i4.0 today

 

 

 

 

 

Paul Wild, Hans Bell, Lukas Ziegler, Rehm Thermal Systems GmbH, February 2017

Introduction – Today and Tomorrow

A number of years have passed since the term Industry 4.0 was first coined by the German Federal Government at the 2011 Hannover trade fair, and in the meantime the associated vision, as well as the research agenda, are characterized by increased clarity and have taken a distinct direction. Association work conducted by the VDMA, Bikom and ZVEI has also had a very positive effect. Industry 4.0 and the Internet of Things involve a pioneering alignment of the modern manufacturing world, as well as networking of production equipment such as machines, devices and sensors with each other and with internal and worldwide information systems.

Goals include greater flexibility, an increased degree of automation and capabilities which permit self-optimization of manufacturing processes, and at the same time reduced investment and R&D expenditures, as well as minimized consumption of resources. In order to map out the actual manufacturing sequences of an intelligent digital factory, all essential process data has to be acquired and evaluated with suitable sensor technology and software.

Based on the example of a convection soldering system, this article demonstrates what modern smart sensors and intelligent systems are capable of with regard to monitoring the condition of soldering system components, and how this additional information can contribute to predictive maintenance.

As shown in figure 1 using the VisionX convection soldering system as an example, more and more new sensors are becoming necessary in particular for the optimization of maintenance intervals, for more precise process timing, and for monitoring and controlling the consumption of resources.

Already today, reflow soldering systems are optimized to a great extent with regard to their (isolated) control functions, as well as their energy consumption, sustainability and manufacturing efficiency. They can be linked with a production line monitoring system which forwards data to a manufacturing execution system (MES) and to enterprise resource planning (ERP). The software used in reflow soldering systems permits traceability concepts by means of which process data, system status, alarms and other information can be transmitted. Communication with the manufacturing world is also viable, for example via a mobile production-line assistant system such as ASYS PULSE Line Assist which makes it possible to monitor an entire SMD production line using a tablet or a smartwatch, is capable of controlling handling modules and even permits self-organizing material logistics with autonomous transport robots (see figure 2).

Table 1 compares current and future options for incorporation into information systems.

Below: Table 1: Incorporation of Reflow Soldering Systems into Information Systems

Already today, reflow soldering systems are optimized to a great extent with regard to their (isolated) control functions, as well as their energy consumption, sustainability and manufacturing efficiency. They can be linked with a production line monitoring system which forwards data to a manufacturing execution system (MES) and to enterprise resource planning (ERP). The software used in reflow soldering systems permits traceability concepts by means of which process data, system status, alarms and other information can be transmitted. Communication with the manufacturing world is also viable, for example via a mobile production-line assistant system such as ASYS PULSE Line Assist which makes it possible to monitor an entire SMD production line using a tablet or a smartwatch, is capable of controlling handling modules and even permits self-organizing material logistics with autonomous transport robots (see figure 2).

Table 1 compares current and future options for incorporation into information systems.

Today Tomorrow
The reflow soldering system is linked to the production line control system The reflow soldering system communicates with the entire manufacturing world
The reflow soldering system is linked to MES and ERP The reflow soldering system communicates with the product – knowledge concerning what is to be produced and how
Traceability concept (transmission of machine and process data) Reflow soldering systems possess forward-looking intelligence and can autonomously optimize reflow processes
Table 1: Incorporation of Reflow Soldering Systems into Information Systems

 

Below: Figure 2: Incorporation of the Reflow Soldering System into a Mobile Line Assist System

In order to continue development of data exchange with the reflow soldering system towards the evolution of a cyber-physical system, new smart sensors and software components will be required which are capable of communicating via a data infrastructure with numerous mechanical and electronic system elements, as well as with the product to be produced. Step by step, this vision is being transformed into reality.

Predictive Maintenance

Today, maintenance work is conducted primarily at specified time intervals. The duration of these intervals depends on the manufacturer’s system-specific recommendations and process circumstances such as the number of shifts and system utilization.

With regard to the pursuit of the defined goals of the intelligent factory such as increased flexibility and self-optimization of the manufacturing process, time-based maintenance is too rigid and insufficiently cost-optimized. Additional smart sensors are required in the reflow soldering system in order to make the transition to condition-based servicing in the sense of predictive maintenance.

Pressure Monitoring

For many years now, reflow soldering systems included in Rehm Thermal Systems’ VisionX series have been equipped with two time-tested residue management systems: pyrolysis in the preheating zone, as well as cold condensation and filtering in the cooling zone. And thus residues in all states of aggregation – gaseous, liquid, solid (particulate) and crystalline – are effectively and energy-efficiently absorbed from the process atmosphere. Deposited residues are initially collected within the system and finally removed during maintenance procedures. Experience gained with more than a thousand system demonstrates that in the case of pyrolysis, replacing the absorber granulate once a year is entirely adequate. Where cold condensation is concerned, maintenance intervals fluctuate greatly depending on process characteristics.

The condition of both systems is continuously monitored by installing pressure monitoring sensors (see figure 3) at the pyrolysis unit and the cold condensation tract, and the system operator is informed of any pending maintenance requirements. Availability of the soldering system can be increased and operating costs can be reduced thanks to forward-looking intelligence integrated into the separator systems.

Below: Figure 3: Condition Monitoring of the Pyrolysis Unit (left) and the Cold Condensation Cooling Tract (right)

Vibration Monitoring

As indicated by the measurement results shown in figure 4, contamination of the overall reflow soldering system is never homogenously distributed throughout the entire process. Concentration of volatile hydrocarbons is higher in preheating at process temperatures of 150 to 200° C than it is in the peak zone and the cooling tract. Contamination of the conveyor system can thus not be ruled out, even if it functions very well. If this contamination exceeds a tolerable level, the conveyor chains may begin to vibrate and, in unfavorable cases, vibration can be carried over to the PCBs to be soldered thus impairing positioning of the components. An intelligent chain lubricating system which doses oil depending on the soldering system’s process temperature can contribute to a significant increase in the intervals between required maintenance.

Below: Figure 4: Concentration of Volatile Hydrocarbons in a VisionXP for Lead-Free Processes

Monitoring of system vibration can also be advantageous. There are two ways in which vibration data can be used. On the one hand, observing existing oscillation at the conveyor level serves the purpose of quality control for the manufacturing process. On the other hand, further potential sources of vibration within the system, for example components with moving parts such as motors, fans and pumps, can be monitored as well. This concept involving condition monitoring of machine components allows us to draw conclusions concerning their operating statuses, thus making predictive maintenance possible.

Figure 5 shows the sensor for monitoring vibration in the conveyor system of a VisionXP+ vacuum reflow soldering system. Any wear of, or interference with the mechanical system which occurs during production is detected and evaluated. As a result, the operator has enough time to plan and implement suitable action before it’s too late and the system comes to a standstill.

Below: Figure 5: Vibration Monitoring for the Conveyor System of a Convection Soldering System

The example in figure 6 shows numerous vibration values measured in conveyor direction over a period of time. The maximum value in the diagram is 27 mg which is non-critical for the production conditions of a reflow soldering process.

Below: Figure 6: Measured Vibration Values for Conveyor Monitoring in a VisionXP+ Vac Convection Soldering Oven

An evaluation of the vibration frequency spectrum is better suited for monitoring system components. The frequency spectrum of a fan depicted as an example in figure 7a (vibration sensor in X direction) demonstrates a small peak with an amplitude of 7 mg at a fan frequency of 35 Hz in undisturbed normal operation. Amplitude is increased to roughly 150 mg when the fan is out-of-balance.

Below: Figure 7a: Fan in Undisturbed Normal Operation

Below: Figure 7b: Out-of-Balance Fan

Smart Motors

A new generation of motors known as electronically commutated motors (abbreviated EC motors) permits direct communication with the motor system for the first time in the history of motor technology. Not only is direct digital control of the motor possible: the motor can now supply data concerning it’s operating status to the reflow soldering system’s information system as well. More than 60 different parameters permit comprehensive monitoring of the motor’s operating status and thus make it possible to detect problems in advance. Figure 8 illustrates monitoring of IGBT temperatures at two motors. Motor 2 has already exceeded the permissible limit value temperature. This information triggers, for example, a warning in the system software and a corresponding display, which in turn results in various measures.

Below: Figure 8: Monitoring Motor Status