Torque wrench Step-by-Step Guide to Calibrating a Torque Wrenches are essential tools used across automotive, aerospace, manufacturing, and industrial settings to apply precise torque to bolts and fasteners. However, even the best torque tools can drift over time, leading to inaccurate readings. This is where torque wrench calibration becomes critical.
In this blog, we’ll walk you through a step-by-step guide to calibrating a torque wrench, covering everything from setup to verification—ensuring safety, compliance, and optimal performance.
What is torque wrench calibration?
Torque wrench calibration is the process of adjusting and verifying the accuracy of a torque wrench against a known standard. This ensures the tool applies the correct torque as per the specified requirement. Calibration helps in:
- Maintaining torque wrench accuracy
- Preventing under- or over-tightening of fasteners
- Complying with ISO, ASTM, and other standards
- Improving equipment lifespan and safety
Why is torque wrench calibration important?
Without proper calibration, torque tools can give incorrect readings, leading to:
- Mechanical failures
- Compromised safety
- Product rework or recalls
- Failed audits or inspections
Regular torque tool calibration helps maintain torque wrench measurement precision and ensures consistency in operations.
When should you calibrate a torque wrench?
Experts recommend calibrating a torque wrench:
- Every 5,000 cycles or 12 months—whichever comes first
- After a significant drop or mechanical shock
- If stored improperly or unused for a long time
- When performance inconsistencies are observed
Step 1: Gather required tools and equipment
- A certified torque calibration system or tester
- A known standard (like a load cell or torque transducer)
- Calibration certificates for traceability
- A stable workspace with no vibration or external forces
Step 2: Set the torque wrench to a specific value
Choose 20%, 60%, and 100% of the wrench’s maximum capacity for testing. For example, if your wrench’s range is 100 Nm, test it at 20 Nm, 60 Nm, and 100 Nm.
Step 3: Secure the wrench to the calibration device
- Mount the torque wrench in a horizontal position to the calibration system.
- Make sure the wrench is stable and aligned correctly to avoid angle errors.
Step 4: Apply torque
- Slowly apply torque in a controlled and consistent manner.
- Repeat this process three times for each test point.
- Record each reading from the calibration device.
Step 5: Calculate the deviation
Compare the readings to the set torque value. Use this formula:
% Error = [(Measured Torque – Set Torque) / Set Torque] x 100
If the error exceeds acceptable limits (usually ±4%), the wrench must be adjusted or repaired.
Step 6: Adjust and re-test (if needed)
If the wrench fails, adjust it using the manufacturer’s instructions. Then repeat the calibration steps to ensure compliance.
Step 7: Record Results and Issue a Certificate
After successful calibration:
- Document all test data and deviation values
- Issue a torque wrench calibration certificate
- Label the wrench with calibration date, due date, and technician initials
- Document all test data and deviation values
Common calibration standards for torque tools
- ISO 6789 (Torque Tools – Hand Torque Tools)
- ASTM E2428 (Torque Wrench Calibration Procedures)
- ASME B107.300 (Hand Tools Standard)
Benefits of professional torque wrench calibration
- Increased operational safety
- Improved product quality
- Better torque wrench reliability
- Compliance with industry audits and inspections
- Extended equipment lifespan
Frequently asked questions
Every 5,000 cycles or once every 12 months, depending on usage and environmental conditions.
You can perform a basic check, but accurate calibration requires certified equipment and professional expertise.
Storage conditions, mechanical shock, frequency of use, and environmental factors like temperature and humidity.
Yes. All torque tools—mechanical or digital—require regular calibration.
Conclusion
Torque wrench calibration is not just about compliance; it’s about maintaining safety, performance, and trust in your tools. Whether you are in automotive repair, aerospace, or manufacturing, having a calibrated torque wrench ensures precision in every turn.
If you’re looking to calibrate a torque wrench or require torque tool calibration services, get in touch with Prism Calibration—your trusted partner in accuracy.
Author Bio
Mr. Parthiv Kinariwala is a leading expert in calibration and testing services, with over 20 years of experience in the industry. As the founder of Prism Calibration, established in 2004, Mr. Kinariwala has been at the forefront of delivering precise and reliable calibration, testing, and validation solutions across various industries. His expertise in providing services that meet international calibration standards has earned the trust of major clients, including Reliance Industries, Zydus Cadila, Indian Oil, ONGC, Adani, and Tata.
With a deep understanding of instrumentation, measurement accuracy, and industrial testing, Mr. Kinariwala ensures that each client receives exceptional service tailored to their specific needs. His unwavering commitment to quality and precision has established Prism Calibration as a trusted partner for some of the largest and most respected organizations in the industry.