Reaming
Finishing holes to precise dimensions with excellent surface finish using specialized cutting tools.
Process Steps
1. Hole Preparation
Drill hole to correct undersize dimension, typically 0.2-0.4mm under final size.
2. Reamer Setup
Mount reamer in floating holder, align with hole axis, set slow speed and steady feed.
3. Initial Alignment
Carefully start reamer, ensuring it enters hole straight and true.
4. Steady Feed
Maintain consistent feed rate through entire cut. Never back out while rotating.
5. Size Verification
Check reamed hole for size, roundness, and surface finish.
Material-Specific Guidelines
Mild Steel
- • Good reaming characteristics
- • Consistent feed rate critical
- • Cutting fluid important for finish
Recommended Speeds: 30-40 SFPM for HSS reamers, 80-100 SFPM for carbide
Tooling Notes: Standard straight flute reamers work well
Stainless Steel
- • Tendency to work harden
- • Lower speeds required
- • Heavy-duty cutting fluid essential
Recommended Speeds: 20-30 SFPM for HSS reamers, 60-80 SFPM for carbide
Tooling Notes: Left-hand spiral flutes recommended for better finish
Aluminum
- • Excellent reaming properties
- • Higher speeds possible
- • Watch for built-up edge
Recommended Speeds: 100-150 SFPM for HSS reamers, 200-300 SFPM for carbide
Tooling Notes: Special aluminum-specific reamers available
Quality Control Specifications
Hole Size
Method: Pin gauges or air gauging
Tolerance: ±0.0005" typical
Frequency: Every hole
Surface Finish
Method: Visual and profilometer
Tolerance: 16-32 microinch typical
Frequency: First piece and periodic
Roundness
Method: Bore gauge multiple positions
Tolerance: 0.0002" TIR typical
Frequency: Sample basis
Straightness
Method: Long pin gauge or CMM
Tolerance: 0.001" per inch typical
Frequency: Critical applications
Operation Difficulty
Intermediate
Safety Guidelines
- • Ensure hole is properly sized for reaming allowance
- • Use correct cutting speed - usually 1/3 to 1/2 of drilling speed
- • Keep reamer perfectly aligned with hole axis
- • Never reverse a reamer while in the hole
- • Use appropriate cutting fluid for material
Required Tooling
Machine Reamers
Various sizes of straight-fluted or spiral-fluted reamers for different hole sizes
Floating Reamer Holder
For maintaining alignment and preventing binding
Pin Gauges
For precise measurement of reamed holes
Inside Micrometers
For checking hole size and roundness
Troubleshooting Guide
Oversized Holes
Check for proper speed (too fast), feed rate (too slow), or misalignment
Poor Surface Finish
Verify cutting fluid, speed, and feed rate. Check reamer condition
Taper in Hole
Check tailstock alignment and ensure proper starting hole size
Chatter Marks
Reduce speed, increase feed rate, or check for tool runout
Pro Tips & Tricks
Drill Size Selection
Drill undersized by 0.015" for holes under 1/2", 0.031" for larger holes. This ensures proper stock for reaming.
Best for: All reamed holes
Feed Rate Control
Maintain consistent feed rate throughout reaming operation. Never allow reamer to dwell.
Best for: All precision reaming
Floating Holder Use
Use floating holder to allow reamer self-centering. Critical for alignment and finish.
Best for: Precision hole requirements
Chamfer Entry
Ensure proper chamfer on hole entry, 45° × diameter/10 minimum size.
Best for: All reamed holes