If quality and consistency are important in the products you make, it is crucial that you have the most accurate and reliable torque screwdriver out there.
There is a wide range in the quality of torque screwdriver options available. Some torque screwdrivers are inexpensive but tend to be inaccurate and short lived. Between inaccuracies, tool repairs and tool replacement, buying the inexpensive model typically ends up being more expensive than purchasing the high quality tool in the long run. When considering different brands, Sturtevant Richmont builds tools that are made to last.
Engineers and purchasing professionals who appreciate the power of the checklist have used these questions as their torque screwdriver checklist.
Here are the five points you should consider when buying a torque screwdriver:
- The ISO 6789 standard for torque screwdrivers is +/- 6% accuracy. How accurate is your torque screwdriver?
- What is the +/- accuracy required for your torque application?
- Is the +/- accuracy quoted in full-scale value or indicated value? This is a huge issue that does not always surface until it is too late. What is the difference between the two? With an indicated value screwdriver the readings up and down the scale will be within the quoted accuracy levels. With full-scale value the screwdriver is most accurate at the maximum torque capability of the screwdriver and then the readings become less accurate as you go down the scale.
- What is the accuracy of your screwdriver when 10 pounds of down thrust is added to the calibration or test sequence?
- What is the accuracy of your screwdriver when 20 pounds of down thrust is added to the calibration or test sequence?
Ease of Use
- Does the handle diameter make it easier or harder to apply the torque?
- How much does the screwdriver weigh?
- If interchangeable bits are required, how fast and easy is it to change the bit? What tools are involved?
- What about ergonomics? Is the handle comfortable? Is it sized properly? Does the handle provide the user with a mark for proper gripping?
- If it is an adjustable screwdriver, how easy or difficult is it to change the setting?
- How difficult is it to read the scale? All screwdrivers can cause repetitive motion injuries. The issue is the dwell, or the degrees of rotation required for the screwdriver to complete the task and reset for the next operation. Some screwdrivers require 120 degrees to reach the reach the dwell, or reset point. The greater the degree of rotation, the greater the likelihood of injury.
- What about the dwell on this tool? How much rotation is required?
- What is the calibration history of the screwdrivers? What calibration cycle do you recommend for this screwdriver?
- Every manufacturer faces the question of outsourcing calibration or keeping it in-house. Both sides have advantages. If you are also using powered screwdrivers in-house verification becomes more advantageous because low cost verification/calibration instruments like the TorqTronics 2 work with both manual tools and power tools.
- Are your screwdrivers tested and calibrated with ten and twenty pounds of weight added to simulate thrust force?
The ISO 6789 standards are an agreed upon consensus by the international community of tool manufacturers. Those manufacturers make both DIY tool and industrial tools. What is acceptable in a DIY project many not work for a sophisticated industrial application. This applies to both accuracy and minimum cycle standards.
- How many cycles will the screwdriver endure in both directions and still be within specification?
- What is the overall cost of ownership? What ratio of spares to tools do you recommend?
- Warranty and durability go hand in hand. What is the warranty on these tools?
Suitability for torque screwdrivers can be defined using several aspects.
- Handle circumference is important. The suitability for workers with the largest hands and smallest hands can be very different based on the handle circumference. A smaller grip requires more hand strength to generate the same torque with a larger screwdriver handle.
- Within the past decade plastic (disposable) torque screwdrivers have become more common. The suitability question revolves around ESD. Does the screwdriver protect from electrostatic discharge during use? This is especially important with electronics applications.
While this is not a complete list and you probably have some questions, this list covers many issues. If you are buying torque tools, it is important that you find the right tool for the job. If real quality is important, buying torque screwdrivers that are accurate, reliable, and durable is the best choice for quality. It is also the best choice for your budget because the total cost of ownership for high quality screwdrivers is always less than the cost of cheaper tools that break and require repair and calibration more frequently.