Manufacturers of seals and other parts utilizing Teflon (Ptfe) rapidly they wind up sweeping the majority of the profits out with all the machining chips when producing components from traditionally compression-molded tubes and rods. PTFE resins are expensive and producing parts from compression-molded rods or even tubes frequently ends up producing just 10-20% of the stuff purchased to the finished parts. The answer is to use isostatic molding methods to produce thin walled tubing.
Isostatic molding originated by the W.S. Shamban Organization in the 1950s and 60s. Initially, when missile nose cones heat shields were produced from Ptfe, an approach was required to evenly compress PTFE Tubing over the round shaped face of a nose cone. This is done by setting PTFE powder above a nose cone shaped aluminum plug, then covering the powder with an elastomeric bladder. The powder, plug and bladder were subsequently put in a pressure vessel and large pressure water pumped in to reach the compression of the powder in the preformed shape ready for stove sintering.
As an interesting side note, as rockets increased, and also the nose cones became too large to fit into stress vessels, the bladder-covered plugs with resin powder sandwiched in were just lowered into the sea to the appropriate level to reach the appropriate compression pressure.
Contemporary isostatic molding devices have come a long ways from the missile nose cone days. Now they use acrylic instead of plain water in cylindrical pressure vessels. Isostatic molding devices typically use a hydraulic pressure system serving intensifier to a customized to conquer the pressure up in the usual 3000 psi hydraulic system components to the higher pressures needed to reach ideal physical properties inside the Ptfe.
The better designs utilize interchangeable mandrels to make the device adaptable to a lot of sizes of tubing, and polyurethane end bits and external diameter forms to transfer the hydraulic pressure in the urethane kidney to varying different sizes of tubing. The soft urethane acts as a liquid itself to exchange the gas pressure to the powdered resin being pressurized. By applying soft end bells, end belling common with earlier models is removed in order for the whole span of the tube is useable.
Minimal hydraulic controls are needed, along with the majority of the hydraulic components required are accessible off-the-shelf. The exclusion is the intensifier, which must typically be designed from scratch to achieve the required pressure boost and volume make-up essentials of such a big, flexible hydraulic system.
Each needs to be custom designed and personalized to match the certain dimension ranges and material compaction guidelines needed. This normally ends up meaning that is a substantial investment in architectural and hardware costs. Additionally, it requires quite a couple of weeks to own a device designed, designed installed and examined. Once that investment is created, however, the pay-back times are reasonably quick, often approach less than 3 years.
Having isostatic capacity allows smaller seal, showing and custom machined PTFE manufacturers the capability to contend with their bigger rivals by radically lowering their scrap rates and permitting them to well bid on high-volume applications.
More infomation here