Drawing is one of the oldest and best ways of communicating and conveying ideas. In most simple words, Drawing is a graphical representation of an idea or entity. Lines in engineering drawing or any other technical drawing are the most important part of communication for engineers. Before the Manucatruring, Fabrication, Assembling, Or Construction of an object, it needs to be designed on a 2d screen. There are different types of drawings like building drawing for civil engineers, machine drawings for mechanical engineers, and circuit diagrams for electrical and electronics engineers.
Engineering drawing is a 3D representation of an object on a 2d screen. It is one of the most important tools of communication between engineers and fabricators to help them transform ideas or imaginary concepts into reality. It provides necessary information about the size, shape, surface quality, material, and manufacturing process of the object. The purpose of engineering drawing is to share technical information and design ideas to answer all related questions and eliminate delays, and extra costs.
The drawing prepared by one person can be utilized by another person from any corner of the world therefore it is important to follow drawing standards to make it universally understandable. For this purpose, the Bureau of Indian Standards (BIS) adopted the International Standards on Code of Practice for Drawing. The other foreign standards are DIN of Germany, BS of Britain, and ANSI of America.
Lines in engineering drawing
Lines in engineering drawings are a critical part of the communication process between the engineer and the fabricator. They are used to describe the shape, size, location, and material of the component or product being designed. Lines can be used to indicate the edges of a component or the features of a component. They can also be used to provide information about the orientation of the component such as the direction of the rotation or the direction of the movement. Lines are also used to indicate dimensions, tolerances, and notes.
In addition, lines also help to provide information about the width of the component, the type of material used, and how the component is to be assembled. Lines in engineering drawings are, therefore an essential part of the design process.
Types of lines in engineering drawing
Each line on the Engineering drawing has a definite meaning and should be drawn by following the drawing standards. Lines are the most basic element of an engineering drawing. It is the foundation of any technical drawing and is used to define the shape and size of objects.
Lines in engineering drawings are used to represent the boundaries of objects and the limits of their features. In engineering drawing, there are several types of lines used to represent different elements. The lines used in engineering drawings are usually straight, but they can also be curved or angled. The type of line used depends on the purpose.
Different types of lines used in engineering drawing are;
Continues wide lines
Solid lines are dark and thick lines that are prominent and clearly visible. These are mainly used to indicate the edges of components and the boundaries of areas on the component. This line is used to represent the edges of objects, such as a part or a surface. It is also used to indicate the boundaries of a feature or a dimension. Continuous lines are also used to mark the edges of a surface or to define the shape of an object. These are usually 0.6 mm thick.
The second type of line used in engineering drawing is the dashed line. This line is used to indicate hidden objects, such as the edges of a surface that are not visible from the outside. Dashed lines are also used to indicate the edges of an object that are hidden by a part or an obstruction. The length of the dashes can be varied to indicate the depth of a feature or the extent of a dimension.
The third type of line used in engineering drawing is the center line. This line is used to divide a surface or an object into two equal parts. Center lines are also used to indicate the center of a circle or an arc. The length of the lines can be varied to indicate the radius of a circle or an arc.
The fourth type of line used in engineering drawing is the hidden line. This line is used to represent the edges of objects that are not visible from the outside. Hidden lines are also used to indicate the edges of an object that are obscured by a part or an obstruction. The line can be either dashed or continuous, depending on the type of object being represented.
The fifth type of line used in engineering drawing is the dimension line. This line is used to indicate the size and location of a feature or an object. Dimension lines are also used to indicate the direction of a feature or the orientation of an object. They can be either straight or curved and the length of the line can be varied to indicate the size of a feature or an object.
These are also known as hatching lines. It is mainly used for sectioned parts of an object. Sectioned lines are drawn inclined at an angle of 45° to the axis or to the main outline of the section.
Extension lines are extended slightly beyond the respective dimension lines to show the extent of a dimension.
Cutting plane lines
A cutting Plane Line is drawn to show the location of a cutting plane. It is a long-dashed dotted
narrow line, made wide at the ends, bends, and changes of direction. The direction of viewing
is shown by means of arrows resting on the cutting plane line. These lines are mainly used to show the inner side of the object that is cut in half.
Break lines are of two types Continuous Narrow Freehand Lines and Continuous Narrow Lines With Zigzags.
The wavy continuous narrow line drawn freehand is used to represent the break of an object. It represented the termination of partial or interrupted views, cuts, and sections if the limit is not a line of symmetry or a center line.
Continuous Narrow Lines With Zigzags mechanically represented termination of partial or interrupted vIews. cuts and sections, if the center section of an object is removed.
Border Lines are continuous wide lines with a minimum thickness of 0.7 mm. These are thick continuous lines that indicate the boundary of an object.
width of the lines used in engineering drawings
Line width means line thickness. BIS recommends two line widths on a drawing. The ratio between the thin and thick lines on a drawing shall not be less than 1:2.
The width of the lines used in engineering drawings is important as it provides information about the size of the component or feature being drawn. Generally, thinner lines indicate smaller components or features, while thicker lines indicate larger components or features.
The width of the lines can also be used to indicate the type of material used to construct the component. For example, thicker lines may be used to indicate a component made of metal while thinner lines may be used to indicate a component made of plastic.
Lines in engineering drawings also help to provide information about how the component or product is to be assembled. For example, a dashed line may be used to indicate the direction of the component’s movement or rotation. Arrows can also be used to indicate the direction of the component’s movement. Additionally, hatch patterns can be used to indicate the type of material used or the type of finish used.
Precedence of Lines
- When a Visible Line coincides with a Hidden Line or Center Line, draw the Visible Line.
Also, extend the Center Line beyond the outlines of the view.
- When a Hidden Line coincides with a Center Line, draw the Hidden Line.
- When a Visible Line coincides with a Cutting Plane, draw the Visible Line.
- When a Centerline coincides with a Cutting Plane, draw the Center Line and show the
Cutting the Plane line outside the outlines of the view at the ends of the Center Line by thick