Cutting tools are key components of low-noise, controlled separation technology in demolition, deconstruction, and on-site metalworking. In the context of Darda GmbH, they primarily comprise shearing and separating inserts on hydraulic attachments such as concrete demolition shears, steel shears, Multi Cutters, and tank cutters. They enable the clean separation of reinforcing steel, sections, sheet metal, and pipelines, complement rock and concrete splitters in selective deconstruction, and support low-emission, low-vibration working methods in sensitive environments.
Definition: What is meant by cutting tool
A cutting tool is a tool with one or more cutting edges that separates materials by shearing, wedge action, or a combination of compression and tension. In deconstruction practice, these are robust, wear-resistant blades and knife inserts operating in hydraulically actuated jaws or shears. Typical representatives in the Darda GmbH portfolio are the cutting inserts on concrete demolition shears, blades on steel shears, universal cutting jaws on Multi Cutters, as well as special cutting heads on tank cutters for low-spark cold cutting. In contrast, rock and concrete splitters act primarily by splitting; both principles—cutting and splitting—are frequently combined in professional deconstruction.
Design and geometry of cutting tools
Cutting tools for demolition and deconstruction tasks are designed for high edge stability, toughness, and repeatable cut quality. Their geometry differs from fine machining tools: the wedge angle is larger, the clearance angle is reduced, and the cutting edge is rounded to prevent chipping. The cut is often progressive—the blades are offset or profiled so that the material cross-section is successively notched and sheared. On concrete demolition shears, cutting inserts are integrated into the crushing jaw: the tooth fields first generate cracks in the concrete, then the blades cut the exposed reinforcement. Steel shears use counter-guided knives with a defined cutting gap to shear sections, sheet, or rebar in a controlled manner. Tank cutters rely on cold-working cutting heads that separate with high hydraulic force without spark-intensive heat input.
Cutting mechanics in steel and reinforced concrete
When separating metallic materials, the shearing process dominates: two blades create local overlap, the material fiber undergoes plastic deformation, and is severed along a shear plane. Important parameters include cutting gap, overlap, edge radius, and guide stiffness. In reinforced concrete, the cover layer is first broken by compressive and tensile stresses; reinforcement is then cut in a targeted manner. Concrete demolition shears combine these operating principles in a single work step. In many projects it is efficient to first use rock and concrete splitters to relieve stresses and reduce volume, and then cut the exposed reinforcement with cutting tools.
Hydraulics, power transmission, and kinematics
Hydraulic power units provide pressure and flow rate that are converted into cutting force and speed via cylinders and linkages. High pressure delivers high cutting forces; sufficient flow rate determines cycle time. Link levers often produce progressive kinematics: as the jaws close, force rises while speed falls—ideal for the force-intensive breakthrough at the end of the cut. Precise blade guidance, zero-backlash bearing points, and correctly adjusted stops are crucial for a uniform cut line and long tool life.
Materials, heat treatment, and service life
Cutting inserts are generally made of high-strength, tough tool steels with a tempered core and a wear-resistant surface layer. The surface is optimized for hardness and abrasion resistance, while the core remains tough against impact loads. Typical wear patterns include edge rounding from abrasion, micro-chipping from particles in concrete, and plastic deformation under overload. Careful heat treatment, error-free fastening with predefined tightening torques, and properly mating seating surfaces are decisive for service life. Depending on the design, cutting edges can be indexed or replaced; regrinding is possible as long as geometry and the hardened zone are retained.
Fields of application in deconstruction and extraction
Concrete demolition and special deconstruction
Cutting tools sever reinforcing steels, embedded components, pipelines, and beams. Concrete demolition shears with integrated cutting edges reduce components and cut reinforcement in one sequence. In sensitive areas with strict limits on noise and vibration, shearing often replaces noisy cut-off grinders.
Strip-out and cutting
In selective deconstruction, cable trays, piping, ventilation ducts, and light-gauge profiles are cold cut. Multi Cutters and steel shears deliver controlled cuts with low spark generation and minimal secondary damage to adjacent components.
Rock excavation and tunnel construction
Rock and concrete splitters are the primary tools here. Cutting tools are additionally used for severing anchor rods, spiles, protective linings, or steel components in the support area.
Natural stone extraction
Extraction is predominantly by splitting. Cutting tools are used to cut metal anchors, attach lifting eyes, or adapt auxiliary structures.
Special application
Tank cutters enable low-spark, cold cutting of vessels, pipelines, and sheet metal—e.g., for work with elevated fire load. The cutting heads are designed for controlled cut quality and minimized emissions.
Types of cutting tools in the context of Darda GmbH
- Cutting inserts on concrete demolition shears for cutting reinforcing steel after the concrete has been broken.
- Steel shears for sections, sheet, and solid stock.
- Multi Cutters as universal, shearing separation tools in deconstruction.
- Combination shears with interchangeable jaw sets for varying materials.
- Tank cutters for cold, low-spark cutting in sensitive zones.
Selection criteria for the right cutting tool
- Material and cross-section: reinforcing steel, sections, sheet, pipelines; strength and wall thickness determine the required cutting force.
- Accessibility: component geometry, required gripping space, obstructions; jaw opening and jaw shape must fit.
- Emission requirements: noise, vibration, dust, sparks; in interior areas cold cutting is often preferred.
- Carrier machine and hydraulics: available pressure/flow rate, weight, reach.
- Process chain: combination with rock and concrete splitters for stress reduction and material separation.
- Economics: service life of the cutting edges, changeover times, spare parts availability, and cutting speed.
Operation, cut quality, and working method
For high cut quality, a controlled lead-in is important: the workpiece is securely clamped, the cut begins near the stronger jaw zone, and is continued progressively. For reinforcement embedded in concrete surfaces, first open the concrete with the concrete demolition shear to expose the bars and minimize lateral loading of the cutting edges. On sections, an offset bite reduces the required peak force. Repeated opening and re-engaging prevents edge crushing. Smooth guidance avoids jamming, reduces heat input, and protects the blades.
Maintenance and wear management
- Regular visual inspection of cutting edges for chipping, cracks, and uneven wear.
- Check fastening bolts for correct preload; retighten as required per manufacturer specifications.
- Keep guides and bearing points clean and suitably lubricated; minimize play.
- Index or replace cutting inserts in good time before geometry deviates beyond limits.
- Careful handling: no levering, stamping, or bending with cutting edges; no overload beyond approved material thicknesses.
Safety, environmental, and legal aspects
Cutting work requires clearly defined work areas, secure footing, and protection against pinch and shear points. Personal protective equipment, barriers, and a low-spark working method are essential especially on utility lines and in fire-sensitive zones. For vessels and pipelines, clearance measurement, emptying, and inerting measures are standard practice. Compliance with applicable regulations and operational permits lies with the executing party; the information in this text is general and non-binding.
Interaction of cutting and splitting
An efficient deconstruction strategy combines methods: rock and concrete splitters loosen components with low vibration input, relieve stresses, and create clean lead-in surfaces. Cutting tools then take over the precise separation of reinforcement, embedded parts, and steelwork. This sequence improves occupational safety, reduces emissions, and increases cost-efficiency in concrete demolition, strip-out, rock excavation, tunnel work, and special applications.