Intro to Workholding 104

This class introduces the role of a workholding device during the manufacturing process and identifies common groups of these devices.

Class Details

Class Name:
Intro to Workholding 104
Description:
This class introduces the role of a workholding device during the manufacturing process and identifies common groups of these devices.
Version:
1.0
Difficulty:
Beginner
Number of Lessons:
18
Additional Language:
Spanish, Chinese

Class Outline

  • Objectives
  • What Is Workholding?
  • The Role of Workholding Devices
  • The Importance of Repeatability
  • Standard Workholding Devices for the Lathe
  • Standard Workholding Devices for the Mill
  • Standard vs. Customized Workholding Devices
  • The Basic Jig
  • The Basic Fixture
  • Modular Fixtures
  • Fixed Locating Components
  • Adjustable Locating Components
  • Clamping Components
  • Cycle Times and Changeovers
  • Indexing Workholding Devices
  • Power Clamping
  • Workholding Devices by Application
  • Summary

Objectives

  • Describe workholding.
  • Describe the role of workholding devices.
  • Define repeatability.
  • Identify standard workholding devices for the lathe.
  • Identify standard workholding devices for the mill.
  • Describe standard and customized workholding devices.
  • Describe the jig.
  • Identify basic fixtures.
  • Describe modular fixtures.
  • Describe fixed locating components.
  • Describe adjustable locating components.
  • Identify common clamps.
  • Describe how workholding devices influence cycle times and changeovers.
  • Describe indexing workholding devices.
  • Describe power clamping.
  • Describe other applications for workholding devices.

Certifications

NIMS
  • CNC Lathe Operations
  • CNC Milling Operations
  • Milling I

Glossary

Vocabulary Term Definition
adjustable locator A locating component that is moveable and is used for workpieces of varying size. Adjustable locators are frequently used for cast parts.
angle-plate fixture A fixture that positions the locating surface of the workpiece at an angle to the machining table.
assembled locator A locating component that is fastened to the workholding device.
assembly The process by which two or more objects are joined together.
base plate The foundation or frame of a fixture that provides a mounting surface for locators and clamps. The base plate is also called a tool body or subplate.
blueprint A document containing all the instructions necessary to manufacture a part. The key sections of a blueprint are the drawing, dimensions, and notes.
boring The process of using a single-point tool to enlarge a preexisting hole. Boring can also be performed to customize chuck jaws on a lathe for a particular part.
boring machine A turning machine used to enlarge preexisting holes with single-point and multi-point cutting tools.
bushing A hardened steel tube used to guide cutting tools such as drills and reamers.
cam A clamping device consisting of a lever and a circular base with an eccentric pivot. As the cam is closed for locking, increasing pressure from the eccentric base holds a workpiece in place.
cam clamp A clamp that uses a gradually curved surface to lock itself in place. Cam clamps may be dislodged by excessive vibration.
changeover The process of switching a machine from one part setup to another.
chuck A workholding device with three or four jaws that clamp and hold a cylindrical workpiece. The chuck is commonly used to hold a workpiece as it rotates on a lathe.
clamp A workholding device that maintains the position of a workpiece by holding it in place against locators.
clamping The secure holding of a workpiece against locators. Clamping must be strong enough to resist the forces that occur during machining.
CNC machining center A sophisticated machine tool controlled by a computer that can perform mulitiple machining operations in the same setup with a variety of tools.
collet A slitted device that holds a workpiece in place as it rotates. A collet has a hole through which the workpiece passes, and it is designed to hold specific dimensions.
column A large four-, six-, or eight-sided device that accommodates the mounting of fixtures, usually on a horizontal milling machine.
counterboring An operation that enlarges the end of a predrilled hole to allow room for a head of a screw or nut.
critical surface An important surface of the workpiece that determines the appropriate workholder design.
cycle time The time it takes to make one part, or the time it takes to execute a series of operations on a single machine tool.
drill plate The top plate of a jig that contains the bushings.
drilling The process of using a multi-point tool to penetrate the surface of a workpiece and make a round hole.
external locating pin A locating device that uses an outside surface to locate a workpiece.
finishing The final operations performed for obtaining desired tolerance and/or surface finish.
fixed locator A locating component that is designed to locate a workpiece in a fixed position.
fixture A customized workholding device used on machine tools to position and hold a part during various machining operations. A fixture is built to hold a specific part design.
hydraulic clamping A clamping system that uses high-pressure liquids to power clamps and hold a workpiece in place.
indexing fixture A workholding device that pivots to expose additional machining areas.
indexing jig A jig designed to position a workpiece at specific locations around a rotational axis. Indexing jigs can be used for drilling holes around a workpiece.
indexing workholding device A workholding device that either enables metal cutting in regular increments or pivots to expose other available machining space.
inspection The examination of a part to ensure that it meets its design specifications.
integral locator A locating component that is built into the workholding device.
internal locating pin A locating device that uses an internal surface to locate a workpiece.
jig A customized workholding device used to position and hold a workpiece while guiding the location of the cutting tool. Jigs are not as common as fixtures and are not used with CNC machines.
lathe A machine tool that holds a cylindrical workpiece at one or both ends and rotates it while various cutting tools remove material. Turning is a common operation performed on the lathe.
layout A manufacturing process by which the component parts of a product are arranged prior to assembly.
locating The process of positioning the workpiece in a designated location. Locating is also used to describe the precise positioning of the workpiece in the horizontal plane.
locating nest A fixed locator that completely surrounds the dimensions of a workpiece. The workpiece rests within the locating nest.
locating pin An assembled locating device that can be used to locate either an outside workpiece surface or an interior hole. Locating pins are available in numerous shapes and sizes.
locating point A point on the workholding device that is meant to contact the workpiece while it is being positioned.
location dimension A dimension that establishes the position of shapes relative to each other. For example, a hole center that is 3 inches from the edge specifies a location dimension.
locator A workholding device used to position a workpiece within a jig or fixture. Locators establish a relationship between the workpiece and the workholding device.
lot The number of parts made in one setup.
machine tool A power-driven machine that uses a cutting tool to create chips and remove metal from a workpiece.
manual clamp A clamp that is secured by hand by the operator. Cam, screw, and toggle clamps may all be manually operated.
milling machine A machine that uses a multi-point tool to remove metal from the surface of a workpiece. Milling machines are commonly used to machine slots, grooves, and flat surfaces in rectangular workpieces.
modular fixture A workholding device that uses standard reusable components to construct a customized workholding device.
plate fixture The most basic type of fixture that contains mounted clamps and locators on a plate for holding the workpiece parallel to the machine table.
pneumatic clamping A clamping system that uses high-pressure air to power clamps and hold a workpiece in place.
power clamping A clamping system that converts hydraulic or pneumatic power into mechanical clamping forces.
reaming The use of a cutting tool to smooth or enlarge a previously drilled hole.
repeatability The ability of a workholding device to position workpieces in the same place, part after part.
rest button A short locating pin that is used to both support and locate a workpiece.
screw clamp A type of clamp that locks securely in place by the turning of threaded devices. A screw clamp is often slow but secure.
spindle The part of the machine tool that spins or rotates. On the mill, the spindle holds a cutting tool. On the lathe, the spindle holds the workpiece.
spring locating pin An adjustable locator with a metal or plastic bulb that is used to push a workpiece up against fixed locators on the opposite side.
spring stop button An adjustable locator with a metal button or tang that pushes a workpiece up against fixed locators on the opposite side. Spring stop buttons exert more force than spring locating pins.
strap clamp A type of clamp that reaches over the workpiece to hold it in place. Strap clamps are often used when extra toughness is required.
supporting The secure location of a workpiece that typically contacts the bottom surface of a workpiece. Supporting is one of the three roles of a workholding device.
swing clamp A clamp containing a swinging arm that moves to facilitate the quick loading and unloading of workpieces.
tapping The process of cutting internal threads in a hole with a rotating multi-point tool.
testing The examination of a part to ensure that it performs its intended function.
threaded adjustable locator A locating device consisting of a threaded screw that adjusts to the varying dimensions of workpieces.
toe clamp A type of clamp with a serrated surface that reaches forward and down to grip the workpiece.
toggle clamp A type of clamp that operates on a pivot and lever system. Toggle clamps lock just past the center of the pivot points.
tolerance The unwanted but acceptable deviation from the desired dimension.
tombstone A large two-sided rectangular device that accommodates the mounting of fixtures.
vise A workholding device with one fixed jaw and one moveable jaw. Vises are often used to hold simple rectangular or cubic workpieces on a mill or machining center.
V-locator A fixed locator that uses an angled interior to position and center the cylindrical surface of a workpiece.
ways Two precisely measured, parallel tracks that support and guide the movement of the carriage and cross slide of the lathe.
workholding The process of securely supporting, locating, and clamping a workpiece for a manufacturing operation.
workholding device A device used to position and hold a workpiece. The workholding device references the tool performing the operation on the part being held.
workpiece A part that is being worked on. It may be subject to cutting, welding, forming, or other operations.