While the popularity of titanium has increased dramatically in recent years (especially in the aerospace, medical, & automotive industries), little has been written about how to form titanium parts accurately and efficiently. Most component manufacturers (OEMs) recognize the inherent advantages of titanium-formed parts (lightweight, strong, bio-compatible, etc) and see the benefits of bringing the manufacturing process in-house, however, choosing the right process and machinery to fit their needs seems daunting.
Below is a competitive analysis of the three most common methods used to form titanium and machinery recommendations for a successful operation.
Manufacturers tend to use cold forming for titanium applications primarily because it is a process they already know. Dedicated machinery isn’t required, PPE is simple, and perceived cycle times are typically lower than other methods because heating of the material is not a factor. While the shorter cycle times are appealing, they do not take into account the extra time needed for secondary finishing applications (annealing, flanging, trimming, etc). Additionally, due to the elongation characteristics of titanium, springback, galling, and cracking are common by-products during cold forming. To overcome these adverse effects, cold forming presses used in titanium forming require very high tonnages (1000+).
Hot forming is rapidly becoming the preferred method to manipulate titanium into complex shapes because of the multiple advantages it offers and the increasing availability of high-quality forming equipment. During the hot forming process, both the tool and blank are heated between 900°F and 1,600°F in a dedicated hydraulic press to increase the malleability of the material. The introduction of heat temporarily changes the material forming characteristics resulting in near-net-shape parts with consistent wall thicknesses and virtually no springback or cracking.
Since the heat acts as a forming agent, tonnage requirements on hot forming presses are typically much lower than those on cold forming presses. To improve forming efficiency, additional press options like bed shuttles, insulated doors, data acquisition, and Active Leveling Control can be included in the machine’s design.
While some similarities exist between hot forming and superplastic forming, the SPF process has its own unique characteristics. SPF uses extreme temperatures (up to 2000°F) in conjunction with argon gas to form high-strength alloys into complex shapes in a single step. During the cycle, the heated material is clamped between a cavity and a plate. The material is then forced into the cavity by argon gas that is injected into the forming chamber. Since the argon gas acts as the second die half, mated tooling is not required. Although cycle times are slower with SPF (20-40+ minutes), the process can result in dramatic material elongations.
In many cases, dedicated hot forming presses also have the ability to perform SPF operations without drastic modifications.
CHOOSING THE RIGHT PARTNERS
While all of the above processes can result in quality titanium parts, the machinery you choose will ultimately determine your success. As with any new forming operation, it is important to evaluate several machinery OEMs and choose a partner who completely understands your manufacturing processes and expectations as well as the application requirements.
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