Aluminum Extrusion Design Truck Cabs
Why Aluminum Cabs?
Most truck cabs used to be constructed with steel. Marion can and does build in steel. In recent years, however, aluminum has taken over as the material of choice because it weighs less, doesn't rust, and increases the efficiency, performance, and safety of the truck.- In an aluminum cab, compared to a steel one, the same horse power engine provides superior acceleration. Reducing the weight of the cab also improves gas mileage, braking, and therefore overall safety.
- Aluminum also increases a truck's safety by lowering its center of gravity, thereby improving manuverablility.
- Because it is a highly durable material that doesn't rust, an aluminum cab will not only last years longer than a steel one, but it will look better and will resell for more.
- Extrusion technology has advanced greatly, and that, along with the leveling of prices between it and steel, makes aluminum the premier cab material.
Three Design Approaches
When designing an aluminum cab, there are basically three approaches:- Follow the "Steel Cab Design" approach, in which the cab is constructed mostly from formed aluminum sheet with few extrusions.
- Use the "Halfway" extrusion approach, where there are about 5 extrusions per cab and the remainder is built with sheet material.
- Follow the full aluminum extrusion approach, using about twenty extrusions and aluminum castings for the corner caps.
As a material, aluminum is an excellent choice for many products because of its light weight, high durability and the fact that it doesn't rust. Aluminum extrusions are stronger, pound for pound, than sheet aluminum. An extrusion is made from an alloy that has a yield point about 52% greater than that of aluminum sheet.
Advantages of Marion's Fully Extruded Approach
The fully extruded design of a Marion cab produces many advantages, including reduced weight, excellent component fit-up, and superior strength. As stated above, extruded aluminum is much stronger than other materials, allowing us to build the strongest possible cab which resists damage, helps protect the occupants, and has the lowest product liability. Additionally, extruded aluminum design cabs provide the following benefits:- Extruded aluminum cabs include the lowest cost to bodywork before painting.
- Door and window fit-up are precise, making replacements faster and less expensive. Every door is promptly replaceable by a stock door so there is no waiting for a custom door. Flatglass fitup and operation is snugger and smoother; window lowering mechanisms are trouble free when secured to extrusions.
- Extruded aluminum provides the flattest, truest surface for a superior finish, and the evenly crowned roof sheds water and ice to eliminate damaging "duck ponds." This also eliminates thick bondo areas that are expensive themselves and make paint repairs expensive.
- All non-aluminum fasteners, hinges, and cab tilt brackets have galvanic isolation for higher quality and long life.
- Superior appearance created by a flat rear wall without weld distortion marks, a smoothly crowned roof, and all around door fit up - even in tilt position.
- Marion workmanship results in cabs passing inspection evey time, avoiding costly rejections.
The Marion Extrusion Design Story
Marion all-aluminum body and cab designs feature the use of aluminum extrusions. They are superior to formed sheet designs in weight to strength ratio. Also, extrusions provide superior dimensional reliability, especially in door fit up.Pound for pound, aluminum extrusions are much stronger than sheet aluminum. Here are the book mechanical properties of the most commonly used sheet and extrusion alloys.
| Alloy-Temper | Used For | Tensile Strength | Yield Strength |
| 3003H14 | Sheet (a few Cents per lb. cheaper than 5052-H32) | 22,000 psi | 21,000 psi |
| 5052-H32 | Sheet (Marion Standard) | 33,000 psi | 28,000 psi |
| 6061-T6 | Extrusions (Marion Standard) | 45,000 psi | 40,000 psi |
On tensile strength (failure point) Marion extrusions are 105% stronger than 3003 sheet; 36% stronger than 5052 sheet. On yield strength (point when distortion begins) Marion extrusions are 90% stronger than 3003 sheet; 43% stronger than 5052 sheet.
An added important feature of Marion’s extrusions is that they are made from 100% "primary" aluminum. Many aluminum extrusion houses use "secondary" (recovered/recycled) aluminum when it is lower in cost. "Secondary" typically includes trace impurities. These impurities can produce extrusions with significantly less strength than their book mechanical properties. Marion’s extruder source uses only "primary" aluminum, to give you the full book value strength.
Marion has more years of experience --since 1964-- in building all-aluminum bodies than any other U.S. Manufacturer.
Marion extrusion design bodies and cabs come with a ten year structural warranty
Our Long-Term Commitment
Marion Body Works has made a long-term commitment to building aluminum cabs. This has been founded by thirty-four years of experience building all-aluminum truck bodies for emergency vehicle duty and our fourteen years of experience using industrial adhesives, with no failures. This commitment is also shown by our investments in state-of-the-art equipment, technologies, and training:
- State-of-the-art aluminum welding equipment.
- CAD and CAM programming for every part, which insures repeatability, easily permits revisions of part designs, and can accommodate design improvements made by the chassis manufacturer.
- Computer controlled fabrication machines.
- Dozens of proprietary aluminum extrusion dies.
- Smooth surface aluminum castings for strength at the stress concentration corners.
- Extensive fixturing of all assembly operations for dimensional accuracy, dependable repeatability, and the lowest cost.
