In 2015, Ford introduced its all-aluminum body F-150 pickup. In 2023, the automaker sold 765,000 F-150s in the U.S., which translates to roughly seven million of these aluminum trucks on the road today. There is a great opportunity to repair these trucks, yet because they’re aluminum, many shops shy away from anything more than fender replacement. It boils down to proper tools and training.
Check out the damage on the cab corner of this aluminum Ford F-250. The panel is about 1.5 millimeters in thickness, and when I asked, “How would you repair this?” everyone’s answer was: replace it. I then asked if the shop has the tools/equipment and training to replace it, and the majority said they would not accept the job. This panel was repaired using the KECO tab repair system — and check out the results using these advanced tools and training.
Besides using self-piercing rivets (SPRs), Ford uses blind structural rivets. In teaching the I-CAR rivet bonding class, I’ve learned that most technicians do not understand why blind rivets are used and their proper removal and installation procedures. I hope this article clears up the confusion.
Auto Material Construction
We’re seeing stronger and lighter materials in today’s vehicles as well as a combination of several different types of steels, together with aluminum, magnesium, plastics and carbon fiber. It should be noted that not everything can be welded, so we’re seeing a number of new and different joining methods. Remember, heat will weaken high-strength steels and destroy ultra-high-strength steels.
For example, Honda began using ultra-high-strength steel in A pillar, B pillar and rocker reinforcements on its 2013 Accord. Honda states that “Parts made of ultra-high-strength steel (UHSS/1,500MPa/USIBOR) must be installed as a complete part. No sectioning allowed. Ultra-high-strength steel requires special welding equipment, procedures and settings. See the welding section of the appropriate body repair manual. Failure to use the proper equipment or follow the proper procedures can result in an unsafe repair.” It further states, “Never do MAG-MIG welding on 1,500 MPa steel.”
OEMs are asking the repair industry to invest in new equipment and training to repair their vehicles properly to pre-loss specifications. I could go on about this trend, but let’s get back to adhesive rivet bonding or, as some refer to it, cold bonding.
Adhesive
Welding will be used less and less, with the alternative being adhesive. Look at Fig. 1 taken from the website, adhesivetest.com.
Fig. 1
Adhesive has excellent tensile strength and is extremely strong when conducting a peel test but is weak when conducting a shear test. To overcome this deficiency, rivets, spot welding or some form of mechanical fasteners need to be used to prevent shearing.
Fig. 2
Fig. 2 is taken from boltproducts.com and shows the definition and term when discussing rivets.
The two most important items in Fig. 1 are the material thickness (also material type) and the shank size. The vehicle engineers will determine everything needed for their particular repair operation, but you need to know the proper shank size to drill or punch the hole in the material. If the hole is the wrong size, the rivet could be loose and shear movement could occur. Too small a hole could cause the metal to distort and again, the panels will not be in full contact with each other.
Rivet Types
Let’s look at the various types of rivets.
Fig. 3
There are four major types of rivets that are used in the repair process: SPRs, flow form, solid and blind rivets (hemlock, monobolt and pop). Looking at the front side of the panels above, the rivet heads look very similar. On the left in Fig. 3 is a panel with a hemlock rivet, and the rivet gun (battery or pneumatic) needs 3,500 pounds of pulling pressure. On the right in Fig. 3 is a pop rivet (from Home Depot) hand-set with a pop rivet tool. You don’t have to be a rocket scientist to see the difference.
Fig. 4
Fig. 5
Next, we’ll look at monobolt and hemlock blind rivets. A monobolt (Fig. 4) is a specific type of blind rivet. The mandrel is pulled into the cylinder and expands the cylinder against the backside of the panel (Fig. 5). This rivet has high shear and tensile properties and fills the hole (Fig. 6).
Fig. 6. Problems that occur when the wrong rivet is used
The other type of blind rivet used in the collision repair process is the hemlock rivet. This rivet also needs a hole for installation and does not need access to the backside of the panel. The mandrel is pulled over the rivet body and the entire rivet is compressed against the rear panel (Fig. 7). See Fig. 8 for the sequence.
Fig. 7. Back side of the panel with hemlock rivet
Fig. 8
This rivet has high shear and tensile properties and fills the hole. It’s excellent for holes that are slightly larger than the recommended hole size.
Tools and Best Practices
Next, let’s discuss necessary tools and best practices for preparation and installation.
The equipment for installation can be either pneumatic or battery-operated. I have both types: an Astro Pnematic PR14 and Gesipa Taurus 4, which are pneumatic, and a Gesipa Power Bird and Milwaukee M18 FUEL 1/4-inch Blind Riveter.
Fig. 9
Fig. 9 shows a blind OEM structural Ford rivet. In its repair manual, Ford specifies the part number and not the size for a specific location. So, how would a technician determine the rivet with the proper grip range? There is a blind rivet gauge from Bolts & Nuts (boltsandnuts.com) along with a chart. Here is how it works:
Fig. 10
- Take the rivet and find the size the rivet body fits in; for the Ford rivet, it is No. 8 (Fig. 10).
Fig. 11
- Next, measure the rivet body length (Fig. 11).
Fig. 12
- Measure the rivet body using the No. 8 slot (Fig. 12).
- The size of the rivet is a No. 82 (do not include mandrel head when measuring).
Fig. 13
- Find No. 82 on the chart, and the measured rivet has a grip range from 1/16 to 1/8 (Fig. 13).
Fig. 14
- Measure the total thickness of the panels that need the rivets (in this example, the total thickness is 1/8 inches) (Fig. 14). The rivet selected will work on this panel. If the rivet is measured in metric, find a conversion chart.
Now, let’s look at preparation and installation of the selected rivet.
Fig. 15
The Ford procedures call for a 6.5-millimeter drill bit for their blind rivets (Fig. 15). In teaching the I-CAR rivet bonding hands-on class (a must-have class for today’s techs), I find that nearly every time, the shops do not have a 6.5-millimeter drill bit. The closest size to a 6.5-millimeter bit is a 1/4-inch.
Fig. 16
The actual size of this drill is 6.25 millimeters (Fig. 16). Before moving on, I want to mention these drill bits. They are from Astro Pneumatic, and you’ll notice that the end of the bit is shaped like a pyramid. The bit does not wander and will step-cut the hole two to three times faster than a standard drill bit. Use it at a low-to medium speed, and it does not get as hot as a high-speed bit. I was at a local OEM training center, and its tech was able to drill multiple holes into martensitic steel (over 1,300 millipascals) without the bit getting dull. Now, back to the drill process.
Fig. 17
Nearly every one of my techs took the drill and enlarged the hole for the 6.5-millimeter rivet to fit. You’ll notice on the 1/4-inch hole, the rivet is not perpendicular to the surface (large gaps around the rivet) (Fig. 17). Remember that I mentioned in the beginning of this article that glue has very poor shear strength, and if the rivet is loose in the hole, the panel will move sideways and cause the bond to break. If that happens, all kinds of problems can occur. Let’s return to the installation process after the correct size hole is drilled.
Fig. 18
Drill a 6.5-millimeter hole. Use locking pliers when drilling to make sure that the joint is tight. Notice that there is a piece of aluminum that is present after drilling (Fig. 18). This needs to be removed prior to the rivet installation, because the rivet will not sit flush to the panel. Use a deburring tool to remove the aluminum chip.
Fig. 19
Deburr the hole, have the correct rivets ready, apply adhesive (if specified) and assemble the necessary clamps (Fig. 19). The rivet tool for the Ford OEM blind rivet needs to have 3,500 pounds of pulling force.
Fig. 20
Press the nose of the rivet gun tightly against the rivet head and, with a pull of the trigger, the rivet is set (Fig. 20).
Summary
As a reminder, here are some guidelines:
- Always refer to OEM riveting procedures and adhesive usage before starting the repair process.
- Check the specs needed for your blind rivet gun to make sure it has the recommended pulling force.
- Use factory rivets.
- Follow the rules, and you and your technicians will have a great riveting experience.
