Deep Hole Drilling Machine Builders: Europe, Asia, Americas

The global deep hole drilling machine market — estimated at approximately $1.8 billion in 2025 — is served by a relatively small number of specialist manufacturers concentrated in Germany, Switzerland, the United Kingdom, the United States, China, and India. Each region has developed distinct technological strengths and market positions.

Overview ​

Deep hole drilling machines are highly specialized capital equipment. Unlike standard CNC machine tools, which are produced in volumes of thousands per year by dozens of manufacturers, deep hole drilling machines are built in limited quantities by a handful of specialist firms. The barriers to entry are high: expertise in high-pressure coolant systems, guide pad geometry, chip evacuation, and long-reach spindle design accumulates over decades.

This article profiles the major builders in each region, their product lines, technology focus, and market position.

European Builders ​

Europe is the historical home of deep hole drilling machine building. The BTA process was developed in Europe, and the region remains the centre of high-end machine production.

TBT Tiefbohrtechnik — Germany ​

TBT, founded in 1966 and headquartered in Dettingen an der Erms near Stuttgart, is widely regarded as the global market leader in deep hole drilling machines.

Product lines:

• ML Series — horizontal BTA/STS drilling machines for medium to large bores
• B Series — heavy-duty machines for large-diameter deep hole drilling
• Varioflex MD 30 — deep hole drilling and milling centre for cubic parts
• ENDURO — dedicated machines for crankshaft and gear shaft end finishing
• Transito — special-purpose machines for the oil and gas industry

Strengths:

• Broadest product range of any European builder
• Deep integration with FANUC robotics for automated, unmanned operation
• In-house contract drilling department (30+ machines) — machines are validated and refined through production use
• Part of the Nagel Group, enabling turnkey solutions including honing and grinding

TBT dominates in oil and gas, petrochemical (centrifugally cast pipe drilling), and automotive high-volume production. Their machines are known for extreme rigidity (polymer-concrete-filled beds) and long-term reliability.

UNISIG — Switzerland ​

UNISIG, founded in 1981 and acquired by Entrust Manufacturing Technologies in 1995, has grown into one of the largest deep hole drilling machine producers globally. Its headquarters and primary engineering are in the United States, but it operates a significant European subsidiary — UNISIG GmbH in Bad Urach, Germany — that manufactures machines to metric standards for the European market.

Product lines:

• UNE Series — gun drilling machines (0.5–40 mm diameter, depth up to 3,000 mm)
• USC-M Series — 5-axis CNC milling combined with deep hole drilling (mould and die industry)
• UNI Series — production deep hole drilling machines
• B Series — BTA/STS machines (65–300 mm bore, depth up to 12,000 mm)

Strengths:

• Widest diameter range of any builder (sub-millimetre medical to 500 mm defence)
• Unique 5-axis + deep hole drilling combination (USC-M) reduces setups for complex parts
• Siemens CNC controls with custom deep hole drilling cycles
• Express delivery program for standard models
• Strong in mould and die, aerospace, oil and gas, defence, and medical

UNISIG's presence in both the US and European markets gives it a dual-region advantage, and its technology centre in Wisconsin provides application development and process validation for customers.

Mollart — United Kingdom ​

Mollart Engineering, founded in 1929, is the oldest of the European deep hole drilling machine builders and is recognised as a world leader in multi-spindle gun drilling technology.

Product lines:

• DRILLSPRINT Series — CNC gun drilling machines (0.5–150 mm diameter, depth up to 3,000 mm)
• Multi-spindle machines — 2, 4, and 8 spindle configurations for high-volume production
• Custom machines — biomass pellet die, hydraulic manifold, mould cooling channel drilling
• Gun drills and tooling — full range of deep hole drilling tools manufactured in-house

Strengths:

• Unmatched multi-spindle expertise — up to 8 simultaneous spindles
• In-house tool manufacturing — drills designed and ground on-site
• Strong in niche high-volume markets: biomass pellet dies, automotive fuel injection, hydraulic components
• Contract machining division (Mollart Cox Engineering) for bores 25–300 mm, up to 10,000 mm length
• ISO 9001 and aerospace-approved

Mollart's acquisition by InCompass in 2023 brought additional capital and a US market connection, while the company continues to design and build all machines at its UK facilities.

Other European Builders ​

Asian Builders ​

Asia has emerged as a significant force in deep hole drilling machine building over the past two decades, primarily driven by Chinese manufacturers and supported by Indian and Japanese players.

HTT Group — China ​

HTT (Shanghai Ningyuan Precision Machinery Corp.) is the largest Chinese deep hole drilling machine builder and a significant global competitor. Founded in 2006, the company has delivered over 460 machines to customers worldwide, including Japan, South Korea, India, and Southeast Asia.

Product range (HTT deep hole drilling machines):

• Gun drilling machines — diameters from 1.5 to 40 mm
• BTA/STS machines — diameters from 20 to 160 mm
• Deep hole boring and skiving machines — for hydraulic cylinder finishing
• Custom multi-station machines — for high-volume production

HTT's competitive advantage is cost — their machines are typically 30–50% less expensive than comparable European models, with lead times of 4–6 months vs 9–12 months for European builders. However, European builders argue that total cost of ownership over 10 years narrows this gap due to differences in reliability, resale value, and service support.

Precihole — India ​

Precihole Machine Tools, based in Mumbai, is India's leading deep hole drilling machine builder. The company manufactures gun drilling, BTA, and ejector drilling machines for the Indian and export markets.

Precihole machines are positioned between Chinese and European builders in both price and capability, and are widely used in Indian automotive, oil and gas, and general engineering sectors.

Other Asian Builders ​

American Builders ​

The North American deep hole drilling machine market has consolidated significantly over the past two decades, with two major players now dominating.

Kays Engineering (Eldorado, DeHoff, TechniDrill) ​

Kays Engineering, headquartered in Marshall, Missouri, owns and builds the three most recognised American deep hole drilling machine brands:

Kays operates a 50,000 sq. ft. manufacturing facility and builds machines for automotive, aerospace, medical, firearms, and petrochemical applications. Their product range covers diameters from 1 mm to 300 mm and depths up to 12,000 mm.

BTA Heller (Sunnen) ​

American Heller was founded in 1952 in Troy, Michigan, as the US arm of the German Heller company. It changed its name to BTA Heller in 2007 and was acquired by Sunnen Products Company in 2018.

BTA Heller is primarily a tooling and system supplier rather than a full machine builder, though they design and supply complete deep hole drilling systems integrated with customer-supplied machine bases. Their acquisition by Sunnen — a leader in bore finishing (honing) — enables combined deep hole drilling and finishing solutions.

Market Comparison ​

Selection Guidance ​

Summary ​

FAQ ​

Which is the largest deep hole drilling machine builder in the world? ​

TBT (TBT Tiefbohrtechnik, Germany) is widely considered the global market leader, with approximately €40 million in annual revenue and the broadest product range. The company has delivered thousands of machines over 50+ years of operation.

Are Chinese deep hole drilling machines competitive with European ones? ​

Chinese machines (primarily from HTT Group) are price-competitive, typically 30–50% less expensive than European equivalents. They have gained significant market share in the mid-range segment, particularly in Asia. For the highest precision, longest tool life, and lowest total cost of ownership over 10+ years, European machines remain preferred.

What happened to Eldorado? ​

Eldorado was a pioneering US gun drilling machine builder based in Milford, Connecticut, operating for over 40 years. Kays Engineering purchased the Eldorado line in 2002 and relocated manufacturing to Marshall, Missouri, where Eldorado machines continue to be built alongside DeHoff and TechniDrill brands.

Does UNISIG build machines in Europe? ​

Yes. UNISIG GmbH, based in Bad Urach, Germany, manufactures deep hole drilling machines for the European market. These machines are built to metric standards (ISO/DIN/IEC) with European electrical components and Siemens controls, addressing the specific requirements of European customers.

Is Mollart still a UK company? ​

Mollart Engineering remains headquartered in Chessington, UK, and designs and builds all machines at its UK facilities in Chessington and Resolven, South Wales. In August 2023, the company was acquired by InCompass, a US-based industrial group, but operations and manufacturing remain in the UK.

What is the minimum hole diameter each builder can achieve? ​

UNISIG and Mollart offer gun drilling machines capable of holes below 1 mm diameter. Most European and American builders achieve 1.5–2 mm minimum diameters for production gun drilling. Chinese builders typically start at 1.5–3 mm. For sub-millimetre holes, micro drilling or EDM are more common alternatives.

How do I choose between BTA and gun drilling machines? ​

The choice depends on diameter and depth: gun drilling is preferred for diameters under 20 mm and very high length-to-diameter ratios (100:1+), while BTA is preferred for diameters over 20 mm and offers 3–5× higher feed rates. Most builders offer both technologies, and the same machine platform can often be configured for either method by changing the spindle and coolant system.

What is the typical lead time for a deep hole drilling machine? ​

European builders typically quote 9–12 months for a custom machine and 4–6 months for a standard model. Chinese builders often quote 4–6 months. American builders fall in between at 6–9 months. Used machines can sometimes be sourced from builder demo floors or dealer networks in 1–3 months.

Which builder offers combined milling and deep hole drilling? ​

UNISIG's USC-M series uniquely combines 5-axis CNC milling with deep hole drilling in a single machine platform, allowing complex parts to be milled and have deep holes drilled in one setup. This eliminates secondary handling and reduces cycle time for mould and die applications.

How has the market changed over the last decade? ​

The major trends include: (1) the rise of Chinese builders, particularly HTT, which has grown from a domestic supplier to an international competitor with 460+ machines delivered; (2) consolidation — Kays absorbed Eldorado and DeHoff, Sunnen acquired BTA Heller, and InCompass acquired Mollart; (3) increasing automation and Industry 4.0 connectivity on European machines; and (4) growing demand for combination machines that mill and drill in a single setup.