North American Leader · Since 1962
FORGING THE
FUTURE
OF STEEL.

Six decades of metallurgical mastery. We deliver
high-performance carbon and graphite solutions
to the world's most demanding foundries and
steel mills.

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Our Expertise
5 Units
USA & China Bases
ISO 9001
Certified Quality
50+
GRAPH-HEX® SKUs
Global
Supply Network

North American Leader and World-Wide Supplier of Graphite and Carbon Additives Since 1962

Larpen Metallurgical Service is the industry expert in designing and adapting graphite and carbon additives for the foundry and steel industry. Established in 1962, we have been delivering unparalleled expertise in service, quality, consistency, and flexibility, ensuring our customers receive the highest quality products tailored to their individual needs.

Product Excellence

Our Products Meet Your Needs

Explore our extensive range of GRAPH-HEX products and other high quality graphite and carbon additives, each designed to meet the diverse needs of the foundry and steel industry. Our advanced processes and commitment to quality allow us to offer the most economical and reliable products in the market.

03 / Carbon engineered for performance.
01
Flagship Line•Carbon

GRAPH-HEX® Recarburizers

Over 50 high-purity carbon additives engineered to individual customer specifications, with sulfur as low as 0.02%.
Specifications →
02
Steel & Iron•Carbon

Machined Graphite

Crystalline graphite for injection applications and EAF processes, with consistent purity and rapid dissolution.
Specifications →
03
Foundry•Carbon

Pet Coke & Silicon Carbide

Low sulfur petroleum cokes (0.35–4.0% S) and Carbolon MA 90% silicon carbide for foundry chemistry.
Specifications →
Our Commitments

The benchmarks of an industry leader.

A family-run business operating with global scale — combining personal service with the rigor of ISO-certified quality systems and continuous improvement.

60+ Years

Family-run heritage since 1962.

ISO 9001

Certified quality management.

Own Laboratory

In-house testing & validation.

5 Plants

USA + China manufacturing.

Global Logistics

On-time delivery worldwide.

Unimetal Group

Backed by global expertise.

Operational Footprint

Strategic North American Presence

See all units & China hub →
HQ

1111 Western Dr, Hartford, WI 53027

Interactive Map · USA + China
Our Evolution

Six decades of metallurgical milestones.

Full timeline →
1962

Founding & Early Years

Henry Seeboth founds Larpen Supply Co, Inc, focused on Magna Flux and non-destructive testing equipment, then expands into foundry supply distribution.

1996

Expansion to Hartford

A new 50,000 sq. ft. manufacturing facility is built in Hartford, WI to meet North American demand.

2002

ISO Certification

Larpen achieves ISO 9001:2000 registration under the new QS 9000 Standard.

Today

Unimetal Group

Integrated into the Unimetal Group, combining family heritage with global technical expertise.

Let's Build Together

Ready to optimize your production?

Talk to our technical team about a custom carbon formulation engineered specifically for your foundry or steel mill.

North American leader in high-performance carbon and graphite solutions for the iron and steel industry since 1962.

AUnimetal GroupCompany
Company
Resources
Headquarters
1111 Western Dr, Hartford, WI 53027 — USA
Call
(15) 3235-7500
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ISO 9001:2008 Certified