Vibration welding air intake manifolds from reinforced nylon 66,
nylon 6 and polypropylene
, J.C. Mah
, X.P. Zou
, C.Y. Wang
, Bobbye Baylis
Department of Chemistry and Chemical Engineering, Royal Military College of Canada, P.O. Box 17000 Station Forces, Kingston, Ont., Canada K7K 7B4
Centre for Automotive Materials and Manufacturing, Queen’s University, Kingston, Ont., Canada K7L 3N6
Siemens VDO Automotive, Tilbury, Ont., Canada
Received 1 April 2003; revised 5 January 2004; accepted 5 February 2004
Vibration welding is a common method for creating complex hollow parts from simpler injection molded components. This work studied
the vibration welding of an industrial air intake manifold (AIM) made from nylon 66, nylon 6 and polypropylene all reinforced with 30%
glass ﬁbres. The meltdown-time proﬁles were measured and compared to those of simple lab-scale butt-weld assemblies. The experimental
results indicated that the meltdown rate of the manifold was controlled by the slower rate of transverse welding. The burst strengths of these
AIM at various welding conditions were also investigated. Results of ﬁnite element analysis indicated that the highest von Mises stresses and
the maximum normal principle stresses at the weld region of the AIM were comparable to the weld strength of corresponding lab-scale
coupons, conﬁrming that the initial failure occurred in the weld region.
q 2004 Elsevier Ltd. All rights reserved.
Keywords: A. Polymer–matrix composites (PMCs); B. Strength; C. Finite element analysis (FEA); Vibration welding
Air intake manifolds (AIM) allow air to be passed into
the engine where it then mixes with fuel to combust. The use
of plastics simpliﬁes the AIM’s design by giving engineers
more freedom in the shape and position of the intake
manifold [1– 3]. On the performance side, the smooth
interior wall of the runners allows air to pass easily through
the manifold with a low-pressure drop. As a result, plastic
AIMs exhibit an increase in air ﬂow capacity of about 3%,
which can result in up to a 3% increase in peak power,
compared with their metal equivalents . Plastic AIMs can
also act as thermal insulators allowing cooler, denser air
ﬂow to pass into the engine, which can contribute to the
increased engine efﬁciency. In addition, the weight of the
manifold can be reduced by up to 50% compared to
conventional sand cast aluminum manifolds . This, in
turn, can also increase vehicle performance and fuel
There are two processes used to make plastic AIMs:
lost core molding and vibration welding [1,8]. In lost core
molding, reinforced polymer is molded over a low-melt-
temperature tin –bismuth alloy . After polymer solidi-
ﬁcation, the over-molded core is melted out and re-used.
The major disadvantages of the lost core molding process
are the high capital cost and the complexity associated
with metal alloy processing. In contrast, vibration welding
provides automotive parts suppliers a simpler and more
robust manufacturing technique with lower capital
Vibration welding is a common technique for joining
injection molded thermoplastic parts [9,10]. It involves
bringing two parts together under a weld pressure ðPÞ in the
range of 0.5–5 MPa. One of the parts is then vibrated at a
frequency ðNÞ of the order of 200 Hz over a peak-to-peak
amplitude ðAÞ of the order of 2 mm. The energy dissipated
by friction and viscous shear stresses melts the polymer at
the weld interface. The molten polymer is then forced from
the interface as the two parts come together (meltdown).
When a preset meltdown depth is reached, the vibration is
1359-835X/$ - see front matter q 2004 Elsevier Ltd. All rights reserved.
Composites: Part A 35 (2004) 1107–1116
Present address: Decoma International, Concord, Ont., Canada.
Present address: GE Plastics, Shanghai, China.
Present address: ABC Plastics, Toronto, Ont., Canada.
Corresponding author. Tel.: þ1-613-541-6000x6609; fax: þ 1-613-
E-mail address: firstname.lastname@example.org (P.J. Bates).