Metal Casting Overview ¶
By: Jordan on Feb. 4, 2021, 3:01 p.m.
Metal Casting has so many different uses, both decorative and practical and we are going to cover both uses throughout this guide.
By taking up metal casting, you will be providing many other craftsmen with a desperately needed service or giving yourself an advantage over others.
Working as a metal caster:
Working with metal is both skilled and dangerous, as a result most people will never attempt it. If you do, however, decide to give it a go you will very quickly find many uses for it and realise how in demand your skills are.
Carpenters often utilise metal as decoration on their designs. You would be able to provide them with very intricate decorations for their work as well as conduct your own business. You could engage in custom work for the general public as well as other craftsmen but you could also provide standardised products (such as the corner brackets) for ease of replication and sale.
As you become more experienced and your skill and range of equipment grows, you could even start making parts for hobby steam engines among other things.
Before you start metal casting:
Molten metals are dangerous, but with common sense and the right equipment the risks are minimal. Wear protective clothing, including close-toe shoes or (preferably) boots. Long trousers and sleeves are a must as well as insulated gloves and goggles. Preferably you would wear a fire resistant apron as well. A well-ventilated area will lessen the risk of dangerous fumes. It is also important to keep a dry chemical fire extinguisher close to hand. While it sounds expensive, dry chemical fire extinguishers are very cheap and you’ll always be able to use it for other projects as well.
What’s the difference between investment and sand casting:
Investment casting, also known as Lost Wax Casting, is a process where you create a replica of the object you want to create out of a very hard wax, then encase it in plaster.
Sand Casting is where you create a mold of the object you want to create, cut it in half, and then insert each half into box known as a “Sand casting flask”. You surround each half with wetted sand (either wetted with oil or water) then you remove the moulds and place one box on top of the other. By tamping the sand down firmly, you create a reusable medium that will hold the shape of the removed mould perfectly.
Investment casting is fantastic for detailed objects, such as jewellery, whereas Sand casting is fantastic for larger objects that require less intricate details (park benches or garden tables for example).
Upon researching this overview, we came across a fantastic forum post IForgeIron and have copied an excerpt about the furnace below.
The central piece of equipment in a foundry is the furnace. For the scale we’re talking about, a crucible furnace is by far the most reasonable thing to build, so it’s all I’ll discuss. You can build a relatively furnace that run on propane or natural gas, which is basically just a vertical gas forge with a lid. However, these furnaces will have a hard time melting iron, if they can do it at all. I strongly recommend buying the manual from Colin Peck (in England) called “The Artful Bodger’s Iron Casting Waste Oil Furnace”. This is what I did, and would never build a different style of furnace. The design of the furnace body is simple and easily modified to use the scrap you have on hand, and he has perfected a burner design that uses a gravity feed to burn waste oil (used vegetable oil, used motor oil, and diesel all work well). There is no nozzle on the burner, so the fuel isn’t atomized, meaning you can use waste oil (free but contaminated with particulates) without clogging the burner. Also, since it is gravity fed there is no need for a pump, and oil at atmospheric pressure is MUCH safer than pressurized gas when you’re working with molten metal. Plus, it puts out much, much more heat than propane or natural gas—I can melt 30 pounds of bronze from a cold start in less than 45 minutes.
There are also a range of electric furnaces as well, but the cost of running them can be very high unless you have your own power source.
Here is also a very indepth video on how to build your own gas furnace. Click here (Click)
Green sand is not actually green. It’s called green because it is used wet (much like how green wood isn’t actually green either). It can be bought from many different places but here is one website where it is currently being sold for £17 per 20kg. Link here (Click)
If you're lifting up metal that is close to 1000c, you're going to need tongs to do it. They can be found in a number of places but here are some for £30 from CooksonGold. Click here (Click)
It is possible to make a DIY crucible and there are loads of websites out there showing you exactly how to do it. Artisan Foundry has an excellent chart to help you with the sizes of crucibles you can get. Do some research on the sort of projects you want to undertake and email them if you need any more help: Click here (Click)
For more information on matching your crucible to your application this is an awesome link: Click here (Click)
We have only covered the very basics in this overview:
Here are some more examples of things you can create with Cast Iron: