Improper fractions: Improper fractions are fractions where the numerator is bigger then the denominator, for example, 4/3, 5/5 or 11/6. They are useful when multiplying and dividing fractions.

Incline: An incline is a surface which slants from the horizontal or vertical. It can be called a slope or gradient.

Initial pinch roll: An initial pinch roll is a rolling machine that will preset the ends of any given cylindrical shape.

Inside radii template: An inside radii template is a template made out of sheet metal or wood that is shaped to the inside radius of any given cylindrical shape and is used to check that the cylindrical shape has the correct radius.

Inverse tangent: This is the operation to find an unknown tangent angle. It undoes the tangent function.

ISO: ISO stands for International Organisation for Standardisation. This organisation publishes documents that define procedures and specifications for a range of materials, processes and services. Companies use these documents to make sure their operations and products are safe, reliable and good quality. Sometimes ISO is used as a shorthand way to talk about quality standards.

Isometric drawing: Isometric drawings were developed to approximate perspective, but are much easier to draw. Isometric drawings show three sides, all in dimensional proportion, but none are shown as a true shape. For example, the sides of a box are drawn as vertical lines, but all horizontal lines are drawn at 30° to the base line.

Item numbers: When there is more than one component or subassembly parts on a drawing, a system of numbering is used to identify different items. All individual items have item numbers i.e. Item 1, Item 2 etc