Brass, when compared with iron, steel or precious metals, has a low melting point, but requires a particular furnace. Many amateur blacksmiths who are approaching smelting for the first time start with aluminum because it requires a simpler procedure. However, brass is the next step. Be sure to follow all safety precautions, especially keep children and pets away from the work area.
Steps
Part 1 of 3: Organizing a Furnace
Step 1. Find out and seek advice for the specific job you need to do
This article will give you general instructions on casting brass, but there are many factors to consider when preparing a furnace. You can find the information you need on the internet or from blast furnace workers to find the furnace that is right for your purposes, that is suitable for the amount and type of metal you want to melt, and is within your budget.
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Step 2. Prepare the furnace
Casting brass requires extensive preparation and a special furnace that can quickly heat the metal before the other components begin to oxidize. You have to buy one that reaches 1100 ° C with a refractory material that can withstand such a temperature. Most brass melts at around 900 ° C, but an instrument that reaches higher temperatures allows you to operate within a good margin of error.
- Choose a furnace model that is large enough to hold the crucible and the material you want to melt.
- Take fuel into consideration. Used oil is a free source of fuel but the right furnace could be very expensive. The ones that run on propane are the cleanest but you have to buy a lot of fuel. Finally, models that use solid fuel are cheap, sometimes you can even build them by hand, but the power supply requires a lot of money, in addition to the fact that you have to clean them regularly.
Step 3. Separate the brass objects you wish to cast
You may already have enough metal, but if you need more, you can go to the scrap yards in your area. Divide brass from other materials, especially non-metallic ones like glass, paper, or fabric.
Step 4. Clean the brass
Wash brass items with soap and water to remove surface contaminants such as oils and oxidation before casting. If the brass is plated, remove the patina with acetone or a specific product for this purpose.
Always wear gloves and work in a ventilated area when removing plaque, especially if you are using a paint remover
Step 5. Buy a crucible
It is a container in which to store the metal while it is in the furnace. For brass alloys a graphite crucible is recommended because it is strong and heats up quickly. There are also crucibles made of other materials, but make sure they are resistant to the temperatures they will be subjected to.
- Before using a new graphite crucible, heat it to 90 ° C for 20 minutes and then wait for it to cool. This way you eliminate excess moisture that could cause splashes.
- Each crucible should only be used for one type of alloy. If you plan to melt aluminum, iron, or other metals as well, you should get a crucible for each.
Step 6. Get the tools
You will need a pair of tongs, a frothing spoon, and a rod to grab and manipulate the crucible to be able to pour the molten metal. The steel tongs allow you to grab the crucible to put it in and out of the furnace. The spoon (made of steel) will be used to remove the processing waste from the surface of the molten metal. Finally the rod allows you to grab the crucible and pour its contents.
- If you are capable of metalworking, you can also make these tools from scratch.
- You can also consider purchasing a pyrometer to measure high temperatures, so it will be easier to tell if the brass is ready to be poured.
Step 7. Place the furnace in a well-ventilated area
It is essential that it is an open area, since the creation of toxic fumes is practically impossible to avoid. An open garage or similar structure is a great solution.
Even when mixing different materials, make sure there is always good air circulation. The furnace produces a lot of carbon dioxide in addition to other gases based on the fuel that powers it
Step 8. Get a box of dry sand
Even the driest surfaces, such as concrete, actually contain moisture. If a drop of molten metal comes into contact with moisture, this immediately transforms into vapor which, expanding, generates lots of metal splashes. To prevent this from happening, put a container full of dry sand near the furnace, move the metal and pour it only over this surface.
Step 9. Get some molds for the ingots
The best way to handle molten brass is to pour it into ingot-shaped molds. Working brass in complex shapes requires a lot of skill, preparation and experience. You can do some research to learn more about sand casting and lost foam casting techniques if you are interested in artistic work or to make objects. Also find an experienced workmate who can help you, as beginners face many setbacks.
Part 2 of 3: Follow Safety Procedures
Step 1. Put on heat resistant gloves, apron and boots
Be aware that smelting metals in the backyard is a hobby that can cause occasional accidents. However this need not be a cause for great concern if you do not neglect personal protective equipment. Leather gloves, boots, and apron should protect you from most minor accidents. You can find them in stores that sell protective equipment for workers.
Step 2. Wear cotton or wool clothing
Always wear a long-sleeved shirt and long pants under your protectors to prevent drops of molten metal from splashing on your bare skin. Cotton and wool, by nature, stop burning very quickly. Avoid synthetic fabrics that burn for a long time and which, when melted, stick to the skin.
Step 3. Protect your face and eyes
Whenever you handle molten metal, wear a mask that protects your face from splashes. Don't neglect your eyes and put on a welder mask or goggles before heating the metal to 1300 ° C; this protects you from excessive UV exposure.
Step 4. Consider purchasing a respirator
Brass is an alloy of copper and zinc, sometimes other metals are also present. Zinc has a relatively low boiling point (907 ° C) which it often reaches before the brass is fully melted. This causes the zinc to burn which in turn produces a white smoke responsible for temporary flu-like symptoms. Other materials, such as lead, may be present that cause long-term damage with prolonged exposure. A respirator suitable for metal fumes (particulate matter P100) should protect you from these dangers.
Children are at a much higher risk of lead poisoning than adults and should always be kept away from the active furnace
Step 5. Tidy up the work area
All flammable or wet materials must be removed from the area where you melt metals as they can cause fires and vapor explosions if hit by drops of molten metal. Keep the space in which you operate free of anything that is not essential for brass casting. Organize a free path between the furnace and the molds.
Step 6. Know where the nearest water is
You don't have to keep any sources of moisture in the vicinity of the furnace, but you must have access to cold running water in more or less the same area. In the worst case, put a bucket of cold water in a place that you can easily reach. If you get burned, immediately immerse the affected area without stopping to remove your clothes.
Part 3 of 3: Melting the Brass
Step 1. Heat the molds and the frothing spoon
Preheat the molds to more than 100 ° C to remove the moisture, otherwise the molten metal will create a lot of splashes. Remove them from the heat and place them on a surface covered with dry sand. Preheat the spoon for the same reasons.
Step 2. Place the crucible in the furnace
If you have a solid fuel model, coals are usually placed around the crucible, however always follow the instructions for your specific furnace.
Step 3. Turn on the furnace
Follow the instructions of your tool or rely on the advice of an expert blacksmith if you have built a handmade furnace. Usually you will have to ignite the coal or ignite the gas.
Step 4. Fill the crucible with brass
After about 10-30 minutes, place the metal in the crucible and handle it gently to avoid breaking it. Wait until the furnace has partially heated up so the brass will melt more quickly preventing the zinc in the alloy from separating and burning.
Step 5. Keep the furnace running until the brass is completely melted
The time required varies according to the power of the furnace. If you have a pyrometer, remember that the brass is completely melted at about 930 ° C with a difference of 27 ° C depending on the type of brass. If you don't have a pyrometer, move on to the next step when the metal glows orange or yellow or the color becomes almost invisible in daylight.
- Remember not to expose yourself to the fumes coming out of the furnace, always wear safety equipment.
- Although heating brass just beyond the melting point ensures simpler casting operations, overheating causes various problems such as oxidation. With time and experience you will be able to judge without hesitation when it is time to pour the metal.
Step 6. Eliminate impurities from the brass surface
Use the steel spoon for this and wipe off any stained or oxidized residue. Throw such impurities on dry sand. This also allows you to tell if the brass is completely melted, however don't try to mix the metal and don't keep the spoon immersed for a long time. If you mix liquid brass you will incorporate air causing defects in the finished product.
Remember that other metals, such as aluminum, produce gases that must be eliminated by mixing them when they are in a liquid state
Step 7. Pour the brass into the molds
Lift the crucible and remove it from the furnace with the steel tongs. Place it on the rod ring. Use the rod and pliers to lift the crucible and carefully pour the molten metal into the molds. There may be splashes, which is why the molds are placed on dry sand, to limit damage. You can now add more brass to the crucible if you need to melt some more, or you can turn off the furnace and wait for everything to cool.
The furnace will take several hours to cool, but the ingots can be handled well sooner
Advice
- Keep a fire extinguisher nearby in case of an emergency.
- Before starting to melt large quantities, start with a little brass, so you can practice safely reaching melting temperature.
- You can build the furnace in your backyard. Consult with an expert before doing this.
