Hardox is a very wear-resistant sheet steel. Hardox is manufactured and exported worldwide by the Swedish company SSAB, which developed the first modern wear-resistant sheet in 1974. As this steel wears slowly, even under large mechanical loads, Hardox is also called wear plate. This fact is especially interesting for companies that quarry gravel and sand as, for example, excavator buckets or dump truck bodies made from HARDOX last fast longer.
This material is characterised by its uniform evenness, high hardness and high strength. The weight of the constructions produced is reduced significantly. This is possible, because the material’s high strength enables thinner metal sheets to be used. HARDOX does not lose its impact resistance, even at low temperatures. As these sheets and plates have very good welding and machining properties, subsequent repairs of wearing parts is not a problem.
By choosing Wear plates with higher hardness levels it is possible to reduce the weight of a construction by up to 15 %. An increase by 50 Brinell extends the life of the workpiece by 50 to 80 percent.
HARDOX is a quenched and tempered steel. Hardening (quenching) and tempering sheets and plates produces the outstanding properties, which can be lost if worked incorrectly. Therefore precautions and protective measures must be taken when bending, welding, cutting and grinding.
Rime works Hardox!
Rime has machines that are particularly suitable for working HARDOX. We undertake to produce wear plates in the best possible quality and to deliver with the best service.
In order to achieve this, we build on the technical expertise of our employees in our production department. Contact us if you need wear-resistant parts made from Hardox! We will be pleased to advise you!
Hardox – bending and folding
Wear plates such as Hardox with high strengths can be cold worked by bending and roll bending. Due to the higher strength, however, factors must be applied to ensure that the bending and roll bending can be carried out with the best possible quality.
Rules of thumb
- The bending force to be applied increases with the increasing strength of the material.
- Metal sheet and plate with higher strength springs back during bending more than normal steel sheets and plates.
- The harder and stronger the metal sheet or plate is, the larger the punch radius and die width that have to be chosen.
Sheet metal surface
Defects and rust deposits can reduce flexibility. Therefore, before bending and folding Hardox such defects must be ground off. During the bending process the machine operator should stand to the side of the press brake, as the high forces that act on the high-strength steel plate can cause cracks in the surface and parts of the workpiece surface can shoot off in the bending direction.
A punch radius is used for HARDOX 450 and 500 which is at least four times the plate thickness.
In the case of softer wear plates the material springs back by between 10 and 18 %. With harder steels the value can lie between 12 and 20 %. For this reason, each material is over-bent slightly, in order to balance out the spring back by the corresponding number of degrees. At Rime we are able to simulate the bending of sheets and plates at the machine. In this way we can set the optimum stroke depth of the punch.
HARDOX wear plates can be machined with high-speed or sintered carbide drills. The choice depends on the available machines. High-strength steel sheets and plates are extremely resistant, which also applies to machining with tools. The resistance of the material can cause severe vibrations during drilling. Therefore, damage to the drill bit or machine is possible.
The following measures are recommended to avoid vibrations and damage:
- small distance between the drill bit and machine pillar
- clamp the workpiece securely
- do not insert any wood under the workpiece
- Use short drill bits and machine spindles, in order to minimise the distance between the tip of the drill and the cantilever arm
- Relax the drill just before penetrating the material, by switching off the feed briefly. This protects the drill against damage.
- Use plenty of cooling liquid (cooling liquid [l/min] ~ drill bit diameter [mm]
HARDOX sheets and plates can also have Threads made in them. However, 4-edged drill bits should be used to drill threads, as these are better able to absorb the high torques involved. We recommend use of thread oil to facilitate the drilling process.
Today this steel is available in the grades: Hardox 400 / 450 / 500 / 550 / 600 / HiTuf or even Extreme. These differ with regard to their hardness, toughness, flexibility and the possibility of welding.
A comparison of different Hardox grades:
- Sheet thickness 3 – 130 mm
- Brinell hardness 370 – 430
- Sheet thickness 3 – 80 mm
- Brinell hardness 425 – 475
These are used if a combination of high wear resistance and good cold working properties is required. These sheets and plates are used, for example, to produce dumper trucks, screens, chutes, rock crushing machines, excavators and conveyors. These steel grades are characterised by their very good weldability.
- Sheet thickness 4 – 32 mm
- Brinell hardness 470 – 530
- Sheet thickness 32 – 80 mm
- Brinell hardness 370 – 430
- Sheet thickness 10 – 50 mm
- Brinell hardness 525 – 575
These are used if high requirements are necessary with regard to wear resistance.
These sheets and plates are used, for example, to make conveyors, blades and cutters, buckets for excavators, gear wheels and crushing plants.
The material must not be heated above 250°C, as otherwise the sheet or plate can lose its outstanding properties.
- Sheet thickness 8 – 50 mm
- Brinell hardness 560 – 640
This is used if high requirements are necessary with regard to wear resistance. This sheet / plate is used, for example, to make chutes, crushers, hammers and shredders.
- Sheet thickness 40 – 120 mm
- Brinell hardness 310 – 370
This is used if extremely high requirements are necessary with regard to toughness (ductility) and wear resistance. It is used to make, for example, demolition tools and cutting edges.
- Sheet thickness 10 mm
- Brinell hardness 700
- Sheet thickness 25 mm
- Brinell hardness 650
This is used if extremely high requirements are necessary with regard to wear resistance.
This sheet / plate is used, for example, to make hammers, crushers, wear protection plate (armour plate) cutting equipment.