Many joints consist of more than one fastener and bringing together surfaces that are not completely flat can be a very challenging torque problem. The sequence of tightening fasteners can have a major influence on the resulting preload and clamping force, which is what holds two parts together. With such joints, consideration should be given to specifying the sequence in which the fasteners are to be tightened. Because the joint surfaces compress, tightening one fastener in the vicinity of another will affect the preload generated by the first fastener tightened. This is called Cross Talk.

A good tightening sequence ensures that an even preload distribution is achieved in the joint. Since joints containing conventional gaskets have a comparatively low compressive stiffness, bolt preloads in such joints are particularly sensitive to the tightening sequence. Based on experience, if the bolts are in a circular pattern, a cris-cross (star) tightening pattern would normally be specified. For non-circular bolt patterns, a spiral pattern starting at the middle would normally be specified. On critical joints or joints that exhibit relaxation, a tightening pattern that tightens the fasteners more than once can be specified to ensure an even preload distribution.

Sequence based fastening is critical to proper process control and a quality fastening result for many applications. If an assembly exhibits cross talk, a phenomenon where torque to one fastener changes the result to another in the in fastening pattern, altering the sequence is often necessary to achieve proper results. Position Control torque arms are designed to reduce the risk of improperly fastened screws, ensuring that every screw is in the correctly tightened in the correct sequence. An encoded torque arm is perfect because it guides the operators sequence and provides feedback if done incorrectly.

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The EZ-Glider Position Control torque arms by Mountz Inc. help manufacturers detect and eliminate costly screw-fastening errors during the assembly process. Position Control torque arms are designed to reduce the risk of improperly fastened screws, ensuring that every screw is in the correctly tightened in the correct sequence. Using the EZ-Glider Position Control torque arm is like putting the eyes and ears of a quality control manager where they are needed most – right on the assembly area.

“Sequence based fastening is critical to proper process control and a quality fastening result for many applications,” said Brad Mountz, President & CEO of Mountz, Inc. “If an assembly exhibits cross talk, a phenomenon where torque to one fastener changes the result to another in the in fastening pattern, altering the sequence is often necessary to achieve proper results. An encoded torque arm is perfect because it guides the operators sequence and provides feedback if done incorrectly.”

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The EZ-Glider torque arms are designed to improve production and quality control during the assembly process. The ergonomic torque arm prevents side load and cross threading, by securely clasping the electric screwdriver or pneumatic screwdriver and keeping the tool in a perpendicular alignment. The EZ-Glider helps remove the operators influence in the assembly process and strengthens quality control. The ergonomic design of the EZ-Glider torque arms reduces RMI (repetitive motion injury) and CTS (carpal tunnel syndrome). The effortless handling of the torque arm provides comfortable tool operation and increased production.

An ergonomic mindset helps ensure safer conditions
Besides the proper selection of ergonomically correct tools and workstations, manufactures should adopt enterprise wide programs that increase the awareness of ergonomics within administrative offices as well as on the production floor.

A successful ergonomic system incorporates employee participation that includes discussion across all levels and directions of an organization. It’s recommended to avoid the one-size-fits-all approach. Every ergonomic concern requires its own evaluation, ideally performed by a person competent in such issues. When indicated, control measures should be designed to eliminate ergonomic stresses specific to the results of the evaluation. Finally, effective follow-up mechanisms must be provided.

- Form a permanent safety committee
- Perform a job safety analysis for every job
- Perform routine inspections, even if no hazards have been reported
- Immediately correct any deficiencies; and conduct an accident investigation for each incident, even “near misses.”

When planning a production area, it pays dividends in the long term to plan the ergonomics of the operation and consult a health and safety inspector or ergonomic manager. Ensure both the workplace and the assembly operation are compatible with the majority of operators who will work there. This can reduce future costs arising from work-related health disorders among operators, along with costs arising from poor product quality. Also, the need to redesign the production system later may be avoided.

The goal for all ergonomic and safety managers is to reduce the number of people suffering from work-related injuries. With the cost for worker’s compensation continuing to increase, companies are looking for ergonomic solutions to reduce the costs of insurance claims.

In the Assembly Area, Does Your Company Have a Strategy for Reducing Injury Loses?

Every workstation is unique. The human being represents the largest collection of variables; therefore a workstation that suits one operator perfectly may be a disaster for another. This could be one of the reasons why problems often arise unexpectedly when a new production unit is started up.

The goal must be to design workstations where every member of the actual workforce can work comfortably. This calls for a large degree of adjustability that often increases the cost. However, the investment can be justified by the resulting high flexibility.

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