Unitherm Furnace, LLC have been creating thermal processing solutions since 1980 to satisfy the needs of our customers with more than 600 furnace installations across America and nearly a thousand repairs, rebuilds and upgrades.

Our versatility and experience in thermal processing equipment, pyrometry instrumentation and controls allows us to create innovative designs and build each system to fit a customer’s specific requirements. These high quality designs, materials and components ensure a long service life.

Whether it’s a ‘standard’ furnace or a custom design, Unitherm can offer a quality solution.


Since its inception in 1980, Unitherm has grown into one of the stalwarts of the thermal processing industry.

The brainchild of Frank Lim, with two decades of experience in the furnace industry and a country in recession, Frank saw a market opportunity for rebuilt furnaces. Building a company that has thrived and developed from the original concept into custom orders for new furnaces.

The understanding of customer’s needs has allowed Unitherm to grow and prosper for nearly 40 years from a small company to a nationwide customer base and Unitherms ovens and furnaces are now installed in a variety of industries including military installations, automotive and aerospace facilities, foundries and metal-forging plants.


Unitherm takes quality seriously and is an ISO 9001:2015 accredited company.

Whether it’s a small standard oven or a large custom furnace, everything is designed and built using as many standard parts and components as possible to ensure that maintenance and long life is inherent.

Unitherm has developed into a one-stop shop for industrial furnace manufacturing and service. The company handles furnace designs, builds, modifications, re-builds, retrofits and upgrades and having its own contract heat treating service means a better understanding of customer needs and solutions.

Calibration Services

Unitherm is a key provider for furnace certifications for the US aerospace and automotive industry.

Our ISO 10725 accreditation allows us to meet the strict AMS2750E Aerospace Specifications; the industry’s toughest!

Calibration services are available at the Wentzville facility or at customer site including full temperature uniformity surveys.

Unitherm Team

Unitherm has a dedicated team of designers, engineers and manufacturing specialists with experience of building large and small furnaces to suit all budgets and levels of technology.