Foil used as tool wrap that is made of stainless steel represents an efficient method of protecting steel parts during heat processing. Although it is very simple to use, it may not be obvious from the start how to employ it correctly and ensure flawless results. For this reasons, you should read the tips below:
- Who can use it
Toolmakers of all kinds, as well as component manufacturers can make use of steel foil successfully. This does not require a vacuum or any kind of special furnace, but simply a regular one for heating up to the desired temperature. It has uses across countless industries.
- Correct enclosure
The handler must wrap the component to be heated in a way that prevents air from getting in. It’s supposed to form an airtight envelope with well secured edges. However, a vent is necessary, as you can see below.
- Creating a vent
A small part of the edge (a few millimeters) left unsealed is necessary, because the heat will expand any air trapped inside. When this happens, the foil can break. To avoid this, leave a small vent so the air can expand. If the foil is wrapped tight around the component, there won’t be enough oxygen inside to cause deterioration. Also, a small vent will not let enough air in, so that it leads to flaws.
- Effective seal
All heat treatment foil must be sealed accordingly when creating the airtight envelope. The best way to do this is to make a double edge or crease. Do this carefully, as to not create any tears or cracks.
- Burning embers
Here’s a tip from an expert toolmaker: burn an ember inside the envelope. This will get rid of any oxygen that’s left inside once you have sealed the package. This needs to be done before the heat treatment cycle begins.
- Increasing the temperatures
This step is recommended because wrap foil happens to act as an insulator. Therefore, the temperature inside the package will be lower than expected, so you must raise it.
Use steel tool wrap with air hardened steels, as this is considered to be its best application. Check with the foil manufacturer and do not raise the temperature above what is given as safe, to avoid melting the wrap. When correctly employed, this method guarantees perfect results for a fraction of the price.