PCD Reamer Exit Burrs in Aluminum: What to Check
Aluminum bores that “finished to size” still hang a thin exit lip or roll—and the first blame is often the PCD reamer drawing.
This page is for burrs after PCD finish (or finish-related exit roll), not create-exit breakout. Create-stage exit defects stay in Control Exit Breakout Before You Blame the Drill Grade. No “PCD never burrs” claim and no life multipliers.
Burr after finish vs create-exit
| Stage | Typical look | First owner |
|---|---|---|
| Create / drill exit | Breakout cap, heavy exit burr before ream | Drill process — exit breakout guide |
| After PCD ream | Thin foil, roll, or whisker at exit/entry after finish | Finish stock, edge, pre-hole, exit support |
If the lip already exists before the reamer enters, fix create exit first. If size is in band but the lip appears only after finish, stay on this checklist.
Allowance, edge prep, and chamfer interaction
Too little effective stock can rub and push material instead of shearing a clean edge. Too much stock can raise force and leave a rolled exit. Size stock with PCD Reamer Allowance and Pre-Hole Size—do not invent a universal mm chart here.
Edge prep and any print chamfer/break-edge callout must match the exit. A sharp print edge with no exit support is a burr generator even with a good diameter.
Pre-hole quality inheritance
Wall damage, lobing, or dirty walls from create can leave material the finish edge must “wipe,” which often shows as a thin exit lip or roll. Qualify the hole with PCD Reamer Pre-Hole Quality after the allowance mm is in window. Cast Al size confusion: Undersize Hole ADC12. Route split: Carbide Drill + PCD Reamer in Aluminum.
High-silicon adhesion/BUE that smears rather than cuts clean: Control Built-Up Edge in PCD Reaming.
When face/seal ops add burr risk
A later face or seal mill can roll the bore edge or move thin walls after reaming. Same-part sequence notes: Face Milling with PCD Reaming on the Same Part. Do not treat this page as a milling guide.
Cost per Good Part → RFQ
Deburr stations, sorting, and scrap beat “cheap” tool invoices. Send scrap photos (before/after finish if possible), alloy/Si% if known, exit type (through/blind/cross), allowance note, and edge/chamfer callouts via Custom Cutting Tool RFQ · Custom PCD Reamer. Cost framing: Cost per Accepted Hole.
Frequently Asked Questions
### We hit size—why still a foil at exit?
Size and burr are different. Check stock, edge prep, pre-hole wall, and exit support.
Is this the same as drill exit breakout?
No. Drill exit is create-stage; this page is after PCD finish.
Does higher Si make burrs inevitable?
Si changes wear/adhesion risk; it does not justify a universal burr guarantee either way—send grade/Si% and photos.
What to send XRZ?
Drawing, alloy/Si%, exit type, scrap photos, create+finish tools, allowance/pre-hole notes → RFQ.