Vacuum pumps are categorized by their operating pressure range and as such are classified as primary pumps, booster pumps or secondary pumps. Within each pressure range are several different pump types, each employing a different technology, and each with some unique advantages in regard to pressure capacity, flow rate, cost and maintenance requirements. Regardless of their design, the basic principle of operation is the same. The vacuum pump functions by removing the molecules of air and other gases from the vacuum chamber (or from the outlet side of a higher vacuum pump if connected in series).
Archives for January 2016
Identifying the Cause of Tool and Die Failure
Steels used for tools and dies differ from most other steels in several aspects. First, they are used in the manufacture of other products by a variety of forming processes. Second, tools and dies are generally used at a higher hardness than most other steel products; 58 to 68 Rockwell C is a typical range. Dies for plastic molding or hot working are usually used a at lower hardness, typically from 30 to 55 Rockwell C.
These high hardness values are required to resist anticipated service stresses and to provide wear resistance. However, the steels must also be tough enough to accommodate service stresses and strains without cracking. Premature failure caused by cracking must be avoided, or at least minimized, to maintain minimum manufacturing costs. Unexpected tool and die failure can shut down a manufacturing line and disrupt production scheduling. Tools and dies must also be produced with the proper size and shape after hardening so that excessive finishing work is not required. Heat-treatment distortion must be controlled, and surface chemistries must not be altered. Because of the careful balance that must be maintained in heat treatment, control of the heat-treatment process is one of the most critical steps in producing successful tools and dies. In addition to controlling the heat-treatment process, tool and die design and steel selection are integral factors in achieving tool and die integrity.