Today we are going to focus specifically on reamers. Reamers are used to produce accurate sized holes with surface finishes that are typically smoother than drilling or boring. A typical reaming job involves drilling or boring the hole to be sized leaving two – three percent of the finish diameter for reaming. So, a 0.5000” diameter chucking reamer should be used to ream a hole that has been roughed to between 0.4850” and 0.4900” in diameter in order to leave adequate material to finish the hole to a diameter of 0.5000” (0.5000*0.97=0.4850 and 0.5000*0.98=0.4900). Speeds and feeds play an important role in the performance of the reamer. Speeds and feeds change with the type of material being reamed (i.e. non-ferrous, cast iron, steel, etc.) as well as the hardness of the material being reamed.
No matter what material you are reaming, the formulas remain the same:
RPM = (SFPM*3.82)
IPR = IPM/RPM
RPM = Rotations Per Minute
SFPM = Surface Feet Per Minute
TOOL DIAMETER = Diameter of the cutter in inches
IPM = Inches Per Minute
IPT = Inches Per Tooth
IPR=Inches Per Revolution
Whether you use carbide tipped, solid carbide or HSS reamers use the reamer manufacture’s speeds and feed chart for surface foot per minute (SFPM) recommendations in the materials and hardness you intend to ream. Here is a link to a reaming speeds and feeds chart for carbide tipped reamers. There are two charts: one for reaming dry (no coolant) and one for reaming with coolant.
For reaming most materials carbide tipped reamers provide a high performance solution. The reaming speeds and feeds chart referenced above provides the appropriate SFPM and IPR for most common materials. When reaming diameters less than approximately 0.1560”, solid carbide or high speed steel reamers are recommended over carbide tipped reamers. This is primarily due to the structural design of carbide tipped reamers vs. solid carbide reamers. Carbide tipped reamers consist of a steel body with carbide tips bonded (brazed) to the steel body. The reamer is then sharpened to design specifications. Reamers less than 0.1560” in diameter do not provide enough mass to bond the carbide tip to the tool steel body. This makes solid carbide or high speed steel reamers a better choice when reaming small holes. If high performance and/or long production runs are required choose solid carbide reamers for small hole diameters.
Carbide is typically more expensive than steel. As a result it is more economical in larger diameters to use a carbide tipped reamer rather then a solid carbide reamer. Another advantage carbide tipped reamers hold over solid carbide reamers is that carbide is brittle. When using carbide tipped reamers the tool steel body can absorb shock loads better than a solid carbide reamer with the same dimensions. Carbide is brittle and has a tendency to break rather then bend. The steel body of the carbide tipped reamer has more of a tendency to bend slightly rather than just breaking.
Check back with us next week. If you have any questions or comments about reaming speeds and feeds or any other cutting tools feel free to leave us a comment here on our blog or on Super Tool’s Contact Us Page.
Super Tool, Inc.