Medium-Frequency Heater: An Efficient Solution for Surface Preparation Before Spraying
In the coating spraying process, the quality of surface preparation directly determines the adhesion, durability, and protective performance of the coating. Medium-frequency heaters, with their unique heating characteristics, have become key equipment for surface preparation before spraying. They are particularly suitable for degreasing, moisture removal, stress relief, and activation treatment of materials such as metals and ceramics, laying a solid foundation for subsequent spraying processes.
| Model |
60KW Induction Preheating PWHT Machine |
| Input Voltage |
3 Phase 380V, 50HZ |
| Output Frequency |
5KHZ ~ 30KHZ |
| Output Power |
60 KW |
| Input Current |
0-90A |
| Cooling Type |
Air cooling |
| Heating Temperature |
Preheat 0 - 350 C |
| Temperature Control |
1 Channel or 4 Channel |
| Heating Pipe size |
Dia: 50 -1000 mm |
| Heating Coil |
Induction Coil, Heating Blanket, Clamp Induction Coil |
| Extend cable |
1-20 meter |
| Heating Blanket |
Induction heating blanket, High temperature tube |
| Alarm |
Over Voltage, Over Current, Over Temperature and so on |
Core Functions: Targeted Solutions for Surface Issues Before Spraying
Surfaces before spraying often have defects such as oil stains, moisture, oxide layers, and internal stress. Medium-frequency heaters achieve comprehensive pretreatment through precise heating:
- Efficient degreasing and moisture removal: Using medium-frequency induction heating, the surface temperature of the workpiece can quickly rise to 120-200°C (adjustable according to the type of contaminants). Heat energy vaporizes surface oil stains and evaporates moisture, which is more environmentally friendly than traditional solvent cleaning. It can also penetrate complex structures such as threads and gaps to remove hidden contaminants. For example, when preparing automotive parts for spraying, surface grease and cutting fluid can be completely removed within 10 minutes.
- Assisting in loosening and removing oxide layers: For metal surfaces with oxide scales or rust, medium-frequency heating can cause cracks in the oxide layer due to the difference in thermal expansion coefficients between the oxide layer and the base material. This makes subsequent physical treatments such as sandblasting and grinding more thorough, especially suitable for the pretreatment of thick-walled steel and castings.
- Stress relief and surface activation: During the heating process, the surface stress of the workpiece is released, reducing the risk of coating cracking caused by stress concentration after spraying. At the same time, moderate heating (such as heating the metal surface to 80-150°C) can enhance surface activity, improve the bonding force between the coating and the base material, and increase the coating adhesion (tested by the cross-cut method) by more than 20%.
Technical Advantages: Adapting to Special Needs of Spraying Pretreatment
The technical characteristics of medium-frequency heaters (usually operating at a frequency of 1-10kHz) are highly matched with the requirements of pre-spraying treatment:
- Surface-oriented heating: The skin effect of medium-frequency current concentrates heat mainly on the surface layer of the workpiece with a depth of 0.5-5mm, avoiding deformation caused by overall overheating of the workpiece. It is particularly suitable for the pretreatment of thin plates and precision parts. For example, when heating an aluminum alloy plate with a thickness of 2mm, the surface temperature reaches 150°C while the core temperature only rises by 30°C, ensuring the dimensional stability of the workpiece.
- Excellent heating uniformity: Through the design of multi-turn induction coils and power closed-loop control, the surface temperature deviation can be controlled within ±5°C, avoiding increased surface oxidation caused by local overheating, ensuring the consistency of the surface state after pretreatment, and providing a uniform adhesion base for spraying.
- Quick response and flexible regulation: The heating speed is 3-5 times that of traditional hot air heating, and it supports stepwise temperature adjustment (such as a segmented process of first 100°C for moisture removal and then 180°C for degreasing), adapting to the pretreatment process specifications of different materials (steel, aluminum, magnesium alloys, etc.).
Application Scenarios: Covering Spraying Pretreatment in Multiple Industries
The adaptability of medium-frequency heaters makes them widely used in pre-spraying treatment in various fields:
- Industrial equipment spraying: Pretreating the surfaces of machine tool housings and pressure vessels to remove residual welding oil and oxide layers, ensuring long-term adhesion of anti-corrosion coatings.
- Automotive and rail transit: Before electrophoretic painting or powder spraying on automobile bodies and high-speed rail carriages, medium-frequency heating is used for degreasing and stress relief to improve the stone impact resistance and aging resistance of the coating.
- Aerospace components: For pre-spraying treatment of titanium alloy and aluminum alloy aerospace parts, the heating temperature is precisely controlled (such as heating the titanium alloy surface to 120°C) to avoid the impact of high temperature on the mechanical properties of the material, while ensuring the stability of the coating under extreme working conditions.
- Medical device manufacturing: Low-temperature (80-100°C) heating and moisture removal are performed on the surface of stainless steel medical equipment, combined with aseptic treatment, to ensure that the sprayed coating meets biocompatibility requirements.
Equipment Features: Balancing Pretreatment Efficiency and Operational Convenience
- Customized coil design: Special induction coils are equipped according to the shape of the workpiece (such as pipes, plates, complex curved surfaces). For example, flexible cable coils can wrap around special-shaped parts, and annular coils are suitable for tubular workpieces, ensuring no dead corners in heating.
- Intelligent process integration: Equipped with a PLC control system, it can preset more than 100 kinds of pretreatment process parameters (temperature curves, holding time, etc.), and support linkage with the spraying production line to realize automatic connection of "heating - cooling - spraying" and reduce manual intervention.
- Energy saving, environmental protection and safety: The heat conversion efficiency is over 75%, saving 30% energy compared with resistance heating; no open flame or exhaust gas emission, in line with environmental protection standards; equipped with over-temperature protection and coil insulation monitoring functions to avoid surface damage of workpieces caused by excessive heating.
Medium-frequency heaters improve coating quality from the source and reduce later maintenance costs through precise and efficient pretreatment of surfaces before spraying. Their advantages in heating directionality and temperature controllability make them core equipment for achieving high-quality and efficient production in modern spraying processes.
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