Technical Drawing Fundamentals and Thermoplastic Types

Technical Drawing and Sketching Fundamentals

To ensure a sketch of an object is well-defined, it must capture all its aspects and various details. To achieve this, one must use as many views of the object as necessary. These images are simply what is seen of the object from different points, and they are always flat if the views are perpendicular.

Definition of a Sketch

A sketch is a simple freehand drawing where the real measurements of the represented object are indicated. To specify these measurements, dimension lines (levels) are used.

How to Trace Dimension Lines

Lines are used to delimit length. One should avoid drawing lines that cross the dimension lines. Reference and cutting auxiliary lines, as well as dimension levels, should be placed outside the drawing area.

Writing Dimension Levels

Dimensions should be written below and from the right of the drawing if the figures are placed on the dimension lines. Another option is to place the figures interspersed within the dimension lines. A drawing must include as many dimensions as necessary to define all magnitudes clearly.

Drawing Plane Figures

To draw plane figures on any reference plane, simply use the corresponding axes that intersect each plane. When plane figures are complicated, use auxiliary lines if necessary.

Representing Solid Objects

To represent simple solid objects limited by flat faces, first position them so their fundamental axes align with the coordinate lines. Then, trace the plan and project the body lines (for example, along the Z-axis) through the various vertices to indicate the body's height. You can also draw the profile of the figure and project it onto the XOY axes, depending on whether the profile is drawn in the YZ or XZ plane. The width or length of the body is then marked along those lines.

Representing a Point in Isometric Systems

Representing a point in an isometric system is very similar to representing a point on coordinate axes. The key is to plot the coordinates along the axes and draw parallels to the other axes from those points. The intersection of these parallels marks the location of the point.

Classification of Thermoplastics

• PET (Symbol 1): Used for bottles, containers, and jars.
• HDPE (Symbol 2): High-density polyethylene used for mop buckets, flasks, and drums.
• PVC (Polyvinyl Chloride, Symbol 3): Used for gutters, sewer downspouts, drainage, and waterproofing.
• PELD (Low-Density Polyethylene, Symbol 4): Used for shopping bags, insulated cables, and hoses.
• PP (Polypropylene, Symbol 5): Used for ropes, syringes, and food packaging.
• PS (Solid Crystalline Polystyrene, Symbol 6): Used for crockery and cutlery.
• EPS (Expanded Polystyrene, Symbol 6): Also known as cork; used for protective packaging and building insulation.
• Polycarbonates (Other): Used for digital records and safety glass.
• Nylon: Used for clothing, carpets, toothbrush bristles, and curtain accessories.