Most of us drive and never think about the efforts that car manufacturers put into the design and testing of the vehicles we rely on. Unless there’s a major lawsuit, where the details of negligence get drawn into the open, we never think about the relative safety of the car we’re driving every day. And often, even in the long drawn out court cases, we’ll simply check the make and model and years of manufacture, note whether any of it corresponds to the car we’re driving and then forget about it.
But understanding the basics of the tests being performed on the various parts that make up a car will restore your faith in the industry and probably in your car too. These are just five of the most commonly performed tests. They’re performed on components around the light controls and the plastics around the seat belt anchors. Every large and small part of the car gets test and retested. These are what those tests look like.
1) Magnetic Particle Testing
All the case hardened parts of a car – from the synchronizing hubs in the gear boxes to the gears and the moving parts of the engine like camshafts – it’s important that the surface (the case) of the steel be harder than the core. Unfortunately, harder steel is nearly always more brittle and more likely to fail than softer steel. Magnetic particle testing is a way of searching for keyway, groove and radial cracks in that case hardened steel. Even the types of cracks that appear have names. Magnetic particle testing lets a technician check relatively big areas and see what’s going on beneath the surface and not just the surface visible to the eye. It’s a relatively inexpensive form of testing too, but it’s limited to tests on ferromagnetic metals (though not just those that have been case hardened). It’s also used to look at the quality of any welded joints or connections between steel surfaces.
2) Eddy Current Testing
Similar to magnetic particle testing only in that it also requires an electric current, eddy current testing is a lot more advanced and requires a more highly skilled technician to perform – and one to understand the results. It’s limited to any type of conductive metal surface – but it will let technicians get a better view of surface and near surface defects. It will penetrate painted or weather coated surfaces a lot better and thus, it’s used a lot more on the structural components of cars, trucks and similar vehicles built mostly from steel. It’s also commonly used to test welds and surfaces, but also in threaded bolt holes and tubing where problems with thickness and cracking can wreak real havoc.
3) Liquid Penetrant Testing
Especially for machined parts, liquid penetrant testing lets manufacturers test big surface areas for relatively little money. The process involves passing a liquid dye through the object and observing if the dye, the penetrant, enters into spaces, usually defects in the material. When the developer is applied to pull the dye back then it’s a much easier way to see the extent and severity of anomalies, weaknesses or failures. It also lets manufacturers test relatively complex materials. It’s a little more toxic and needs to be cleaned up a little more thoroughly
4) Ultrasonic Testing
Ultrasonic my sound like the most technologically advanced method used by auto manufactures (it’s not) but it’s increasingly popular. It’s fast, and gives immediate results and lets you test the case hardened components and even laser-welded welds. Ultrasonic waves detect imperfections in welded joints without ever touching them. The method is even sometimes integrated into an assembly line so that every weld gets tested. Another reason for the popularity of ultrasound techniques is that they’re simply far less expensive than “destructive testing” methods and as they can be performed “on the fly” you’re literally testing every unit and rejecting only the failures. Ultrasonic testing requires highly trained technicians and good access to the surfaces being tested, but by and large the results are consistent and the method is used across multiple industries and not just in automotive manufacture.
5) Hardness Testing
Before you go thinking we’re talking about banging on fenders, hardness testing is limited to testing for “resistance to deformation” and it’s usually performed on the specialty alloys and steels buried deep down in your car. The things that wear out are often the parts that have been heat treated and that tend to be more costly. It’s important to make sure then that they’re up to the job. Like in any automotive question, the consequences are just too devastating to let things slide. Hardness is primarily an area for metallurgists but technicians will help in many areas performing what are often seemingly simple but tough-to-understand tests. The results, of course, have a lot riding on them.
All these tests are commonly performed, but not widely understood outside the industry (though many other industries rely on them too). As the automotive industry continues to decentralize, many of these tests are performed by or for the parts suppliers rather than for the big three. Magna Chek is working with at least as many suppliers of tough-to-classify parts and components as final car manufacturers. In each case, we strive to make sure that the defects and dangers are well managed and understood long before your new car hits the showroom, much less the open road.