- SPECIAL REPORTS
Despite having 21st century technology, we still use assembly processes that were firmly rooted in the early 20th century. Control over the assembly sequence is vital in creating sophisticated, customized, high quality products.
The assembly sequence is often left to the worker, who may or may not assemble the product in the required sequence. Assembly sequence control is vital, but how do you gain control of that process? While you may not be able to control the worker, you can control the tools. Control is easy with a DC nut-runner or tools connected to a processor.
What about hand tools? How can you control them to gain assembly sequence control? Radio equipped hand tools and communicating controllers have proven to be a very viable solution to gaining control of the assembly sequence. This recent development has brought the assembly process into the 21st century.
A torque controller and radio equipped hand tools create a system that provides robust communication between controller and tools. The type of radio that is used is important. Bluetooth technology is great for your car, but applying Bluetooth in a factory setting creates major drawbacks.
One drawback is battery life. How long does the battery in a cell phone and/or Bluetooth earpiece last? How long would those same type of batteries last in an industrial application? It is the Bluetooth communication protocols that limit battery life.
Channel hopping is another drawback. Where only one Bluetooth device is functioning there little channel hopping. When multiple Bluetooth radios are in close proximity, channel hopping becomes a nightmare.
XBee radios operating on 12 channels within the 2.4GHz frequency is a superior alternative. There is no channel hopping and battery life is much longer.
How Does It Work?
The controller organizes groups of fasteners, tools and specification information into parameters. The parameters are organized into numbered jobs.
The controller brings up a job number and the associated parameters in a predetermined, hard sequence. Both the controller and tool direct the worker on the required assembly activity. Since one tool is assigned to a parameter, the controller activates only the tool associated with the current parameter.
No matter how many times a worker tries to use a suspended state tool, the controller only recognizes activity from the active tool.
The controller and the tool provide the worker with visual and auditory feedback on progressing through the parameter. A batch total and batch count are provided so the operator is always aware of where they are in completing a parameter.
In addition, visual and auditory feedback is given as each fastener is tightened. Different and immediate feedback is provided for conforming and nonconforming torque event. The batch count should not advance with a non-conforming event. As a parameter is completed, the controller should advance to the next parameter in the sequence.
The same circuit providing feedback should also generate report data with each torque event, date and time-stamped. Hand tools can no longer get out of hand.
These radio-controlled systems add value connected to the MES or operating as a stand-alone system. Either scenario provides both control and valuable data.
The sequence of assembling highly customizable equipment like tractors, heavy equipment, or aircraft is no longer in the hands of uncontrollable hand tools.
Companies have implemented these radio controlled, hand tool systems to reduce rework and warranty costs. While the ROI for these initiatives is very viable, the larger return comes from improving throughput and worker productivity.
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