Both the order and orientation of mounting hardware need to be considered during assembly. Devices such as ‘‘star’’ or ‘‘tooth’’ washers may have one side with sharp edges intended to cut into the mating surface to keep the hardware from coming loose in
operation. Figure 4-15 is an example of this kind of lock washer. Unless otherwise specified the sharp edges of the lock washer should be against the flat washer.
Acceptable – Class 1,2,3 • Proper hardware sequence and orientation, see Figures
4-14 and 4-15. • Slot or hole are covered with flat washer, see Figure 4-16.
Acceptable – Class 1 Defect – Class 2,3
• Less than one and one-half threads extend beyond the threaded hardware, e.g., nut unless thread extension
would interfere with other component. • Thread extension more than 3 mm [0.1 in] plus one and
one-half threads for bolts or screws up to 25 mm [1 in]. • Thread extension more than 6.3 mm [0.25 in] plus one and
one-half threads for bolts or screws over 25 mm [1 in]. • Bolts or screws without locking mechanisms extend less
than one and one-half threads beyond the threaded hard- ware.
1 2
2 3
4 3
4 1
Figure 4-14
1. Lock washer, sharp edge showing towards flat washer 2. Flat washer
3. Nonconductive material laminate, etc. 4. Metal not conductive pattern or foil
Figure 4-15
1. Lock washer, sharp edge towards flat washer 2. Flat washer
3. Solder lug
4.1.5 Hardware Installation – Threaded Fasteners and Other Threaded Hardware
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July 2014
Defect – Class 1,2,3 • Thread extension interferes with adjacent component.
• Hardware material or sequence not in conformance with drawing.
• Lock washer against nonmetallaminate. • Flat washer missing, see Figures 4-17 and 4-18.
• Hardware missing or improperly installed, see Figure 4-19.
1
2 3
2 3
1
Figure 4-16
1. Slot or hole 2. Lock washer
3. Flat washer
2 3
1
2 1
3
Figure 4-17
1. Lock washer 2. Nonmetal
3. Metal not conductive pattern or foil
1
2
Figure 4-18
1. Slot or hole 2. Lock washer
Figure 4-19
4.1.5 Hardware Installation – Threaded Fasteners and Other Threaded Hardware cont.
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July 2014
In addition to threaded fasteners used for installation of an item onto an assembly, there are other types of threaded items that may be used on individual parts within an assembly. These may require tightening to a specified torque value, or standard indus-
try practice, to preclude loosening or part damage. Such items include, but are not limited to, connector coupling nuts, connec- tor strain relief clampspottingmolding boots, etc., fuse holder mounting nuts, and any other similar threaded items.
Where torque requirements are not specified, follow standard industry practices. However, some of these threaded items may be made of plastic or other material that can be damaged if excessive torque is applied during assembly; and for these items, it may
be necessary to tighten the item to a specified torque value.
Acceptable – Class 1,2,3 • Fasteners are tight and split-ring lock washers, when used,
are fully compressed. • Fastener torque value, if specified, is within limits.
• No evidence of damage resulting from over-tightening of the threaded item.
Figure 4-20
4.1.5.1 Hardware Installation – Threaded Fasteners and Other Threaded Hardware – Torque
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July 2014
Defect – Class 1,2,3 • Threaded items are not tight and split ring lock washer, if
used, is not compressed, see Figure 4-21. • Fastener torque value, if specified, is not within limits.
• Hardware is loose, see Figure 4-22. • Evidence of damage resulting from over-tightening of the
threaded item.
Figure 4-21
Figure 4-22
4.1.5.1 Hardware Installation – Threaded Fasteners and Other Threaded Hardware – Torque cont.
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July 2014
When the use of terminal lugs is not required, wires are wrapped around screw type terminals in a manner that precludes loos- ening when the screw is tightened, and the ends of the wire are kept short to preclude shorting to ground or other current carry-
ing conductors.
If a washer is used, the wirelead is mounted under the washer. Unless otherwise noted, all requirements apply to both stranded and solid wires.
Special hardware stakingsecuring criteria may be required.
Target – Class 1,2,3 • Original lay of the strands is not disturbed stranded wire.
• Wire wrapped a minimum of 270° around the screw body. • Wire end secured under screw head.
• Wire wrapped in the correct direction. • All strands are under screw head.
Figure 4-23
4.1.5.2 Hardware Installation – Threaded Fasteners and Other Threaded Hardware – Wires
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July 2014
Acceptable – Class 1,2,3 • Less than one-third of the wire diameter protrudes from
under the screw head. • Wire extending outside the screw head does not violate
minimum electrical clearance. • Mechanical attachment of the wire is in contact between the
screw head and the contact surface for a minimum of 180° around the screw head.
• No insulation in the contact area. • Wire does not overlap itself.
Defect – Class 1,2,3 • More than one-third of the wire diameter protrudes from
under the screw head. • Wire not wrapped around screw body, see Figure 4-26-A.
• Wire is wrapped more than 360°, see Figure 4-26-B. • Solid wire wrapped in wrong direction, see Figure 4-26-C.
• Stranded wire wrapped in wrong direction tightening the screw unwinds the twisted wire, see Figure 4-26-D.
• Insulation in the contact area, see Figure 4-26-E. • Stranded wire is tinned not shown.
• Missing solder or adhesive as required per customer requirements not shown.
Figure 4-24
Figure 4-25
Figure 4-26
4.1.5.2 Hardware Installation – Threaded Fasteners and Other Threaded Hardware – Wires cont.
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July 2014
This section covers the height relationship of the face of the jackpost to the associated connector face. This is critical to obtain maximum connector pin contact.
Hardware stack-up for mounted connectors may be varied in order to locate the face of the jackpost flush to 0.75 mm [0.030 in] below the face of the connector.
Acceptable – Class 1,2,3 • Jackpost face is flush to 0.75 mm [0.030 in] below the face
of the connector. • Height is obtained by adding or removing washers supplied
with jackpost.
Defect – Class 1,2,3 • Jackpost face extends above the connector face, see Figure
4-28. • Face of jackpost is greater than 0.75 mm [0.030 in] below
the connector face, see Figure 4-29.
Figure 4-27
Figure 4-28
Figure 4-29
4.2 Jackpost Mounting
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July 2014
This section covers two types of pin installations; edge connector pins and connector pins. Installation of these devices is usually done with automated equipment. Visual inspection of this mechanical operation includes: correct pins, damaged pins, bent and
broken pins, damaged spring contacts and damage to the substrate or conductive pattern. For connector mounting criteria see 7.1.8. For connector damage criteria see 9.5.
Acceptable – Class 1,2,3 • Contact is contained within the insulator, see Figure 4-30-A.
• Gap is within specified tolerance, see Figure 4-30-B.
Note: To provide allowance for an extraction tool, the gap between the contact shoulder and the land needs to be
adequate for each manufacturer’s repair tooling.
Defect – Class 1,2,3 • Contact is above insulator, see Figure 4-30-C.
• Gap between contact shoulder and land is greater than specified, see Figure 4-30-B.
B C
A
Figure 4-30
4.3 Connector Pins
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July 2014
4.3.1 Connector Pins – Edge Connector Pins
Target – Class 1,2,3 • Pins are straight, not twisted and properly seated.
• Pin height is within tolerance.
Acceptable – Class 1,2,3 • Pins are bent off center by 50 pin thickness or less.
Note: Nominal height tolerance is per pin connector or master drawing specification. The connector pins and mating con-
nector must have a good electrical contact.
Figure 4-31
1. No discernible damage 2. Land
