Need Of Engineering Drawing
Engineering drawings are generated by the mechanical engineers to enable the manufacturer to manufacture the product or component. An engineering drawing can be defined as a type of technical drawing, is used to fully and clearly define the product or components geometry and dimensions to manufacture the products.
Engineering drawing is also a graphical language that communicates ideas and information from one mind to another.
The general purpose of an engineering drawing is to clearly and accurately capture all geometric features of a product or component so that a manufacturer or engineer can produce the required item without any deviation in the shape and size.
It may also describe the process of making the item, may be used to convey engineering ideas during the design process, or may provide a record of an existing item.
Increasingly, engineering drawings are prepared using computer aided design tools that can also create files used to instruct machines how to manufacture the item.
These Engineering or Technical Drawings serve a number of different purposes.
One of the most important is to capture the intention of the designer and all of the requirements associated with the newly designed product. The next benefit or purpose of the engineering drawing is to act as a communication tool.
Typically the Engineering Drawings convey the following critical information:
- Drawing Views – The first tool in your engineering drawing toolbox is the drawing view. Drawing Views are simply the representation of your component from multiple perspectives (Front, Side, Top, etc). Even the simplest components cannot be completely understood just by looking at it in one 2-D viewing plane (front). This is why engineering drawings contain multiple views, so that the full geometry of the complete part can be understood. There are many different views available to the designer (front, back, top, bottom, left, right, isometric), however most engineering drawings contain 3 different views of the same component. A general rule of thumb is that you should use minimum views as possible to fully convey the geometry of the part, and give the reader some perspective of the different features of the component.
- Geometry – the shape of the object; represented as views; how the object will look when it is viewed from various angles, such as front, top, side, etc.
- Dimensions – the size of the object is captured in accepted units.
- Tolerances – Tolerances are the allowable variations for each dimension.
- Material – represents what the item is made of.
- Finish – specifies the surface quality of the item, functional or cosmetic. For example, a mass-marketed product usually requires a much higher surface quality than, say, a component that goes inside industrial machinery.
- Title Block – Contains drawing number, description, company logo, proprietary, company logo, revision, scale, title block tolerance and angle of projection.
- General Notes – Contains the general notes like “Remove all burrs and sharp corners”. All dimensions are in inches/mm” etc…
- Revision table – It provides the complete history of the part changes starting from the initial release to production.
- Bill Of Material – Bill of material shows the list of parts and quantity for that assembly model. It also contains non geometric materials like grease, oil etc…
- Cross references – In case of multiple sheet drawings, the cross references are used to give the information of the related views in the sheets.