4 An Application from a Defect—A Friction …
157
was used in the study. In this study, the authors identified four different regions in
the channel, namely the nugget, channel roof , channel bottom and remaining region,
which was named as ‘R’. R was found to be a part of the nugget zone which was filled
with materials from RS, the width of which was 25% of the pin diameter. The width
of the channel was equal to the remaining 75% of the pin diameter. The influence
of ω, v and α on the channel size was studied by observing the material flow with
stop action tool method. The study showed that two defects namely step defect that
is formed as an extended solidified material in the channel line and groove defect
which forms at the channel roof due to insufficient material flow appeared [62]. The
step defect was formed at hot process condition due to severe heat generation and
can be eliminated by using low values of ω. Again, the groove defect was seen at
cold process conditions due to tool o wheat generation that was unable to flow the
material properly. In that study, a comparison of two-pin profiles to investigate the
effect of tool geometry on MFSC was performed. For the investigation, an upper
conical pin (UCP) and a straight cylindrical pin (SCP) were used. It was found that
at the same process parameters, the UCP tool increased the channel height by 32%,
and the hydraulic diameter was increased from 2.90 to 3.50 mm because of reduction
in falling material into the channel cavity [63].
4.6.4 Hybrid FSC (HFSC)
HFSC is a new version of the FSC process that can produce a continuous channel,
as well as a weld simultaneously by rotating a specially fabricated tool. The tip of
the pin is used for joining two metal plates, whereas the rest of the pin is used to
extract material from the bottom of the upper plate [50]. The HFSC tool is shown in
Fig. 4.11.
The main features of this technique are:
• HFSC allows to get the benefit of FSW and FSC, simultaneously.
• Useful for tailor-made components.
• Specially designed shoulder and pin are used to join the materials as well as to
form the channel within it simultaneously.
For the thermal management of chassis component for electronic application,
the HFSC was introduced by using a specifically designed tool that is capable of
joining, as well as channeling simultaneously in a plate or combination of different
material plates in a single pass [64]. To investigate the thermal efficiency of the
channel and also to verify the feasibility of the process, HFSC was done on two
overlapped AA5754-H111 plates with the thickness of the top plate being 8 mm and
a bottom plate of 5 mm thickness. It was found that the HFSC is repeatable and
can produce channels with various dimensions and profiles. For better evaluation
of the cooling efficiency of the HFSCs, a FEM model of real chassis of electronic
components with multiple heat sources was developed. The channel dimensions were
made the same as the dimensions being obtained by HFSC. It was found that the
157
was used in the study. In this study, the authors identified four different regions in
the channel, namely the nugget, channel roof , channel bottom and remaining region,
which was named as ‘R’. R was found to be a part of the nugget zone which was filled
with materials from RS, the width of which was 25% of the pin diameter. The width
of the channel was equal to the remaining 75% of the pin diameter. The influence
of ω, v and α on the channel size was studied by observing the material flow with
stop action tool method. The study showed that two defects namely step defect that
is formed as an extended solidified material in the channel line and groove defect
which forms at the channel roof due to insufficient material flow appeared [62]. The
step defect was formed at hot process condition due to severe heat generation and
can be eliminated by using low values of ω. Again, the groove defect was seen at
cold process conditions due to tool o wheat generation that was unable to flow the
material properly. In that study, a comparison of two-pin profiles to investigate the
effect of tool geometry on MFSC was performed. For the investigation, an upper
conical pin (UCP) and a straight cylindrical pin (SCP) were used. It was found that
at the same process parameters, the UCP tool increased the channel height by 32%,
and the hydraulic diameter was increased from 2.90 to 3.50 mm because of reduction
in falling material into the channel cavity [63].
4.6.4 Hybrid FSC (HFSC)
HFSC is a new version of the FSC process that can produce a continuous channel,
as well as a weld simultaneously by rotating a specially fabricated tool. The tip of
the pin is used for joining two metal plates, whereas the rest of the pin is used to
extract material from the bottom of the upper plate [50]. The HFSC tool is shown in
Fig. 4.11.
The main features of this technique are:
• HFSC allows to get the benefit of FSW and FSC, simultaneously.
• Useful for tailor-made components.
• Specially designed shoulder and pin are used to join the materials as well as to
form the channel within it simultaneously.
For the thermal management of chassis component for electronic application,
the HFSC was introduced by using a specifically designed tool that is capable of
joining, as well as channeling simultaneously in a plate or combination of different
material plates in a single pass [64]. To investigate the thermal efficiency of the
channel and also to verify the feasibility of the process, HFSC was done on two
overlapped AA5754-H111 plates with the thickness of the top plate being 8 mm and
a bottom plate of 5 mm thickness. It was found that the HFSC is repeatable and
can produce channels with various dimensions and profiles. For better evaluation
of the cooling efficiency of the HFSCs, a FEM model of real chassis of electronic
components with multiple heat sources was developed. The channel dimensions were
made the same as the dimensions being obtained by HFSC. It was found that the