I am going to create a list of possible solutions for an iron casting company where I am doing my PhD thesis. They make cast iron skillets by grey sand iron casting. So far, I came up with these possible solutions (please note 'material science' is NOT my expertise):
- mold shrinkage
- decreasing the dense of product (for example via increasing micor-prosity)
What are the other possible strategies to reduce the weight of cast iron products? Which iron casting process supports your suggested strategy?
The question is very interesting.
May be, one idea is to elevate the Si percentaje to improve the castability and for this reason you can reduce the thickness.
I'm not an expert in this field.
I can suppose.
Put into the mold the elements for weight reduction.
Change the shape of the part with the smallest volume of surfaces.
One of the major contributors to the thickness of a cast iron skillet is the prevention of "hot spots" .
http://www.seriouseats.com/2010/02/everything-you-need-to-know-about-cast-iron-cooking.html
The article blames the poor thermal conductivity of cast iron, but that isn't the whole story. What is needed is greater in-plane than out-of-plane thermal conductivity. Modern cookware manufacturers create laminated bottoms to their pots and pans, with a copper or aluminum spacer to spread the heat.
There are a couple of ways one could attack this. One is to align the grains of the casting in a radial direction in the bottom of the pan. Some work has already been done using a eutectic cast iron alloy:
http://www.afe.polsl.pl/index.php/en/3755/directional-solidification-of-ledeburite.pdf
The use of a eutectic alloy may not support the mechanical requirements of the application, or some additional processing may be necessary (e.g. heat treatment to turn white iron into malleable iron). A thesis topic might be to demonstrate differential thermal conductivity in a directionally-solidified casting.
Another possibility would be to coat the burner side of the pan with a material with high thermal conductivity. When I was a kid, I had a camping cookware set plated with copper. This has a couple of disadvantages, including poor wear resistance and incompatibility with induction cooktops. Since you're looking for wear-resistant, heat-resistant, high thermal conductivity, I might suggest silicon carbide or a cermet using SiC. Diamond has even higher thermal conductivity, but won't stand up to flame. Because you want strong adhesion on a single flat surface with a high deposition rate, you might consider an HVOF process. The thesis topic might be evaluating mechanical and thermal properties of sprayed thermal conduction coating on cast iron.
Please contact me if either of these ideas goes to patent.
If you make porous cast iron, you decrease its strength.
A revolutionary way to make cast iron lighter is to use aluminium instead of it. You can strengthen Al-parts with cast iron via composite casting locally, like the liners ín engine blocks ot ring carriers in pistons.
An evolutionary way to make cast iron lighter is to optimize its casting geometry and composition. Composition means increasing silicon content, geometry - make the walls thinner, replace thick-walled parts with ribs ans so on.
Dear Farshad Madani,
The most simple answer to your question is probably: there is no sensible strategy to decrease the mass of cast iron skillets without affecting the product's cuisine properties. To underline this statement I make the following tentative remarks.
1. The castability and the Ten Commands of Casting Design put their own demands in terms of (differences in) wall thickness, e.g. a strength increase will not automatically lead to a mass reduction.
2. Suggestions to incorporate other materials in- or outside e.g. the bottom of the skillets, will inevitably imply more complicated manufacturing, while the 'Point 1' demands remain. So, one can hardly expect a mass decrease. Besides, this incorporation will affect product properties like heat transfer.
3. I think that the above remarks also skip increasing the microporosity as a strategy.
4. The only way that remains for cast iron cooking utensils is: optimizing castability in terms of mouldings and compositions in a steady evolutionary approach.
5. If indeed the mass of the cuisine utensils is taken as a design parameter, then you need to redesign the product starting with the functional and processing demands and incorporating the materials selection into this design process. The reference provides an introduction to this approach.
Reference
Materials Science in Design and Engineering, Delft NL
cf. Chapter 1, Chapter 10, Chapter 11
http://www.delftacademicpress.nl/m017.php
Here is a method with glass hollow beads
of size of about 60 micrometers in diameter.
It works with zinc and aluminium.
http://www.eurekamagazine.co.uk/design-engineering-news/glass-beads-slash-weight-of-cast-metal-parts/6498/
http://www.pro-physik.de/details/news/1118073/Ausgezeichnetes_Material.html
Regards,
Joachim
To obtain thin-walled castings of low weight
1) получение высокопрочных сплавов; - 2) формовочные процессы для точных методов литья, в том числе с использованием песчаных форм, полученных по разовым моделям, и возможностью регулируемого охлаждения отливок в песчаных формах; - 3) термообработка заготовок для получения мелкодисперсной микроструктуры металлической матрицы и повышенных свойств литых конструкций, в частности, в отливках из графитизированных чугунов; - 4) экологическая безопасность процессов с применением вакуумирования формы, безвредных модельно-формовочных материалов, хладагентов и нагреваемых технологических сред.
Dear Farshad Madani,
The suggestion of Joachim Pimiskern seems valuable. It fits into the approach given by point 5 of my contribution.
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