Maximizing Error-proofing in Manufacturing with MES/MOM Controlled Assembly Tools

By Anthony Borges, Marketing Manager, PINpoint Information Systems

Introduction / Summary

This document summarizes the error-proofing solution a leading heavy machinery manufacturer implemented and standardized on in order to greatly reduce product defects due to improperly fastened bolts in transmission systems. Electric assembly tools called nutrunners are used by assembly line workers to fasten bolts to a predetermined torque measurement (see Figure 1.).

Their decision to implement a manufacturing execution system (MES) or manufacturing operations management (MOM) software to both ‘monitor’ and ‘control’ all aspects of the assembly tools and line worker processes yielded unprecedented results by reducing bolted joint failures and Warranty claims by 94%.

Figure 1. Fastening application with electric pistol grip nutrunner

Background / Problems

The heavy equipment manufacturer struggled for years to solve a major problem they had, where products were leaving the factory and entering into service with improperly set bolts in the vehicle’s transmission system. These defective products inevitably lead to an increase in Warranty claims. The losses and waste in
time and expenses as a result created an urgent call to action to remedy the situation.                

Initially the manufacturer had invested millions of dollars into the latest electric nutrunners, controllers, and associated integration costs. The electric fastening assembly tools specified were to monitor all fastening operations in order to identify defects and repair them before the machines entered service. One (1) year after the implementation of the new assembly tools the customer regretfully reported that there were no measureable improvements in the number of bolted joint failures.

The reason the new nutrunners did not reduce bolted joint failures was due to loop-holes in the system itself. The modern fastening tools did contribute new features which in theory were to ‘capture’ any defects, i.e. if a certain torque (Nm) specification was not met, or number of rotations, set angle, etc., then the system was to record and alert line workers and supervisors of any issues. The system fell short in that it could be bypassed or ‘tricked’ by line workers into thinking a job was completed successfully when it was not.

Solution

The solution was to integrate a manufacturing execution system in order to error-proof all processes on the assembly line, be it by tool or device, or human. Further, the system contributed to a paradigm shift in that a culture of ‘full-accountability’ was born into the customer’s manufacturing operations.

The MES/MOM provided the customer a web based ‘configurable’ plant floor management system with the added-value of integral manufacturing optimization features. The MES/MOM filled the void between the customer’s Enterprise Resource Planning (ERP) system and the processes on the assembly line themselves. With the capabilities to both ‘monitor’ and ‘control’ the assembly line processes the MES/MOM ensured no one bit of information or action was unaccounted for. In-turn the process history recorded served to allow for the query of data and output of valuable manufacturing reports which were used to further optimize their manufacturing processes.

Concerning their specific physical problem of bolted joint failures the MES/MOM provided full-control over the electric tool itself, with the capability to ‘lock’ the tool should an installation parameter not be met. Locking out the nutrunners eliminated any chance of the line worker from attempting to pass the defective part. The implementation of the MES/MOM solution yielded instant results as shown (Figure 2.):

Figure 2. MES/MOM reduced bolted joint failures 94% and decreased Warranty claims, as reported by the customer:

Since the MES/MOM is configurable the Process Engineers had the flexibility to set the installation parameters as required, e.g. if the first attempt at setting a bolt failed, that is the tool output a torque or angle measurement not in accordance with the set tolerance in the software - the MES/MOM can then be set to allow for a reversal of the tool, and then for another attempt; should the second or even third attempt fail, then at that time the tool may be locked out and an alert raised. The programming of the MES/MOM is flexible, easy and familiar in a drag-and-drop or WYSIWYG user interface; it is as simple as opening a website browser from a laptop/Smartphone, making the change and hitting ‘save’ – all in real-time.

Above the capabilities to monitor all processes and control devices, the MES/MOM serves to first confirm if even there is a line worker present at the station; and who that person is? The MES/MOM verifies line worker credentials before any work instructions can be provided or tools enabled. Each line worker or manager (user) of the system is provided with her/his own login and password. When the worker arrives at the station to begin the shift she/he logs in and is met by the first instructions which may be to verify whether they have completed a training course, for example, or have achieved a required certification to do the job? Only once the worker is verified may the process continue; the system may next present work instructions, or a quality alert, message video, or any instruction as required.

The MES/MOM over-sees all aspects of the production process and is therefore able to detect and raise alerts of mistakes as they occur; as issues happen the system is capable of sending an alert to a manager with the latest Andon software technology already built in. Textual, graphical, audio and video alerts can be sent via email/text, stack lights, public address systems and on large screen displays.

MES/MOM Software

The MES/MOM software has been developed since 1997 and it continues to be evolved and pushed-forward by leading manufactures. Thoroughly proven it is in use daily around the world in multiple languages by leading automotive, aerospace, heavy machinery, agricultural, and power sports vehicle manufacturers. The software is meticulously designed and tested to ITIL standards before any official version release.

Conclusion

The decision of the heavy machinery manufacturer to implement PINpoint MES/MOM software to both ‘monitor’ and ‘control’ all aspects of the assembly tools and line worker processes yielded unprecedented results by reducing bolted joint failures and Warranty claims by 94%.

PINpoint ensured defects did not go undetected and encouraged problem solving on-the-fly. PINpoint introduced a culture of ‘full-accountability’ into their manufacturing operations; “…enabling a culture based on data and facts, rather than opinions and guesses.”

Related Links

Interactive Presentation 

Production Analytics Demo (Video)

About the Author

Anthony offers over a decade of manufacturing optimization knowledge, with an aptitude for solving problems which increase manufacturing efficiency. He has successfully provided solutions to various multinational manufacturers involving the latest technology in sensors, laser (detection, measurement, welding, cutting, and marking systems), PLC, machine vision, microscope, and software solutions.

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