The Driller
  • Sign In
  • Create Account
  • Sign Out
  • My Account
  • NEWS
  • CLASSIFIEDS
  • EQUIPMENT
  • SAFETY
  • VIDEOS
  • EDUCATION
  • SOURCEBOOK
  • EVENTS
  • SUBMIT
  • ABOUT
  • SIGN UP
cart
facebook twitter linkedin youtube
  • NEWS
  • Water
  • Geothermal
  • Construction
  • Environmental
  • Mining
  • All Industry News
  • EQUIPMENT
  • Rigs & Heavy Equipment
  • Consumables
  • Pumps
  • Featured Products
  • VIDEOS
  • Newscast
  • Drill Talks
  • Ask Brock
  • Emerging Drillers
  • EDUCATION
  • Drilling Business Insights
  • Reference Desk
  • Sponsored Insights
  • EVENTS
  • Conferences & Demo Days
  • Newscast LIVE
  • SUBMIT
  • Drillers @Work
  • ABOUT
  • Contact
  • Advertise
The Driller
search
cart
facebook twitter linkedin youtube
  • Sign In
  • Create Account
  • Sign Out
  • My Account
The Driller
  • NEWS
    • Water
    • Geothermal
    • Construction
    • Environmental
    • Mining
    • All Industry News
  • CLASSIFIEDS
  • EQUIPMENT
    • Rigs & Heavy Equipment
    • Consumables
    • Pumps
    • Featured Products
  • SAFETY
  • VIDEOS
    • Newscast
    • Drill Talks
    • Ask Brock
    • Emerging Drillers
  • EDUCATION
    • Drilling Business Insights
    • Reference Desk
    • Sponsored Insights
  • SOURCEBOOK
  • EVENTS
    • Conferences & Demo Days
    • Newscast LIVE
  • SUBMIT
    • Drillers @Work
  • ABOUT
    • Contact
    • Advertise
  • SIGN UP
EquipmentMining & Mineral Exploration DrillingDrilling Consumables

Best Value in DTH Tools Determined by Application, Ground Conditions

By Ray Shelor
DTH Tools

Concave, flat front and convex bits. Concave works best in medium to hard, fractured formations. Source: Atlas Copco

DTH Tools

Flat front is optimized for hard, abrasive formations. Source: Atlas Copco

DTH Tools

Convex is ideal for soft to medium, non-abrasive formations. Source: Atlas Copco

DTH Tools
DTH Tools
DTH Tools
July 1, 2015
The wide range of applications and drilling conditions suitable to down-the-hole pneumatic percussion technique requires consideration of more than one type of tool to drill efficiently and profitably.

Article Index:

  • Choosing the Correct Hammer
  • Selecting the Correct Bit
  • Premium or Economy
  • Application Considerations


Choosing the Correct Hammer

The selection of hammer size is largely determined by the hole diameter and type of rock formation. The optimum blasthole range for DTH drilling is 3½ to 10 inches. Smaller holes are typically drilled with a top hammer rather than DTH hammer, and larger holes generally use the rotary drilling technique, mainly with the focus on hole straightness.

As a general rule, the smallest hole diameter a DTH hammer can drill is its nominal size. A 4-inch hammer is optimally designed to drill a 4-inch hole. The closer the hole diameter is to the hammer’s diameter, the more restricted the hole’s evacuating airflow is. Drilling holes at the nominal size leaves adequate space for cuttings to evacuate the hole up the annulus between the hammer and drill pipe diameters and the internal diameter of the hole’s wall.

Maximum bit size for production drilling is the nominal hammer diameter plus 1 inch. For instance, a 4-inch hammer’s maximum bit size is regarded to be 5 inches in diameter. Pipe diameter should be close to the hammer diameter to provide optimum flushing, reducing the chances of getting stuck in the hole.

Pipe (tubes) made from cold-drawn tubing provide a superior surface finish and tolerance compared to tubes made from hot-rolled tubing. A better finish reduces the risk from metal chips from the tubes, called scaling. Scaling that flows through the hammer is a major cause of premature hammer failure.

Friction-welded joints add strength. Heat treating the threads of end-pieces ensures optimum durability and strength of the thread profile. Preserving the thread profile keeps coupling and uncoupling smooth, without adding time to the average rate of penetration.


Selecting the Correct Bit

The bodies of quality bits are precision machined from alloy steel, heat treated to a specified hardness, providing surface compression for fatigue resistance, and then fitted with precision carbide buttons.

Convex-faced, ballistic-button designs are preferable for fastest cuttings removal. This bit design cuts clean with minimal re-crushing, making it ideal for soft to medium, non-abrasive formations.

In hard and abrasive formations, flat-front designs offer best bit life, especially those that feature strong gauge rows with large spherical buttons that are easy to regrind and maintain. An alternative in these conditions is a concave design with spherical buttons.

Concave bit faces work well in medium to hard, fractured formations. In this type of application, a concave bit minimizes hole deviation.


Premium or Economy

A fundamental question is whether one needs a reliable, low-cost hammer or a premium hammer. Buying more than one less-expensive hammer to achieve the same drill feet of a single premium hammer is false economy.


Application Considerations

Manufacturers design DTH hammers to address the challenges presented by the full array of rock types and applications. For deeper hole applications, hammers are designed to work with different air requirements as bailing velocity requirements change.

Quarrying projects are long-term jobs that will easily outlast the hammer. Frequently replacing hammers would be cost-prohibitive. Dimensional stone quarrying demands consistently straight holes. DTH hammers offer more precision to hole straightness than top hammers.

Mineral exploration generally requires robust hammers capable of running high pressures, often in dirty, remote environments. Operators tend to prefer simple, reliable designs in this application.

Reverse circulation with specialized DTH hammers is less expensive than diamond coring technique. The RC hammers use the same engineered technology and components as standard DTH hammers, but use RC tubes with inner and outer walls for direct airflow to allow the cuttings to pass up through the pipe to a cyclone for collection bags, rather than the typical hole cleaning up the hole’s annulus.

Like quarries, open pit mines typically have high equipment utilization, drilling most of the working day.

Some premium hammers for these applications can now be rebuilt twice before replacement.

Properly training drillers to recognize and maintain optimum drilling parameters prevents premature failure of hammers.

Hammer value involves more than component material and design. Additional factors must be taken into consideration. The market offers a range of quality in both economy and premium hammer selections. The hammer must not only be durable enough to be reliable throughout its anticipated lifespan, but its cost of operation figures in. The greater the hammer efficiency, the better the savings in fuel and energy, resulting in lower cost per drilled foot.

Additionally, drillers should consider the manufacturer’s product support. A consultation from the manufacturer provides advice on DTH requirements. A knowledgeable product support specialist will also help determine which hammer provides the highest profitability for a project.

KEYWORDS: drill bits DTH hammers exploration drilling quarrying well drilling

Share This Story

Looking for a reprint of this article?
From high-res PDFs to custom plaques, order your copy today!

Ray Shelor is senior product manager of Atlas Copco DTH equipment.

Recommended Content

JOIN TODAY
to unlock your recommendations.

Already have an account? Sign In

  • geotechnical drilling rig

    6 Onsite Phrases Environmental Drillers Hate

    Here are six phrases that highlight common frustrations...
    Opinions
    By: Jeff Garby
  • Wayne Nash

    Pipe Stuck? Common Causes and Solutions for Drillers

    If you have drilled for any length of time, sooner or...
    Opinions
    By: Wayne Nash
  • submersible pumps, water well pumps

    Selecting and Sizing Submersible Pump Cable

    This article helps pump installers and servicers decide...
    Markets
    By: Bob Pelikan
You must login or register in order to post a comment.

Report Abusive Comment

Subscribe For Free!
  • eNewsletters
  • Online Registration
  • Subscription Customer Service
  • Manage My Preferences

The Driller Newscast: New York Geo Talks 2025 Conference with Hands-on Driller Education

The Driller Newscast: New York Geo Talks 2025 Conference with Hands-on Driller Education

The Driller Newscast: Coiled Tubing Drilling and the Future of Geothermal

The Driller Newscast: Coiled Tubing Drilling and the Future of Geothermal

The Driller Newscast, Episode 147: Global Geothermal Collaboration at NY-GEO 2025

The Driller Newscast, Episode 147: Global Geothermal Collaboration at NY-GEO 2025

The Driller Newscast: 21st Century Drillers | Part 1 DEMAND

The Driller Newscast: 21st Century Drillers | Part 1 DEMAND

More Videos

Sponsored Content

Sponsored Content is a special paid section where industry companies provide high quality, objective, non-commercial content around topics of interest to the The Driller audience. All Sponsored Content is supplied by the advertising company and any opinions expressed in this article are those of the author and not necessarily reflect the views of The Driller or its parent company, BNP Media. Interested in participating in our Sponsored Content section? Contact your local rep!

close
  • demo of a DM450 drilling rig during a customer factory visit
    Sponsored byGeoprobe

    Built for You: Smarter Drill Rigs, Stronger Support, Bigger Opportunities

Popular Stories

MainPhotoTwoBrothers.jpg

Two Brothers' Journey Through the Drilling Industry

Tariffs

Tariffs Shake Up the Drilling Industry

AI and Drought Concerns

AI’s Growing Thirst for Water and Power

The Driller Classifieds

COMPRESSORS

EAST WEST MACHINERY & DRILLING IS BUYING AND SELLING AIR COMPRESSORS, AIR BOOSTERS, AIR ENDS & PARTS
Company: East West Machinery

DRILL RIGS

LOOKING FOR LATE MODEL TOPHEADS & DRILLTECH D25'S
Company: Spikes’s Rig Sales

DRILL RIG PARTS

MEETING DRILLERS NEEDS AROUND THE WORLD
Company: East West Machinery

ELEVATORS

SEMCO INC. PIPE ELEVATORS
Company: Semco Inc.

GROUTERS

GROUTING EQUIPMENT - GROUT PUMPS & GROUT HOSE REELS
Company: Geo-Loop Inc.

PUMP HOISTS

SEMCO INC. - BASIC PUMP HOISTS
Company: Semco Inc.

WELL PACKERS

LANSAS PRODUCTS - INFLATABLE WELL PACKERS
Company: Vanderlans Lansas Products

WELL SCREENS

WELL SCREENS & SLOTTED PIPE
Company: Alloy Screen Works

Products

Water Quality Engineering: Physical / Chemical Treatment Processes

Water Quality Engineering: Physical / Chemical Treatment Processes

By carefully explaining both the underlying theory and the underlying mathematics, this text enables readers to fully grasp the fundamentals of physical and chemical treatment processes for water and wastewater.

See More Products

Subscribe to The Driller Newscast

Related Articles

  • Rock-Tech International DTH Tools

    Rock-Tech International DTH Tools

    See More
  • Halco

    Halco Rock Tools Unveils Superior DTH Hammer Range for Oil Drilling, Gas Drilling

    See More
  • Rockmore T line

    Rockmore International Launches First Hammer in New T Series DTH Line

    See More
×
Concave, flat front and convex bits. Concave works best in medium to hard, fractured formations. Source: Atlas Copco
Flat front is optimized for hard, abrasive formations. Source: Atlas Copco
Convex is ideal for soft to medium, non-abrasive formations. Source: Atlas Copco

Dig deeper into the drilling and water supply industry!

Build your knowledge with The Driller, covering the people, equipment and technologies across drilling markets.

SIGN UP NOW
  • RESOURCES
    • Advertise
    • Contact Us
    • Directories
    • Store
    • Want More
    • Classifieds
  • SIGN UP TODAY
    • Create Account
    • eNewsletters
    • Customer Service
    • Manage Preferences
  • SERVICES
    • Marketing Services
    • Reprints
    • Market Research
    • List Rental
    • Survey/Respondent Access
  • STAY CONNECTED
    • LinkedIn
    • Facebook
    • YouTube
    • X (Twitter)
  • PRIVACY
    • PRIVACY POLICY
    • TERMS & CONDITIONS
    • DO NOT SELL MY PERSONAL INFORMATION
    • PRIVACY REQUEST
    • ACCESSIBILITY

Copyright ©2025. All Rights Reserved BNP Media.

Design, CMS, Hosting & Web Development :: ePublishing

The Driller
search
cart
facebook twitter linkedin youtube
  • Sign In
  • Create Account
  • Sign Out
  • My Account
The Driller
  • NEWS
    • Water
    • Geothermal
    • Construction
    • Environmental
    • Mining
    • All Industry News
  • CLASSIFIEDS
  • EQUIPMENT
    • Rigs & Heavy Equipment
    • Consumables
    • Pumps
    • Featured Products
  • SAFETY
  • VIDEOS
    • Newscast
    • Drill Talks
    • Ask Brock
    • Emerging Drillers
  • EDUCATION
    • Drilling Business Insights
    • Reference Desk
    • Sponsored Insights
  • SOURCEBOOK
  • EVENTS
    • Conferences & Demo Days
    • Newscast LIVE
  • SUBMIT
    • Drillers @Work
  • ABOUT
    • Contact
    • Advertise
  • SIGN UP