Drilling deserves more respect
Milling, turning and drilling are the foundational machining processes. Their chip removal processes are also the most efficient way to remove material from a workpiece. Of the three, drilling has the highest removal rate, which is why it’s the most efficient way to make chips. Evidence of this can be found when digging around an old shop.
Milling, turning and drilling are the foundational machining processes. Their chip removal processes are also the most efficient way to remove material from a workpiece. Of the three, drilling has the highest removal rate, which is why it’s the most efficient way to make chips. Evidence of this can be found when digging around an old shop.
By old, I mean one that is 40 or 50 years old and hasn’t been cleaned out. Not only will you find drills in ever imaginable diameter and length, they will have tapered shanks on them so that they can be used in every machine. The machine tools in the shop will also indicate that drilling is an efficient process. You can expect to find multiple spindle drill presses, radial arm drills and drill point grinders.
While drilling is a prominent and efficient process in modern shops, it is not utilized as frequently as it could be. Considering the advantages of drilling, shops today should be drilling far more often than they do.
Less Expensive
Drilling provides significant cost advantages over the other processes. With CNC controls and CAM software, a programmer can utilize milling techniques like helical entry, ramp entry and Z-axis plunging to make a hole. All of these techniques are effective methods, but drills typically cost less than milling tools and have a much longer service life. Also, given drilling’s higher material removal rate versus milling, it allows shops to reserve expensive milling machine time for more appropriate operations. Plus, drills move a larger volume of chips between sharpening, further reducing their lifetime cost.
Dependable Accurancy
When necessary, drilling can be very accurate. Valve housings for hydraulic power steering require close tolerance holes so that high pressure fittings seat and seal correctly. Specially designed drills are utilized and the holes are completed in one pass. The drilling process is capable of holding 0.005 mm hole diameters with a 0.4 µm surface finish. In many shops these holes would be created with multiple tools.
Drills Are Universal
Drilling on a lathe or a mill can be done with the same tools. Turning tools and milling tools, on the other hand, are usually not interchangeable across machine tools.
Easier To Program
Drilling processes are also much easier to create because the CNC controller has several canned drilling cycles available for use. Programming a drilling routine only requires a few lines of CNC code. Plus, drilling cycles are modal, meaning once a cycle is called, the programmer simply needs to provide the coordinates of the next hole, and then the cycle is repeated with a single line. Milling routines that make holes in parts require numerous lines of code and the number of lines only increases with complexity. What’s more, there are no canned cycles for milling.
Leveraging Special Drills
Complex internal geometries can be created using special drills. Multiple diameters, chamfers and radii can be made into the drill body so that other operations like boring are eliminated. This is especially helpful when the geometry has high length-to-diameter ratios. When the length-to-diameter ratio goes over 4:1, boring tools can become unstable and chatter becomes a problem.
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Cutting Tool Engineering
Don’t be led astray by trendy machining strategies. A
good drilling operation is frequently the better option. Leveraging Special Drills materials like 304 and 316 stainless Complex internal geometries can steels. be created using special drills. Mul- tiple diameters, chamfers and radii Choosing The Right Drill can be made into the drill body There are numerous styles of so that other operations like bor- drills available on the market so the.
Don’t be led astray by trendy machining strategies. A good drilling operation is frequently the better option. Leveraging Special Drills materials like 304 and 316 stainless Complex internal geometries can steels. be created using special drills. Mul- tiple diameters, chamfers and radii Choosing The Right Drill can be made into the drill body There are numerous styles of so that other operations like bor- drills available on the market so the ing are eliminated. This is espe- process can be tuned to fit every cially helpful when the geometry application. For high production
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good drilling operation is frequently the better option. Leveraging Special Drills materials like 304 and 316 stainless Complex internal geometries can steels. be created using special drills. Mul- tiple diameters, chamfers and radii Choosing The Right Drill can be made into the drill body There are numerous styles of so that other operations like bor- drills available on the market so the.
Don’t be led astray by trendy machining strategies. A good drilling operation is frequently the better option. Leveraging Special Drills materials like 304 and 316 stainless Complex internal geometries can steels. be created using special drills. Mul- tiple diameters, chamfers and radii Choosing The Right Drill can be made into the drill body There are numerous styles of so that other operations like bor- drills available on the market so the ing are eliminated. This is espe- process can be tuned to fit every cially helpful when the geometry application. For high production
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April 2026
Of course, there are special boring tools that can be used, but they are expensive, and you still have to bear the cost of additional cycle time. If accuracy is an issue, then pair the drill with a reamer with the same geometry. A reamer is just a fancy drill and it’s faster than boring. High-Speed Steel (HSS) With the exception of drills, HSS is no longer used for cutting tools outside of hobby machinists and some specialized repair work.
Several well known cutting tool manufacturers offer HSS drills for production applications. These are not the old-fashioned twist drills that come in paper envelopes. These drills are manufactured from powder metals and have the latest coatings applied to them. High-speed drills like these offer three distinct advantages.
First, they cost less than carbide and similar materials. Second, they are tougher than carbide so they do not chip and break as easily. Third, their edge is sharper, which makes them very effective in soft or gummy materials. The sharper edge and slower rotational speeds remove some of the challenges associated with difficult materials like 304 and 316 stainless steels.
Choosing The Right Drill
There are numerous styles of drills available on the market so the process can be tuned to fit every application. For high production runs where speed and longevity are critical, there are solid carbide, indexable carbide tips and indexable drills with inserts available. When you need a lot of different sizes, spade drills are a good option as one body can hold a multitude of point diameters. These are also a great choice when you need to make big holes on modern machines that lack the torque of the old-fashioned geared drill presses and mills.
If you need precise holes, then modern carbide drills held in high-precision toolholders are often capable of holding 0.025 mm or better. Get them with three flutes and you can get close to reamer tolerances. Do you have to go deep?
Manufacturers offer drills capable of going 50 times the diameter in depth for deep hole applications. These have allowed shops to machine components on HMCs and VMCs that would have required specialized gun drill machines in the past. Drilling offers many advantages when compared to other machining processes. Yet, CNC machines and CAM software have made high-speed machining, trochoidal milling and similar operations sexy and cool.
Don’t be led astray, a good drilling operation is frequently the better option.
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