W MoSi2 heating elements

W-type heaters are a variant of molybdenum disilicide (MoSi2) heating elements built for furnace roofs and other spaces where the clear height is limited. Instead of the usual two vertical shanks, a W-type element uses a longer, bent hot zone that lets you mount the element horizontally or in a tight cavity while keeping the terminal ends outside the hot zone.

For applications where the furnace roof is particularly low, horizontally mounted elements can be used. In such cases, four-shank elements may be used where the surface temperature of the element will not exceed 1800°C. They are available in Grade MD-31 in 3/6, 4/9, 6/12, 9/18 and 12/24 sizes. Multi-shank elements have advantages over two-shank elements: the hot zones are longer, so fewer elements are needed and cold-end losses are reduced.

W-type MoSi2 specification

Every W-type MoSi2 element is described by five parameters:

Parameter	Meaning	Units
Grade	Max service temperature class	1700 / 1800 / 1900
Diameter D1/D2	Cold-end / hot-zone diameter	mm / mm
Heated length Le*	Length of the active hot zone	in. or mm
Terminal length Lu*	Length of the cold terminal	in. or mm
Shank spacing A*	Distance between shanks	in. or mm

Specify Le, Lu and A in the same units (all in inches, or all in mm).

How to order a W-type MoSi2 element

Write the grade, diameters and the three lengths in one string. Examples:

Configuration	Order code
Grade 1800, D1=3mm, D2=6mm, Le=5.5in, Lu=5in, A=0.98in	MOSI2, 18-3/6-5.5-5-0.98in.
Grade 1700, D1=6mm, D2=12mm, Le=300mm, Lu=250mm, A=50mm	MOSI2, 17-6/12-300-250-50mm

These are typical MoSi2 configurations; we can supply custom bent shapes to your drawing.

Customers of MoSi2 elements get two added benefits — unparalleled price and experienced engineering support. Anyone can sell MoSi2, but designing the system is where the value is. MoSi2 systems must be engineered for your furnace to get the best performance and service life. Compare MoSi2 with SiC to pick the right material, or read our MoSi2 diameter guide.

HeatingDriver engineers can assist with:

analyzing the relationship between furnace temperature, element temperature and element surface load;
selecting the element surface load for your furnace construction, atmosphere and operating temperature;
choosing the most suitable element size and style for your application.

For temperature-class selection, see our EQ1700U, EQ1800U and EQ1850U element pages, or browse the full MoSi2 heating element range.

Frequently asked questions

What is a W-type MoSi2 heating element?

A W-type MoSi2 element is a molybdenum disilicide heater whose hot zone is bent into a W (or extended-U) shape so it can be mounted horizontally or in a low furnace roof. The bent layout gives a longer hot zone than a standard two-shank element of the same footprint.

What temperature grades are available for W-type MoSi2 elements?

We supply Grade 1700, 1800 and 1900 (max service temperature in °C). Grade 1700 and 1800 are the common choices for air atmospheres; Grade 1900 is used for special high-temperature needs.

How do I specify and order a W-type MoSi2 element?

Give us the grade, the cold-end/hot-zone diameter (D1/D2), heated length (Le), terminal length (Lu) and shank spacing (A), all in the same unit. We return a code such as MOSI2, 18-3/6-5.5-5-0.98in. and can build custom bends from your drawing.

When should I choose W-type instead of U-type MoSi2?

Choose W-type when the furnace roof is low or you need a long horizontal hot zone in a short cavity. For standard vertical mounting with two terminals, see our U-type MoSi2 elements.