Stainless steel inlays are precisely manufactured inserts, liners, or bushings made of stainless steel that, in construction, demolition, and cutting technology, specifically protect components against corrosion and wear, distribute loads evenly, or provide precise functional surfaces. In practice, they appear as support plates, sliding and sealing faces, spacer rings, or bearing bushings—such as in concrete demolition shears and in hydraulic rock and concrete splitters from Darda GmbH, as well as in the associated hydraulic systems (e.g., Power Units). Thanks to the combination of high resistance to moisture, cement slurry, and chlorides together with sufficient toughness, stainless steel inlays support tool reliability in harsh operating environments such as concrete demolition, rock demolition, or tunnel construction.
Definition: What is meant by stainless steel inlay
A stainless steel inlay is an inserted or integrated component made of corrosion-resistant steel (stainless steel) that is introduced into another component or tool to fulfill a specific function. Typical functions are wear protection, corrosion barrier, guidance, load distribution, sealing, and the provision of precise mating surfaces. In contrast to coatings, the inlay is a distinct, replaceable part with a defined geometry. In demolition technology, this includes, for example, stainless steel bushings at joint points, support and impact-protection plates on the tool jaws of concrete demolition shears, as well as sealing lands or spacer washers in rock and concrete splitters.
Design and functions of stainless steel inlays
Stainless steel inlays are engineered so that the most highly stressed contact and functional zones become more robust and durable without oversizing the base component. Depending on the task, sheet inlays, milled plates, turned bushings, rings, or profiles are used. Important working principles include separating dissimilar materials to reduce friction wear, increasing surface pressure bearing capacity in support areas, providing corrosion-stable sealing and sliding faces, and minimizing galvanic effects between the base body and the mating partner. In concrete demolition shears, a stainless steel inlay supports the dimensional stability of the bearing location and impedes the ingress of abrasive particles; in rock and concrete splitters, stainless steel inlays protect contact faces against splitting burrs and moisture.
Functional roles and typical configurations
Depending on the assembly and application, stainless steel inlays fulfill different roles. In demolition and splitting technology, the following configurations are particularly common:
- Wear and impact protection: support plates at contact surfaces exposed to impact and abrasion (e.g., jaw liner plates on concrete demolition shears).
- Guides and bearing bushings: turned stainless steel parts at joints to protect against moisture, cement slurry, and splash water.
- Sealing faces and seat rings: corrosion-resistant lands for seals, wipers, and valve seats in hydraulically actuated assemblies.
- Load distribution and spacing: inlays as shims/spacers to set clearance, preload, and defined pressure.
- Corrosion barrier: separation elements between unalloyed steels and wet, chloride-bearing media in concrete demolition.
Material selection: stainless steel grades, properties, and surfaces
The choice of stainless steel grade depends on media, temperature, mechanical load, and desired manufacturing depth. Austenitic steels such as 1.4301 (A2) are often used for general corrosion resistance, and 1.4404 or 1.4571 (A4) for increased resistance to chlorides. In particularly abrasive environments or at high surface pressures, duplex grades such as 1.4462 can offer the right balance of strength and corrosion resistance. Surface conditions (ground, blasted, polished) influence the tendency to gall and sealing quality; after machining, pickling and passivation are established methods for restoring the protective passive layer in line with recognized engineering practice.
Property profile and trade-offs
- Corrosion: chlorides, moisture, and cement slurry promote pitting and crevice corrosion; higher molybdenum contents (e.g., in 1.4404) increase resistance.
- Wear: austenitics are tough but relatively soft; in sliding pairs, work hardening can be advantageous, and under impact loading, toughness is crucial.
- Manufacturing: machinability, edge retention, and weldability vary between grades; heat input must be controlled to avoid embrittlement.
Manufacturing and integration into assemblies
Depending on geometry, stainless steel inlays are laser cut, waterjet cut, punched, milled, or turned; complex shapes are produced via investment casting or additive processes. Integration is achieved through interference fits, bolting, keys, positive-locking grooves, or bonded joints. In hydraulically actuated tools from Darda GmbH, precise tolerances and clean edges are important so that inlays reliably support seals, pins, and guides.
Fastening types and notes
- Press and shrink fit: for bushings and rings at joints; cleanliness and surface quality are decisive.
- Bolting: replaceable support plates on tool jaws; observe thread locking and specified tightening torques.
- Bonded joint (welding/brazing): only with suitable filler metals; dissimilar materials can cause stresses or corrosive couples.
- Adhesive bonding: for large-area, thin liners; substrate preparation and layer thickness control are essential.
Application in concrete demolition shears and rock and concrete splitters
In concrete demolition shears, stainless steel inlays used as replaceable support or sliding plates protect contact faces against abrasion from aggregates, reinforcement, and quartz dust. Stainless steel bushings at pin bearings reduce the risk of corrosion under splash water, which supports joint dimensional stability and the repeatability of the shear movement. In rock and concrete splitters, inlays serve as spacer and protection rings to reduce local notch effects at contact zones, and as corrosion-resistant sealing faces that promote hydraulic tightness under changing environmental conditions.
Examples from practice
- Jaw liner plates: stainless steel liners on shear jaws that can be removed and inspected easily protect the base body against abrasive wear.
- Joint bushings: stainless steel bushings as separation elements between pin and base body facilitate lubrication and maintenance in damp environments.
- Sealing lands: corrosion-stable seats for wipers/seals on moving cylinder parts of a splitter.
- Spacer washers: precise shims to set axial zero play in bearing locations.
Areas of use: demolition, strip-out, rock demolition, and natural stone
The advantages of stainless steel inlays become apparent especially in wet, abrasive, and chloride-bearing environments. In concrete demolition and specialized deconstruction, as well as during strip-out and cutting, tools are often exposed to moisture, slurries, and changing temperatures. In rock demolition and tunnel construction, micro-abrasive dusts and mineral suspensions stress the functional surfaces. In natural stone extraction, quartz content is highly abrasive. Stainless steel inlays help keep sliding and sealing interfaces stable and make maintenance efforts predictable—both for concrete demolition shears and for rock and concrete splitters.
Concrete demolition and specialized deconstruction
In components with chloride exposure (e.g., parking decks, bridges), stainless steel inlays minimize the risk of contact corrosion on exposed functional surfaces of the tools. The combination of sealing lands and bushings supports the service life of joint and sealing systems.
Strip-out and cutting
Where coolant and flushing media are used, corrosion-resistant liners maintain the dimensional accuracy of mating surfaces. Inlays also facilitate cleaning and inspection, since smooth stainless steel surfaces reduce dirt adhesion.
Rock demolition and tunnel construction
In rock demolition and tunnel construction, fine mineral particles promote three-body abrasion. Stainless steel bushings and support plates reduce wear in joints and at impact faces subjected to high load cycles.
Natural stone extraction
Support and protection plates made of stainless steel at contact points with quartz and feldspar reduce material removal from base components and help preserve the geometry of clamping and splitting interfaces.
Special applications
In chemically demanding environments or maritime settings, suitable stainless steel grades offer a robust compromise between corrosion resistance and toughness—a relevant aspect for longer service intervals.
Design: sizing, tolerances, and friction pairings
The geometry of stainless steel inlays follows the required contact pressures, the mating materials, and the assembly paths. For interference fits, roughness, cylindricity, and dimensional tolerances are critical; for sealing faces, flatness and waviness are key features. Friction pairings should be chosen to avoid galling: stainless steel against stainless steel is critical at high surface pressure and requires suitable lubricants or surface modifications; pairings of stainless steel against hardened tool steel or coated counterfaces are often more favorable. In concrete demolition shears and rock and concrete splitters, it is advisable to consider the real contact pressures to adapt inlay thickness and support radius to the loads.
Design guidelines
- Edges: small chamfers/radii reduce notch stresses and chipping at support plates.
- Drainage: holes/grooves prevent moisture pockets at hidden contact locations.
- Service access: design liners so that screw points are accessible and wear zones are visible.
Assembly, maintenance, and inspection
Before assembly, clean and keep contact faces dry; a thin corrosion-protection film can prevent discoloration. Interference fits are drawn in evenly and concentrically. In operation, regular visual inspection for scoring, edge breakouts, loosened fasteners, and signs of pitting corrosion is recommended. Replacement intervals depend on load profile, media, and particle exposure. For concrete demolition shears, check bearing clearance at bushings and pins; for rock and concrete splitters, ensure sealing faces are flat and spacer washers are intact. Select lubricants compatible with seals and stainless steel surfaces.
Standards, quality assurance, and documentation
For material selection, standardized material lists and property specifications are decisive. Inspections for dimensional accuracy, hardness, and surface condition are part of quality assurance. In corrosion-prone applications, additional resistance evidence (e.g., salt spray tests) can be useful. Traceable documentation of inlay geometry and installation instructions facilitates maintenance and spare parts supply—especially for highly stressed assemblies of concrete demolition shears and rock and concrete splitters from Darda GmbH.
Typical failure modes and remedies
In practice, galling in sliding pairs, cold welding under high surface pressure, pitting and crevice corrosion under chloride influence, and edge chipping due to impact loads are encountered most frequently. Remedies include suitable material pairings, adequate lubrication, smooth edge radii, avoidance of standing moisture, and, if necessary, switching to a higher-alloy stainless steel grade or adapting inlay thickness. Loosening of bolted liner plates can be prevented by defined preload and locking elements.
Selection checklist for planning and operation
- Clarify media and particle exposure (moisture, chlorides, slurries, dust).
- Determine load spectra and contact pressures (static/dynamic, impact share).
- Select a suitable stainless steel grade (balance corrosion and wear requirements).
- Define geometry and fastening (serviceability, replaceability).
- Specify friction pairings and lubrication (minimize galling tendency).
- Specify surface condition, edges, and fits (sealing and sliding quality).
- Plan maintenance and inspection intervals (visual checks, bearing clearance, sealing faces).