Vehicle body clamping problem solved

Edited by the Manufacturingtalk editorial team Feb 22, 2006

Engineering company was able to solve the difficult problem of designing and developing a new clamping system for transporting 'body-in-white' assemblies through phosphating and electro-coating.

Like many other vehicle manufacturers, Nissan Motors Manufacturing send their welded bodies through Electro-coat and Phosphate processes prior to being painted.

The bodies are transported through large tanks on special carriers connected to a conveyor system and to ensure that the bodies cannot 'float' off within the tanks, each carrier includes a mechanical clamping device that protrudes through an aperture in the transmission tunnel.

As the aperture was in a similar position for each of the vehicles they produced, a single clamp could be used.

However, with the introduction of new model to the Sunderland plant, the Nissan engineers were given a new challenge.

The aperture in the new vehicle was much smaller, a different shape and in a completely different position.

This meant that the existing clamp would clash with the body if used as it was.

Having just successfully completed a tooling project for the previous new vehicle, CK Industrial were approached by Nissan to see whether they could come up with a solution to the problem.

The requirement, therefore, was to design a mechanism that could clamp in two different places.

Added to this, the mechanism on each carrier had to be purely mechanical, as the bodies were travelling through a harsh environment and could not have any pneumatic or electrical control.

One idea considered was that of using removable 'slaves', whereby, a clamping device was loaded in the body shop according to the model type.

This was disregarded, however, because as well as the large number of slaves required (i e, one per vehicle), it also gave potential Health and Safety issues with the loading of the slaves.

An alternative idea put forward by CK was the use of a type of 'see-saw' mechanism, which would be pivoted to the correct position dependant upon vehicle type.

Following discussion with Nissan engineers and commercial negotiation, CK were eventually awarded the contract to implement this idea.

In the Paintshop, the clamping mechanisms are operated automatically at drop lifter stations at either end of the electro-coat and Phosphate processes.

Therefore the scope of the project also included a body recognition camera system and a modification to the electrical/pneumatic system to operate the relevant clamp of the 'see-saw' dependant upon body type identified.

CK's 3D CAD capability meant that with all the relevant product data, the design could be modelled first and demonstrated to the Nissan engineers before cutting any metal.

This was a service that was not always available to them on previous vehicle program launches, but allowed them to highlight any concerns they had and potentially avoid costly on-site changes.

As the nature of the requirement meant that to provide body clearance, the clamping mechanism would have to protrude below the level of the existing carrier, there was a concern about what clearance was available within the existing tanks.

Therefore, having agreed that the extra distance should not exceed 50mm, during a site survey CK fitted a small tool to an existing carrier, which they ran through the system.

This simple test identified a number of clash areas that Nissan were able to modify before they would have caused a problem on the initial production run.

As a part of the design process, CK staff met with Maintenance teams to understand their main issues and see whether these could be addressed within the new design.

As a result, a new spring concept was developed which would improve the situation of seize up encountered when the system is left idle overnight and weekends.

CK's site in Wickford, Essex, UK, already had a 'pilot build' factory with a steel structure set up to be able to suspend bodies on carriers.

For this project, they were simply able to adapt it to be similar to the system at Sunderland using vehicle bodies and an overhead carriers loaned to them by Nissan.

This allowed them to simulate the drop lifter system so that the clamping process could be fully tried out in the presence of the Nissan engineers, prior to shipment.

This is a service that CK offers to all of its customers.

Following successful installation of the clamping system over a single weekend, the first new vehicle body was shipped through the pre-treatment processes during normal production hours with no lost vehicles.

So as to fully try out the 'see-saw' concept, the initial prototype sling tooling was left in the system and has now been running in current production for over six weeks without any reported problems.

The bulk tooling is currently in manufacture so that it can be fitted to the 80 carriers in the system, ready for the first trial production phase of the new vehicle in June 2006.

This tooling will be supplied with a specially designed setting fixture, that will be used during installation to compensate for any sling variations, thus ensuring that the position of the clamps is consistent in relation to the body location pins.

In summary, the innovative thinking plus the design and manufacturing capabilities of CK Industrial fully achieved the objectives of the Nissan engineers and management, on what they considered the most challenging manufacturing problem associated with the Paintshop processes for the new vehicle.