Bonding systems are used for the secure connection of all components of an electrical winding among themselves and with the laminated core.

Heat is always the basis of the process. It is required to bond the self-bonding wires together or to bond the insulating resins with the winding. For heating, current is passed through the windings. This causes electrical losses in the winding resistances, which heats up the winding. We call this principle the "current heating method". Through the precise measurement and control of the flowing current, the heating process can be precisely and reproducibly controlled.

With SCHLEICH bonding systems, up to 8 bonding processes can be run simultaneously and independently of each other.

With our bonding systems, coils made with self-bonding wire can be thermally bonded directly after winding. If required, a test can be run before and after thermal bonding.

The windings made with self-bonding wire are heated to the melting temperature of the self-bonding enamel using temperature-controlled electrical heat. After reaching the desired target temperature and subsequent cooling, the winding wires bond together. The entire winding then forms a solid unit.

The process-reliable procedure is computer-controlled and monitored.

Depending on the current density, stator, and winding size, different heating times result. By varying the current density, heating times between 1 and 300 s can be achieved. The goal is to achieve a very uniform temperature distribution within the winding and thus a very good, homogeneous bonding in all winding parts.

The bonding systems are suitable for all types of windings. Provided that the winding contacting allows a significantly increased current flow compared to normal operation, both individual coils and single-phase and three-phase stators and armatures can be reliably thermally bonded.

Manual Bonding Systems

In manual bonding systems, the contacting of the winding ends is performed by the operator. A variety of different manual contacting variants are available for this purpose. These are specialized for high temperatures and high currents.

The contacting devices can also be equipped with an automatic opening function. This saves working time, as the operator no longer has to individually release the winding ends from the contacting after thermal bonding.

Automatic Bonding Systems 

In automatic bonding systems, which are designed as a continuous production line, the entire process runs fully automatically. The workpiece carriers with the winding goods to be thermally bonded are automatically stopped and separated by the bonding system or the line control. They are then lifted into the bonding position. The subsequent shaping by forming tools and the contacting of the free winding ends or a connector also occur fully automatically.

Unstripped winding ends can also be contacted. Specialized contacting tools ensure that the wire is contacted through the insulation.

The SCHLEICH universal concept considers thermal bonding as a work step in a chain of test steps.

It is not economically viable to thermally bond a faulty winding. Therefore, additional tests are often run on the winding before electrical heating. It may also be useful to run a final test after the heating process.

Depending on the scope of the desired tests, the MTC3 Winding Test System or the GLP3 Function Test System is used as the base device. The software functionality is identical for both test devices. The MTC3 has the additional advantage over the GLP3 that surge test and partial discharge tests can also be run. The configuration is custom, so that the test methods and the type of current heating required precisely match your application.

For testing, process control of the electricity heat and the storage of heating/test plans as well as the results, we consistently rely on the integration of an industrial PC. A simple and clear user interface makes it easy for the operator to control the system.

The displays during testing and current heating are clear; only the important data and graphics are shown.

Numerous statistical evaluations support quality assurance. A variety of different print protocols serve your customer as proof of the quality delivered.

For heating, direct or alternating current flows through the winding. The power loss generated at the winding resistance is converted into heat.

To achieve a short heating time, a high current density is aimed for. This is limited by the wire cross-section and, if applicable, by the type of contacting. To prevent damage, the wire and contacting must not be overloaded.

A power module in the heating system is responsible for current generation, which is controlled and regulated by the system's software.

The system's very fast and highly accurate measurement technology delivers hundreds of thousands of current and voltage measured values per second. From these measured values, the software continuously calculates, among other things, the winding temperature. Based on the determined process values, the software regulates the power module according to different heating methods.

Method with constant voltage 

This is the simplest method. The voltage is kept constant throughout the entire heating process. The initially flowing current continuously decreases because the copper resistance of the winding increases with rising temperature. The thermal energy supplied to the winding decreases.

The advantage of this method is that the temperature rises relatively slowly, resulting in good and uniform through-heating of the winding. The temperature difference between the winding in the winding head and the winding in the slot is therefore usually small when the curing temperature is reached. However, since the maximum current density is only achieved at the beginning of heating, the desired final temperature is only reached after a relatively long time.

Method with constant current 

In this method, the current is kept constant throughout the entire heating process. Since the copper resistance of the winding increases with rising temperature, this is only possible through a voltage increase controlled by the regulator.

Compared to constant voltage, the desired final temperature is reached significantly faster.

Method with elevated initial temperatures 

This method can be applied, for example, during repair work. In such cases, the winding is often still very warm. The heating system determines this elevated winding temperature and starts the heating process with this initial value.

Additionally, constant final temperature 

The time during which the bondable enamel layer on the wire surface can soften and form a connection with adjacent wires may be too short if switched off immediately upon reaching the softening temperature. As a result, the wires in the slot may remain somewhat cooler than in the winding head due to the surrounding laminated core. This can lead to a loss of quality.

The constant voltage or constant current method can therefore also be configured so that, if required, it does not switch off immediately upon reaching the desired softening temperature, but rather maintains the temperature constantly for some time.

This extends the time during which the bondable enamel layer on the wire surface can soften homogeneously and form a secure connection with adjacent wires.

Method with temperature profile 

To do this, the setter specifies the desired heating profile in different time zones. In the event that the integrated power module supplies the current or the voltage cannot deliver, this is checked in a preliminary plausibility check and corrected if necessary.

This procedure is the standard approach for an impregnation system, which is also used for thermal bonding.

The software is based on the Microsoft Windows^® operating system. The optimized user interface enables the operator-friendly execution of 

• Heating with Current 
• Testing 
• Heating/Test Plan Creation 
• Printing of Test Protocols 
• Statistical Evaluation of Results

All heating processes and, if applicable, tests are run fully automatically. The measurement results are continuously displayed and evaluated during the processes. The clear GO/NO-GO display visualizes the automatic evaluation. 

The process flow is edited by simply adding or removing heating and test steps. This allows the process to be optimally adapted to various requirements. Each individual step can be quickly edited by double-clicking on the respective step. 

The comprehensive built-in operator management ensures that only authorized personnel can run these changes. Additional work instructions make the heating system the perfect ISO 9001-compliant production system.

A particular strength of SCHLEICH lies in the mechanical adaptation of stators and their specialized contacting. The heating system and mechanics are manufactured according to your specific requirements. Manually or pneumatically operated four-wire terminals are used. It is crucial that they perfectly transmit both high currents and measurement signals.

Design is carried out directly at our in-house 3D CAD workstations. State-of-the-art CNC machines in our mechanical production guarantee professional and cost-effective manufacturing of components.

Contacting devices

Expanding Mandrels

Forming Tools

Heating and test plans, as well as results, can be stored locally or on a central server. This ensures high data safety and optimal data exchange between various test systems.

The heating systems operate optimally in all network infrastructures. This feature provides the ideal platform for collecting, managing, analyzing, and distributing information.

Proven and widely used Microsoft^® technologies are used as memory.

The heating systems can also be ideally networked with ERP, PPS, and CAQ systems. For all requirements, we provide extensively proven and customer-optimized standard solutions.

The Windows^®-based heating systems can be operated in arbitrarily complex network topologies. You can install any number of test devices at various company locations worldwide, all working with a central server memory for test plans and test results. Our extensive experience in the global networking of our test devices gives you the safety to provide the same product quality regardless of the production location.

Naturally, all test plan, printing, labeling, and statistics tasks can also be run on the individual testing devices. However, to avoid disrupting the production process, it is advisable for networked systems to use separate workstations for these tasks. These workstations operate with the same software as the testing devices to achieve the highest possible ease of use.

The label templates can also be stored centrally on a server. The testing device loads the appropriate label according to the respective test plan and transfers the data to a thermal transfer printer after the test. The labels can also be designed according to your specifications.

In the event of remote maintenance (via Remote Access), we can temporarily dial into your network if required and switch directly to the individual testing device. We then see the screen content of your testing device directly at our location. With your permission, we also have access to the mouse and keyboard. These operations are, of course, only carried out in consultation with you and require your separate access authorization.

The heating systems are ideally suited for integration into automation systems. For this purpose, it provides an enormous variety of different interfaces for communication with various automation systems.

Typical requirements are:

• Control of complete processes and components
  – Processing of inputs, signal generators, scanners, RFID readers…
  – Setting of outputs for e.g. cylinders…
  – Control of Motors and drives…
• Exchanging Start, Stop, and result signals
• Direct communication with a PLC control
• Bidirectional communication
  – Receiving test plans and test parameters
  – Sending qualitative and quantitative test results
  – Sending raw data
• Communication with robots, cameras…

These tasks are fulfilled by our configurable standard software modules, which reduce the effort for integrating the MTC3 into automation systems to a minimum.

Data exchange between heating systems and other IT systems is carried out via proven solutions.

Typical applications:

• Importing production orders from ERP systems
• Automatic dynamic generation of heating and test plans from production orders and bills of material
• Automatic generation of serial numbers from production order data
• Reporting of results to ERP systems
• Receiving label data for label printing
• Communication with specialized systems in the automotive industry

Our standard software modules reduce the effort for integrating the heating systems into an IT system to a minimum.

Traceability provides you with the ability to obtain clear and complete information about the entire manufacturing process, even retrospectively. In the event of quality problems during production or after delivery, traceability offers you the option to respond in a targeted manner.

We provide responses to the following questions:

• Which end products, assemblies, and components are affected?
• Which customers have the end products, assemblies, and components?
• Which assemblies and components are built into the end product?
• When, where, and by whom were which parts processed in the manufacturing process?
• Who manufactured or supplied the assemblies and components?
• Which test results are available for the individual assemblies and the end product?

A prerequisite for the response to these questions is the unique identification of each component, assembly, and final product with a number or code. Additional information such as customer number, supplier number, batch number, etc., may be required for improved traceability and search functionality.

The heating systems are able to record these identifications and additional information, e.g., via barcode input, and save them together with the test results, test date, and operator name in the device's memory or on the network. Based on this information, it can later be traced where, when, and by whom components were processed or delivered in the manufacturing process.

• Current Heating Systems
• Electrical Heating of all Types of Coils
• DC Bonding Systems
• AC Bonding Systems for Connected Three-Phase Windings
• Up to 100 kW
• Up to 2,500 A
• Up to 1,000 V
• Up to 250 A/mm² and more – depending on the load capacity of the winding contacting
• Five heating strategies
  • constant voltage
  • constant current
  • constant temperature
  • Temperature profile
• Thermal bonding of multiple coils in series or parallel connection

• Standard and flash thermal bonding technology
• Display of the temperature profile during thermal bonding for up to 8 parallel bonding processes

• built-in four-wire resistance measurement
• Online Temperature Monitoring
• Online Terminal Point Monitoring (optional)
• Dynamic Excess Current Monitor
• Earth Fault Monitoring (optional)
• Monitoring of built-in sensors/temperature probes

• Combinable with the following additional tests:
  • surge test
  • Partial discharge
  • High voltage AC / DC
  • Rotating field …
• Integration into an existing automated production line
• Integration into an integrator's system
  • Communication with PLC control based on all common bus systems
  • Communication with product carriers, e.g., via RFID
  • Communication/data exchange with ERP or MES systems