Gun Drilling


deep hole gun drillingConfluent Maine’s expertise in gun drilling dates back to 1947. World War II had just ended when pioneering machinist Howard Dearborn developed the technology and processes that act as the foundation for our advanced precision deep hole gun drilling capabilities. We’ve had over 60 years to expand on that base and the result is unparalleled expertise in machining extremely challenging holes in a wide range of alloys.

Brief History of Gun Drilling

Gun drilling, invented in Europe more than two centuries ago, is the process of drilling deep, straight holes in a variety of materials, ferrous and non-ferrous alike. It was first invented…READ MORE>>

Gun drilling, as practiced by THI, is a precision drilling process that produces deep, straight holes in a variety of specialty alloys. A gun drill tool differs from a conventional twist drill by its unique head geometry; a standard gun drill has a single effective cutting edge. Coolant is delivered to the cutting site through a hole down the length of the drill and chips are evacuated along the drill’s flute (a longitudinal “V” shaped groove). Guide pads burnish the hole and help maintain straightness. The result of this precise and sophisticated process is a drilled tube with precise diameter, tight concentricity tolerances and an excellent finish.

deep hole gun drilling

Confluent Maine machines custom tubing, shafts and tubular components for a wide variety of industries, meeting the specialized needs of our partners in the aerospace, medical, energy, gas and oil, nuclear power generation, food and beverage and agricultural industries, just to name a few. Examples of our precision gun drilling services meeting our customer’s application needs include:

  • Nuclear reactor components, including drive rods and other seamless precision tubes
  • Shafts and test harness tubular components for aerospace turbines
  • Precision hollows for nitinol tubing and component manufacturers.
  • Stainless steel precision hollows for the peripheral stent and endoscopy markets
  • Cannulated bars for medical device manufacturing
  • Seamless tubing for rotorcraft landing gear
  • Chemical process tubing for Low Density Polyethylene production
  • Refractory metal heat exchanger tubing and hot-zone components

Standard gun drilling produces a straight hole but allows for a “drift” rate through the part. This occurs because as the drill encounters small inconsistencies or inclusions in the metal, the drill path deflects slightly off of center. Typical industry drift rates average about .001″ per inch drilled. So, as tubular components extend beyond 20 inches, the risk of eccentric parts (tubes with significant wall variation) grows dramatically.

Confluent Maine’ deep hole gun drilling processes virtually eliminate this drift. Our machinists are able to maintain Total Indicated Runout (TIR) of .004″ in tubes up to 72″ long and achieve TIR of .006 – .008″ on tubes up to 25 feet in length. Confluent Maine drills holes that range from .055″ up to 3+ inches at depth to hole ratios that lead the industry.

“I’ve been looking for my entire career for a company with your capabilities.” – customer in LDPE manufacturing

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