Recently, I responded to a forum with an opening statement: “What the heck is going on? Cars haven’t changed much, but lately I’m seeing all of these supplements.” In my career, the past 10 years have offered far more change at a faster pace than ever before in terms of vehicle structural design. While features such as electronics, connectivity, creature comforts and power have changed, the most alarming change is far less visual — it’s structural. So how does this affect estimating and repair strategy? Let’s take a look at the “cause and effect” of these changes and why estimate writing increasingly requires an in-depth knowledge of repair.
Remember the days of following general sectioning guidelines and procedures? Well that‘s pretty much history now. Over the course of my career, I’ve performed thousands of structural repairs and sectioned hundreds of frame rails by simply using a common sense approach of following general sectioning guidelines, but not anymore. With today’s vehicles, I will not consider a structural repair without a knowledge of metallurgy, OEM position statements, and model-specific procedures from the vehicle manufacturer. So what happened? Advanced materials used in structures have progressed at an amazing rate, offering additional strength with less weight. Then there’s the Ford F-150 with its all-aluminum body, so even more change.
|As more stringent fuel economy requirements are enforced, several vehicle manufacturers have chosen to combine advanced materials to reduce vehicle weight, as shown on this BMW body, which is primarily constructed of carbon fiber and aluminum.|
First, let’s look at some of the properties of advanced high-strength steel materials. There are several ways that we can describe the varying strengths of steel, with the most common being tensile strength. Tensile strength is the maximum amount of force that can be applied before the material fails (fractures). We are accustomed to finding a tensile strength rating listed in pounds per square inch (PSI), but it is much more common to see it listed in Megapascal (MPa), the metric equivalent, in most collision repair manuals or vehicle manufacturer’s publications. A comparison between the two measurements from psi to MPa is 1 MPa = 145.038 psi, while 1500MPa = 217,556psi. You may also recall in general sectioning guidelines that repairability of mild steel rated to mid-60,000 psi was excellent, and high-strength steel (HSS/HSSLA) was defined as beginning at 70,000 psi repairs were more tentative and varied with OEM statements, while ultra high strength steels (UHSS) beginning at 100,000 psi was considered non-repairable. It’s hard to imagine 1,500 MPa strength, as compared to vehicles of the early century, but it’s here, and we need awareness before repairs can begin.
Regarding specific advanced materials, it’s relevant for us to consider that any advanced structural material will have specific characteristics, as well as repair and /or replace procedure considerations, along with all kinds of names and terminologies. The terminology is an important consideration. Most structural repair procedures or the vehicle manufacturer’s repair/service information will contain an area that defines the steel type that is used on specific vehicles, as well as the repairability and limitations. Perhaps the first step when writing an estimate to perform a structural repair would be to obtain the vehicle manufacturer’s procedures to identify the material type. When writing an estimate, the following should be considered:
Is repair an option, or is replacement necessary? Then if replace, can it be accomplished through a sectioning location or must it be installed in its entirety? Consider what happens to a repair plan when the B-Pillar reinforcement requires replacement. Often we end up cutting an access hole in the upper roof rail aperture to access the weld mount locations. Now we implicate damage to the roof panel when re-installing the window cut, not to mention the additional R&I operations.