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:
“And the purpose of the many stops and starts will be made clear:
Backing into the old affair of not wanting to grow
Into the night, which becomes a house, a parting of the ways
Taking us far into sleep. A dumb love.”
—John Ashbery (b. 1927)
“For a woman to get a rewarding sense of total creation by way of the multiple monotonous chores that are her daily lot would be as irrational as for an assembly line worker to rejoice that he had created an automobile because he tightened a bolt.”
—Edith Mendel Stern (1901–1975)