Category Archives: ARTICLES

Know Your Customer, Know Your Competition

Every supplier has opinions of their customers and what seems to motivate them to buy. Success in meeting economic goals is always dependent on the accuracy of those views. Following is one view of what makes the product development engineer tick in 2006. Of course the first question is whether engineering or procurement is your… Read More »

Drive Features – How Low Can You Go?

Here in metro Detroit, a popular subject for editorials and panel debate is why it seems the passion America once held for the automobile is in decline. Does the legislation and message coming out of Washington promote the development of appliances on wheels? Are manufacturers too risk-adverse and infested with a “bean-counting” mentality to ignite… Read More »

Dissecting the Nut Factor

A Riddle, Wrapped In a Mystery, Inside an Enigma It is recognized that we measure torque when tightening threaded fasteners only because measuring bolt tension, the more important quantity, is much more difficult. The relationship between the torque applied to a fastener and the tension created from the resulting bolt elongation is most commonly described… Read More »

Calibration Techniques for Ultrasonic Tension Measurement

The fundamentals of using ultrasonic pulse-echo technology for bolt strain measurement, detecting change in the time required for a pulse of energy to travel the length of the fastener after elongation, can be performed with very good resolution and repeatability. The challenge is utilizing this core capability in a manner such that the resulting calculation… Read More »

Bolted Joint FAQs

Two of the most commonly asked questions about fasteners are “When should fine-thread fasteners be used?” and “is it preferable to apply torque to the nut rather than the bolt head?” Many different factors influence those decisions, but here are some basic answers to both questions. WHEN SHOULD FINE-THREADED FASTENERS BE USED? For a given… Read More »

Use of Washers and Flange Heads

It is likely that most common answer to the question “What is the main benefit of flat washers or flange head nuts and bolts?” would be that the increased bearing area they provide distributes the bolt load over a greater area thus decreasing the potential for compressive yield. While true, during testing we were able… Read More »

Torque Control vs. Angle Control

In previous columns. I’ve explained why tightening fasteners to a particular torque does not mean the resulting bolt tension will be either accurate or repeatable. That’s one of the biggest challenges of using bolted joints that depend on clamp load. However, another means of tightening that does not rely on the torque tension relationship is… Read More »

Problems Solved

Bolted joints are the vast majority of our consulting business. Our work is divided evenly between validating joints under development and troubleshooting problems with existing joints. Our troubleshooting experience led us to develop the matrix below to help engineers solve common problems with bolted joints. Distilling even the most common problems and solutions into the… Read More »

Nine Common Bolting Boo-Boos

As with most endeavors where success can’t be measured by keeping score, a good job of engineering is often defined by not doing a bad job. In other words, the most direct measurement of successful joint design and assembly is a lack of joint problems. As an independent test lab, we evaluate joint capabilities, failure… Read More »

More Data, Less Knowledge?

Several times before. I have discussed the need for physical testing in the development and validation of bolted joints. However, just as both the quality of the joint and the quality of the joint designer’s knowledge base will be limited by reliance on numerical analysis, the same limitations occur when experience and applied experimentation is… Read More »