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Level 2:  Tolerance Stack-Up Analysis

[for Plus and Minus and Geometric Tolerancing]
per the ASME Y14.5-2009 and 1994 Standards

Through this course, participants will be able to:

 

·  Calculate minimum and maximum wall thickness, airspaces and interferences for assemblies.

 

·  Create loop analysis/circuit diagrams for tolerance stack up analysis for both plus and minus toleranced dimensions and geometric tolerances.

 

·  Create both simple and complex number charts for stack-up analysis using a variety of geometric tolerances, basic dimensions, resultant conditions, virtual conditions and plus and minus toleranced dimensions.

 

·  Do tolerance stack up analysis for floating fastener assemblies for clearance holes, screws and shafts.

 

·  Do tolerance stack up analysis for fixed fastener assemblies using screws, clearance holes, slots, tabs, overall dimensions and projected tolerance zones for threaded holes.

 

·  Calculate minimum and maximum gaps for assemblies that use a variety of datum structures.

 

·  Learn a system of logic and mathematics to analyze geometric tolerances.

 

·  Calculate the effects of angular stack-up using trigonometry and proportions.

 

·  Calculate statistical geometric tolerances using a variety of methods and learn how to re-integrate these geometric tolerances back into the assembly’s details.

 

 

WHO SHOULD ATTEND?

Prerequisite:  GD&T Level 1   This course is directed to anyone with the professional responsibility of analyzing or applying geometric tolerances to assemblies, or anyone seeking a more thorough understanding of tolerance analysis.  Attendees should have a basic working knowledge of ASME Y14.5.  A knowledge of GD&T principles is required to allow all participants to be successful in learning the techniques of tolerance stack up analysis. [Each course participant needs to bring a hand-held calculator.]

 

 

WHAT WILL THIS COURSE COVER?

Course participants will be trained to apply tolerance stack up analysis techniques to a wide variety of assemblies, from the very simple to the more complex situations commonly faced in industry today.  Both plus and minus and geometrically toleranced assemblies will be examined and stack up analysis taught and practiced on each.  Many different datum structures will be discussed and analyzed.  The concepts taught in this course are:  loop analysis (also known as circuit diagrams), number charting, virtual condition, resultant condition, inner and outer boundaries, minimum airspace, maximum wall thickness, maximum interference, minimum and maximum overall dimensions, fixed and floating fastener assembly conditions, projected geometric tolerance zones, the logic of tolerance stack up analysis, statistical tolerancing , and much more.

 

This 2nd Edition of the Tolerance Stack-Up Analysis (January 2010) text is easier to understand, and (in the text as well as training sessions) includes more discussion on what can go wrong, shows how to tell right from wrong stack-up routes, and includes more on Statistical Analysis, as well as Worst Case Tolerance Stack-Up Analysis.  This revision reads smoother and adds information that eases the learning process.  The terminology in this 2nd Edition has been updated to comply with ASME Y14.5-2009.

 

 

COURSE LENGTH:   Course length of 3 days.

 

COURSE MATERIALS:  Tolerance Stack Up Analysis [for Plus and Minus and Geometric Tolerancing] 2nd Edition text/workbook-answerbook. This text is per the ASME Y14.5-2009 and 1994 standards.

 

COURSE OUTLINE:  The course outline follows the Table of Contents listing, chapter by chapter.

TEXT CONTENTS (chapter by chapter):

#1 THE BASICS
• Where to begin a stack
• Designating positive and negative routes
• What are you calculating?
• What dimensions are factors
• How to push the parts to create the worst case
• Which geometric tolerances are and are not factors
• Finding the mean
• Calculating boundaries for GD&T, MMC, LMC and RFS Material Condition modifiers
• Mean boundaries with equal bilateral tolerances

#2 STACK-UP ANALYSIS OF AN ELEVEN PART ASSEMBLY USING PLUS AND MINUS TOLERANCING
• The calculations
• The loop analysis chart
• The numbers analysis chart
• Finding MIN and MAX gaps

#3 VERTICAL vs. HORIZONTAL LOOP ANALYSES FOR FEATURES OF SIZE
• Where to start and end
• Graphing the loop
• Minimum and maximum gap analysis

#4 ASSEMBLIES WITH PLUS AND MINUS TOLERANCES
• Multiple dimension loops
• Positive and negative values
• Airspace vs. interferences

#5 FLOATING FASTENER FIVE PART ASSEMBLY ANALYSIS
• Resultant conditions
• Virtual conditions
• Inner and outer boundaries
• Mean boundaries
• Converting to radii
• Mixing widths and diameters
• Complex loop analyses with geometric dimensioning and tolerancing

#6 FIXED FASTENER ASSEMBLIES
• Calculating overall minimum and maximum assembly dimensions
• Mixing slots, tabs, holes and shafts
• Calculating minimum and maximum gaps within the assembly
• Projected tolerance zones for total runout as a factor
• Determining if geometric tolerances are a factor
• Ruling out features and patterns as factors

#7 A RAIL ASSEMBLY
• Threaded features
• Multiple geometric controls
• Projected tolerance zones
• Gaps with and without perpendicularity as a factor
• Calculating interference
• Theoretically vs. physically worst case possibilities
• When logic becomes an integral step
• Factoring in assembly conditions
• Maximum wall thickness vs. minimum airspace for assemblies

#8 SINGLE-PART ANALYSIS
• Two-single segment positional controls
• Switching datum reference frames and accumulating geometric tolerances
• Datum features at MMC (pattern shift)
• Profile tolerances
• Flatness
• Envelopes of perfect form at MMC
• Creating envelopes of perfect orientation at MMC
• MIN and MAX axial separation
• Datum planes vs. datum features
• Separate requirements and accumulating tolerance
• Tolerances in degrees; Trigonometric function introduction
• Composite positional tolerancing

#9 FIVE PART ROTATING ASSEMBLY ANALYSIS
• Position
• Perpendicularity
• Parallelism
• Profile
• Flatness
• Threaded holes with projected tolerance zones
• Mounted screws
• Part to part analysis (from two parts to an infinite number of parts
• Runout
• Total runout
• Concentricity
• Positional coaxiality
• Simplifying a complex assembly
• Determining assembly housing requirements
• Radial clearance MIN and MAX calculations
• Interference calculations

#10 TRIGONOMETRY AND PROPORTIONS IN TOLERANCE STACK-UP ANALYSIS
• Rocking datum features
• Constructing a valid datum
• Consideration of differing orientations from measurement to assembly
• An in-depth assembly analysis using trigonometric functions
• Computer programs vs. a personal analysis
• Vertical stacking as it effects horizontal housing requirements
• When stacked parts are not flat or parallel
• Formulae to calculate worst case fit conditions when trigonometry is a factor
• Using proportions and trigonometry to calculate fit conditions beyond the GD&T formulae

#11 THE THEORY OF STATISTICAL PROBABILITY
• Gaussian Frequency Curve
• Standard Deviations
• Plus or Minus 3 Sigma
• Root Sum Square Formula
• Steps to Calculate and Apply Statistical Tolerances
• Statistical Tolerancing Applied to Plus and Minus Toleranced Assemblies
• Statistical Tolerancing Applied to Geometric Toleranced Assemblies
• When Best to Allow Statistical Tolerances and When it Should Not Be Allowed
• The Logic of Statistical Tolerancing
• Modifying the Root Sum Square Formula with a Safety/Correction Factor
• Reintegrating the Statistical Tolerance into the Assembly

 

 

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