How Plastics Wear Against Metal

How Plastics Wear Against Metal
In tests mating thermoplastic composites and AISI 1141 cold-rolled steel counter-faces, the highest composite wear factors (greatest wear) resulted with the smoothest range (8-12 µin.) of metal surface finishes.  This result, contrary to what might be expected intuitively, is attributed to the adhesion-and-deformation friction mechanism of metal/plastic combinations.  The 12 to 16 µin. range yielded the lowest wear factors, and the 50 to 70 µin. surface-finish range generally produced intermediate wear-factors for most composites (unreinforced formulations were exceptions). … Read more

BUYING PLASTIC PARTS: The Ultimate Checklist

How to Buy Pastic Parts

by Dean West
Most of the world’s fasteners are produced from metal, but many users have switched to plastic as a better material for their application.  If you’re considering plastic fasteners… There are several pieces of information you’ll want to have to insure that you end up with what you need.
What Are The Options?
Many prospective customers contact Craftech for help in determining what options would best suit their applications.  … Read more

History of the Screw

History of the Screw
A complete history of the screw is not available. There is historical evidence that by the first century it was used in a screw press. But screw presses  used by the Romans to squeeze olives for oil and grapes for wine have been found.  Archytas of Tarrentum is credited by the Greeks with the invention of the first screw.  However, Archimedes the Greek philosopher  is also credited with inventing the screw around 234 BC. … Read more

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4 THERMAL PROPERTIES OF PLASTICS

Generally, there are four commonly used thermal properties of plastics: Heat Deflection Temperature, Continuous Service Temperature, Melting Point or for some, Glass Transition Temperature (Tg) and Coefficient of Thermal Expansion.

Heat Deflection Temperature (ASTM D648)
Heat Deflection Temperature or heat distortion temperature (HDT) is the temperature at which a polymer deforms to heating or cooling under a specified load. ASTM stands for the American Society for Testing and Materials which is an international society that develops and publishes voluntary technical standards for materials among other things. … Read more

The Shape of a Machine Screw

So the screw in my reading lamp fell out and disappeared. I propped it up but from time to time it would let loose and crash down on my face. A trip to the hardware store was clearly in order.  Replacing the screw was easier said than done.  There are so many types. Different threads, head styles, lengths, drives and other criteria.  So what was that screw?
 
The Simple Screw
The screw is one of the six classical simple machines. … Read more