When providing the best possible error solution for assembly lines in the fastening process, many companies look to “zero-defect” philosophy or “getting it right the first time.” What is the right way to ensure that you have the right torque, required amount of fasteners, required amount of load, and that your product meets end-user expectations? In error proofing, the five main areas to consider are: torque OK, bolt counting, joint OK, collecting data, and zero-fault fastening.

Step one in error proofing begins with the tool shutting off at the required torque, or “torque OK”. What does this mean? Conventional tools used 20 – 30 years ago depended on experienced operators with an understanding of all components in the build to determine what was right the first time. In today’s work place there are more products built and at a faster rate. These increased throughputs raise profitability. Tools designed for today’s assembly environment simplify processes with features like a tool shutting off at the correct torque, signaling to the operator that it is okay to move onto the next process. Shut-off tools are capable of hitting a pre-determined torque either by mechanical device or electronic signal. Various models are available ranging from clutch-activate air tools and gear-driven tools, to transducerized electric tools, each with their own level of accuracy. Typically, the end user decides critical versus non-critical fastening and will choose the appropriate tool based on the safety level for each fastener.

Facilities require step two, bolt counting, when “torque OK” is not enough. The operator now has a method to certify that the fasteners are correctly installed. For example, in a complicated assembly where an operator must hit ten fasteners, a visual signal is given after the assembly process is complete. This is basic counting.

Step three of error proofing can be achieved through joint security, or “joint OK”, when tooling includes angle monitoring. A conventional tool will not tell you if you have achieved both torque and angle constraints – it will shut off at “torque OK.” This does not detect if the fastener cross-threads or strips out. Additionally, it does not detect if there are a missing washers, lock rings or gaskets. Angle monitoring allows you to detect all of these items. Adding angle constraints to your torque strategy will determine that your part is assembled to the required torque and angle specification.

Step four is collecting data. Typically, a transducerized tool is used to determine the exact date, time and serial number of the part being assembled. DC controlled transducerized nutrunners are capable of storing joint information and time of assembly, creating a log of historical data for reference at any time. This can be a crucial time saver in the event of a field recall. Transducerized tools also have the benefit of line control, which allows you to physically stop the line if any of the above methods are missed.

Finally, Step five, what is error proofing without accommodating and tracking for faulty parts or faulty fasteners? If the product cannot pass in-station error proofing, the operator must either stop the line or send the product to the repair station. Zero-fault fastening encompasses this portion of the assembly process to be certain that nothing is undetected and what is detected is fixed. When your product leaves the plant, you will be 100% confident it is ‘right the first time.’

Atlas Copco uses the Error Proofing method to help assemblers reach their goals of productivity and profitability. Contact your local representative today. We are committed to your superior productivity through interaction and innovation.

For more information, visit www.atlascopco.us