Isothermal Forging

요약:

Through achievement of a consistently identical temperature between die and workpiece a uniform deformation can be achieved throughout the material.
Isothermal forging is leading the way to improve efficiency and quality and in particular has driven good advancements in producing a range of titanium alloy components.

Metal-forming processes, which help to exercise a high degree of control over the deformation behaviour, microstructure evolution, and hence control the properties that can be achieved, are called as advanced forming processes. Isothermal forging, near-isothermal or hot die forging, multiaxial isothermal forging plus pack rolling, superplastic forming and diffusion bonding are some of such processes being used to produce various components from titanium alloys.

In Isothermal forging, the die and the workpiece are maintained at the same temperature throughout the forging cycle. As the die and workpiece are maintained at the same temperature, die chilling is eliminated, thereby resulting in uniform deformation of the material. The inherent advantage of the process can be used to produce net to near-net shape components with fewer processing steps. Further, forgings with small corners and fillet radii, less draft angles and smaller forge envelopes can be produced, leading to optimum utilisation of the materials.

A high degree of control can be exercised over the processing parameters and forging can be carried out at very slow strain rates, thereby reducing the load required to process strain-rate sensitive materials like titanium alloys. All these lead to a high degree of consistency in the structure and property that can be achieved from one forging to another.

Isothermal forging is a hot working process that attempts to maintain the work piece at its maximum elevated temperature throughout the entire operation. This is achieved by heating the die to the temperature of, or slightly below the temperature of the starting work piece. As forces exerted by the die form the work, cooling of the work piece between the mold work interface is eliminated, and thus flow characteristics of the metal are greatly improved. Isothermal forging may or may not be performed in a vacuum. Equipment costs for this manufacturing process are high, and the added expense of this type of operation should be justified on a case by case basis.

As an industrial process isothermal forging is competing with the other more classical technologies for closed die forging. For what material cost is concerned, in the case of components made of Ti-alloy with complex shapes, it is possible to reach savings up to 40 – 45%. It must also be said that for some components it is possible to finish forge in one step after having performed with different equipment. Machining costs are also generally reduced and, depending on complexity and final tolerances, the savings can reach up to 30%. Apart of the mentioned potential saving factors the isothermal forging process also calls for aspects which render its application, if not less attractive, at least less competitive.

Tooling made of heat resistant alloys is 2 – 3 times more expensive than conventional dies. Another important aspect is the necessity for a very precise process control, particularly for what dies’ heating and lubrication is concerned and, not at last, the process length which does not allow cycle times comparable to other forging processes. Following the above considerations application of isothermally produced forgings are almost exclusively used for safety critical components for aerospace and jet engines. Nevertheless, the authors of this paper would like to present a development they made in the application of isothermal forging in the medical / orthopaedic field.



Figure 1: Isothermal forging

Summarized/characteristic features of isothermal forging

Form pressing with die temperatures almost equal to the work temperature

  • Melted pockets due to local overheating caused by too high forming rates
  • Low temperature gradient tool / work piece
  • No flashed removal
  • High quality parts in almost "ready-to-use" shape
  • Shorter production times for finished part


References

1. T. Raghu, I. Balasundar, M. Sudhakara Rao: Isothermal and Near Isothermal Processing of Titanium Alloys, Defence Science Journal, Vol. 61, No. 1, January 2011, p. 72-80;

2. thelibraryofmanufacturing.com, Accessed 03-2016;

3. G.Martinelli, R.Peroni: Isothermal Forging of Ti-alloys for Medical Applications, Ti-2007, Presented at the 11th World Conference on Titanium, Kyoto, Japan – June 4- 7, 2007;

4. K.Siegert, R.Malek, R.Neher: Forging Process, Isothermal forging, TALAT-Training in Aluminum Application Technologies Lecture 3402, Institut für Umformtechnik, Universität Stuttgart, Stuttgart, Germany,1994

기술 자료 검색

검색할 어구를 입력하십시오:

검색 범위

본문
키워드

머릿글
요약

Total Materia는 다양한 나라와 규격에 따른 수천개의 주조 재료에 대한 정보를 포함하고 있습니다.

재질의 화학적 조성, 기계적 특성, 물리적 특성, 고급 물성 데이터 등의 전체적인 특성 정보들을 어디서든 검토하실 수 있습니다.

고금 검색 내 규격 설명 기능을 이용하여, 규격 내 재질에 설명된 키워드를 통해 재질을 검색하실 수 있습니다.

검색 범위 좀 더 줄이기를 원하신다면 국가/규격과 같은 다른 조건을 지정할 수 있습니다.

검색 버튼을 클릭합니다.


선택된 정보에 부합하는 일련의 재질이 검색됩니다.


결과 리스트에서 재질을 선택하시면, 일련의 규격 사양 소그룹이 나타납니다.

여기에서 선택한 재질의 특정 특성 데이터를 검토하실 수도 있고, 강력한 상호 참조 표를 이용하여 유사 재질이나 등가 재질을 검토하는 것 또한 가능합니다.


예를 들어, 소그룹 내 화학적 조성 링크를 클릭하시면, 재질의 화학적 조성 데이터를 검토하실 수 있습니다.

Total Materia 데이터베이스를 사용해 보실 수 있는 기회가 있습니다. 저희는 Total Materia 무료 체험을 통해 150,000명 이상의 사용자가 이용하고 있는 커뮤니티로 귀하를 초대합니다.