Thermal Shock Resistant Elements

Thermal shock is the stress a material feels when its temperature changes quickly, for example when a hot furnace door is opened or a cold load goes into a hot chamber. One part of the material expands or shrinks faster than the rest, and brittle materials like ceramics can crack.

Many furnaces work in short cycles: heat, hold, cool, repeat. In these furnaces, heating elements and the ceramic parts around them need to cope with thermal shock, or they break early and the furnace stops.

What makes an element resistant to thermal shock

• The right material. Some ceramic materials, such as cordierite and some silicon carbide grades, expand very little when heated, so they handle fast changes better.
• The right shape. Thin, even walls and smooth curves heat up evenly. Sharp corners and sudden changes in thickness are where cracks usually start.
• Good supports. Elements need to move a little as they expand. Supports and holders that let them move freely lower the stress.

What we can supply

• Heating elements chosen for frequent heating and cooling cycles
• Ceramic tubes, holders and supports that let the elements expand freely
• Advice on heating and cooling rates for your furnace

Where they are used

• Batch furnaces that are opened many times a day
• Laboratory furnaces and test equipment
• Dental and jewellery furnaces
• Heat treatment lines with fast cycles

Tips to make elements last longer

1. Heat up and cool down at the rate the element maker gives, especially when the furnace is cold.
2. Do not open the furnace door wide at full temperature if you can avoid it.
3. Keep the load from touching the elements.
4. Check the supports regularly and replace cracked ones early.

How to order

Tell us about your furnace: its type, the highest temperature, how often it heats and cools, and which element you use now. We will suggest the element and support type that fits.

Contact us for advice and a price.