Release for forging and hot forming processes
When it comes to high temperature processing, traditional lubricants such as oils, graphite, and molybdenum disulfide suffer oxidation and performance degradation. Boron nitride excels in lubrication and protection of tooling for processing that requires temperatures above 500°C. CeraGlide® Boron Nitride Coatings provide a safe, easy to use release solution for high temperature metal forming processes.
Isothermal forging is a hot working method where the elevated temperature is maintained uniformly in the workpiece throughout the forming process. This is achieved by keeping the die heated in an enclosed, atmosphere-controlled system as the part is deformed. By eliminating localized die cooling, the material will flow evenly throughout the workpiece. This results in very uniform deformation and enables rotationally symmetric parts to be formed, which is critical for parts like disks in jet engines that undergo high stresses in use. Some additional advantages include:
- Fewer process steps - high precision is achievable, allowing a near-net shape part to be formed out of a single workpiece without requiring significant finishing steps
- Reduced material utilization - less material is required per part, reducing overall cost and improving efficiency
- Slow strain rates - forming slowly and under hot conditions allows strain-rate sensitive materials, like titanium and its alloys, to form without cracking
Good lubrication of the workpiece is critical in this application, allowing for good flow characteristics and reduced tackiness of the workpiece. Traditional lubricants like graphite and molybdenum disulfide (MoS2) fail at the elevated temperatures required for isothermal forging. Particularly for materials like nickel-based superalloys, where temperatures up to 1200°C are used, boron nitride is the best choice. CeraGlide® BN Coatings are industry-proven in this field, with decades of successful use in isothermal forging applications.
Superplastic forming (SPF) is an advanced shaping technique used to create complex, near net-shape components from alloys that exhibit superplasticity. Inert gas pressure is used to force a metal sheet in its superplastic state, in which it is very soft and deformable, against a die to form a part. At the correct temperature and strain rate, these alloys, such as Ti6Al4V and 5000 or 6000 series aluminum, can stretch up to 200-1000% of their original size. This technology enables large, complex parts to be formed in one operation with superior precision, surface finish, and negligible residual stresses compared to traditional forming techniques.
Many of the challenges associated with superplastic forming arise from friction and adhesion between the parts and the mold. CeraGlide® BN Coatings can help mitigate these challenges.
|Challenges in SPF Process||CeraGlide® BN Solutions|
|Localized part thinning due to friction and uneven material flow||Low coefficient of friction at high temperature and uniform coating distribution via spray application minimize friction and adhesion, even in tight contours.|
|Surface defects and galling due to friction and adhesion between sheet and mold|
|Surface defects due to material build-up on mold||Alumina binder phase promotes adhesion to the forming metal without buildup on the tooling die|
|Part warping due to poor mold release||Individual BN platelets flow with the stretched metal, maintaining lubrication throughout forming for excellent mold release|
|Extended part cleaning||EHS-friendly water based formulation that can be easily washed off finished parts|
CeraGlide® Boron Nitride Coating grades SF+ and 10SF+ are well suited for both forging and SPF processes. 10SF+is a dilute form of SF+, intended for use with robotic spray systems. SF+ can be diluted to the desired consistency depending on application method.