et attaches d’appareils évolutifs:
Le mode de construction d’un appareil se renouvelle
rapidement en raison des changements tout aussi rapides du
produit, du lieu de fabrication et du changement de propriétaire
de l’entreprise. Les fabricants d’appareils et
les fournisseurs des éléments de montage et
d’attaches s’adaptent à cette situation
en proposant des métaux plus fins, de l’acier
inoxydable et prépeint entre autres nouveaux designs
propres à l’industrie de l’appareillage
en évolution permanente.
|Montage und Befestigung:
Montage und Befestigung für die Geräteentwicklung:
Aufgrund schneller Änderungen bei Modellen, Fabrikstandorten
und Firmenbesitzverhältnissen ändert sich die Gerätekonstruktion
ständig. Die Gerätehersteller und ihre Zulieferer
für Montage und Befestigung reagieren mit dünneren
Metallen, vorlackiertem und rostfreiem Stahl und anderen Änderungen
im Design auf die sich immer weiter entwickelnde Geräte-Industrie.
|Assemblaggio e Fissaggio per Apparecchi in Evoluzione:
A causa dei rapidi cambiamenti nei modelli, siti di produzione,
e proprietà dell’Azienda, il modo in cui un
apparecchio è costruito cambia costantemente. I
produttori di apparecchi ed i loro fornitori di assemblaggio
e fissaggio rispondono fornendo metalli più sottili,
acciaio inossidabile e precedentemente sottoposto a trattamento
colorante ed altri cambiamenti del modello nell’industria
costantemente in evoluzione degli apparecchi.
times, they are a-changin'. Rapid change in models, manufacturing locations,
and company ownership has been a given in the appliance industry for
years. Long gone are the days when companies regularly came out with
new models every 5 years.
In most segments of the
industry, competition is torrid, and pressure is intense to meet market
interest with frequent model changes. At the same time, manufacturers
are working with suppliers to incorporate materials, designs, and assembly
techniques aimed at keeping assembly costs down and quality up.
Fasteners, Inc. (Cranston, RI, U.S.) supplies a range
of fasteners for appliance production and installation.
The company offers stainless steel fasteners, washers,
nuts, and bolts, all of which are available with specialized
coatings for superior corrosion protection.
some of today's appliance models use thinner sheet metal panels.
While keeping material costs and weight to a minimum, such panels
have reportedly lead to problems with standard sheet metal screws
not holding joints tightly. One solution has been developed by Leland
Powell Fasteners, Inc. (Martin, TN, U.S.). Its Grip-Lite screws are
said to provide improved drive-to-strip ratios with precision-controlled
threads under the head, increased strip-out ratio with full formed
thread within one pitch of the head, and increased strip-out torque
with special serrations under the head. In addition, a radius screw
point reportedly eliminates cutting wire insulation in the assembly,
preventing the screw from drilling its own hole if the assembly is
misaligned and eliminating sharp points that can cause injuries during
On the quality
front, the company notes that fewer part numbers means less chance
of the wrong screw arriving at the assembly line. With this in mind,
it works with manufacturers to standardize fasteners. In one case,
it reports that more than 100 different thin sheet metal applications
were re-specified to use a single size of Grip-Lite screw and in
some cases, even eliminating nuts, clips, or tapped holes.
new approach is aimed at compressor mounting in base
pans for window units, condenser split systems, and other
types of A/C systems. The approach, from Richard Associates
(Johnson City, TN, U.S.) obsoletes sleeves, shoulder
bolts, and welding of weld bolts. It also permits use
of pre-painted sheet metal, which can result in dollar
savings in welding and painting equipment. The mounting
bolt is a combination threaded bolt and stud that is
threaded up through an extruded hole in the base pan.
Serrations and seal rings under the head prohibit thread
stripout and water leaks in window unit base pans, using
the splash cooling reservoir in the pan. Also, one standard
length will fit many compressor sizes from one to five
tons. Once the compressor is set in place, a push nut
locks down on the stud portion of the bolt, on top of
the grommet, and keeps the compressor secure in place.
toward use of pre-coated sheet metal, aluminum, stainless steel,
and plastics has sharply cut traditional resistance or spot welding
in major appliance assembly. In this environment, ATTEXOR
Inc. (Springfield, MA, U.S.) reports that clinching continues
to gain market share. Clinching is a fastener-less assembly method,
where a rivet-like joint is produced from the sheets and profiles
to be assembled through a cold-flow punching and squeezing action.
In addition to avoiding the cost for buying, sorting, and feeding
separate fasteners like screws or rivets, the company points out
that clinching is clean and silent, as well as fast, with assembly
cycle times less than 1 sec. No sparks or fumes or strong electromagnetic
fields are associated with clinching.
clinching to be the dominating assembly method for major appliances
in the years to come," notes Hans Bergkvist, ATTEXOR president and
CEO. "We are also probably going to see more hybrid assembly, where
the point connections of clinching are complemented by the line of
surface bonding offered by various types of adhesives. We are working
together with leading actors in the adhesives arena to further assess
the key parameters when it comes to assembly by clinching and adhesives
to a study from the Adhesive and Sealant Council, the estimated overall
volume growth rate for adhesives used in appliances will be 2.5 percent
in the next 2 years. The Council points out that most adhesives are
used for bonding insulation, labeling, decorative trim, and nameplates.
Structural adhesives have found limited use because the need for
repair and replacement has generally relied on the use of screws,
nuts, and bolts. However, an increase in the use of dissimilar substrates,
plastics, and thinner gauge materials in construction may spur additional
Adhesives suppliers point
out that the ability of an adhesive to distribute a load over its entire
bond area rather than in a limited area - as with a mechanical fastener,
spot weld, clinch, or rivet - may lead to improved assembly durability
and fatigue resistance. "We have a demonstration of 'Bolts versus Bonds'
which shows an assembly that is joined with bolts and adhesives being
tested to failure," says Scott R. Tremblay, application engineering, Henkel
Loctite Corporation (Rocky Hill, CT, U.S.). "The bolted section
of the assembly fails before the bonded section due to the fact that
the force on the bolted section is concentrated on the leading edge
of the bolt shaft, while the adhesive distributes the weight over the
entire bond area of the joint."
Mortorq spiral drive system developed by Phillips
Screw Company (Wakefield, MA, U.S.) was introduced
into the aerospace industry more than 5 years ago. The
technology is now applied to other markets, where it
reportedly can create an assembly that is smaller, lighter,
and cheaper. One advantage is that because of the reduced
head height, it is now possible to use thinner materials
and still hide the fastener in a shallower countersink.
According to the company, without a countersunk screw,
the shallower head height will create more clearance
for internal parts and more design flexibility.
fasteners, however, are said to offer benefits over adhesives at
very elevated temperatures. Once temperatures exceed 400°F, structural
adhesive options diminish rapidly. But for many applications, adhesive
processes work well and may offer cost benefits over mechanical fasteners
because of lower total material costs and the elimination of tooling
costs associated with the joining operation. Also, the number of
parts (bolts, nuts, washers, rivets, etc.) used in the manufacturing
is minimized, and the elimination of inventorying and stocking these
parts can reduce complexity. In addition, the ability to automate
the adhesive assembly process frequently lowers labor costs.
Bond Inc. (Hackensack, NJ, U.S.) believes that the wider usage
of adhesive technologies for the assembly of appliances has the
promise of reducing direct manufacturing costs by as much as 25
to 30 percent due largely to the increasing employment of plastics
and elastomers in the design and assembly of appliances. "In the
last few years the performance and especially durability in service
of newly developed plastics and elastomers has greatly improved," says
James Brenner, president. "Designers and hence appliance producers
have gained better awareness and recognition of the potential of
these improved materials for appliance production."
In the adhesives
and gaskets area, many companies are demanding operator-free equipment,
with the exception of loading and unloading products, observes Don
Leone of Ashby
Cross Company (Newburyport, MA, U.S.). The reason, he says, comes
down to one word: error. The greater the human intervention, the
greater the error rate.
out a continued drive toward automatic foam dispensing for gaskets.
More generally, computer technology remains important, and his company
continues to increase its PC- (microprocessor-) based equipment offerings. "This
further drives the equipment to operator-free-operation," Mr. Leone
applications it is sufficient to dispense the adhesive directly from
the bottle or tube onto the surfaces to be adhered," adds Mr. Tremblay
of Henkel Loctite. "In other cases, more precise and automated dispensing
and curing is required. To meet this need, adhesive suppliers have
developed equipment especially designed to make application of products
economical, fast, precise, and clean. The benefits of automated assembly
include higher production rates, consistent dispensing and curing,
reduced labor, higher production yields to minimize scrap, and improved
quality and aesthetics."
continues to be an important part of appliance assembly, and a key
component of this involves getting the automated manufacturing process
established quickly. To meet this need, many automation suppliers
are starting to provide pre-configured and pre-assembled equipment
that can be installed quickly, with machinery up and running almost
custom Cartesian robot systems from Bosch
Rexroth Corporation (Buchanan, MI, U.S.) are one example. "We've
taken our standard linear axes and now offer them as pre-configured
multi-axis systems," says Kevin Gingerich, the company's director
of Marketing Services. "Customers simply specify a few basic parameters
and receive a 'plug-and-play' unit customized to their application."
cells were frequently custom-designed in the past, the customer can
now save time in three places - the design phase, in which the unit
is conceived; the purchasing and specification phase, in which the
parts to build the custom unit would be sourced and acquired; and
the build and start-up phase, in which a custom unit would need to
be built, programmed, and brought into operation. The total time
savings could easily be weeks and possibly even months, all of which
translates into higher profits for the end manufacturer.
"It's a little
like outsourcing some of your manufacturing engineering and design
work to experts who do that type of automation all the time," says
Mr. Gingerich. "We think that manufacturers will continue to focus
on cutting as much time as possible out of their new product launch
cycles in order to get from idea to cash as quickly as possible.
Assembly and fastening suppliers need to help them get there."
PosiDot valve from Liquid
Control Corp. (North Canton, OH, U.S.)
helped a medical device manufacturer dispense
1.5 cc's of epoxy into a small cavity on the
handle of a medical device known as an ablation
wand (inset). The wand is used in a surgical
process to help correct heart arrhythmias.
meter, mix, and dispense valve is said to dispense
accurate shots and beads from 0.005 cc's up
to 5 cc's, and handle ratios from 1:1 to 25:1
of two-component epoxies, urethanes, silicones,
and most reactive resin systems. In this application,
there is a wand cavity about 2- to 2.5-in long
that is filled with epoxy. The potted section
runs from the blue finger grip down to the
tube that comes out of the device. The valve
was used to dispense epoxy so that the electronic
connection in the wand is protected, the PVC
tube is securely bonded over a stainless steel
tube, and the handle of the device is bonded
to the stainless steel tip.
Achieving optimum assembly efficiency often requires
some ingenuity. AEG in Nuremburg, Germany, a maker of clothes washers,
needed to automatically feed and drive 17 screws to hold drum halves
together. The difficulty was that the screw-holes were placed so tightly
next to each other that access with standard feeder tooling was impossible.
Therefore, the assembly system needed to be equipped with separate
loading, inserting, and driving stations.
The appliance company purchased five identical automatic
screwdriving machines from DEPRAG (Amberg,
Germany) to address the situation. The supplier designed a holding-mask
with screw presence sensors, which allows the screws to be automatically
pre-loaded. Once all 17 screws are loaded into the holding mask, magnetic
sockets lift the screws out of the mask and insert them into the drum
When all screws are loaded into the drum, the drum advances
to the driving station, and 17 automatic screwdrivers drive each screw
to the correct torque and depth. A Siemens PLC
controls the machines. (For more information see Upside
While tried and true assembly methods sometimes continue
to work well, it is not a bad idea to do a periodic review. One major
appliance company did so and found an alternative to a spot welding
operation. Previously, the spot welder was swung into place in a hard-to-reach
washer cabinet hole to apply a single weld. This was a cumbersome,
After a review, the appliance company switched to a
Tog-L-Loc system from BTM
Corporation (Marysville, MI, U.S.). The appliance OEM reports that
the hand-held, air-over-hydraulic clinch lock unit, supported by a
balancer, is easier to maneuver and operate. The company feels that
nothing is compromised in joint quality with the new approach.
new controller for electric assembly tools monitors
the entire fastening process and controls the final
torque. When coupled with a tool, the Smart Torq
Error-Proofer from ASG (Cleveland, OH, U.S.), a division
of Jergens, Inc., automatically learns an assembly's
fastener installation characteristics. Once learned,
the device monitors the fastening event by comparing
learned characteristics to those being experienced
while the fastener is installed. By monitoring the
event versus just controlling torque, the controller
is said to catch problems during the process, such
as differences in workpiece characteristics, fasteners,
or assembly tool performance. The device monitors
the number of fasteners installed and detects cross-threading,
premature shut-off, re-hits, cam-outs, and missed
fasteners, as well as incorrect torque.
BTM adds that clinched joints are consistently applied, and that the
joint expands and contracts at the same rate as the surrounding material.
Spot welding, however, may be subject to cold weld, too much flash,
the presence of oil, tip conditions, and power fluctuations, which
affect the quality and consistency.
Possible inconsistencies aside, spot welding may also
be losing ground as many appliance companies go to pre-painted steel.
This was the case at HVAC equipment maker Trane's Cullen, LA, U.S.
location. Late last year, the company began production of commercial
size (5.5- to 20-ton) air handlers, which are the inside portion in
split systems. The parts had previously been spot welded and then post
painted in another facility. For production in Cullen, Trane decided
not to spot weld the now pre-painted steel because of the appearance.
Instead, it selected the FAS-NER System from AKH,
Inc. (Indianapolis, IN, U.S.). The punch and die operation automatically
feeds, punches, inserts, and locks a self-piercing FAS-NER to produce
a solid joint in one high-cycle operation.
"This has been a good clean operation on the press," Skipper
Martin, manufacturing engineer at Trane's Cullen location, tells APPLIANCE. "There
is a more consistent and stronger joint than when we spot welded. Beyond
that, appearance is nice since the fasteners are flush with the sheet
metal surface, and their color has been selected to match that of the
As appliance designs continue
to evolve, appliance companies and their suppliers will surely
continue to adjust and improve assembly and fastening processes
and materials to meet whatever comes their way.
Assembly & Fastening
the Evolving Appliance
Clamp, Inc. (Somerset, NJ, U.S.), produces a line
of self-compensating hose clamps for low-pressure applications
in single wire, double wire, and constant tension band
(CTB) configurations. These clamps expand and contract
with the hose in response to temperature changes in
the application. According to the company, they cannot
be over- or under-tightened and are installed and removed
easily using either manual or pneumatic tools.