Consumable cost is not the unit price. What matters is parts per pellet, and that depends heavily on mounting, dressing and process parameters.
1. Mounting: flatness comes off the plate
When pellets are bonded to a lapping plate, an uneven adhesive layer copies the plate error straight onto the workpiece. The classic symptom is “the first few parts after a change are fine, then they drift out of tolerance” — the adhesive is still flowing under load. The fix:
- Check plate flatness and cleanliness before mounting; remove all old adhesive
- Keep the adhesive layer thin and even; let it cure before loading the machine
- Run a new plate in unloaded first, so the whole set enters service together
2. Dressing: not only when it stops cutting
Once a pellet glazes or loads, cutting force and grinding heat rise, and surface quality falls off a cliff. Waiting until “it won't cut” means a batch is already scrap. Dress on a count or time interval instead of by feel:
- Light, regular dressing by part count or running hours keeps grains exposed
- Keep the dressing amount and tool fixed, so plate topography does not change each time
- Record the first-part inspection after dressing as the baseline for that interval
3. Life management: treat consumables as process parameters
Keep a simple log per batch: batch number, date mounted, parts produced, rework rate, reason for change. Two or three months of data gives you a real life range, and lets you compare on consumable cost per thousand parts rather than price per pellet. A pellet at half the price and half the life costs twice as much.
4. Polishing pads are the forgotten variable
When polishing goes wrong, everyone checks pellets and powder and forgets the pad. An aged or dished pad distributes pressure unevenly, which shows up as “the edge of every part on this plate polishes dull”. Conditioning the pad with a dedicated conditioning pellet is often more effective than changing the slurry.