|
Ti Squared Technologies, Inc. produces high quality, economical titanium components in our well-established foundry using perfected processes and methods which safeguards and minimizes flaws such as voids, inclusions, and weld repair defects which are rare but can potentially affect the design life of your product. Our quality control department ensures that all flaws are appropriately addressed and corrected if possible or the components are rejected and recast.
The extensive and continued use of titanium in the aerospace industry, specifically in turbojet engine critical components such as frames and blades, has brought a significant amount of confidence in titanium alloy systems’ quality and durability. Consumers also appreciate the reliability, light weight and strength of titanium made products. Ti Squared Technologies continually helps various industries to bring titanium products and components to market and to assists in new product development.
Ti SQUARED TECHNOLOGIES’ TITANIUM INVESTMENT CASTING PROCESS
Ti Squared employs the lost-wax investment molding process which is the principal technology for aerospace castings, first introduced in the 1960s. Using hard dies a wax pattern of a component part is produced by injection molding. Once the wax mold assembly is joined together with sprues, runners, gates, and risers, it is then coated with a ceramic material consisting of a low reactivity compound which posses the capacity to withstand thermal shock from contact with molten titanium.
After the primary or face coating additional applications of ceramic stucco and slurries are applied until the mold has the proper strength and rigidity for subsequent handling. Each ceramic layer is allowed to dry and cure under controlled temperature and humidity. Once the ceramic mold is completed, the wax is melted in our autoclave and fired in our kiln to develop full strength and burn out any organic residues prior to the casting.
Casting begins with the pouring of molten titanium into the ceramic mold under vacuum seal. Once solidified the castings are removed from the furnace and cooled. The ceramic assembly, including the sprues, gates, and risers are removed prior to proceeding to the hot-isostatic pressing, known as HIP processing.
The HIP process subjects the casting to elevated temperature and isostatic gas pressure which helps in the elimination of internal void defects which is accomplished by collapse and diffusion bonding. Once completed the castings are inspected for defects. Surface-connected voids cannot be healed with the HIP process, nor can inclusions. All other discoverable defects are removed by grinding and weld repairing using gas-tungsten arc techniques.
Voids
Voids are areas lacking solid material in the casting which may occur from shrink porosity, gas pores, or weld lack-of-fusion cavities. A shrink void results when the molten metal becomes solid and contracts. Through our HIP processing most voids are corrected. However, Ti Squared Technologies minimizes voids by using sound gating practices which ensures a ready source of molten filler metal to remove the shrinkage out of the part. Gas pores are created by trapped gases which form bubbles in the casting and are rare and usually small. Weld lack-of-fusion cavities may develop during weld repair of the casting, and are not considered true casting defects, but since they occur during post-casting foundry processing they are still considered a defect. Ti Squared works diligently in proper surface preparation and adequate heat delivery in the weld pool to minimize the occurrence of this type of defect.
Inclusions
Inclusions in regard to titanium castings are exogenous solid defects which typically refer to ceramic shell inclusions and metallic tungsten.
Our foundry cleanliness and strict contamination controls are effective in significantly reducing the incidence of ceramic shell defects in our titanium castings.
Tungsten inclusions are caused by improper welding techniques and are the accidental contact of the tungsten electrode to the melt pool. The small amount of tungsten which becomes deposited is typically obvious to the welder and the area is reworked. Since tungsten has a high atomic number, it is highly detectable under x-ray relative to titanium, and it is typically found, removed, or repaired.
Ti Squared Technologies, Inc. continues to research, develop and implement best practices in titanium casting and foundry techniques to achieve optimal results for your investment casting needs
|
