Φ4/9 MoSi2 Heating Elements for Dental & Compact Furnaces

The Φ4/9 element (4 mm hot zone, 9 mm cold end) is the dental-industry standard. It is the size specified for furnaces such as the Sirona HTC Infire, and it sits at the sweet spot between the tiny Φ3/6 and the general-purpose Φ6/12.

Specification at a glance

Parameter	Φ4/9 value
Hot-zone diameter	4 mm
Cold-end diameter	9 mm
Typical max current (air, steady state)	~250 A
Common grades	EQ1800 (most dental builds)
Typical use	Dental zirconia sintering, small lab and jewelry furnaces

The Φ4/9 is detailed alongside the other sizes in our MoSi2 diameter guide, with current and surface-load context in the current-limits table.

Why dental furnaces use Φ4/9

Zirconia sintering holds around 1450–1550°C. A Φ4/9 element in EQ1800 grade runs well below its 1800°C ceiling, which is the single biggest factor in long element life. We supply the Φ4/9 as a direct replacement for Sirona HTC Infire and similar units — see the Φ4/9 U-type element for Sirona HTC Infire.

Choosing the right dental element

If you are specifying or replacing a dental sintering element, our dental sintering guide and element-selection guide walk through grade, diameter and quantity. For the broader picture, the EQ1700/1800/1850 temperature explainer shows why EQ1800 is the dental default.

Fit and ordering

We cut Φ4/9 elements to your U-bend reach and shank length. Browse the U-type MoSi2 range or send us your furnace drawing for a matched set.

About the author: Prepared by the HeatingDriver Application Engineering team, engineers with nearly 20 years of experience in high-temperature elements for dental, ceramics and research furnaces. See our full MoSi2 range or send us your temperature profile for a recommendation.

Browse EQ1800 elements or contact us for a dental-furnace sizing check.

Why specify with HeatingDriver

Why specify with HeatingDriver — HeatingDriver is a manufacturer and exporter of MoSi2 (molybdenum disilicide) heating elements with nearly 20 years of experience. We supply EQ1700U / EQ1800U / EQ1850U grades for 1700–1850°C, free drawing review, custom sizes and shapes, and technical support for furnace builders worldwide. Browse our MoSi2 heating elements.

What are Φ 4/9 MoSi2 elements?

Φ 4/9 has a 4 mm hot-zone and 9 mm cold-end diameter, a compact size widely used in dental and small furnaces.

Why are Φ 4/9 elements popular for dental furnaces?

They fit compact dental zirconia sintering chambers while reaching the 1450–1550°C sintering temperature, often in EQ1800U grade.

What grades are available in Φ 4/9?

Φ 4/9 elements are available in EQ1700U, EQ1800U and EQ1850U grades for 1700–1850°C.

What surface load do they use?

Φ 4/9 elements are specified at 4–9 W/cm² surface load, matched to the furnace duty.