Product category:
Fasteners, threaded and non-threaded
News Release from: Profil UK | Subject: Clinch nuts and studs
Edited by the Engineeringtalk Editorial
Team on 02 September 2005
Clinch nuts and studs go off-road in new
Discovery
Land-Rover has specified more than 320 of Profil's clinch nuts and studs in the assembly of its latest generation, T5 platform Discovery vehicles.
Leading vehicle manufacturer Land-Rover is taking full advantage of the cost and quality benefits associated with Profil's pierce fastening methods, by specifying more than 320 of the company's clinch nuts and studs in the assembly of its latest generation, T5 platform Discovery vehicles The use of Profil fastening technology has become Land-Rover's preferred method of providing male and female threads in sheet metal components and body panels, superseding welded and other standard threaded fasteners in many areas of the company's vehicles
This article was originally published on Engineeringtalk on 24 Oct 2002 at 8.00am (UK)
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And it's easy to see why.
Profil pierce/clinch fasteners offer the benefits of high speed installation, reliable high strength, foolproof quality control, excellent water sealing and both vibration and corrosion resistance; all backed by minimal installed costs.
According to Profil UK's Adrian Ellis, pierce/clinch fastening is the ideal process for today's automotive manufacturers.
"Not only can the fasteners be installed during the pressed components forming process - using a dedicated station within the multistage progression tooling - but they can also accommodate panel thicknesses from 0.6 to 6.0mm thick".
"What's more, they are just as suitable for use with coated or uncoated materials, high grade, stainless and sandwich steels, and can even be installed in aluminium and magnesium castings".
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"These are major benefits over welded fastening methods, which are not only slow, but open to many more process variables than pierce/clinch installation methods", he adds.
Vehicle manufactures recognise that vibration and fatigue resistance are vital performance criteria for any onboard fastening application.
Here, Profil fixings also score heavily over welded methods, which can lead to failures through thermal disruption of the sheet metal structure, or potential heat damage to coated or plated surfaces - if they can be welded successfully at all.
By contrast, pierce/clinch nuts and studs are ideal for use with corrosion resistant finishes and materials, such as galvanised steel or zintec, as well as the growing number of aluminium panels found on modern motor vehicles.
On Land-Rover's Discovery series, up to 321 off M6, M8 and M10 threaded nuts and studs are used throughout each model variant.
These range from low to medium strength applications, such as the installation of 15 off M6 and M8 RND type nuts on the gear-change console, which are subsequently used to secure items including the vehicle's crash sensor unit.
Higher strength Profil fasteners are specified in several safety critical applications, including seat mountings.
In addition, the process's inherent placement accuracy is used to good effect in the use of unthreaded Profil nuts to provide location points for the vehicle's sunroof assembly.
"As pierce/clinch fasteners are installed as part of the presswork process, they offer significantly better positional accuracy and repeatability than other fixing methods", says Ellis.
"In most applications, tolerances of +0.2mm can readily be maintained, while a figure of five times this value might be expected for corresponding welded parts".
In the sunroof application, the unthreaded Profil nuts also provide an additional function in order to fulfil an important application requirement.
During their installation, the bodies of the fasteners are swaged over to form complete rivet heads on the blind side of the workpiece, ensuring an excellent water seal with the primary roof structure.
This is maintained during the sunroof's final installation through the use of self-tapping bolts, which cut their own threads into the plain bores of the Profil nuts already employed to accurately position the assembly.
Land-Rover also takes advantage of the system's assured panel sealing in other designated "wet" areas of the vehicle too.
These include the provision of under bonnet anchorage points and the use of deep flange Profil EMF style nuts within the wheel arches to produce the required stand for galvanic corrosion to be prevented between the vehicle's aluminium body panels and primary steel structure.
The fastening system's impressive performance benefits are also underpinned by overwhelming financial considerations.
Through their ability to be secured in sheet metal components as part of their multistage forming process, nuts or studs can be installed at more than 100 fasteners per minute - an order of magnitude faster than methods.
"Even in manually fed applications, up to 30% installed cost savings can be achieved", maintains Ellis.
"However, a key factor is that automatic sensing can easily be incorporated into the press, to ensure that no components can be made without the required fasteners being correctly installed".
"This is in marked contrast to other joining processes; and one that is well recognised by Land-Rover", he adds.
Further considerations include the consistency of installation.
Unlike welded fasteners, which may be prone to failures through too little or too much heat penetration, pierce/clinch fastening avoids the potential problems of thermal marking and its associated initiation of corrosion centres, not to mention the risk of stray weld spatter that can compromise the surface finish or aesthetic qualities of finished assemblies.
"In-press monitoring means that Land-Rover's components are effectively 100% inspected before shipment and, as a result, achieve zero defects at final assembly", says Ellis.
"This not only provides significant productivity benefits, but also leads to a dramatic reduction in the rework and warranty costs associated with normal threaded fasteners".
"By our calculations, this saving alone offsets the piece part cost of our studs and nuts".
"When combined with the cost advantages of in-press installation, it could be argued that Land-Rover is effectively installing all 320 of our fasteners in its Discovery models for free". Request a free brochure from Profil UK ...
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