WorldWide Drilling Resource

15 WorldWide Drilling Resource ® JUNE 2013 Physics: The Physical Properties of Materials by Britt Storkson Owner, P2FlowLLC The study of physics is the study of materials’ physical properties, meaning: What is this material like? What is its mass (weight)? What is its strength-to- weight ratio? How does it behave under certain stresses or temperatures? Can it be cast or machined easily? Can it be stamped or otherwise formed? Is it useful to create one or more products? Is it cost effective to make one or more products? People sometimes complain plastic materials are often used to replace metal parts simply because they are cheaper. While this is often the case, it isn’t always the case. I worked in a sawmill some years ago where they used UHMW (ultra- high molecular weight) plastics in the U-shaped trays where metal chains (sort of like bicycle chains) would transport sawdust to be stored in large silos. Originally, the metal chain would slide along the bottom of the tray and the sawdust would be trapped in the chain to be transported to the storage silo. Over time, the metal-to-metal con- tact would wear out the tray and the tray would have to be replaced at great expense. Placing UHMW plastic sheets in the bottom of these trays for the metal chains to ride on instead of the bare metal great- ly increased the life of these trays. In fact, the UHMW plastic-lined trays actu- ally outlasted the plain metal trays many times over. So while the UHMW plastic cost more, when replacement labor and downtime was figured in, it actually cost considerably less. Often, aluminum is used in place of cast iron for automotive parts. While aluminum cannot replace every auto- motive part because it simply isn’t strong enough, properly engineered aluminum parts are quite satisfactory for automo- tive service. Physical evaluation demon- strated the strength of cast iron simply wasn’t needed in many areas. Aluminum was lighter and cheaper and, properly applied, provided adequate strength. Aluminum is also softer, so it doesn’t wear out machine tools (drills, cutters, grinders, etc.) quite as quickly...another cost savings. There are also many dif- ferent grades of metals for engineers to choose from. So they can pick just the right material for the application. Of course, better material costs more, so there is the ever-present cost versus quality challenge. Why put an engine in a car that will last for 500,000 miles when the rest of the car will only last 200,000? Product manufacturers try to choose the part that will do the job adequately yet not be overly expensive for the customer to buy. Product manufacturers also offer different “grades” of product. You can buy a good quality product, and pay more for it. Or you can buy a lower grade prod- uct, but it typically won’t last as long. More choices equals a better value for the customer and it’s a good thing. Britt Britt Storkson may be contacted via e-mail at admin@ worldwidedrillingresource.com