Scrap that looks like a “bad carbide grade” is often packed chips: flutes clogged, torque climbing, walls scratched—then a sudden break that gets blamed on the blank.
This page is a chip-packing checklist for solid carbide drilling: how packing presents, what to inspect (flute, chip form, coolant), blind/through traps, and what to change first before you redesign geometry. Deep-hole peck strategy stays in Deep-hole peck & chip escape; here we stop false grade swaps.
How packing presents (≠ “just a deep hole”)
Packing shows as packed flutes on pull-out, rising spindle load, burnt or blue chips, longitudinal wall scratches, or breakage after a few holes. Depth can contribute—but shallow blind holes and cross-holes pack too when chips cannot leave.
If the failure mode is evacuation, a harder grade without chip space usually repeats the scrap. Breakage patterns that follow packing: Why solid carbide drills break.
Flute space, chip form, and coolant direction checklist
Walk this list before touching the tool drawing:
- Flute volume vs chip size — long stringy chips vs broken chips; do chips clear the flute on retract?
- Coolant reaching the tip — flood that never hits the cut vs directed/through-coolant path.
- Peck / retract logic — dwell that rubs; pecks that re-cut a packed slug.
- Stickout — long overhang that reduces effective chip pumping.
- Filtration / tramp oil — coolant that cannot carry chips even when “pressure looks fine.”
Do not invent a pressure or flow number here. Record what the machine actually delivers, then decide if When flood coolant is not enough or product through coolant carbide drill is in scope.
Blind vs through vs cross-hole traps
| Hole type | Packing trap | First checks |
|---|---|---|
| Blind | Chips return only through flutes; bottom slug | Peck depth, tip coolant, flute volume |
| Through | Exit support / chip shower at breakthrough | Exit control: Exit breakout & burr control |
| Cross-hole / interrupted | Chip shape changes; edges load unevenly | Program motion, coolant aim, whether packing starts at the interruption |
Deep L/D strategies: Deep-hole peck & chip escape—use it for peck recipes, not as a substitute for this symptom checklist.
Change cycle, coolant, and stickout before new geometry
Order of attack when packing is the scrap mode:
- Stabilize stickout/holder/runout — Stickout, runout & toolholders
- Fix coolant delivery and chip size (peck, speed/feed process window — no fake SFM tables here; see Carbide drill speeds & feeds (process-first) for process-first setup)
- Only then review geometry / through-coolant / series choice — Solid carbide drill geometry · Choose carbide drill series by material · Solid Carbide Drill
Swapping grade first is how plants buy the same packed flute twice.
When packing drives Cost per Good Part → RFQ
If you can, photograph flutes after a stop, the chip shape, and the wall scratch pattern. Those three images often beat adjectives when XRZ reviews whether packing is flute volume, coolant aim, or peck logic.
Count changes, scrap, downtime, and breakage against accepted holes. If evacuation still fails after setup fixes, send drawing, depth, blind/through, coolant route, stickout, and scrap mode via Custom Cutting Tool RFQ.
Frequently Asked Questions
Is packing only a deep-hole problem?
No—blind and interrupted holes pack at moderate depth.
Should we increase peck count first?
Only if chips clear; more pecks into a packed flute can worsen re-cutting.
When is through-coolant justified?
When tip delivery and chip transport stay weak after flood/setup fixes—evaluate with real machine data.
What to send XRZ?
Drawing, depth, hole type, coolant, stickout/runout, chip photos if available, scrap mode → RFQ.
Next step
Run the checklist, then send the hole drawing for a drill engineering review—not a grade lottery.