Hammer teeth, also known as carbide bars or sand-making bars, are indispensable wear-resistant components in vertical impact crushers. They are fixed on the crusher’s material throwing head by means of bonding or insert welding, and works based on the rock-on-rock crushing principle. This component plays a crucial role in the preparation of manufactured sand and gravel aggregates in various industries such as mining, sand and gravel, cement, metallurgy, and hydropower engineering.

Demand Situation of Cemented Carbide Hammer Teeth
As a key raw material for concrete production, the demand for sand and gravel remains high in the construction industry, and it even tends to surpass that of water, becoming an important resource for global mining and trading. According to a report by the United Nations Environment Programme, it is predicted that the global demand for sand and gravel will continue to grow at an average annual rate of 5% in the future. Against this backdrop, cemented carbide hammer teeth not only face a broad market development space but also bear increasingly higher market usage requirements.

As the core wear-resistant component of manufactured sand equipment, cemented carbide hammer teeth play a crucial role in the impact crushing process of stone materials. With the vigorous development of the manufactured sand industry, the demand for cemented carbide hammer teeth has been increasing year by year, with the annual demand stably standing at around 400 tons, and the growth momentum remains unabated.

 

Type Design of Cemented Carbide Hammer Teeth

The design of hammer teeth varies greatly according to the properties of the crushed materials (hardness, brittleness, viscosity, etc.) and the type of crusher (jaw crusher, impact crusher, hammer crusher, etc.):

 

Hammer Teeth for Hammer Crushers

They are mostly distributed in a single row or multiple rows at the end of the hammer head. The tooth shape is relatively thick, suitable for medium and low hardness materials such as coal and limestone. After the tooth tip is worn, it can be repaired by turning over or surfacing welding.

 

Hammer Teeth for Impact Crusher Blow Bars

The toothed structure is often integrally formed with the blow bar, and the tooth edge is sharper, which is suitable for crushing concrete blocks, ores, etc. It crushes materials by using the impact force of high-speed rotation and the shearing force of the teeth.

 

Tooth Plate Teeth for Jaw Crushers

Although they do not belong to “hammer heads”, the principle is similar – the tooth plates on the movable jaw and fixed jaw are in a staggered tooth shape, which crushes hard rocks through extrusion and shearing. The tooth shape needs to be wear-resistant and not easy to block.

 

Shapes of Cemented Carbide Hammer Teeth

Straight long strips: This is a relatively common shape, generally with a long length. The cross-sectional shape can be regular shapes such as rectangles and squares, as well as irregular shapes such as trapezoids. The straight long sand-making strips are suitable for various sand-making equipment, can provide stable grinding and crushing effects in the sand-making process, and their length, width, and thickness can be adjusted according to different sand-making needs.

 

Arc-shaped long strips

For example, the R-series arc-shaped wear-resistant carbide strips used in the impeller head of sand making machines. Compared with the slender shape, this arc-shaped sand strip is more stable when impacted, less likely to pop out and damage the machine body. Moreover, under the same material conditions, it increases the effective working area, which can extend the service life of the impeller head and reduce production costs.

Parabolic teeth

They are mainly used as side teeth and center teeth of DTH (Down-the-Hole) drill bits, and are suitable for rocks with medium abrasiveness and relatively high hardness. Their shape is parabolic, which enables them to better adapt to the characteristics of rocks during the crushing process and reduce tooth wear.

Trapezoid Teeth

Trapezoidal sand-making machine carbide bars usually consist of a horizontal crossbar and a vertical vertical bar, with a shape similar to a trapezoid. This shape of sand bar can provide a unique crushing and grinding method during the sand-making process, and is suitable for some specific sand-making processes and material crushing needs.

Core Functions of Cemented Carbide Hammer Teeth

Enhancing crushing capacity
The toothed structure can concentrate impact force through sharp tooth tips, just like “teeth crushing food”, making it easier to tear and crush materials with high hardness or strong toughness (such as ores, construction waste, metal scraps, etc.). Compared with smooth hammers, it can reduce the impact area, increase the pressure per unit area, and improve crushing efficiency.

Controlling material particle size
The design of parameters such as tooth spacing and height can cooperate with the structure of the crushing cavity to control the particle size of the crushed materials (for example, finer crushing requires denser teeth, while coarser crushing can use sparse teeth).

Guiding material flow
The arrangement angle of some teeth can guide the movement trajectory of materials in the crushing cavity, avoid material accumulation, and ensure the continuous and stable crushing process.

 

Chinese Standards for Cemented Carbide Hammer Teeth

In order to standardize industry requirements and ensure product quality, China has issued YS/T 1610-2023 “Cemented Carbide Hammer Teeth”. The introduction of this standard will undoubtedly fill the gap in the industry and inject new vitality into the development of the industry. The standard was officially released on December 29, 2023, and came into effect on July 1, 2024. It covers various aspects such as technical requirements, test methods, and inspection rules for cemented carbide hammer teeth, and also specifies in detail the classification, model designation rules, and chemical composition of the products. This article will briefly sort out this Chinese product standard.

 

Physical Performance Standards

Considering that the strength requirement for hammer teeth is relatively low, this standard mainly evaluates product performance with reference to magnetism, hardness, and density. Cemented carbides with different properties can be obtained by adjusting the Co content, trace elements, and the proportion of tungsten carbide powder raw materials. Generally speaking, as the Co content increases, the strength and toughness of the carbide will increase, but the hardness will decrease accordingly. Therefore, the physical properties of the products should meet the requirements specified in Table 1, and special requirements need to be jointly agreed upon by both the supplier and the buyer.

Metallographic Structure

Porosity, defined as the ratio of the pore area to the total area within the field of view, is a crucial indicator for evaluating the quality of cemented carbides. During the inspection of cemented carbides, pores are classified into three categories: Type A pores (size less than 10 μm) and Type B pores (size between 10 μm and 25 μm). The percentage content of these pores must be controlled within specific limits to prevent fractures during use, thereby ensuring the service life of the product. Additionally, Type C pores, also known as carburized and graphite phases, should have a carburization content of less than 2%, with no surface darkening that could affect the customer’s requirements for gluing or welding. It is worth noting that the metallographic structure of cemented carbides adjusts correspondingly with changes in Co and WC content.

Dimensional Tolerances and Geometric Tolerances

Dimensional deviation refers to the variation obtained when measuring different points of the same dimension with the assistance of a vernier caliper. These deviations must be controlled within the ranges specified in Table 2 to ensure the dimensional accuracy and quality of the product.

 

Geometric Tolerances of Products

Hammer teeth products are mainly assembled by welding or gluing, and the requirements for other geometric tolerances are not strict, with only the bending degree needing to be controlled. Bending degree is an important factor affecting assembly difficulty, so it is necessary to ensure that the bending degree of hammer teeth does not exceed 5mm, and that of non-working surfaces does not exceed 8mm.

 

Appearance Quality

The product surface should be sandblasted to remove dirt and sintering traces, and there shall be no visually visible cracks, delamination, or under-pressing defects. Mold sticking with a height not exceeding 1mm is allowed, as well as edge chipping with length and width both not exceeding 0mm and depth not exceeding 6mm. In addition, the product surface can have pits with length not exceeding 0mm and depth not exceeding 2mm.

 

özet

The formulation of the standard YS/T 1610-2023 “Cemented karbit Hammer Teeth” marks that such products have clear specifications and acceptance criteria. During the compilation of the standard, we extensively collected technical requirements from domestic and foreign customers, and combined with the actual production of domestic enterprises, unified the product performance parameters. The release and implementation of this standard will effectively improve the overall quality of cemented carbide hammer teeth products, raise the industry access threshold, and realize the rational utilization of resources and reduction of waste.