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Drilling Steel with Die Drills


Steel is a hard material to drill.  The same characteristics that make steel enticing to use in products are the same characteristics that make it difficult to machine and drill.  There are cutting tools that can drill steel.  Selecting the proper drill to use depends heavily on the properties of the steel such as the hardness (measured in Rockwell or Brinnell) and the type of steel (i.e. low carbon steels, medium strength steels, and high strength steels, etc).

 Die drills work well when drilling steel.  They are excellent in hardened steel 35 to 65 Rockwell C.  They will cut without annealing the workpiece.  The type of point on the die drill is important.  Standard die drills typically come with a negative or positive edge.  Each edge type typically has 118° or 140° point.  The die drill body diameter is smaller than the tool diameter to prevent gauling.

Positive point tools are for use on machines with less spindle horsepower.  The thinned web permits higher feed rates than otherwise possible.

Negative point tools are for higher hardness materials.

118° Point tools are for general duty work.

140° tools are for drilling tough and abrasive materials.

Spade Type Die Drills are a variation of the die drills mentioned above.  They are best used for shallow holes approximately 2 tool diameters deep.  Their short heavy duty construction allows more rigidity for tough applications where longer length drills are not needed.  Spade Type Die Drills come standard with 120° or 140° cam relieved points.

In all applications, use copious amounts of coolant.  Also use light feed (0.001” – 0.002” IPR) with steady pressure, and keep the workpiece clear of chips.  Run at 75-110 SFPM.  For more on speeds and feeds check out our blog posts Introduction to Speeds and Feeds and Drilling Speeds and Feeds.

Super Tool offers negative and positive edge die drills as standard tools each with either 118° or 140° points.  To aid in tool selection here is a link to Super Tool’s Die Drill Selection Guide.

If you have any questions or would like more information on Die Drills or on Drilling Steel please leave us a comment here on our blog or fill out the form on Super Tool’s Contact Us Page.

Bryan Enander
Super Tool, Inc.