Having trouble viewing this email? View it online here

WELCOME   We have been busy developing the second edition of our Engineers Guide To Spring Technology. We had a great response from the first edition and are keen to ensure that we continue to help solve your common design problems. In this edition we take a look at some of jargon that is often used and offer the first part of our Spring Glossary. We also have a closer look at failure prevention for Torsion Springs. Please let us know if there are any other design problems or questions that you would like answering. Sit back and enjoy polishing up your technical knowledge...

Failure Prevention Of Torsion Springs   Some years ago, a customer complained about some large torsion springs we had supplied a few weeks earlier, as they had failed soon after being installed. The stresses that the springs were subjected to were within acceptable limits and we were initially unable to offer an explanation as to the cause of failure. However, examination under magnification of the area around the breakages revealed some marks in the wire surface. Further, higher magnification inspection showed that these marks were in fact weld pools. When these findings were given to our customer, investigation revealed that one of their employees had struck an arc on the springs with a welding electrode; why we don't know! It was explained to the customer, that although the weld pools appeared to have a depth of perhaps only 5% of the spring diameter, the surface of the wire diameter adjacent to the spring's outer diameter is where the bulk of the stress is concentrated, and even small imperfections can lead to sudden failure under load. The moral of the story is, 'cover up your springs when welding is taking place nearby'. Did You Know?   If you ever experience entanglement with compression springs have you thought about adding a dead coil to the ends and middle? We have worked with a number of clients on this very topic and dead coils are proven to reduce entanglement. We have also developed solutions to prevent entanglement that involve putting coils in the centre of a spring to prevent crossing. We can also look to prevent entanglement by packing compression springs in smaller quantities or through using our custom and specialised packaging solutions.     Spring Glossary - Part 1   Angle of Grind Angle subtended by the ground end surface of the spring. Buckling The tendency of a compression spring to bow or to deflect laterally, when loaded. Modulus of Rigidity (G) Coefficient of stiffness for materials used in extension and compression springs; the modulus in shear. Pitch The distance from any point in the section of one coil to the corresponding point in the next coil when measured parallel to the axis of the spring. Stress Relieving Low-temperature heat treatment designed to relieve the detrimental stresses induced by the manufacturing processes. Slenderness Ratio Ratio of spring length (LO) to mean coil diameter (D). Shot Peening Impacting the surfaces of the spring with pellets to induce compressive stresses and thereby improve fatigue life.