Tipping semi-trailers — ranging from 7.5m to 11.5m in length — using a common design and components

Creating a new, modular line of tipping semi-trailers

Zamarbú wanted to develop a range of lightweight steel semi-trailer chassis, from 7500mm to 11500mm in length, for different types of tippers. Their goal was to create an additional product line for Zamarbú, who was keen to participate in the growing market for lightweight steel trailers.

The new steel chassis had to be competitive with their existing aluminum models for both weight and torsional stiffness. Plus, Zamarbú wanted components that were highly modular between the new steel models, to allow flexibility in product offerings and cost-efficient manufacturing.

Expertise in lightweighting steel designs and DFM

Zamarbú came to SSAB’s Product Development and Engineering (PDE) for their expertise in lightweighting steel designs and design for manufacturability (DFM). For DFM, Zamarbú wanted all of the new components to be made using existing, in-house equipment.

The project was started with a PDE innovation workshop, which is based on the SSAB ONE lean methodology. All stakeholders gather to set targets and priorities that guide the entire design, product development, and engineering. The workshop helped reduce the amount of time for a comprehensive product development to less than 3 months by maximizing collaboration and transparency.

Design iterations optimize semi-trailer performance and manufacturing

SSAB Product Engineering presented Zamarbú with two different design solutions for the main, longitudinal beam. Both designs needed to provide for modularity across the entire range of chassis lengths, that is from 7500 mm to 11500mm.

The first design option was a main beam comprised of three components: a front and rear beam, connected by a cast gooseneck. This design allowed for high flexibility in manufacturing, but did not rank well in terms of weight and costs. In addition to being heavier, the stresses on the cast gooseneck were determined to be too high. Also, C-beams needed to be connected to the gooseneck, which interfered with the connection of other components and mechanisms.

The second design option was a main I-beam with common elements for the rearmost and front components. This design option required more components than the first option, but was clearly much lighter and cost efficient.

I Beam Chassis

2D and 3D CAD parametric models run on the full range of sizes

SSAB Product Engineering also provided Zamarbú with 2D and 3D CAD parametric models covering the full product range, in all of its various lengths.

The Product Engineering team had weekly update meetings with Zamarbú. These meetings included the in-depth discussion of component designs. Product Engineering provided several design iterations until all criteria were met and approved by Zamarbú. As part of this process, Product Engineering also delivered several FEM simulations for the most restrictive load cases, to analyze both torsion and, at the start of tipping, flexion.

FEM Chassis tipping

Zamarbú also leveraged Product Engineering’s expertise for determining manufacturing feasibility and cost analysis for each component. Steel sheet thicknesses were standardized for all components – not only reducing inventories and costs, but also optimizing nesting during cutting operations.

Lightweighting semi-trailer chassis with high-strength structural steel

Product Engineering specified SSAB Strenx^® 700MC Plus high-strength structural steel for the entire chassis, which allowed for tighter bending radii, enabling both higher static stiffness and fatigue resistance. All chassis components were designed to excel in performance, while being as lightweight as possible. Lightweighting included optimizing the component thicknesses – and even details such as cutting chassis holes in triangular patterns.

Complete Chassis 7500

Product Engineering also designed the components to be easy to manufacture on Zamarbú’s existing machinery and straightforward to assemble.

The Product Engineering-developed and engineered designs, with detailed production and assembly documents, enable Zamarbú to make any length chassis – from 7500 mm to 11500 mm – from the same design, and with a high share of common components across all sizes.

In less than 3 months, Zamarbú goes-to-market with range of lightweight steel tipping semi-trailers

Zamarbú’s new line of semi-trailer chassis for tippers is practically same weight as chassis made in aluminium – and they take approximately the same amount of time to assemble. Unit costs, however, are 8% lower compared to an aluminum chassis. And in only 3 months’ time, Zamarbú’s product offerings have been greatly expanded to take advantage of the growing market for lightweight steel semi-trailer chassis for tippers.

Chassis portfolio