup

The position of tooling and fixturing for a machining operation. The setup of clamps for an operation will depend on the workpiece, finished part specifications, manufacturing operation, and machine tool setup.

simple machines

A basic mechanical device that uses mechanical advantage to multiply, transform, or change the direction of force. Simple machines include the screw, lever, and inclined plane.

speed

The rate at which a workpiece rotates past the cutting tool in turning or the rate at which the tool rotates in milling, drilling, and grinding. Speed is often measured in revolutions per minute (rpm) in turning, milling, and grinding and in surface feet per minute (sfm), or meters per minute (m/min), in drilling.

stability

The ability to remain firmly in position. Clamps with good stability prevent workpieces from moving or shifting during a manufacturing operation.

step block

The component of a strap clamp that serves as a fulcrum and raises the strap to the appropriate height. Step blocks have a series of risers, meaning a single step block can be used to move a strap to varying heights.

strap

The component of a strap clamp that serves as the clamping arm and makes contact with and grips the workpiece. Straps are generally strips of metal with a curved end that holds the workpiece.

strap clamps

A fixture clamping device made from a series of interchangeable components. Strap clamps have slower setup speed but provide good clamping force.

stud

An externally threaded fastener that is often threaded at both ends and fitted with a nut. Studs are used with some cam clamps as the component that makes contact with the workpiece in a small area.

supporting

Reinforcing a workpiece around or from underneath. Supporting a workpiece helps prevent workpiece deformation and locates the workpiece.

supports

A fixture component that provides reinforcement to the workpiece during machining to prevent it from breaking or deforming. Supports include rest buttons, support pins, and centers.

surface finish

The degree of roughness and variation on the surface of a part after it has been manufactured. Surface finish can be damaged by excessive pressure from clamps, vibrating against fixture components, or improper securing and location.

swarf

The combination of chips, fluid, and debris produced during metal cutting or grinding. Swarf can damage vision if it comes into contact with the eyes.

swing clamps

A type of clamp that rotates around and moves up and down a fixed axis. Swing clamps move quickly into and out of place to facilitate easy loading and unloading of workpieces.

tapered

Gradually reducing in size. Tapered clamping arms narrow at the portion that makes contact with the workpiece to fit in smaller spaces.

test sample

A piece of scrap made of a similar material and of a similar size to the workpiece. Test samples are clamped first to see how the clamping forces will affect the workpiece.

testing

A manufacturing process where a part is examined to ensure that it can properly perform its intended task. Testing occurs once a part is finished.

third-class lever

A lever in which the effort is placed between the fulcrum and the load. Third-class levers are often used as clamps for fixtures, particularly when using strap clamps.

threaded fastener

A device that uses compatible threads to hold two or more objects together. Common threaded fasteners include screws, bolts, and nuts.

threads

A long, spiraling groove or ridge that may appear on the interior or exterior of an object. Threads help fasteners, such as screws, transform motion, grip material and hold components together.

threads per inch

TPI. The number of threads in a linear inch. Threads per inch helps determine if a fastener will tighten quickly, fewer threads per inch, or grip tighter, more threads per inch.

throw

The length of an inclined plane. Throws that are longer will increase the mechanical advantage of the inclined plane and make the load easier to raise.

toe clamps

A small clamp which has a clamping arm with a serrated edge that reaches forward and down to grip a workpiece by its top or edge. Toe clamps leave the top surface of a workpiece clear for machining applications.

toggle clamps

A type of clamp with a clamping arm that rotates around a locking pivot pin. Toggle clamps lock into place when an operator pulls a lever down that immobilizes the pivot pin.

tolerances

An unwanted but acceptable deviation between an actual part dimension and its intended design. Tolerances are improved through proper clamping, which limits part movement during manufacturing.

torque

A force that attempts to twist or rotate a material. Torque is used to turn the screw of a clamp and larger amounts of torque create greater clamping force.

U-strap clamp

A strap clamp with an open-ended, U-shaped strap. U-strap clamps are well suited for gripping cylindrical workpieces.

vacuum chucks

A workholding device that uses air suction to hold a workpiece. Vacuum chucks, or vacuum clamps, are used with non-metallic workpieces.

vacuum clamps

A workholding device that uses air suction to hold a workpiece. Vacuum clamps, or vacuum chucks, are used with non-metallic workpieces.

vacuum pump

A device that draws air out of a closed system. Vacuum pumps can be used to run vacuum clamping systems by creating an area of lower air pressure compared to the ambient atmosphere.

vibration

A rapid, continued, repeated motion in a machine or other structure. Vibration is caused by small shifts in the workpiece that can negatively affect tolerance and surface finish.

wear

The erosion of material as a result of friction. Wear typically is caused by two or more objects in contact with one another.

wedge

A triangular object that is used to transform downward force into lateral force. Wedges are used in wedge clamps to allow them to grip the side of a workpiece.

wedge clamps

A clamp that uses a wedge to gradually exert pressure to push out angled surfaces on both sides of the wedge. Wedge clamps grip the edges of workpieces through the lateral clamping force of its two angled surfaces.

welding

A joining process that uses heat, friction, or a combination of methods to fuse two materials together permanently. Welding is used in a variety of industries from auto manufacturing to aerospace engineering.

woodworking

An operation designed to cut or otherwise shape a workpiece made of wood. Woodworking operations include sawing and turning and generate lower cutting forces than metal cutting because of the softer workpiece material.

workholding

The process of securely supporting, locating, and clamping a workpiece for a manufacturing operation. Workholding helps to ensure that parts are created accurately and with good repeatability.

workholding devices

A device used to secure, support, and locate a workpiece during a manufacturing operation. Common workholding devices include chucks, collets, vises, and fixtures, all of which have some form of clamp or clamps.