Many of us probably think a bolt is just a bolt; some of us may not even know the difference between a bolt and a screw. Heat treatment is the key difference from one bolt to another, and understanding that difference is key to correct assembly design. If the wrong bolt is chosen for a given design, it becomes the weakest link and catastrophic failure will result.

Did you know that a sewing needle should be threaded from only one direction? That’s because the punched eyelet has a small burr on one side.

Without springs, modern civilization would not exist. How and who discovered the first spring will never be known, but what we do know is that a spring, which is a piece of steel with memory, returns to its original shape when flexed.

Whenever energy and power are needed in today’s age of miniaturization, rare-earth magnets are called upon to play a vital role. Applications abound, from the family car that uses on average 30 such magnets to powerful levitation systems on magnetic trains. All of this is made possible by elements with strange-sounding names: neodymium, lanthanum, samarium, yttrium and scandium – some of the “rare earths” or Lanthanide elements in the periodic table.

While not his first invention, the hammer – and, in particular, the hammer head – has helped man expand his universe like no other invention until the advent of the personal computer. Through the centuries the hammer head has kept up with the times, evolving from the Stone Age to the Bronze Age to the Iron Age and through the Industrial Revolution (the Steel Age) to encompass materials such as stainless steels, tool steels and nonferrous alloys. Without heat treating, however, today’s hammer head would be no more useful as a tool than the ones whose heads were made of stone.

 

Scissors come in all shapes and sizes and are used for applications as simple as cutting paper and as challenging as cutting Kevlar – and for everything in between.

Consider the humble paper clip, whose utility highly depends on the properties of the metal developed by heat treatment. It may just be a thin piece of steel wire traditionally bent into a double-oval shape, but no one has invented a better method of holding loose sheets of paper together over the past century. In effect, a paper clip consists of two metal surfaces that are pressed against one another by the elasticity of the metal wire from which the paper clip is made.