By using a high-strength abrasion-resistant steel like Hardox® wear plate instead of mild steel, you can minimize the amount of reinforcing materials needed. Not only does using fewer stiffeners reduce the body’s weight, but you can reduce the high stresses caused by too many welds or bolted joints.
Another benefit of minimizing the number of components is reduced manufacturing time. By using less reinforcement, you don’t need to produce and assemble as much material.
The engineering and design approach Design for Manufacturing and Assembling (DfMA) refers to designing products to be easier to manufacture and assemble. The use of Hardox® wear steel instead of mild steel is aligned with this approach, which is intended to have a positive impact on a final product’s quality and cost.
The illustration below shows an example of an upgrade from mild steel to Hardox® 450 and Strenx® 700 MC. By minimizing the amount of stiffeners and using other methods of stiffening, like bending, the number of components was slashed from 50 to 19 parts. In addition, the weight savings resulting from this upgrade are 51 percent and the estimated emission savings are 3 tonnes (3.3 tons) CO2 per body.
Illustration of how a tipper made of mild steel (left) can be upgraded to a much more efficient one using high-strength steel (right).
In the graph below, the cost of the old version can be compared with the new version in high-strength steel. Although the initial material cost is higher for high-strength steel, its use in manufacturing brings both labor and cost savings. Both welding and cutting costs are lower than with the old design, which is typical since the thickness of a plate in high-strength steel can often be reduced. During cutting, the thinner the material is, the more easy and time-efficient the process.
In some cases, the manufacturing costs related to Hardox® steel are not lower. However, the lifespan of the product is also crucial to consider. By minimizing the number of parts, fewer welds and joints need to be used. Welds are often subject to fatigue and can thus decrease a product’s service life.
Example of relative production costs for an old design container vs. a new design container.
When using the Design for Manufacturing and Assembling (DfMA) approach, the question is always how exactly to fabricate a component. The illustration below illustrates two different potential solutions.
The first uses two pieces that are joined together. Here, the risk of the sharp corners and the weld quality will be critical. In contrast, the second solution uses only one part, which is bent. This solution will have some bending radii limitations. But instead, there will be no sharp corners, which will have a positive effect on load distribution and fatigue.
Two-piece component (left) vs. one-piece component (right).
As the illustration below shows, a box design will probably need to consist of two or three parts, while the U-shape will only need one part. However, the U-shape brings with it a higher bending cost.
The box profile will instead have a welding cost associated with it, and the corner welds will always involve a critical moment. In terms of load distribution, the U-shape design will have better load distribution than the box design. Additionally, the box design entails both higher welding and higher cutting costs, but lower bending costs compared with the U-shape.
Three-piece box tipper section (left) vs. one-piece U-shape tipper section (right).
The information in this report is only applicable to SSAB’s products and should not be applied to any other products than original SSAB products.