MIL-DTL-21604F
3.4.1.5 Pure tin. The use of pure tin, as an underplate or final finish, is prohibited both internally and externally.
Tin content of switch components and solder shall not exceed 97 percent, by mass. Tin shall be alloyed with a
minimum of 3 percent lead, by mass (see 6.4.8)
3.4.2 Insulation.
3.4.2.1 Plastic laminates. Unless otherwise specified (see 3.1 and 6.2), plastic laminates shall be in accordance
3.4.2.2 Plastic molding. Unless otherwise specified (see 3.1 and 6.2), plastic molding material shall be type MAI-
3.4.2.3 Fungus resistance. Switches shall withstand 90 days of exposure to fungus with no degradation in
performance (see 4.8.16).
3.4.2.4 Flammable material. Insulation material shall be fire retardant.
3.4.3 Recovered materials. Unless otherwise specified herein, all equipment, material, and articles incorporated in
the products covered by this specification shall be new and may be fabricated using materials produced from
recovered materials to the maximum extent practicable without jeopardizing the intended use. The term "recovered
materials" means materials which have been collected or recovered from solid waste and reprocessed to become a
source of raw materials, as opposed to virgin raw materials. Unless otherwise specified, none of the above shall be
interpreted to mean that the use of used or rebuilt products is allowed under this specification.
3.5 Interface and physical dimension requirements. Switches shall be of closed construction so that the switching
mechanism and the switching contacts are fully enclosed (except terminals), to prevent foreign matter from entering
the switch mechanism or interfering with the contacts. Switches shall be constructed to ensure proper operation
when mounted in any position. The switches shall be of the design, construction, and physical dimensions specified
(see 3.1) and the switch circuit configuration shall conform to the applicable rotor designation specified (see 3.1 and
6.2).
3.5.1 Threaded parts. Unless otherwise specified (see 3.1 and 6.2), threaded parts shall be in accordance with
FED-STD-H28. Wherever possible, unified screw threads shall be used. Where a special diameter-pitch
combination is required, the thread shall be of American National Form and of any pitch which is used in the fine-
thread series.
3.5.1.1 Engagement of threaded parts. Threaded parts shall engage at least three full threads in soft metals like
aluminum and its alloys. A minimum of two full threads shall be used in harder materials such as brass or steel.
When a screw mates with a plastic part, a threaded metal insert shall be contained herein.
3.5.1.2 Locking of screw-thread assemblies. Unless otherwise specified (see 3.1), all screw-thread assemblies
shall be rendered resistant to loosening under vibration. Unless otherwise specified (see 3.1), bronze, stainless steel,
or suitably plated steel split type, or internal-tooth lockwashers shall be provided under all nuts or screw heads. The
use of locknuts is permitted in lieu of lockwashers.
3.5.1.3 Hardware.
3.5.1.3.1 Mounting hardware. The mounting hardware shall be as specified (see 3.1). Unless otherwise specified
(see 6.2), mounting hardware shall be assembled in the proper order as shown on the applicable specification sheet
for direct Government acquisition or supplied un-assembled along with terminal hardware as specified (see
3.5.1.3.2 Terminal hardware. The terminal hardware shall be as specified (see 3.1 and 6.2). If the terminal
hardware is not assembled to the switch, it shall be placed in a bag and firmly secured to the switch.
3.5.1.3.3 Knobs. Unless otherwise specified (see 6.2), switches shall be provided with knobs as specified (see
3.1).
4
For Parts Inquires call Parts Hangar, Inc (727) 493-0744
© Copyright 2015 Integrated Publishing, Inc.
A Service Disabled Veteran Owned Small Business