Door & Decorative Hardware Metal Finishing and Buffing

Door & Decorative Hardware:  Although door knobs, levers and lock sets have been the mainstay of this industry it also includes other components such as hinges, kick plates and door knockers.  These parts are most often made of brass but the door levers (as opposed to the round door knobs) are usually made from zinc because their unique shape lends to a zinc die cast operation. 

Tangential buffing is usually used if the brass components have simple geometries (flat sheet kick plates or round door knobs).  This allows for faster production and an often lower cost for the buffing consumables (the buffs and buffing compound).  For round parts a simple rotary buffing machine is used with multiple buff heads to finish the top and side of the part.  For flat parts a simple reciprocating table is often used that moves back and forth under a wide buff head.  In each case the last head or stroke is always the color stroke to provide a bright clean finish.

Zinc die cast levers have the same thin skin issues as other zinc parts—they usually use the less aggressive Mush Buffing Process to reduce the chance of buffing through the skin to reveal the porous layer below.  The porous layer has air pockets (seen as pin holes) that are very difficult to cover in the plating process and often requires scraping these levers when holes appear after buffing.  Continued buffing usually just drags out the hole (like a comet tail) instead of removing it.

Because both Zinc and Brass are prone to oxidation or corrosion they must be quickly plated or painted to maintain a bright, clean surface.  In the event that the queue is more than a 20 to 24 hours before being plated then it is possible to add an anti-corrosive to the buffing compound.  This additive will protect the surface from oxidation for several days or even weeks depending on temperature and humidity.