Tightening structures using a hand-held tool is a common action in a manufacturing environment. Bolts, nuts, and screws in products often have torque requirements to ensure the safety and quality of the product. Hand tool poka-yoke equipment is designed to eliminate the errors associated with torque tightening. I tried a number of these systems and wanted to share my experience with you.
The poka-yoke system is a fairly simple concept, where the hand tool is connected to a fastening controller. Depending on the level of controller, you can set the required torque, measure and record a history of torque outputs from the tool, record and count the number of bolts/nuts/screws, as well as detect cross threading, double tightening, stripped thread or interference from foreign objects. When an error is detected, buzzer and light features are triggered and the tool switches off. By doing this, operators know that there is an error and they can fix the issue before the product is completed.
Ergonomic Features and Benefits:
- Eliminates wrench torque checks, which often involve high forces being applied with awkward wrist postures
- Eliminates rework, which involves dis-assembly of the product (high forces, awkward postures, longer duration of task)
- Eliminates repetition of tightening through a one-check system
- Depending on the level of controller, can involve significant capital expenditure (however the ROI is offset by the time saved eliminating wrench torque checks)
- Not every hand tool is compatible with poka-yoke systems (check with the manufacture which tools can be used with the controller selected)
- Single controllers cannot be set to check many tightening variations
In summary, some poka-yoke systems can require high capital expenditure, however the benefits of eliminating the high force and awkward postures during wrench torque checks and the time saved make poka-yoke systems a viable ergonomic improvement in the manufacturing environment.