KLEEMANN blow bars


Crushing tools for impact crushers

KLEEMANN impact crushers can be used for a wide range of applications. From classical processing of natural stone and the recycling of high volumes of building rubble to quarrying and mining applications – the focus is always on two particular challenges: increasing utilization rates and lowering operating costs. The crushing tools are subject to varying degrees of wear depending on various influencing factors.


Highlights

Genuine KLEEMANN blow bars offer much more than just the right sizes. The materials used, alloying elements and the entire casting process are important foundations for a reliable crushing tool. KLEEMANN impact crushers can be used for a wide range of applications. From classical processing of natural stone and the recycling of high volumes of building rubble to quarrying and mining applications – the focus is always on two particular challenges: Increasing the service life of blow bars and lowering operating costs.

Utilisation factor
Symmetrical construction
Drilled holes
Chamfering
Clamping surface
Guide to choosing the right blow bars

The cost-effective usage of blow bars is influenced by a number of factors. e.g. the feed material, rotor speed, moisture content, feed size and the crushing ratio. Determine the ideal blow bar for your specific application with the aid of the following points. Access a choice of various different blow bars and begin your crushing project with economically optimised crushing tools.

Questions about the
selection of the right blow bars for your applications:
  • What material do you want to crush (e.g. concrete rubble)?
  • How would you classify the feed size (e.g. largest grain size 600 mm)?
  • How would you rate the abrasiveness of the material?
  • Does the material contain uncrushable pieces?
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Determine the right blow bars for your application with the help of the following overview:
Check the availability of the blow bars you find for specific crusher types:
Recommended application for blow bars
Version Material Kleemann designation Properties Recommended applications
Monolithic blow bars Manganese steel Monomangan Manganese steel is used when high impact resistance and elasticity are essential prerequisites. Sufficiently high impact force consolidates the manganese steel of the blow bar (cold consolidation) and thus reduces wear.
  • For very low abrasiveness, e.g. limestone
  • For very large feed sizes
  • In the case of a high proportion of uncrushable objects in the feed material, e.g. scrap iron
Martensitic steel Mono martensitic This steel unites hardness and impact resistance for cases where the use of chrome steel would lead to breakage. Furthermore, martensitic steel blow bars have a longer service life than manganese steel blow bars when processing abrasive materials.
  • Building rubble
  • Blasted natural stone (quarry stone)
  • In the case of large-sized feed material (dependent on the geometry of the crusher inlet)
Chrome steel Monochrom Chrome steel is characterised in particular by its extreme hardness and has the advantage of being particularly wear resistant. Chrome steel is the best choice for applications where manganese steel or martensitic steel blow bars would wear out too quickly.
  • Recycling of building rubble and concrete with low to medium iron content
    • Maximum feed size 500 mm with crushability of < 40%
    • Maximum feed size 400 mm with crushability of < 30%
  • Medium hard to abrasive natural stone (quarry stone)
  • Asphalt
Metal matrix composites Martensitic steel with ceramic insert Martensitic steel - ceramic I The blow bar consist of a martensitic steel body internally reinforced with ceramic inserts. This composite material combines the hardness of ceramics with the mechanical properties of steel and has a 2 to 4 times longer service life compared to blow bars made from single alloys.
  • Recycling of building rubble with low to medium iron content
  • Concrete
  • Natural stone
Martensitic steel-ceramic II
(MartPower
MartXtra) 		The cast ceramic insert is deeper and more elongated. This ensures that the impact edge remains intact until completely worn down, extending the service life compared to conventional MartComp/MartXpert blow bars for abrasive applications.
  • Recycling of building rubble with medium iron content
  • Concrete
  • Natural stone
  • Asphalt
Chrome steel with ceramic insert Chrome steel - ceramic
(ChromComp
ChromXpert) 		The combination of the chrome steel body and ceramic inserts ensures a constant wear profile when processing highly abrasive pre-crushed materials as encountered especially in gravel pits and quarries.
  • Secondary crushing stage for extremely abrasive natural stone or river gravel
  • Asphalt with smaller feed size (smaller than 350 mm)
  • Asphalt with smaller feed size (smaller than 350 mm)
Checking the blow bars

The correct assessment of blow bar wear is a prerequisite for the cost-effective operation of an impact crushing plant. Replacing blow bars at the right time guarantees successful operations and significantly reduces operating costs. It is common for blow bars not to wear evenly across their full width. The wear limit is reached when the specified minimum wear dimension is no longer fulfilled at any one point on the blow bar.

The blow bars are symmetrically shaped and can therefore be turned after the wear limit has been reached:
  • Open the impact crusher as described in the instruction manual.
  • Switch off the plant components and the diesel generator.
  • Secure the rotor.
  • Visually check the wear limits on all blow bars.
  • Visually check the blow bars for cracks and breakouts.
  • Turn around or replace the blow bars as necessary.
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Please note that changing the blow bars too late will lead to increased wear on the rotor and the blow bar mountings. The consequences of this are costly subsequent damage and prolonged machine downtimes. Apart from the necessary renewal of the rotor armouring (hard facing), the clamping wedges for blow bar mounting are frequently also damaged.

Heavily worn blow bar

The wear limit is 15–20 mm

General notes on the replacement of blow bars:

  • For preliminary cleaning of the crushing chamber, it is recommended to fill the crusher with clean, coarse material for several minutes.
  • Installation and removal of blow bars must always be carried out by a minimum of two persons.
  • Always use suitable lifting gear and tackle.
  • Completely extend the crusher gap before installing new blow bars to ensure that replacement in order to avoid a collision between the blow bars and the toggle after installation.
  • Improper replacement of blow bars can lead to serious damage to the crusher.
  • Operate the rotor only when the blow bars have been correctly installed.
  • Always replace blow bars one after another.
  • Replace all blow bars even if only one of them is broken.
  • Before making final adjustments, briefly run the machine at its highest rotational speed (for the EVO 1800 rpm), then check the wedge clamps and, if necessary, tighten any loose bolts and screws.
  • Always use conical spring washers with the clamping bolts of tensioning devices. Re-tighten the clamping bolts after approx, two operating hours.
  • Caution: An unsecured rotor can lead to serious injuries. Therefore: Always observe safety regulations and instructions!

A detailed description of how to replace blow bars can be found in the instruction manual for the respective machine.

Wear due to delaying the replacement of blow bars too long

Peripheral wear on the rotor resulting from wear on the outer face of the blow bar

Facts

Blow bar components

In addition to their shape, the blow bars benefit from the properties of their respective components:

  • The chamfering of the impact edge, aligned to the rotor's rotational direction, ensure longer crushing effectiveness and better crushing performance for a prolonged period of time.
  • The holes on the side ensure easy and quick handling when turning or exchanging the blow bar.
  • The lug on the back assures ideal transfer of the centrifugal forces to the rotor (C-shape only).
  • The clamping wedges fix the blow bars in position and ensure that they rest correctly on the contact surfaces of the rotor. The machined clamping surface provides a precise fit over the entire length with a reduced risk of breakage.

Depending on the crusher size and application, KLEEMANN impact crushers are fitted with one of a selection of different rotors. The number of blow bars installed depends primarily on the crushing chamber geometry and its corresponding intake behaviour. In the case of smaller crushing chamber geometries (< 1100 mm intake width and a rotor diameter of < 1100 mm), rotors with two or three blow bars are used. Larger crushing chamber geometries (over 1,200 mm with larger rotor diameters > 1,200 mm) are equipped with rotors featuring four blow bars to increase the operational spectrum. In the majority of applications, these rotors are operated with two high blow bars and two low blow bars.

Blow bar geometries

The crushers use different blow bar geometries, depending on the model series.

KLEEMANN offers three different shapes:
X-shape, S-shape and C-shape.

X-shape

MR 100 series
MR 122 series
MR 150 series
MR 170 series

Detail view

S-shape

MR 130 series

Detail view

C-shape

MR 110 EVO series
MR 130 EVO series

Detail view
Blow bar metallurgy

In practice, different materials for manufacturing blow bars have become established standards. These include manganese steels, steels with martensitic structure (referred to in the following as martensitic steels), chrome steels and Metal Matrix Composites with ceramics (MMCs), in which the various types of steel are combined with special ceramics.

Manganese steel

Martensitic steel

Chrome steel

Martensitic steel with ceramic insert

An increase in the steel's wear resistance (hardness) is generally accompanied by a reduction in the impact resistance or load bearing capacity of the material. In order to simultaneously ensure optimal utilisation rates and low risks of breakage, the appropriate blow bars must be selected according to the material to be crushed, the non-crushable content and the feed size.