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:
“Good night, good night. Parting is such sweet sorrow
That I shall say good night till it be morrow.”
—William Shakespeare (1564–1616)
“Our job is now clear. All Americans must be prepared to make, on a 24 hour schedule, every war weapon possible and the war factory line will use men and materials which will bring, the war effort to every man, woman, and child in America. All one hundred thirty million of us will be needed to answer the sunrise stealth of the Sabbath Day Assassins.”
—Lyndon Baines Johnson (1908–1973)