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Bosses
Plastics One Injection Molding
Bosses are used for locating, mounting, and assembly purposes. There are boss design
guidelines that must be followed to insure the highest quality in molded parts. Again,
one of the main points to consider is nominal wall thickness. Too many times bosses
are designed with thick wall sections that can affect the appearance of the plastic part
and the final product.
Rule of thumb: the wall thickness around a boss design feature (t) should be 60% of the
nominal part thickness (T) if that thickness is less than 1/8". If the nominal part thickness is
greater than 1/8" the boss wall thickness should be 40% of the nominal wall.
Boss diameter, wall thickness, and height design parameters. While boss heights
vary by design, the following guidelines will help avoid surface imperfections like sink
marks and voids: the height of the boss should be no more than 2 1/2 times the
diameter of the hole in the boss.
 Please observe the
"60/40" rule (see above) for the wall thickness at the bottom of the boss.
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