Download ppt - Drafting and Dimensioning Standards

Planchard Copyright 2012Drafting Standards Institutions ANSI - American National Standards Institute - This institute creates the engineering standards for North AmericaISO - International Organization for Standardization - This is a world wide organization that creates engineering standards with approximately 100 participating countries.


Planchard Copyright 2012Drafting Standards Institutions DIN - Deutsches Institut fr Normung - The German Standards Institute created many standards used world wide such as the standards for camera film.JIS - Japanese Industrial Standard - Created after WWII for Japanese standards.


Planchard Copyright 2012Drafting Standards Institutions BSI - British Standards Institute - The national standards organization for the UK and an influential member of the ISO.GOST - Gosudarstvennye Standarty State Standard - Standards cover over 20 industries including Petroleum, Chemical, Mining & Mineral Resources, Power & Electrical Equipment, and Oil & Gas products. This body of standards has been adopted by the Commonwealth of Independent States (CIS) and is administered by the Euro-Asian Council of Standardization, Metrology, and Certification (EASC).


Planchard Copyright 2012Drafting Standards Institutions GB - Guojia Biaozhun, Standards - A set of mandatory and recommended standards regulated by SAC (Standardization Administration of China). Each GB Standard has a GB Standard number followed by the year when it's issued.


Planchard Copyright 2012ANSI Drafting Standards - DimensionsDimensioning: is the process of defining the size, form and location of geometric features and components on an engineering drawing. Two general types of dimensions are used in drawings:Size dimensions - size of holes and size of features.Location dimensions - location of holes.


Planchard Copyright 2012ANSI Drafting Standards - DimensionsArrowheads are used to terminate dimension lines. The point of the arrowheads on the leader line must make contact with the Feature line. The standard size ratio for all arrowheads on Mechanical Drawings is ~2.5:1 (Length to width).


Planchard Copyright 2012ANSI Drafting Standards - DimensionsInsert a gap so people are not confused between the Feature line andthe extension line (ANSI standard).Extension Line - extended from the view to indicate the edges referenced with the dimension line. Dual Dimensions Primary units IPS; Secondary units (MMGS) .


Planchard Copyright 2012ANSI Drafting Standards - DimensionsRemember - a location dimension locates holes or other part features. A size dimension provides a radius, diameter, length, width, thickness, etc.


Planchard Copyright 2012ANSI Drafting Standards - DimensionsA leader dimension is a leader line used to point toward a diameter or radius. A linear dimension is a dimension that is either horizontal or vertical to the dimensioning plane.


Planchard Copyright 2012ANSI Drafting Standards - Dimensions An arc is always dimensioned by its radius. ANSI standards require a radius dimension to be preceded by the letter (symbol) R as illustrated. A angular dimension is used to specify the amount of degrees between two lines.


Planchard Copyright 2012ANSI Drafting Standards - DimensionsA point or a center of an arc or circle is generally measured from two finished surfaces. The method of location the center is preferred to making an angular measurement. As illustrated, the center of the circle and arc may be found easily be scribing the vertical and horizontal center lines from the machined surfaces.


Planchard Copyright 2012ANSI Drafting Standards - DimensionsIf a number of holes are to be equally spaced on a circle, then the exact location of the first hole is given by a location dimension. To locate the remaining holes, the location dimension is followed by 1.) the diameter of the holes, 2.) the number of holes, and 3.) then the notation EQUALLY SPACED or EQ SP as illustrated.


Planchard Copyright 2012ANSI Drafting Standards - DimensionsHoles are often dimensioned in relation to one another and to a finished surface. Dimensions are usually given, in such cases, in the view which the shape of the holes, that is, square, round, or elongated. The preferred method of placing these dimensions as illustrated.


Planchard Copyright 2012ANSI Drafting Standards - DimensionsThere are basically two types of dimensioning systems use in creating parts and drawingsU.S. (IPS)Metric (MMGS)

*Dimensioning standards based on ASME Y14.5-2009.


Planchard Copyright 2012ANSI Drafting Standards - DimensionsThe U.S. system uses the decimal inch value. When the decimal inch system is used, a zero is not used to the left of the decimal point for values less than one inch, and trailing zeros are used as illustrated.


Planchard Copyright 2012ANSI Drafting Standards - DimensionsWorking drawing are usually drawn with all U.S. or all metric dimensions. Sometimes the object manufactured requires both U.S. and metric measuring system. Dual dimensioning may be necessary. The optional secondary units are normally displayed in brackets [ ].


Planchard Copyright 2012ANSI Drafting Standards - DimensionsPlacement of Linear Dimensions - Order of Preference. When there is not enough room on the drawing view between the extension lines to accommodate either the dimension value or the dimension lines - located the outside extension lines as illustrated.


Planchard Copyright 2012ANSI Drafting Standards - DimensionsLinear Dimensioning Ordinate dimensioning is also known as Datum dimensioning or Baseline dimensioningUsed when the location of features must be controlled from a common reference point or plane. Baseline dimensioning ensures the tolerance in manufacturing does not add up.


Planchard Copyright 2012ANSI Drafting Standards - DimensionsLinear Dimensioning Dimensioning from feature to feature is known as Chain Dimensioning. Chain Dimensioning is commonly used and easy to insert.


Planchard Copyright 2012ANSI Drafting Standards - DimensionsLinear Dimensioning Chains of dimension should only be used if the function of the object won't be affected by the accumulation of the tolerances. View the two examples!


Planchard Copyright 2012ANSI Drafting Standards - DimensionsDimensioning Check ListEach dimension should be written clearly with only one way to be interpreted.A feature should be dimensioned only once.Dimensions and extension lines should not cross.Each feature should be dimensioned.Dimension features or surfaces should be done to a logical reference point.


Planchard Copyright 2012ANSI Drafting Standards - DimensionsDimensioning Check ListDimension features on a view should clearly show its true shape.Enough space should be provided to avoid crowding and misinterpretation.Extension lines and object lines should not overlap.Dimensions should be placed outside the part.Center lines or marks should be used on all circles and holes.


Planchard Copyright 2012ANSI Drafting Standards - DimensionsDimensioning Check ListExtension lines do not cross unless situation is unavoidable. Stagger dimension text.Largest dimension placed farthest from profile. Dimensions should be evenly spaced and grouped.


Planchard Copyright 2012ANSI Drafting Standards - DimensionsDimensioning Check ListArrow heads do not overlap.Break extension lines that cross close to arrowhead.Flip arrows to the inside if needed for room.Move dimensions to the view that displays the outline of the feature. Insure that all dimensions are accounted for. DO NOT OVER OR UNDER DIMENSION
