GEOMETRIC DIMENSIONING TOLERANCING (GD T) ME 250:Design Manufacturing I School of Mechanical Engineering Shanghai Jiao Tong University 1
Shanghai Jiao Tong University 1 GEOMETRIC DIMENSIONING & TOLERANCING (GD & T) ME 250: Design & Manufacturing I School of Mechanical Engineering
Outline Tolerance Definitions Datums ■Form Controls Rules for Tolerancing Location Control Orientation Controls ■Runout Controls Profile Controls ■Surface Finish Shanghai Jiao Tong University 2
Shanghai Jiao Tong University 2 Outline n Tolerance n Definitions n Datums n Form Controls n Rules for Tolerancing n Location Control n Orientation Controls n Runout Controls n Profile Controls n Surface Finish
Rules for Tolerancing RULE-1:For features-of-size,where only a size dimension is specified,the surfaces shall not extend beyond a boundary (envelope)of perfect form at MMC. a“perfect form”means perfect flatness, straightness,circularity,cylindricity Shanghai Jiao Tong University 3
Shanghai Jiao Tong University 3 Rules for Tolerancing n RULE-1: For features-of-size, where only a size dimension is specified, the surfaces shall not extend beyond a boundary (envelope) of perfect form at MMC. n “perfect form” means perfect flatness, straightness, circularity, cylindricity
Rule-1 for Tolerancing 10.8 10.6 INTERPRETATION PER RULE#1 ⑦1O.8 BOUNDARY PART SIZE-010.7- OF PERFECT FORM 0.1 FORM ERROR ALLOWED AT MMC 14.0 BOUNDARY OF PERFECT FORM AT MMC 146 14.0 HOLE SIZE-014.6 0.6 FORM ERROR ALLOWED Shanghai Jiao Tong University 4
Shanghai Jiao Tong University 4 Rule-1 for Tolerancing
Rule-1 for Tolerancing Rule-1 applies to all feature-of-size (and only to feature-of-size)on a drawing. Rule-1 says that a feature-of-size must have perfect form if the feature-of-size is at MMC. If the part was at less than MMC,a form error equal to the amount of departure would be permissible. If the part was at LMC,a form error equal to the amount of departure would be permissible. Shanghai Jiao Tong University 5
Shanghai Jiao Tong University 5 Rule-1 for Tolerancing n Rule-1 applies to all feature-of-size (and only to feature-of-size) on a drawing. n Rule-1 says that a feature-of-size must have perfect form if the feature-of-size is at MMC. n If the part was at less than MMC, a form error equal to the amount of departure would be permissible. n If the part was at LMC, a form error equal to the amount of departure would be permissible