FEC AFC1200 - Manual (Page 12)

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6.1.3.2 Area Yield Method
The Area Yield Method will be the primary controlling method on fasteners that do not have a
clearly definable yield point. These fasteners will exhibit a gradual change in torque rate as
the fastener is elongated. This calculation of the elongation area (EA) allows the system to
simulate the fastener as if it had displayed a clearly defined yield point. When the actual
elongation area (EA) is equal to or greater than the calculated/simulated elongation area, the
proper bolt stretch (LENGTH) has been obtained.
TORQUE / ANGLE
* SCREW PITCH
* LENGTH
* ANGLE
* YIELD RATE
* CONSTANT
A
B
AREA "EA"
A
B
AREA "EA"
ELGA
=
ELGA
ANGLE ANGLE
ACTUAL EQUIVALENT
THE FASTENING PROCESS
WILL STOP WHEN:
EA
2
A x B
ELGA
>
TORQUE
TORQUE
= ELONGATION A NGLE
1ST
CROSSOVER AREA
TORQUE / ANGLE
PRESET ITEMS
o
FIG. 6-1-3-2 Yield Control Function for Area Yield Method
{ Area Yield Method Fastening
P After presetting the fastening sequence (SET SEQUENCE Section 7.5) to perform
the desired number of steps, the System fastening parameters (PARAMETER SET
section 7.1) must be configured according to the Engineered fastening
specification.
P Multiple-step fastening will be performed according to the Torque and Angle
Control method procedures. Area Yield Control will begin when the fasteners have
attained or exceeded CROSSOVER AREA torque/angle. No incremental steps
may be performed which will occur after the commencement of the Area Yield
Control (CROSSOVER AREA). It is therefore highly recommended that Yield
Control operations be restricted to no more than two steps.
Chapter 6: Fastening Instructions User Console Version A3.53
Page 6-12