Graphic language can be universally understood even if spoken and written words are not. There are two types of graphic drawings: artistic and technical. Technical drawings are used to represent the physical characteristics of an object without interpretation or abstract ideas. Different types of technical drawings represent floor plans, three-dimensional views of machine parts, exploded views showing each piece of an assembled part, or can be used as a graph to reflect numerical data. In the past, technical drawings were made using a drafting table, a pencil, a T-square, a compass and a series of triangles. Today, computer-aided drafting programs have largely replaced drafting tools.
Architectural drawings are complex. A typical house or other building requires several floor-plan drawings. One drawing represents an overhead view of rooms, walls, cabinets, doors and windows. Another floor plan shows the electrical wiring; one shows plumbing and gas lines; still another shows air and heating ducts. Other drawings include details of the roof, cornices, sills, and footings. A separate drawing is used to represent sidewalks, driveways, lawns and shrubbery. External view drawings show the finished product.
Three-view projection drawings are drawn as if you were viewing an object from the top, front and end. Depending on the complexity of the part, additional views can be added. This type of technical drawing presents three-dimensional objects in a series of two-dimensional views. With dimensions added, a craftsman can recreate the object from the drawing. Another example of projection drawings is the exploded view. A complex object with several parts can be drawn so that each part is represented and so that the proper location of each part is also represented. This method is valuable to technicians during assembly.
A sectional-view technical drawing represents a cutaway view of a part as if it were split down the middle. They are commonly used for complex parts with a series of holes or irregular shapes, such as a pulley or a centring bushing. A cutaway view eliminates excessive hidden lines that can cause confusion. All areas in contact with the cutting plane are cross-hatched for clarification.
Graphs are primarily used to present raw data, data analysis and data computation. There are several forms of graphs including bar, pie and line graphs. Bar graphs are often used for profit and loss data and sales-over-time data. Pie graphs are many times used to show data relating to percentages. Line graphs are used in many fields including mathematics, engineering and economic theory.