As can be seen from the seal cross-section shown in Fig. 14.2, shaft seals are complex shapes that require advanced mold design and molding techniques (see Section 7.3 for discussion of fluoroelastomer molding). For some time, most shaft seals were made in the United States by compression molding. Injection molding of shaft seals is prevalent in Europe, and is being used increasingly in the United States. An advantage of compression molding is that preforms (usually rings cut from extruded tubing) are used that closely approximate the amount of stock required for the final parts, so compound waste is minimized. For injection molding, the amount of cured stock in the central sprue and runner (actually a thin sheet leading to the seal lip) is often large compared to the stock required for the final part, so the waste of high-cost fluoroelastomer may be high. Such waste is reduced in modern injection molding designs.
This is essential for hunters who may have to wade through streams or cross flooded areas This is essential for hunters who may have to wade through streams or cross flooded areas
The slip-on design eliminates the need for laces, making these shoes easy to put on and take off, while the cushioned insole provides support and cushioning for your feet The slip-on design eliminates the need for laces, making these shoes easy to put on and take off, while the cushioned insole provides support and cushioning for your feet
Secondly, it helps sustain the vehicle's resale value; prospective buyers often overlook cars with evident suspension issues Secondly, it helps sustain the vehicle's resale value; prospective buyers often overlook cars with evident suspension issues