The Material Handling Industry (lifting, rigging, mooring, towing…) is moving rapidly to forge solutions. Abandoning other alternative technologies such as casting, plate plasma-flame cutting, additive manufacturing …
The main difference between forging and other alternative steel processing technologies is that the forging is mechanically advanced after solidification. Thanks to this mechanical performance, inner steel structure is fine, stringy & aligned, creating a strong structured net/mesh.
With this grain flow in the steel part and considering applications in which the principal applied stresses, forgings offer lot of advantages:
- Superior strength of final part.
- Structural integrity and product reliability.
- Reduced process control and inspection requirements.
- More predictable response to heat treating.
Hooks applications are not different; forged and cast hooks are available in the market. Previous DIN 15400 specification talks about this, noting the influence that the casting process, as compared to forging, has on the properties of hooks and shall be taken into consideration.
The new EN 13001-3-5 will consider both options however it points out and highlights main differences, clearly defining that some material factors within cast hooks reduce the static limit design force as well as their fatigue strength.
Definitively, if a dependable hook and a safe lift is our goal, the forged option is the best choice. In addition, the high-strength properties of the forge process could be used to reduce sectional thickness and overall weight without compromising final part integrity. Of course, never forgetting that when using a hook, the design engineer needs to evaluate all loading characteristics and conditions.
WHY FORGED: REASONS TO MOVE
Advantages of forging versus other technologies (casting, plate flame-plasma cutting, 3D-printing …)
- Grain size: during forging process grain size is refined.
- Grain orienting (fiber): during forging process grains are being aligned, creating a stronger netting structure.
- Less defects: thanks to forging process, alloy segregations and imperfections are minimal /decreased
- Less repair maintenance Cost: thanks to a cleaner structure, no cavities and less surface indications during lifetime.
- Longer life spam: from fatigue strength perspective (dynamic factor).
* First two advantages are the main reasons why forged product is safer than non-forged. Thanks to a stronger & cleaner netting structure, stem failure and sudden break is minimal. Forged structure is predictable, as it’s noticeable when something is wrong as its deformation is visually evident to identify. Non forged products can fail abruptly without warning.
* The third advantage is the main reason why forged products have a higher guarantee than non-forged products.
* Last two advantages are the main reasons why forged products are an efficient & competitive option considering entire lifetime of the product.
THE KEY FACTOR: DESIGN STAGE
It’s well known that moving from casting to forging is not as simple as sending the same drawing design to a different technology foundry. The scope of this new policy and market trend is deeper, and designers need to be involved to follow this market trend creating safe products to be:
FEASIBLE: design a compact product reducing sizes and keeping safety factors, to proof test the hooks separately in a bench prior to crane test.
COMPETITIVE: reducing weights, increasing safety factors and life time.
EFFICIENT: reducing maintenance cost, increasing life spam of rigging accessories.
Even if cost price during the purchase phase is not comparable, the whole market should consider the following: forging is a stronger and safer option, There is less repair/maintenance cost during the life spam, which is longer with forged. Hook failure is minimal & predictable and replacement time is longer than using alternative technologies.