A very warm welcome (Arial, 24-point bold font) Discover what's under the surface (Arial, 20-point bold font in italics)
HORN Technology Days 2015 Technical presentation: Wear parts - Reducing costs through the use of high-performance carbide rods Speaker: Mark Turnidge 2
What is carbide? A composite manufactured by means of powder metallurgy and consisting of a hard material (tungsten carbide, WC) and a metallic binder (cobalt, Co) Hard material ensures: Hardness Wear resistance Metallic binder ensures: Toughness WC Co WC Micrograph of WC-Co carbide 5 µm 3
Carbide production Tungsten oxide Reduce Granulated material Tungsten Carburising Spray drying Tungsten carbide Grinding Co (Ni,Fe) Mixing TiC, TaC, NbC Cr 3 C 2, VC, MoC 4
Granulated material Carbide production Production of feedstock Shaping Pressing Injection moulding Presintering Final sintering Green part machining Final machining -Eroding -Turning -Grinding -Polishing -Coating 5
Carbide shaping The aim of the shaping processes is to create a product with a shape that is close to its final form. During injection moulding, parts with rod or pipe-shaped cross-sections are manufactured. Pressing aids are mixed with the powder and it is worked, plasticised and granulated (feedstock). The mass is pressed through an extrusion nozzle at high pressure. During cold isostatic pressing, powder is poured into an elastic mould and pressed into a moulded shape at a high level of fluid pressure. The moulded shapes (green parts) are then machined mechanically using standard processes (turning, milling, etc.) until they reach the desired shape (step drill/tree milling cutter, etc.). 6
Usage properties of carbide are determined by - Hardness - Bending strength - Fracture toughness Properties of carbide grades are determined by - Binder content ( % ) - Grain size ( coarse, medium, fine, superfine ) - Binder type ( Co, Ni ) - Composite carbide content (TiC, TaC, NbC ) 7
The binder content affects: The grain size - Hardness - Bending strength - Fracture toughness - Abrasion resistance - In some cases, corrosion resistance - Hardness - Bending strength - Fracture toughness - Abrasion resistance - Heat resistance 8
The binder type affects: - Corrosion resistance - Magnetic properties - In some cases, hardness, bending strength and toughness The composite carbide - Hardness - Bending strength - Fracture toughness - Abrasion resistance - Heat resistance - In some cases, corrosion resistance 9
Carbide properties as a function of Co content and WC grain size High degree of hardness (= wear resistance) Cobalt content Grain size Cobalt content Bending strength Fracture toughness Cobalt content Grain size Grain size 10
HV30 [N/mm²] Hardness 3000 2500 2000 1500 1000 500 0.5 µm 0.7 µm 1-2 µm 3 µm 0 2 4 6 8 10 12 14 16 Co [%] 11
[Mpa] 4500 4000 3500 3000 2500 2000 Bending strength < 0.5 µm 0.7 µm 1 µm 1500 6 9 12 15 Co [%] 12
[MN/m 3/2 ] 32 27 22 17 Fracture toughness (K IC ) 3 µm 1-2 µm 12 7 0.7 µm 0 4 8 12 16 20 Co [%] 13
Super < 0.5µ Fine 0.5 µ - 1.0 µ Medium 1.0 µ - 3.0 µ Coarse > 3.0 µ 14
The most important variables for optimising properties, in relation to the application, are as demonstrated the binder content and the grain size. To satisfy high toughness requirements, the binder content may be up to 12% in the case of rods and blanks for precision tools. The highest degree of hardness and wear resistance is ensured by a low binder content of 6% and a fine to superfine grain size. Grain sizes vary between superfine and fine in order to ensure a cleanly ground cutting edge as well as cutting edge stability. 15
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Conclusion Every process has its own unique demands, whether it s hardness or wear resistance or toughness or corrosive. No two applications are exactly the same. The performance and durability of any tools is in the details and all you have to do is tell us what they are. We will listen to your needs and develop or recommend a carbide grade that works for you, that could very well turn out to be simpler, better and less expensive. 17
Conclusion Reduce your costs through the use of high-performance carbide rods of HORN. We work one-on-one with customers all over the world to meet their individual application challenges and obstacles. So go ahead, please ask us. We are there for you. If we don t know the answer to your question, we will find the answer. 18