Combination PCD Reamers (Combination Reamers / Drill Reamers) for One-Pass Holemaking
01 Scope and Positioning
Combination reamers (often referred to as drill reamers or combination reamers) integrate drilling and reaming—often with chamfering, spotfacing, or counterboring—into one tool to reduce tool changes and stabilise hole quality.
Within the PCD reamer family, a combination PCD reamer is typically selected when cycle time and feature-to-bore consistency are limited by multi-tool transitions rather than by the finishing capability itself.
This is a dedicated branch page focused on combination reaming and reaming-integrated holemaking. For the general definition of PCD reamers, working principle, typical applications, PCD grade selection, and chip-control fundamentals, refer to:
What Is a PCD Reamer and Its Functions?
PCD REAMER:
SOLID CARBIDE REAMERS :
BRAZED CARBIDE REAMERS :
02 Fast Positioning (Combination Reamer vs Standard Reamer vs Guided Reaming Concept)
Use the process-integration requirement as the boundary:
Combination PCD Reamers
Selected when tool changes and operation-to-operation variation are the bottleneck. One tool creates the pre-hole and finishes the bore (and, where specified, the chamfer/spotface/counterbore) in the same cycle, reducing stack-up from multiple tools and offsets.
Standard reamer (non-integrated)
Selected when the pre-hole axis and allowance are already stable enough and separating tools does not limit cycle time or consistency. This is the simpler route when tool changes and transition-related variation are not the limiting factor.
Guide-pad / guided reaming concept
Selected when alignment, straightness, and stable contact are the priority drivers. Guide pads (or guiding lands) support the tool inside the bore and can be used with or without a pilot, depending on whether a dedicated reference bore is available.
The video on the right shows a case-study example of our combination PCD reamer. Due to customer confidentiality, we can only display the tool’s exterior appearance. For reference only.
03 Related Pages
04 What Combination Reaming Controls in Production
Combination reaming is specified when the manufacturing constraint is not “can we hit size,” but “can we hold size and relationships at production speed with fewer transitions.” Typical production targets include:
Reduced tool changes and non-cutting time (shorter cycle time)
Higher repeatability by removing transition variation between drilling, chamfering, spotfacing, counterboring, and reaming
Improved bore-to-feature relationship control (chamfer/spotface/counterbore relative to the finished bore)
Lower offset-history effects (less cumulative correction drift across shifts and machines)
In many high-volume lines, the largest gain comes from eliminating tool transitions and their stack-up—not from increasing cutting speed.
05 Typical Combination Concepts (Reaming-Integrated Tools)
Combination tools are defined by the sequence they integrate and the feature relationship the drawing must control. Common holemaking combinations include:
Drill-reamer (drill + ream)
Drillsink (drill + countersink/chamfer) + ream
Spotface/counterbore + ream
Step bore finishing in one pass (step + ream), where the final sizing and surface are achieved in the same tool path
Application-defined combinations for complex hole features, where the goal is a controlled relationship between multiple features and the finished bore
In all cases, the reaming section remains a finishing cut. The upstream integrated sections must be designed to feed the reaming edges with stable allowance and chip evacuation.
06 Selection Boundary (When a Combination PCD Reamer Is the Right Choice)
Use a combination reamer when:
Tool change time and non-cutting time dominate the cycle
Multiple tools create cumulative runout/offset stack-up (drill → chamfer → counterbore → ream)
The drawing requires tight bore-to-feature relationship control (chamfer width/angle, spotface depth, counterbore location relative to the finished bore)
Process stability improves by keeping the axis and feature sequence in one tool cycle
High-volume production demands repeatable outcomes with fewer variables
Prefer separate tools when:
Pre-hole location/axis or allowance varies widely part-to-part
Chip evacuation is already the limiting factor and an integrated sequence increases chip packing risk
The required features are spread across long depths or interrupted sections where one tool cannot evacuate chips reliably
Machine rigidity or coolant capability is insufficient for a longer, more complex cutting sequence
A combination tool is not a substitute for stable upstream conditions. If the pre-hole is unstable, the finishing section will show instability first.
07 Process Requirements That Decide the Result
Combination reaming is sensitive to the entire holemaking chain. The integrated sequence increases the importance of stability in four areas:
Axis control and runout (TIR)
Because multiple operations share one tool, runout and axis control directly impact both bore size and feature symmetry. Verify TIR at the cutting edges and confirm toolholder and spindle condition before tuning feeds and speeds.
Allowance management into the finishing section
The reaming edges require a consistent finishing allowance. If the integrated drilling/counterboring sections produce variable allowance, the finishing size will scatter and surface integrity at transitions can degrade.
Chip evacuation across the full sequence
Integrated steps can generate mixed chip forms. Chips produced upstream must not recycle into the reaming section. Through-coolant or well-directed coolant often determines whether one-pass finishing is stable or intermittent.
Entry and transition stability
Many defects originate at transitions: drill-to-ream, chamfer-to-bore, counterbore-to-ream. The lead-in design and transition geometry must prevent chip packing and avoid sudden load spikes that damage the finishing edges.
08 Geometry Choices That Matter for Combination Reaming
Sequence design (order of cutting sections)
The order must protect the finishing edges. Upstream sections should create stable guidance and allowance for the reaming section, not overload it.
Guidance strategy (pilot, guide pads, guiding lands)
When alignment or straightness is critical, guidance becomes a stabiliser. The choice depends on whether a reference bore exists and whether the tool must follow an established axis.
Flute count and chip space
Chip space must match the most demanding chip condition in the sequence. Higher flute counts can improve guidance but may reduce chip capacity. Choose based on chip form, depth, and coolant capability.
Coolant routing (including through-coolant)
In integrated tools, coolant design is not optional. Coolant must protect the finishing section from chip recycling and heat concentration.
09 Inspection and Process Control (How to Validate a Combination Reamer)
Validate two outputs separately: (1) finished bore size/geometry, and (2) feature-to-bore relationships created in the same pass.
A practical production approach is to monitor:
Bore diameter and surface finish (or Ra target, where specified)
At least one relationship-critical checkpoint (chamfer width/angle, spotface depth, counterbore position, or step relationship)
Visual checks at transitions for scratches and waviness, which often indicate chip recycling or unstable transition load
In production, transition-related defects often appear before size drift.
10 Troubleshooting Guide (Symptoms → Likely Causes)
Bore size drifts faster than expected
Often runout change, allowance inconsistency into the finishing section, or toolholder/spindle variation. Confirm TIR, verify the pre-hole allowance, and stabilise the integrated upstream cut.
Chamfer/spotface/counterbore varies relative to the finished bore
Typically axis shift, offset-history effects, or instability at transitions. Confirm that the tool is not being “corrected” differently across machines or shifts.
Random scratches near the transition into the finished bore
Most commonly chip recycling or chip packing from upstream sections. Improve coolant delivery, check chip evacuation path, and review transition geometry.
Finish degrades early while size appears stable
Often chip transport issues, rubbing due to low allowance, or built-up edge in ductile alloys. Stabilise allowance and coolant before changing geometry.
Localised edge damage at the reaming section
Often load spikes at transition, interrupted engagement, or excessive allowance. Check the sequence order and whether the finishing edges are entering under unstable conditions.
11 RFQ Checklist (What to Provide for Fast Quoting)
To quote a combination PCD reamer accurately, provide:
Workpiece material (for aluminium, Si% if known; for copper/brass, alloy grade if available)
Hole type (through/blind), bore depth, and L/D ratio
Target finished bore diameter and tolerance, plus surface finish requirement
Integrated features required: chamfer angle/width, spotface/counterbore dimensions, step relationships, and any profile-related segments
Pre-hole method and current condition (drilling/boring route, allowance range, roundness condition)
Machine type and tool interface (holder type, spindle taper, connection limits)
Runout level or target (TIR at the cutting edges, if measured)
Coolant method (through-coolant if required) and evacuation constraints
Production volume and tool-life objective (cost-per-part target)
Any functional requirement on coaxiality/concentricity or feature-to-bore positional control
