Manufacturing companies globally that use fasteners, bolts, and nuts must ensure their torque process and quality standards comply with international standards, like ISO. Establishing quality guidelines comes down to developing a detailed manufacturing process control and executing it with quality assembly torque tools capable of meeting specifications, along with verifying the tools, the process, and the results.
For moderate—to high-volume fastening applications, assembly power tools are often the tool of choice to meet the pressing production demands. There are various quality power tool options to select from, and some brands and tool types are better than others. Educating yourself and testing a power tool to confirm how it performs in your fastening application is key. The tool you select will have an important impact on the fastening quality of the products being produced.
- Torque-controlled power assembly tools are available in different categories:
- Air Screwdrivers
- Electric screwdrivers
- Battery screwdrivers
- Current control screwdrivers
- Transducerized screwdriver
- Transducerized cordless screwdriver
- Pneumatic pulse tools
Battery pulse tools
All these types of power tools must be preset to a target torque value, as specified by the assembly process. They must also be verified frequently to ensure that the correct torque is delivered every time they are operated.
Torque verification plan and schedule
Torque measurement is a key component of any quality control process. Simply tightening a fastener or bolt down until it’s snug and tight and assuming the torque control process is complete is no longer sufficient. Measuring torque doesn’t stop once the assembly process is complete. As part of the overall quality control process, manufacturers should include a torque verification program, a method to detect loose fasteners or any signs of joint relaxation. Torque verification validates the fastening process, the torque tool, the product design, and the materials used for the application.
Precise torque control is a key to quality assembly and can ensure that products perform as expected. A single fastener, inaccurately or incorrectly tightened, can lead to a product’s failure, which impacts the bottom line. In many cases, companies spend a great deal of time and money disposing of or repairing damaged parts during assembly, resulting from improper torquing.
Key reasons for conducting a torque verification:
- Substantiates that assembly procedures reflect actual practice (what we say is
what we do). - Reveals the consistency with the assembly process (from person to person or daily).
- Uncovers inaccuracies with the assembly process so it can be quickly corrected.
- Promotes ongoing corrective actions.
- Encourages process improvement.
A quality manufacturing process must have a daily torque verification plan for any assembly power tools used in the production area. Manufacturing processes have critical and non-critical assembly parts. An engineer should identify these to create a Torque Verification Program, select a power tool for a fastening application, and establish a maintenance program.
- Power tools used for critical assembly parts must be verified before the start of each manufacturing shift.
- Power tools used for non-critical assembly parts should be verified daily.
- All power tools must be verified after being serviced or after being relocated to a new workstation or fastening application.
- A power tool that drifts out tolerance must be removed from the production area immediately.
- Potential issues that cause the power tool to be out of tolerance:
- Routing maintenance is required for the power tool.
- A power tool is due to recalibration based on usage.
- Poor quality fasteners used for the application impact the tool’s performance.
- Any changes to the joint components, such as humidity, lubrication, and materials change.
- Torque measurement equipment has not been recalibrated as scheduled.
Using a Static / Reaction Torque Analyzer or Torque Sensor
There are two types:
a. Torque analyzer with built-in torque sensor
b. A stand-alone torque sensor that connects externally to a torque analyzer
Both types of equipment fulfill the exact torque measurement needs. A torque analyzer or sensor is a finely tuned instrument for calibrating and verifying torque tools. Many brands are in the market, and some test equipment is more sophisticated than others. To select the proper torque analyzer or torque sensor, consider the needs of your tool, the quality of the measurement equipment, the features of the analyzer or sensor, safety certifications, and, most importantly, ISO 17025 Standards.
The torque analyzer or sensor has a rated torque range capacity. The power tool’s torque capacity must be between the torque analyzer’s or sensor’s torque range capacity. Mountz recommends that the power tool’s maximum torque capacity should be between 20% and 80% of the capacity of the torque analyzer or sensor.
Using a Rotary Torque Sensor
These sensors are ideal for dynamic torque measurement applications. They plug into a torque tester or analyzer. The rotary torque sensor is the ideal torque-auditing tool for testing the torque applied to the assembly application. It’s an instrument that quickly attaches to a power tool’s drive without interfering with the tool’s ability to fasten a screw or bolt. As the tool’s operator, whether human or robotic, tightens the fastener, the rotary torque sensor detects how much torque is applied until the tool shuts off and torque is applied to the fastener. Rotary torque sensors measure torque under actual joint conditions, returning the most accurate results possible.
Many brands are in the market, and some rotary torque sensors are more sophisticated than others. To select the proper rotary torque sensor, consider the needs of your power tool, the quality of the measurement equipment, the features of the sensor, safety certifications, and, most importantly, ISO 17025 Standards.
The rotary torque sensor has a rated torque range capacity. The power tool’s torque capacity must fall within the torque range capacity of the torque sensor. Mountz recommends that the power tool’s maximum torque capacity fall within the torque sensor’s 20% to 80% capacity.
Mountz, Inc. can help your company increase safety and reduce costs with our full line of torque analyzers and sensors. To see our full range of products, shop our store. Contact us anytime to ask a question. To inquire about price, request a quote. If you’d like to see our equipment in person, schedule an appointment.
