The activities at Joyworks are neither routine or well defined. That’s what makes it such a neat place to consider and try new things. Okay, I admit it, we can work on whatever we want to. Of late, we’ve been producing sample Austempered Ductile Iron (ADI) conversion parts that, if successful, will replace multi-piece steel components with one-piece ADI castings. We have been casting hardenability step blocks for Applied Process Inc. and we’ve even been analyzing a unique, proprietary design for a bow hunting tree stand. Based on feedback from our sphere of influence we anticipate that design activities will become an ever increasing portion of the activities at Joyworks.
It has been our observation that, in general, mechanical and design engineers are experts at designing functional shapes but know little about the materials that they specify. Meanwhile, the materials engineers can give you chapter and verse on the materials but are woefully lacking in design knowledge. Add to that the fact that most graduating engineers in both those fields have little experience at actually making complex components…..experiencing the difficulties and failures that add up to manufacturing wisdom.
So, it is with some consternation that we read in several trade publications that Ford is looking to reduce the mass of the F-150 pickup truck by 750 lbs. (about 15%), for the sole purpose of increasing the fuel efficiency of America’s most popular vehicle. On the surface this seems to be a noble goal. The weight reduction is expected to come largely from substituting aluminum for iron and steel. For example they have cited the cargo box, tailgate, doors, control arms and steering knuckles as targets for conversion to aluminum. They expect that the conversion will increase the cost of the vehicle by $1,500 and increase the fuel mileage by 8%.
At Joyworks we are not (specifically) automotive engineers, but we are engineers with both design and materials experience. A quick calculation based on the aforementioned outcome provides some food for thought. If you make the assumptions of driving 10,000 miles per year and gasoline selling for $3.50/gallon, the slimmed-down F-150 will return your initial investment in 10 years. (5 years if you drive twice as much). Not so hot in the return-on-investment category.
How can that be? An 8% increase in fuel efficiency is HUGE. Well…..so is the amount of energy that goes into the production of the aluminum. That $1,500 premium that F-150 buyers pay will be, in effect, $1,500 worth of energy purchased up front. Converting bauxite ore to high-performance aluminum sheet, forgings or castings uses three times the amount of energy as that required to convert iron ore to either steel or iron sheet, forgings or castings. So, in life-cycle energy the savings are minimal…..but Ford will be able to meet the Federal Government’s mpg regulations whether they make energy sense or not.
Moving away from energy, how will Ford make up for the stiffness deficit in aluminum vs. steel or ductile iron? The resonant frequency of the vehicle is bound to be negatively affected. What about the noise issue? Aluminum rings like a bell…….what will be the effect on the F-150’s NVH performance. And what about vehicle modifications in service. I drive a pickup truck and I can tell you that these trucks are going to get modified. What happens the first time somebody attaches a fifth-wheel through an aluminum box F-150 using steel screws? You’ll be able to SEE the aluminum corrode away. Can you imagine what the aluminum tailgate on a working F-150 will look like after being used on the job site for several years? It will look like a piece of aluminum foil that has been crumpled up and then hastily flattened out.
There is no free lunch. Most materials considered to be “light-weight” use massive amounts of energy in their production and have issues with stiffness, noise damping, corrosion resistance, recyclability and manufacturability. But many designers are ignorant of the larger picture when these material selections are made. At Joyworks we’ll do our part to make that picture clearer. Meanwhile, you might want to ask some questions the next time you’re chatting with a Ford design engineer. The stuff we use to make stuff really does matter.