Companies of seals and other factors utilizing Teflon (PTFE) easily that they end up capturing nearly all of their profits out with the machining chips when producing components from typically compression-molded rods and tubes. HDPE Rod resins are expensive and making parts from compression-molded rods as well as pipes often ends up yielding only 10-20% of the material ordered in to the finished parts. Since PTFE, once sintered, cannot be reground and re-used, 80% of the material cost result in the waste. The clear answer is to use isostatic molding ways to produce thin walled tubing.
Isostatic molding originated by the W.S. Shamban Company in the 1950s and 60s. Originally, when missile nose cones heat shields were manufactured from PTFE, a method was required to evenly pack PTFE powder across the round shaped surface of a nose cone. This was done by setting PTFE powder over a nose cone shaped metal plug, then covering the powder with an elastomeric kidney. The plug, powder and kidney were then placed in a pressure vessel and high pressure water moved in to attain the compression of the powder in to the preformed form ready for oven sintering.
As an interesting side note, as rockets became, and the nose cones became too big to fit into pres-sure vessels, the bladder-covered plugs with resin dust sandwiched inside were simply lowered into the ocean to the appropriate degree to accomplish the appropriate pressure pressure.
Modern isostatic molding machines attended a long ways in the missile nose cone days. Today they use gas instead of water in cylindrical pres-sure vessels. Isostatic molding products usually make use of a hydraulic pressure system serving a custom intensifier to stop the pressure up from the common 3000 psi hydraulic system components to the higher pressures had a need to obtain ideal physical properties in the carved Delrin Sheet.
The greater types employ compatible mandrels to really make the unit adaptable to several sizes of tubing, and memory end pieces and external diameter forms to transfer the hydraulic pressure in the urethane bladder to varying different sizes of tubing. The soft urethane acts as a substance itself to transfer the hydraulic pressure to the powdered resin being squeezed. Through the use of gentle end bells, end belling common with earlier patterns is removed so that the total period of the molded tv is usable.
Small hydraulic controls are required, and the vast majority of the hydraulic elements required are available off-the-shelf. The exception is the intensifier, which must generally be designed from scratch to achieve the necessary pressure raise and volume make-up requirements of this kind of large, flexible hydraulic system.
The only problem with isostatic molding will there be are no machines you can only purchase off-the shelf. Each must be custom-designed and tailored to meet the particular size ranges and product compression variables needed. This generally speaking ends up meaning there's a sizable investment in design and hard-ware costs. Additionally it requires many months to get a machine designed, created installed and tested. Once that expenditure is made, though, the payback times are relatively small, frequently way less-than three years.
Having isostatic capacity allows smaller seal, showing and custom machined PTFE producers the ability to compete with their larger competitors by substantially reducing their scrap rates and allowing them to competitively bid on high volume applications Homepage.