Super Plastic Forming
These FAQs were answered during the MTC webinar. Please click here for more details.
Can we reduce costs by using simple molds for small volume prototyping?
We will consider ways to reduce the cost and let you know. However, since it is difficult to use simple molds, it is more expensive for small quantities. For example, if you want to manufacture a prototype of A5083 material, depending on the shape of the prototype, it may be relatively inexpensive to use a casting mold instead of a forging mold. However, voids may appear on the mold surface. If this is filled in by welding, the mold can withstand small volume production.
How much does the mold cost?
It depends on the mold material and shape, etc. For a 500mm square x 200mm high mold, the iron mold costs about 2 to 3 million yen, and the SUS mold costs about 5 to 6 million yen. The price includes the processing cost of the mold itself.
Is it possible to replace the pressurizing medium from expensive argon gas to nitrogen?
It is possible. However, care must be taken with titanium alloys and other materials that react with nitrogen such as nitriding in the superplastic temperature range.
Why is the processing temperature of titanium alloy and stainless steel as high as 900°C?
Since the superplasticity temperature range is higher than the softening temperature of the material, the process is performed at a higher temperature range than other processing.
With the mold at molding temperature, how much deformation is there in the mold after processing?
We design and select materials to minimize deformation as much as possible, however deformation of about 1/1000 to 1/100 of the product size will occur. Therefore, if the mold becomes deformed and falls out of the tolerance of the product, it can be reused by machining the surface of the mold. If the shape of the mold cannot be machined, it will be the end of the mold's life.
Will there be cracks or chips during molding?
It may crack, but it will not chip. There is a superplasticity temperature range, so if the temperature is too high, cracking will occur. On the other hand, if the temperature is too low, material rigidity will prevail and the material will not expand.
Is it possible to predict changes in wall thickness due to molding?
Predictions can be made through preliminary simulations. We also accept orders for simulation only.
How much difference will there be between the thick and thin parts of the product when it is molded using a mold with an uneven bottom surface?
Although it depends on the shape of the unevenness, there is not a large difference in the thickness of the plate between areas. It is about 0.1 mm at most.
Do you have any experience with SPF on forgings?
No. However, theoretically, superplasticity should occur in some materials, so there is a possibility of stretching.
What happens when compressive stress is applied to the material, as in forging?
Basically, superplastic deformation is possible, although it may be beyond the range of superplastic expression because the deformation speed differs between the outside and the inside.
Is it possible to mold each part to have a different wall thickness?
It is possible. There is a method to apply thickness processing to the material before molding. Analysis simulation is performed.
I hear that SPF is often used in the molding of aerospace equipment. What are the advantages of using SPF?
It is used for parts that need to be light and strong. It is possible to reduce the number of welding and bolting points by using the integrated molding that is one of the advantages of SPF. This improves the vibration strength and at the same time increases the flight safety (rate). It is also effective in reducing weight. In terms of manufacturing, fewer man-hours are required to produce the product, which reduces human error.
What are some specific applications of SPF?
It is used in a variety of places around us, such as tire covers, car body covers, and train bodies.
Is it possible to make a spherical shape without using a mold?
We have no experience with this. Hemispherical shape is possible.
I think SPF is a good forming method, but is it because of the cost that Ti64 is mainly processed by pressing and forging?
In comparison to forging, there is the issue of cost. However, SPF is the mainstream method for shapes that cannot be produced by forging (integrally formed parts and complex shapes).
Is it possible to use SPF for shapes that can be produced by pressure and blow molding of resin?
It depends on the shape. The minimum radius is about 3 times the thickness of the plate, so if the radius is small, it is better to use resin. R: Indicates the radius of a curve (circle).
What is the strength of the material before and after processing?
Depending on the molding time, the maximum strength will be reduced by about 20-30%.
What are the criteria for determining whether a material is suitable or unsuitable for SPF?
Determine if the material is easy to stretch. It is difficult if the material tears when stretched. Check the material composition, etc., and consider whether the material is suitable for SPF. We conduct a high-temperature tensile test on the specimen, calculate the stress of the material, and determine that superplasticity has occurred if the strain rate sensitivity index is about 0.3-0.8 mm.
What is the thinness limit of the board thickness that can be supported by SPF?
It is about 2.5T to 3T. It depends on the material, how much to bend, and other conditions. It is also limited by the press capacity and gas pressure capacity of the equipment. T=Unit mm
Are there any restrictions on the thickness of plates that can be formed with Inconel 718?
For Inconel 718, it is about 2T. The plate thickness is also limited by the press capacity and gas pressure capacity of the equipment. T=Unit mm
Is it possible to use CFRP (carbon fiber reinforced plastic) for SPF?
We are not able to provide this service. However, it is possible to sinter SIC/SIC composites using the NITE method, although it is not SPF.
Do you have test facilities that can handle new alloys and small prototypes that we want to test for SPF in experiments?
We do not own any new alloys. We don't own any prototypes, but we are working on mass production machines to handle prototypes.
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