BMW April 2022

Much has been said about support of initiatives such as green parts, recycled usage and more importantly, the ability to save-a-car by reducing cost below write-off thresholds.

Due to the long financial impact on the automotive aftermarket, there has never been more pressure to think about the repair of parts rather than spending much more valuable liquidity on new parts. There is a balance but, labour-sell provides greater profit overall. 

Some vehicle manufacturers give explicit guidance, whilst others give blanket statements on this repair protocol. The world of auto body repair has become a culture of constant change and advancements in metals and plastics, as well as glass and other construction materials used in automotive manufacturing which have accelerated at a blistering pace compared to just a few years ago. Over time, plastic has become such a large percentage of a vehicle’s make-up that plastic repair has become a mainstay in the collision industry. New equipment and better tools complete strong and durable repairs.

The mainstay of plastic repair to the body shop is the ability of understanding, training in all aspects of best practice and justifying the investment in equipment and skills training. Plastic repair is a process just like any other labour process. In many cases it can almost be an art, however time is needed to do the job correctly.

There is a cost analysis involved in the repair versus replace decision. In some cases, either the cost of the part or the availability of the part makes owning this stellar equipment advantageous. If the cost does not justify the repair, we quote to replace. In this day and age of business there is immense pressure on turnaround times to complete a job. Alternative repairs like this can become a win-win for everyone.

With the influx of ADAS components and sensors, shops are reluctant to do repairs where the repair can still be done. Some of this is based on sensors and the location of Radar. According to OEM positions and statements, repairs in some areas are not feasible. Following factory repair methods procedures must become part of our culture, however in many cases, with a little research, you will find that there are still many opportunities to repair plastic bumpers.

No matter which plastic repair process you use, whether it’s adhesive repair or nitrogen welding, knowing all the products at your disposal and which will work best for your repair needs is fundamental. Cutting corners or skipping steps during any repair process will eventually come back to haunt you. If an artisan has not been given proper training on how to do a job, it’s not their fault. Asking someone to do a task but giving no instruction will inevitably create a major headache down the road. Many plastic repairs fail due to not knowing or following the proper steps to repair a bumper cover. One of the biggest reasons for plastic repair failures is contamination of the bumper. One of the first procedures that must be done after removing the cover is to wash the bumper skin with soap and water, front and back. Contamination can come from anywhere. Your hands and tools will be transferring contaminants from the environment of operation. Keeping everything clean is good basic practice throughout your body shop, no matter the process. 

Plastic repairs are a viable repair and will remain so into the future. Researching where and why a repair can be done or not will take a little more time, but that time can be worth it for a shop and artisan. Training is the key, not just for the technician, but for an estimator too. It’s hard to negotiate repair time when you don’t have the training to know all the proper procedures involved in that repair.

There will always be limits to repair and unless a manufacturer mandates fitting a new bumper skin regardless of damage, it is possible to repair them. Typically, this means repairing the areas not close to the location of the important installed position of sensors:

What is Radar? Radar uses electromagnetic waves sent out from the module, and then reflected – the reflected waves are then detected by the same module. So, each module is both sending and receiving electromagnetic waves. The sensor is situated behind a plain area of bumper skin (no ribs, no clips) and the system is tuned to cope with the signal reduction caused by the bumper plastic, as well as the bumper paint system. It is:

Not permitted to fit metal staples to cracks within 200mm of the sensor area, or if guided by the vehicle manufacturer, at all.

Not permitted to exceed the total thickness of filler / base / primer/ finish paint coats which was applied by the factory within 200mm of the sensor area, or if guided by the vehicle manufacturer, at all.

What are “pop-up bonnet” sensors? There are two types – an accelerometer, much like the SRS impact sensor, and a pair of sensors connected by a tube. The latter is less sensitive to an increase in bumper weight, but the “pop-up bonnet” accelerometer sensor is much more finely tuned to detect low speed impact energy levels than an SRS impact sensor. So, the manufacturer may state if the bumper skin is holed or cracked, it is not possible to make a basic repair and then fill to shape due to the increased weight, and so different dynamic signature. 

Ultimately the output must provide a flawless finish – The most common problems encountered when repairing plastics are:

Orange peel – caused by unsuitable solvent combinations.

Poor adhesion – caused by insufficient cleaning or unsuitable adhesion promoters.

Pinholes – caused when the paint is applied too soon.

Lifting – caused by improper isolation and/or through-sanding.

In summary the Motor Body Repair (MBR) fraternity are notorious for the amount of waste each one produces, but actually this is an area of great opportunity both environmentally and economically. Managed badly, waste disposal can be a huge overhead expense, but managed well it can even be turned into an additional revenue stream. Carbon footprint and emissions are becoming a huge and fast rising priority for all businesses and the best approach will be to analyse what you can control and what will have the biggest impact on profit with the resources you have available.


by Steve Kessel, CRA Operations Director

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