Steel and steel-related industrial processes have significantly transformed the modern world. Steel has not only become an indispensable material in the construction of global infrastructure and industry but has also created new industrial markets and requirements. Today, steel is still one of the materials that will continue to shape the development of products and structures.
Over the years, the company SIJ Ravne Systems has worked together with partners to develop advanced tool steel for the most demanding industrial applications.
Wood veneer knives with pressure bars are used to peel different types of wood. Softwoods, such as pine and spruce, are the most difficult woods to peel. After several years of testing in different companies, we have concluded that this is primarily due to old knots in the tree trunks. In conifers, resin accumulates in the lower part of the broken branch, so the branch breaks off some distance away from the trunk itself (usually 10-20 cm). The trunk then continues growing around the dead branch stump for decades, causing the formation of a "floating" knot. When peeling the wood to create veneer, a problem arises when the knife hits the old knot, which is surrounded by brittle, dried-out resin. When the blade hits the knot, a piece of the cutting edge is chipped away. Solid knives can lose up to 1 mm or more. Although removing 0.25-0.5 mm of the knife edge restores its sharpness, it does mean that solid knives wear out up to twice as fast or that their working life is halved.
With the development of our advanced tool steel – compound – inlay and application for veneer knives for softwoods, we can significantly increase the durability of our knives. In addition, our new hardening and straightening process further improves the properties of our knives. This significantly increases a lifespan of knifes and reduces interruptions in the veneer production process. Previously, the knife blade was deformed when it hit a knot, resulting in chipping or shearing of the contact material. In turn, this affected the consistency of the veneer's thickness and reduced the length of veneer that could be cut from the trunk. Other problems associated with this were an increase in the use of glue (plywood), additional corrective measures (sewing veneer) and a higher reject rate. By combining new technologies, we believe we can reduce the frequency of the defects described above and also enable knives to operate in extreme conditions for 50 percent longer than they have previously.
Our new advanced laser cladding technologies have been applied to improve the pressure bars which are a critical element of the peeling system, enabling us to offer our customers a truly "cutting edge" solution.
Basic technical data:
Key features of the tool steel developed for veneer knives:
- Hardness = 61 HRc (or HV30 = 770)
- Tensile strength > 2100 MPa
- Impact toughness > 8 J/mm2
- Working life = 8 hours
- Cutting speed: up to 400 m/min
- Microstructure: residual austenite level < 0.5 %
Key features of the pressure strip:
- Base material - selected structural steel (chemical composition: C, Si, Mn, S, P)
- Welded alloy - special weld-on material grade (chemical composition: Co, Cr, W, C, Fe, Ni, Mn, Si)
- Welded alloy is resistant to wear, tannins and similar elements in wood