Steve serves as Senior Editor of Machine Design. He has 23 years of service and has a B.S. Biomedical Engineering from Steve was a Flight officer in the U.S. Navy. He is currently responsible for areas such as aerospace and medical.
When engineers need to make curved or bent pieces of sheet metal, they use company-written tables, rules of thumb, and guesstimates to determine the length of straight stock needed for bending into a precisely measures curved part. But these methods are unavailable to some engineers.
Tamper-resistant or security fasteners are often used to prevent unauthorized entry. They are often non-removable or require a special tool to remove them. Higher-quality tamper-proof fasteners have hardened heads, making it difficult to form a new drive slot with a file.
A major cause of failures in metal fasteners is electrochemical corrosion (rust), or so-called galvanic action. Engineers and designers alike can greatly reduce this type of corrosion by specifying fasteners made of the proper materials or with the right coatings.
Bolts and screws can be outfitted with a variety of different head styles. Which style an engineer specifies depends on several factors: the type of driving or installation equipment used, the type of joint load, and the external appearance desired.
Some plastic resins get blended with fillers to reduce costs. Properly used mineral fillers can also improve moldability and stability, increase heat-deflection temperature, reduce thermal expansion, and change other performance characteristics as well.
Engineers have long used stress-strain curves to uncover a host of material properties including elastic limit, elastic and plastic ranges, yield point, ultimate and rupture strengths, and the moduli of resilience and toughness.