Preparation of Assembly Drawings
● Introduction
A machine assembly or subassembly is a combination of various links or parts grouped together to perform some function. A drawing that shows the various parts of the machine or engine in their working position is called an assembly drawing.
From the study of an assembly drawing, one can find the way and sequence in which the various parts are assembled together.
In this Blog, the students are given the exercises on assembly drawings to be prepared from details drawing or part drawings.
● Step to prepare assembly drawings:
(a) Select the suitable scale :- if the space is the problem and in case of symmetrical views about main centre line, only half views may be drawn.
(b) At least one view, usually the front view must be shown sectional i.e. either full section or half section.
(c) No need to show the all dotted lines, as the view will become crowded. As sectional views show the interior details, only a few major dotted lines should be shown on the assembly drawing.
(d) Section lines should be drawn 45° to horizontal. Different patterns one drawn for the different mating parts.
(e) Compute overall dimensions and then make the outline blocks for each view to be drawn.
(f) It is not necessary to give all the dimensions of all the component on an assembly drawing. Only the major dimensions are shown.
(g) Draw the main part of assembly first and then add the rest of the parts in the sequence of assembly.
(h) Prepare the part list. It is usually made right above the name plate or on the right hand top corner. Take letter height 5 or 10 mm.
(i) The title of the assembly drawing is to be written below the views and is of 10 mm letter height.
(j) Complete the title block or name plate. Bill of material is a part list of assembly drawing having specific information in a tabular form.
It contains
a) Part number
b) Part name
c) Part Material
d) Quantity required for assembly
In some cases, size can be added. The above information on assembly drawing is useful at the time of assembly process, manufacturing processes, inspection processes, etc.
Note: Students are suggested that they should develop all the views simultaneously not one after another.
