Table of Contents
Assembly Drawings are those drawings which shows an entirety of a machine or system with all its components located and identified. The purpose of an assembly drawings is item identification, labeling the sequence for assembly and sometimes to even mention standard requirements. These drawings also show orthogonal plans, sections, elevations, weight, mass, Bill of Materials(BOM) etc. These drawings act as universal graphic language between two technical people so that they can convey their ideas.
Assembly drawings are made for machineries, devices, units and products. They can also be a part of Mechanical Drafting Services helping to assemble a complex part of a mechanism or simply to amass a kit like in the case of furniture. An assembly drawing should meet the below three requirements:
- Maintenance requirement
- Operational requirement
- Manufacturing requirements
Importance of Assembly Drawings:
Assembly Drawings prepared by any technical person must be clear with no scope for misinterpretation. To produce machine and automobiles on a mass scale which constitute of many assemblies and sub-assemblies wouldn’t be possible if not for clear, correct and accurate drawings. To draft these drawings, the person must have a thorough technical knowledge of the both the principles and conventional practice of drafting. If not this could be open to misinterpretation and possibly litigation. Moreover, the person interpreting these drawings must also be proficient in understanding the graphical language used in the assembly drawings, or else it would be challenging to produce the machine in the intended manner.
In the absence of Assembly Drawings, the ideas on technical matters have to be conveyed by speech or writing, instead of graphical language. This makes it difficult for the shop floor level to understand, as well as is error prone and time and labour consuming. It is the effective use of Assembly Drawings that objects such as aircrafts, automobiles, locomotives, etc., have been produced.
Based on the use Assembly Drawings are generally classified into below five categories:
Types of Assembly Drawings:
The main purpose of General Assembly Drawings is to identify the various components and show their working relationship. It contains a detailed drawing of the said component, the sub assembly and how to make the final assembly. They can be further divided into four categories:
1. General Assembly Drawings:
a. Design Drawings: These are drawings which are made on the design stage. These drawings show the machine which is to be assembled from all angles. These drawings or layout aid in visualizing the performance of the machine. Here the shape and clearances of various parts comprising the machine can be clearly seen.
b. Detailed Drawings: A detailed assembly drawing shows how all the components of a machine are assembled and also provides specifics like the materials used, the dimensions, joining techniques etc. These drawings are ideally used for assembling smaller machines which comprise of smaller parts. In addition to the regular assembly drawings, enlarged views of specific parts and how they will fit together can also be drawn up.
In assemblies such as automobile, lathe etc. comprise of pre-assembled components as well as individual parts. These distinct groups of components can be assembled, and often tested, as a unit before they are put into their final arrangement. These pre-assembled units are known as sub-assemblies. A sub-assembly drawing refers to an assembly drawing of a group of related parts, that form a part in a more complicated machine.
c. Assembly Drawings for catalogues: These are special assembly drawings which have been prepared for company catalogues. These drawings show only the relevant details and dimensions that would interest a potential buyer.
d. Assembly Drawings for instruction manuals: Assembly Drawings for instruction manuals are used when a machine which is in assembled condition has to be knocked down to check for all the parts. It is then shipped away to be reassembled and installed elsewhere. In these drawings each component is numbered, which is useful in the reassembly process.
2. Installation Drawings:
These are the drawings which are constructed for the erection or the assembly of a product. It provides information regarding how a component will be positioned in relation to its supporting or adjacent components. It also provides information about dimensional data, hardware description and general configuration. These drawings provide useful information for assembling the machine, as they reveal all the parts of a machine in their correct working position.
3. Exploded Assembly Drawing
These are technical drawings of an object that shows its various components. The 3D exploded diagrams generated through Assembly Modeling Services shows the components slightly separated or suspended in surrounding space in sequence of assembly. This gives an idea about how the final product will fit together. These drawings are simple to understand for even a layman, and hence are used in parts catalogs, assembly, manuals or instruction materials.
4. Schematic Assembly Drawing
A schematic is defined as picture that shows something in a simple manner by using symbols. A schematic drawing represents the components of a process or a device using standardized symbols and lines. This simplified illustration of the machine or of a system, replaces all the elements, by their respective conventional representations. These drawings are useful as its very difficult to understand the operating principles of complicated machinery, merely from the assembly drawings. Schematic representation of the unit facilitates easy understanding of its operating principle.
5. Machine Shop Drawing
The machine shop drawings are for the end user i.e. the person operating the machine. Since the machinist is not concerned with the dimensions and information related to the previous stages only the information pertaining to functioning of the machine is provided. Based on the same principle, one may have forge shop drawing, pattern shop drawing, sheet metal drawing, etc.
Conclusion:
It takes skill and expertise in order to create machine drawings. The engineer must be aware of the principle of operation and the application of the machine. Any error in creation of these drawings could negatively impact the functioning of the machine.