Titanium is one of the most prolific elements on Earth, but extruding it from its basic ore is an expensive and time consuming effort. A processing method developed in the 1930's by Wilhelm Kroll spawned the use of the metal in the 1950's. Since titanium is almost 50% lighter and about 30% stronger than steel it became a natural choice for the aerospace industry. An added bonus is its superior corrosion & heat resistance. The marine industry also uses titanium; the Navy builds submarines & propellers from it along with engine parts & shafts. When exposed to air it oxidizes like other metals. The difference is it doesn't rust - it forms a protective surface shield which makes it immune to salt water corrosion. This fact didn't go unnoticed by manufacturers since it makes a great material for dive watches. IWC pioneered the use of titanium in the 1970's, and the success of the Porsche Design Chronograph was a big part of the positive turnaround by the company. In 1984 they followed it up with the Ocean 2000, named for its 2000 meter water resistance rating. IWC Porsche Design Chrongraph: Unfortunately IWC and Ferdinand Porsche dissolved their relationship in the 1990's and Porsche bought Eterna...but I digress so back to the subject. Other benefits to using titanium for watch cases: it's light weight and it's hypoallergenic (unlike the gold alloys that contain nickel as discussed in previous posts). Now for the drawbacks: besides price titanium can be stained or scratched easily despite it's corrosion resistance. Some manufacturers coat their products with hard substances to protect against this. Citizen, the world's largest maker of titanium watches, uses a patented multi-layer glass coating. Citizen Promaster: Some other manufacturers are getting into the act as well. Here's a Smith & Wesson modeled after the Audemars Piguet Royal Oak?) There are several ways to process titanium into shaped parts. Most are variations of a process called sintering, and slight changes in certain steps will result in different grades of finished product. Watch cases are made with titanium hydride powder (TiH2). The manufacturing procedure starts by mixing the TiH2 powder with a thermoplastic binding agent then heating it to 170˚C. The mixture ratio is 64% TiH2, 32% polyethylene oxide, and 4% polypropylene. This forms a paste which is cooled to 140˚C causing it to granulate. These granules are injected into a mold in the desired shape which is large enough to account for @ 15% shrinkage of the finished item. The mold is placed in a vacuum chamber and heated progressively to 300˚C over the course of 8 hours. This slowly burns off the binding agent. The temperature is kept constant and the chamber is filled with hydrogen. While evenly circulating the atmosphere in the chamber, the temperature is gradually increased from 300˚C to 1200˚C over 4 hours. All the hydrogen in the TiH2 is drawn out during this phase slowly enough so that it leaves no bubbles on the watch case. Afterwards, the hydrogen atmosphere is replaced by nitrogen while maintaining 1200˚C. After 20 minutes in nitrogen the temperature is progressively lowered at a rate of 300˚C per hour. Once completely cooled the result is a finished watch case that's ready for fine grinding and polishing.
I love my Ti PO! I know everyone drools over the 2500 LM but in my opinion this model is very comparable. The weight difference between the Ti and the stainless is astounding, especialy on the bracelet.