A parting line in moldmaking is the place where two or more parts of the mold meet. Parting lines occur due to minute inherit gaps between two mating faces of halves of the die. The material filling into these gaps is generally called molding flash or simply flashing. Parting lines generally show up as a raised line around the product (witness mark) on commodity products such as toys.
Many applications (seals, tight running molded parts) that require precision for shape control, call for removal of flashes. Secondary operations are thus employed, in addition to high precision molding dies to remove these flashes.
Flashes are known to improve sealing between mating faces in some instances (Fuel tank seals, hydraulic power steering gear, etc.), and thus flashes are permitted to some extent in special cases.
In engineering drawing, parting line is often abbrivated as PL. ASME's Y14.8 standard specifies a symbol for parting line.
Famous quotes containing the words parting and/or line:
“Is all the counsel that we two have shared,
The sisters’ vows, the hours that we have spent
When we have chid the hasty-footed time
For parting us—O, is all forgot?
All schooldays’ friendship, childhood innocence?”
—William Shakespeare (1564–1616)
“What is line? It is life. A line must live at each point along its course in such a way that the artist’s presence makes itself felt above that of the model.... With the writer, line takes precedence over form and content. It runs through the words he assembles. It strikes a continuous note unperceived by ear or eye. It is, in a way, the soul’s style, and if the line ceases to have a life of its own, if it only describes an arabesque, the soul is missing and the writing dies.”
—Jean Cocteau (1889–1963)