engineering Engineering is the practice of using natural science, mathematics, and the engineering design process to Problem solving#Engineering, solve problems within technology, increase efficiency and productivity, and improve Systems engineering, s ...

, draft is the amount of taper for

molded Molding (American English) or moulding (British and Commonwealth English; see spelling differences) is the process of manufacturing by shaping liquid or pliable raw material using a rigid frame called a mold or matrix. This itself may have ...

cast Cast may refer to: Music * Cast (band), an English alternative rock band * Cast (Mexican band), a progressive Mexican rock band * The Cast, a Scottish musical duo: Mairi Campbell and Dave Francis * ''Cast'', a 2012 album by Trespassers William ...

parts perpendicular to the

parting line A parting line, in industrial casting of molds, is the border line between the two halves of the mold (known as the “core” and the “cavity.”), which draft direction change at here. One can check the parting line in the mould or product wh ...

. It can be measured in degrees or mm/mm (in/in). Consider the fabrication of a hollow plastic box, without lid. Once the plastic has hardened around the mold, the mold must be removed. As the plastic hardens, it may contract slightly. By tapering the sides of the mold by an appropriate "draft angle", for instance 2° (two degrees), the mold will be easier to remove. This is a practice that is used, in applicable cases, when working with fiberglass. If the mold is to be removed from the top, the box should taper in towards the bottom, such that measuring the bottom internal dimension will yield a smaller length and width than measuring the top from which the mold is extracted. By specifying the opening length and width, a draft angle, and a depth, it is not necessary to specify the

dimensions In physics and mathematics, the dimension of a mathematical space (or object) is informally defined as the minimum number of coordinates needed to specify any point within it. Thus, a line has a dimension of one (1D) because only one coordi ...

for the internal surface, as these may be calculated from the above. The manufacture of a part that incorporates zero or negative angles may require a mold that can be separated into two or more parts, in order to release the casting.

External links

* Draft and draft angle images from the Bayer Material Science websit

Retrieved 2009-09-18. * http://www.toolingu.com/definition-500255-54059-draft-angle.html {{Metalworking navbox, cast open Plastics industry