Dimensioning Flashcards
What is a dimension in technical drawings?
A numerical value expressed in an appropriate unit of measurement, indicated graphically with lines, symbols, and notes.
What are the types of dimensions?
Functional dimension (F), Non-functional dimension (NF), Auxiliary or Reference dimension (AUX/REF).
What is a functional dimension (F)?
A dimension essential to the function of the component or space, generally shown with limits.
What is a non-functional dimension (NF)?
A dimension not essential for the function of the component or space.
What is an auxiliary or reference dimension (AUX/REF)?
A dimension given for information only, derived from the values on the drawing or related documents, and does not govern production or inspection.
What are size dimensions
Dimensions that give the size of a component, such as part, hole, slot, depth, width, or radius.
What are location dimensions?
Dimensions that fix the relationship of features such as the center of holes, slots, or significant forms.
What are location dimensions?
Dimensions that fix the relationship of features such as the center of holes, slots, or significant forms.
What is a feature in dimensioning?
An individual characteristic such as a flat surface, cylindrical surface, shoulder, screw thread, slot, curve, or profile.
End product
It is a part ready for direct use or assembly or it can be a part ready for further process. e.g., a casting, shoulder screw etc.
What are the elements of dimensioning?
Extension line, dimension line, leader line, termination of dimension line, original indication, and dimension.
What is an extension line?
t is a thin line projecting from the feature and extending beyond the dimension line. Extension lines (Projection lines) should not cross the dimension lines, but where not possible the lines should not break
What is a dimension line?
These are thin continuous lines, terminated at ends by arrow heads, dots or oblique lines touching the extension line. Dimension line may cut or cross another dimension line where there is no other way. Dimensioning hidden lines to be avoided.
What is a leader line?
A thin continuous line connecting a note or dimension with the feature to which it applies.
What is the ratio of length to width for arrowheads?
3:1.
What are oblique strokes used for in dimension line termination?
Short lines inclined at 45°.
What is the diameter of origin used for indication purposes?
3 mm.
What is the aligned system of dimensioning?
Dimensions are placed perpendicular to the dimension lines, near the middle, and can be read from the bottom or the right-hand side of the drawing.
What is the unidirectional system of dimensioning?
Dimensions are placed parallel to the horizontal dimension line and can only be read from the bottom of the drawing sheet.
What is chain dimensioning?
It is used where the possible accumulation of tolerances does not infringe(effect) on the functional requirement of the component
.On an engineering drawing, where the end point of one dimension is the starting point for the next - Chain dimensioning
What is parallel dimensioning?
Dimensions of features are taken from one datum/common origin and are shown parallel to other and placed, so that the dimensional values can easily be added.
Dimensioning used where a number of dimensions have a common starting point/datum - Parallel dimensioning
What is superimposed running dimensioning?
(Progressive
dimensioning): It is a simplified dimensioning also Cumulative error is controlled.
It starts from one origin with arrow heads in one direction only.
This may be used where there are space limitations and where no legibility problems would occur.
What is dimensioning by coordinates?
This system is much used for components, produced on jig boring machine.
Two edges are taken as datum (references)
Instead of dimensioning in superimposed way, same may be tabulated and given. This method is useful in indicating places/positions in country, city and site plans.
Type of dimensioning where dimensions are Dimensioning by coordinates expressed by X and Y coordinates -
What is combined dimensioning?
Dimensions are given in chain dimensioning and parallel dimensioning. Common feature is combined.
Progressive dimensioning
Modified form of parallel dimensioning used when space is short and one end is the common datum point and dimension progresses towards other end
