DW-HF-90KW RF Induction Heating Equipment for Brazing, Hardening and Metal Heat Treatment

The HLQ DW-HF-90KW RF Induction Heating Equipment is a high-frequency industrial induction heating system designed for localized metal heating, induction brazing, surface hardening, annealing and selected forging applications.

The equipment uses IGBT inverter technology and a separated power generator and output transformer arrangement to deliver high-frequency electrical energy to a matched induction heating coil.

The DW-HF-90KW has a published maximum oscillation rating of 90 kVA, an operating frequency range of 30–80 kHz and a three-phase 380 V, 50/60 Hz input supply.

Typical applications include copper and brass tube brazing, diamond tool brazing, gear and shaft heat treatment, localized metal annealing and heating steel rods for forming operations.

Important technical clarification: The published 90 kVA oscillation rating is not equivalent to a verified 90 kW of useful thermal power absorbed by the workpiece. Actual heating performance depends on generator output characteristics, coil design, material properties and electromagnetic coupling.

Quick Answer

What is the DW-HF-90KW RF Induction Heating Equipment?

The HLQ DW-HF-90KW is a high-frequency induction heater designed to generate localized heat inside electrically conductive metals. It uses an IGBT-based power generator, a separate output transformer and an application-specific induction coil.

The system operates within a published frequency range of 30–80 kHz and has a maximum oscillation rating of 90 kVA. It is designed for three-phase 380 V, 50/60 Hz electrical input and requires water cooling.

Main applications: industrial induction brazing, copper tube brazing, tool brazing, gear and shaft surface hardening, metal annealing, localized heat treatment and selected rod-end heating operations.

Model selection: DW-HF-90KW is most appropriately evaluated for industrial heating processes requiring high-frequency electromagnetic coupling and a relatively concentrated heating zone. The final suitability depends on workpiece dimensions, heating depth, required temperature and production cycle.

Engineering caution: The equipment’s published rating does not independently establish the heating time, melting capacity, hardening depth or production throughput of a particular application.

Table of Contents

1. What is the DW-HF-90KW RF Induction Heating Equipment?
2. Key Applications
3. Suitable Materials
4. Working Principle
5. Technical Specifications
6. Recommended Model Selection
7. Process Workflow
8. Common Problems and Solutions
9. Engineering Selection Guide
10. Advantages and Limitations
11. Why Choose HLQ?
12. 10 Core FAQs

What is the DW-HF-90KW RF Induction Heating Equipment?

The DW-HF-90KW RF Induction Heating Equipment is an industrial electromagnetic heating system that converts three-phase electrical power into high-frequency electrical energy.

This energy is supplied to a specially designed induction coil positioned around or near a conductive metal workpiece.

When high-frequency alternating current passes through the coil, it creates an alternating magnetic field. The field induces electrical currents within the metal, producing heat through electrical resistance.

Unlike conventional external heating methods, induction heating generates energy directly within electrically conductive material.

The heating pattern can be concentrated around a specific joint, surface or section of a workpiece, depending on the induction coil design.

Main Equipment Components

What Makes the DW-HF-90KW Different?

The DW-HF-90KW belongs to HLQ’s high-frequency induction heating equipment category.

Its published operating frequency of 30–80 kHz makes it suitable for evaluation in applications requiring localized heating of metal joints, surfaces and selected component sections.

The equipment uses a separated generator and output unit arrangement.

This configuration can make it easier to position the output transformer near a heating station while locating the main generator in a more suitable operating area.

The machine also supports different induction coil shapes for different workpiece geometries.

High-Frequency Induction Heating vs. Medium-Frequency Heating

The correct frequency cannot be determined solely from nominal power. Workpiece geometry, magnetic properties, electrical resistivity and the heating process must also be considered.

Key Applications

The DW-HF-90KW can be evaluated for multiple industrial metal-heating applications when the generator, induction coil and process controls are appropriately configured.

1. Induction Brazing of Copper and Brass Tubes

Induction brazing is a process in which the joint area of two components is heated until a selected brazing filler metal melts and flows into the joint.

The base metals are normally not melted during the brazing process.

High-frequency induction heating can be used for copper tubes, brass fittings and selected dissimilar-metal assemblies.

Typical applications include:

• Copper tube to copper fitting brazing.
• Copper tube to brass connector brazing.
• HVAC refrigeration pipe brazing.
• Heat exchanger tube connections.
• Industrial copper piping assemblies.
• Selected stainless-steel-to-copper brazed joints.

The heating process must be matched to the joint dimensions, filler alloy, flux or protective atmosphere and the required brazing temperature.

For detailed application information, see induction brazing copper tubes.

2. Induction Brazing of Diamond Tools

Diamond cutting tools and industrial tool segments may require controlled brazing to attach suitable cutting elements to metallic holders.

Induction heating can concentrate energy near the brazing interface, allowing the joint to be heated without necessarily heating the entire tool assembly to the same temperature.

Successful brazing depends on filler-metal selection, bonding characteristics, temperature control and the thermal sensitivity of the tool material.

Explore the related induction brazing diamond tools application.

3. Gear and Shaft Surface Hardening

Induction hardening is a localized heat-treatment process used to increase the surface hardness and wear resistance of suitable steels.

The workpiece surface is heated to an appropriate austenitizing temperature and then quenched using a selected cooling medium.

The required heating temperature, quench rate and hardening depth depend on the material grade, original microstructure and mechanical performance requirements.

Potential applications include:

• Steel shaft surface hardening.
• Gear tooth and gear-ring hardening.
• Machine spindle hardening.
• Selected bearing surfaces.
• Industrial pins and mechanical components.

For automated or production-oriented applications, see shaft induction hardening equipment.

4. Localized Metal Annealing

Induction annealing is used to modify selected material properties through a controlled heating and cooling process.

Depending on the material, annealing may reduce hardness, improve ductility or modify residual stresses and microstructure.

Potential workpieces include steel tubes, stainless-steel components, brass fittings, copper assemblies and other conductive materials.

The induction power supply must be matched to the annealing temperature, required heating depth and thermal cycle.

For further engineering information, see the induction annealing process guide.

5. Heating Steel Rods for Forging

Induction heating can raise the temperature of a selected steel rod or bar section before mechanical deformation.

Typical forming operations include upsetting, heading, bending and selected die-forging applications.

For small and medium cross-sections, high-frequency induction equipment may be considered after evaluating the required heating depth and cycle time.

For larger bars or applications requiring more uniform through-heating, lower-frequency induction equipment may be more appropriate.

See the related induction forging bar ends applications.

6. Heating Metal Components Before Shrink Fitting

Induction heating can be used to expand selected metallic components before assembly.

Components such as rings, hubs, bushings and couplings may be heated to produce sufficient thermal expansion for an interference-fit assembly.

Heating requirements depend on the component material, dimensional interference, coefficient of thermal expansion and maximum allowable temperature.

7. Selected Small Metal Melting Applications

Induction equipment can be used for metal melting when the generator, induction coil, crucible and cooling system are designed for the specific melting process.

However, the DW-HF-90KW’s published specifications do not establish a universal melting capacity or confirm compatibility with every metal.

The suitability of a melting application must be evaluated according to metal type, charge mass, melting temperature, crucible design and electromagnetic coupling.

Application Suitability Comparison

Suitable Materials

Induction heating requires an electrically conductive material.

The heating characteristics of a metal depend on its electrical resistivity, magnetic permeability, thermal conductivity, specific heat capacity and geometry.

Ferromagnetic carbon steels can provide strong electromagnetic coupling below their Curie temperature.

Nonferrous metals such as copper, brass and aluminum can also be induction heated, although their different electrical and thermal properties require appropriate coil and generator matching.

Material Compatibility Table

How Material Properties Affect Heating

Working Principle

How Does RF Induction Heating Work?

RF induction heating operates through electromagnetic induction.

The power generator converts standard industrial AC electricity into high-frequency electrical energy.

This energy is supplied to an induction coil, producing a rapidly alternating magnetic field.

When an electrically conductive metal is placed within the field, electrical currents are induced inside the workpiece.

These currents generate heat due to the electrical resistance of the material.

The magnitude and distribution of heating depend on the electromagnetic properties of the metal, the frequency, the induction coil geometry and the applied power.

RF Induction Heating Process

How Does Frequency Affect Heating Depth?

The distribution of induced electrical current depends partly on the operating frequency.

At higher frequencies, current generally becomes more concentrated near the surface of a conductive workpiece.

The characteristic electromagnetic penetration depth is commonly described using the skin-depth relationship:

δ = √(2ρ / ωμ)

Where:

• δ = electromagnetic skin depth, m.
• ρ = electrical resistivity, Ω·m.
• ω = angular frequency, rad/s.
• μ = magnetic permeability, H/m.

The equation is a simplified electromagnetic relationship and does not directly establish the final hardened case depth or the total depth reached by heat conduction.

For ferromagnetic steel, magnetic permeability changes with temperature, particularly near the Curie temperature. As a result, the actual heating process must account for temperature-dependent material behavior.

Important Factors Affecting Heating Performance

Technical Specifications

The following table reproduces the published technical parameters of the HLQ DW-HF-90KW RF Induction Heating Equipment.

Some values require additional manufacturer confirmation because the original page does not provide complete measurement conditions or definitions.

DW-HF-90KW Main Technical Parameters

Power and Control Features

Electrical Installation Requirements

The power supply must be designed using verified electrical input data.

For a balanced three-phase system, apparent electrical power is approximately:

S = √3 × V × I / 1000

Where:

• S = three-phase apparent power, kVA.
• V = line-to-line voltage, V.
• I = line current, A.

Using the published maximum input apparent power of 99 kVA at 380 V:

I = 99,000 / (√3 × 380)

Calculated current ≈ 150.4 A

This is an arithmetic calculation based on the published apparent-power rating. It is not a certified maximum input current, a circuit-breaker recommendation or a substitute for the manufacturer’s electrical installation drawing.

Final installation must account for actual input current, power factor, protective devices, conductor sizing, earthing and applicable electrical codes.

Cooling Water Requirements

Cooling water must be available and verified before energizing the induction heating equipment.

Recommended Model Selection

The correct induction heating equipment should be selected according to the workpiece, heating process and production requirements.

Although the DW-HF-90KW is identified by a 90KW model designation, the published electrical specification uses kVA for the oscillation rating.

Model selection should therefore be based on confirmed electrical and thermal performance rather than assuming that the model number represents useful thermal power.

DW-HF-90KW Application Selection Guide

High-Frequency Model Comparison

The following comparison provides general engineering guidance based on the neighboring HLQ high-frequency product series. It should not be interpreted as a certified specification table for every production revision.

For a broader comparison between medium-frequency, high-frequency and ultra-high-frequency equipment, refer to the HLQ induction heating power supply selection guide.

Model Selection by Workpiece Characteristics

Process Workflow

Step 1: Define the Heating Application

Determine whether the required process is brazing, surface hardening, annealing, shrink fitting or forging preparation.

Different applications require different heating temperatures, coil arrangements and operating procedures.

Step 2: Identify the Workpiece Material

Confirm the metal grade, geometry, dimensions and relevant material properties.

For hardening applications, verify the original heat-treatment condition and required final hardness.

Step 3: Estimate the Thermal Energy Requirement

Calculate the approximate heated mass and temperature increase.

Include a suitable allowance for thermal losses and heating outside the intended region.

Step 4: Select the Induction Coil

Choose an induction coil according to workpiece dimensions, target heating pattern and loading requirements.

The coil must be electrically compatible with the output transformer and resonant circuit.

Step 5: Prepare the Electrical and Cooling Systems

Verify the three-phase electrical supply, grounding, cooling-water circulation, protective devices and output connections.

All installation and servicing must be performed by qualified personnel.

Step 6: Configure the Heating Parameters

Set the required operating parameters using the available power-control and timing functions.

For repeatable production, establish an approved heating cycle based on representative test pieces.

Step 7: Perform a Trial Heating Operation

Conduct an initial trial under controlled conditions.

Monitor the workpiece temperature and verify the response of the heating equipment.

Step 8: Complete the Process

Carry out the required brazing, quenching, controlled cooling or subsequent forming operation.

The correct finishing procedure depends on the application.

Step 9: Inspect the Workpiece

Check the processed component against the required acceptance criteria.

Inspection may involve brazed-joint testing, hardness measurement, dimensional inspection or metallurgical examination.

Step 10: Record the Qualified Parameters

After confirming the process, document the approved settings and inspection results.

These records help maintain repeatability during production.

Process Workflow Summary

Common Problems and Solutions

Induction heating performance can be affected by electrical matching, workpiece properties, induction coil geometry, cooling conditions and process settings.

RF Induction Heating Troubleshooting Guide

Preventive Maintenance Checklist

Engineering Selection Guide

Correct induction heater selection begins with the required thermal energy, production speed and the characteristics of the workpiece.

The nominal oscillation rating alone cannot establish the actual useful heating power delivered to the metal.

1. Calculate the Workpiece Mass

For a cylindrical metal rod:

m = π × D² × L × ρ / 4

Where:

• m = workpiece mass, kg.
• D = rod diameter, m.
• L = rod length, m.
• ρ = material density, kg/m³.

2. Calculate the Required Thermal Energy

A first-order sensible-heat estimate is:

Q = m × Cp × ΔT

Where:

• Q = thermal energy, kJ.
• m = workpiece mass, kg.
• Cp = mean specific heat capacity, kJ/(kg·K).
• ΔT = temperature increase, K.

This estimate assumes an approximately uniform temperature increase and does not include losses to surrounding equipment, thermal radiation or adjacent workpiece regions.

3. Engineering Example: Heating a Steel Rod

Consider a hypothetical induction heating application involving a cylindrical steel rod.

Calculated rod mass:

m = π × 0.04² × 0.15 × 7850 / 4

m ≈ 1.48 kg

Calculated sensible heat:

Q = 1.48 × 0.60 × 830

Q ≈ 737 kJ

Equivalent electrical-energy units:

Q = 737 / 3600

Q ≈ 0.205 kWh

This is the approximate energy absorbed by the assumed uniformly heated rod, not the electrical consumption of the DW-HF-90KW.

4. Estimate Heating Time

If useful thermal power absorbed by the workpiece is known, a simplified heating time can be calculated:

t = Q / P_useful

Where:

• t = heating time, seconds.
• Q = required thermal energy, kJ.
• P_useful = useful thermal power absorbed by the workpiece, kW.

For the hypothetical 737 kJ steel rod:

Important: The useful thermal power values above are independent engineering assumptions. They are not measured performance values for the DW-HF-90KW and cannot be calculated directly from the published 90 kVA oscillation rating.

Actual heating time depends on workpiece temperature distribution, electromagnetic coupling, coil geometry, power-control settings, heat losses and equipment operating conditions.

5. Cooling Water Heat-Removal Calculation

The approximate heat removed by circulating water can be estimated as:

P_cooling = ṁ × Cp × ΔT

Where:

• P_cooling = heat-removal capacity, kW.
• ṁ = water mass flow, kg/s.
• Cp = specific heat capacity of water, approximately 4.18 kJ/(kg·K).
• ΔT = cooling-water temperature increase, K.

For an illustrative water flow of 6 L/min and a temperature increase of 10°C:

ṁ ≈ 0.10 kg/s

P = 0.10 × 4.18 × 10

Calculated Heat Removal ≈ 4.18 kW

Cooling Water Flow Comparison

These figures represent theoretical water heat-removal capacities under the assumed conditions.

They do not establish the actual cooling load of the DW-HF-90KW, and they should not be used as the sole basis for selecting a water chiller.

6. Engineering Selection Checklist

Advantages and Limitations

Advantages of DW-HF-90KW RF Induction Heating Equipment

1. Localized Heating

Induction heating can concentrate thermal energy in selected regions of conductive metal components.

This is particularly useful for brazing joints, selected surface-hardening patterns and partial heating applications.

2. IGBT Power Conversion

The equipment uses IGBT inverter technology for high-frequency electrical power conversion.

The actual electrical efficiency and operating characteristics depend on the equipment configuration and operating load.

3. High-Frequency Operating Range

The published 30–80 kHz operating range supports evaluation of applications requiring localized electromagnetic heating.

4. Separated Output Unit

The generator and output assembly are separated, allowing flexibility in arranging the heating station.

5. Interchangeable Induction Coils

Different induction coil geometries can be used for different workpieces when properly designed and electrically matched.

6. Power and Timing Functions

The original product description identifies current and power operating modes and optional timer-equipped configurations.

Appropriate heating-cycle control can improve repeatability in production applications.

7. Industrial Application Flexibility

The same general induction generator technology can be considered for multiple heating processes when compatible coils and operating parameters are used.

Limitations and Engineering Precautions

RF Induction Heating vs. Flame Heating vs. Resistance Heating

The most appropriate heating method should be selected using actual process energy requirements, heating time, quality targets and total operating conditions.

Why Choose HLQ?

HLQ Induction Equipment Co., Ltd. supplies industrial induction heating equipment for metal brazing, heat treatment, forging, melting and related manufacturing applications.

High-Frequency Induction Heating Technology

The DW-HF-90KW uses IGBT inverter technology and a published frequency range of 30–80 kHz for localized heating applications.

Separated Generator and Output Arrangement

The equipment configuration provides flexibility for arranging the power generator and the induction heating station.

Application-Specific Induction Coil Selection

Different metal components require different induction coil geometries and electrical matching.

Proper coil selection is essential for efficient heating and repeatable industrial processes.

Industrial Metal Processing Applications

HLQ’s product range includes equipment used for brazing, surface hardening, annealing, forging preparation and other induction heating operations.

Engineering-Based Equipment Selection

The suitability of an induction heating system should be assessed using actual material properties, heating requirements, production rates and cooling conditions.

Representative process testing and confirmed technical specifications provide a more reliable foundation for equipment selection than nominal power alone.

10 Core FAQs

1. What is RF induction heating equipment?

RF induction heating equipment is an industrial power system that generates a high-frequency alternating magnetic field through an induction coil. The field induces electrical currents inside conductive metal, producing heat through electrical resistance. Typical applications include brazing, surface hardening, annealing and localized metal heating.

2. What is the operating frequency of the DW-HF-90KW?

The published operating frequency range is 30–80 kHz. The actual operating point depends on the generator configuration, resonant circuit, induction coil and workpiece load.

3. Does DW-HF-90KW provide 90 kW of heating power?

The original product page lists a maximum oscillation rating of 90 kVA, not a separately verified 90 kW of useful thermal output. The actual power absorbed by a workpiece depends on electrical output characteristics and electromagnetic coupling. Manufacturer testing is required to establish guaranteed thermal performance.

4. Can the DW-HF-90KW be used for copper tube brazing?

Potentially. High-frequency induction equipment can be used for copper tube and brass fitting brazing with appropriate coil geometry, filler alloy, joint preparation and heating parameters. A representative brazing test is recommended to confirm heating time and joint quality.

5. Can this RF induction heater harden steel gears and shafts?

The equipment can be evaluated for suitable surface-hardening applications. The final hardening result depends on steel grade, operating frequency, heating pattern, quenching method and required case depth. A complete hardening process requires suitable quenching equipment and quality inspection.

6. What cooling water does the DW-HF-90KW require?

The published specifications identify a cooling-water parameter of 0.3 MPa and a flow of at least 6 L/min. The exact pressure definition, allowable inlet temperature, cooling-circuit arrangement and required heat-rejection capacity should be confirmed before installation.

7. Can the DW-HF-90KW operate continuously?

The original specification states a 100% duty cycle at 30°C. This claim is conditional on appropriate cooling and operating conditions. Actual continuous-operation capability must be verified for the installed generator, output unit, coil and cooling system.

8. What is the difference between DW-HF-90KW and DW-MF-90KW?

DW-HF-90KW belongs to the high-frequency induction heating category and has a published frequency range of 30–80 kHz. DW-MF-90 belongs to the medium-frequency equipment family. Their frequency ranges, typical electromagnetic penetration and suitable applications differ. They should not be treated as interchangeable machines.

9. Can the DW-HF-90KW melt steel, copper or aluminum?

Induction melting may be possible with an appropriately engineered power supply, crucible, induction coil and cooling arrangement. However, the DW-HF-90KW product page does not establish guaranteed melting capacity for particular metals or charge sizes. Each melting application requires a separate engineering assessment.

10. How do I select the correct induction heating equipment?

Start by identifying the material, dimensions, initial temperature, target temperature, required heating time and production rate. Calculate the approximate thermal energy required, then consider electromagnetic coupling, frequency selection, cooling requirements and the appropriate induction coil. The final equipment configuration should be confirmed through manufacturer specifications and representative testing.

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