Extensive experience in industry and shipping
Our range of services in Thermal metal spraying
The metal spraying division has qualified specialist personnel with extensive expertise in controlled surface coating of machine components, including special alloys. We have developed our own metal spraying processes, which are certified by DNV GL.
A large number of shipping companies have been using our comprehensive range of services in this field for many years, for example for the short-term repair of piston rods for all engine types. If required, we are able to supply you immediately from our exchange stock in order to avoid downtime.
Our range of service
- Repair of piston rods, spindles, and various types of shafts
- Rotors and bearing shields of electric motors and pumps
- Water jackets
- HVOF coating of exhaust valve stems
- Ceramic coating of shaft sleeves in stern tube sealing systems
- Repair of worn bearing and sealing seats as well as bores on various shafts
- Ceramic coating on electric motors for insulation purposes
- Hard coating of shaft protection sleeves in pump construction
- Corrosion-resistant coating of damaged or new hydraulic piston rods
- Abrasion-resistant coating of rotors and housings in cellular sluices
- Repair of machine components with restoration of tolerance values
- Abrasion protection
Repair of piston rods for the maritime industry
Our licensed process for extended operating times
TMH Drechsler has, using its Sulzer-licensed process acquired in 1993, reconditioned more than 1,800 piston rods for two-stroke marine diesel engines as well as power plants. The majority of the repairs involve various engine types such as Sulzer, B&W, and Mitsubishi.
Over the past two decades, we have continuously further developed our process and can demonstrate reconditioned piston rods with service lives of over 45,000 operating hours without measurable wear.
Short delivery times and transport service
Various replacement piston rods are ready for immediate shipment.
The delivery time for piston rods is only one week – if required, we can also deliver within just a few days. We are happy to arrange the collection and return transport of your machine components using our own service vehicles.
Thermal coating – metal spraying process
In metal spraying, the molten spray material is usually atomized using compressed air, but also by other atomizing gases or gas flows from the heat source. The particles impact the substrate surface with very high kinetic energy, deform upon impact, and the sprayed material rapidly cools on the relatively cold substrate. The result is a coating composed of metal, oxides, and tiny interstitial voids.
Advantages of thermal coating
- Almost any material can be coated/sprayed
- The base material to be coated is not thermally altered
- Nearly any component size (independent of the base material) can be coated
- Excellent automation capability of the thermal spraying process
- Flexible use
- High dimensional accuracy
- High quality standards
- The sprayed layer can contain multiple elements or combinations (e.g. Cr, Ni, carbides, etc.)
DNV GL-certification
We are certified by DNV GL for the metal spraying of piston rods.
Our processes
- Wire flame spraying
The wire or rod-shaped spray material is continuously melted in a fuel gas–oxygen flame and propelled onto the workpiece surface by the combustion gases alone or additionally supported by an atomizing gas such as compressed air or nitrogen. Upon impact and solidification, mechanical bonding occurs along with the formation of diffusion zones. - Powder flame spraying
In powder flame spraying, the continuously supplied powdered spray material is partially or fully melted in an acetylene–oxygen flame. It is accelerated by the expanding combustion gases and sprayed onto the prepared workpiece surface.Typical applications include, for example, shaft protection sleeves, roller table rollers, bearing seats, fans, and rotors of extruder screws, etc.
- Arc spraying
In arc spraying, two wire-shaped spray consumables of the same or different types are melted in an electric arc. The arc burns stably between the two wires, which are polarized as an anode and a cathode. Using an atomizing gas, the molten metal particles are propelled onto the prepared surface of the workpiece at a speed of approximately 120 m/s. In the case of atmospheric arc spraying, the atomizing gas is usually compressed air. The wires are continuously fed forward. Arc spraying is a high-performance wire spraying process, but only electrically conductive materials can be sprayed. Typical applications include large-area coating of components, wear protection, and corrosion protection, etc. At DMI Drechsler, this process is also used to apply wear-resistant coatings to piston rods.
- High-Velocity Oxygen Fuel Spraying (HVOF)
In high-velocity oxygen fuel spraying (HVOF), continuous gas combustion takes place under high pressure within a combustion chamber, in the central axis of which the powdered spray material is fed either axially or radially. Due to the high pressure of the fuel gas–oxygen mixture generated in the combustion chamber, a very high flow velocity is produced in the gas jet, exceeding 750 m/s (supersonic). These high particle velocities result in dense coating layers with excellent adhesion properties. This process produces extremely thin coatings with high dimensional accuracy. Typical applications include sliding surfaces, hydraulic rods, rollers, components for petrochemical and chemical machinery such as pumps, valves, ball valves, mechanical seals, valve spindles, etc.
