9 inputs determine the right vacuum end-effector.

A distributor-facing pre-quote checklist. If the customer answers most of these at the first call, the second call is the quote.

1. 01
   What's the part being picked — material, surface finish, weight, and dimensions?

   Every spec decision flows from this. Material drives cup elastomer (NBR for general, silicone for hot or food-contact, FKM/fluorosilicone for oily). Surface finish drives cup geometry (flat for rigid, bellows for curved or compliant). Weight drives total cup area required. Get a photo and a part spec sheet before quoting.
2. 02
   Is the part surface flat-rigid, curved, porous, or textured/oily?

   The four surface conditions each have a different cup answer. Wrong cup geometry is the #1 failure mode — a flat cup on a curved part dumps vacuum past the unsealed edge. Photograph the part contact surface; don't trust verbal descriptions of geometry.
3. 03
   What's the cycle rate — picks per minute?

   Under 30 picks/min, a single-stage ejector with no release valve is fine. Above 60 picks/min you want a multi-stage ejector with a vacuum-release valve to detach the part fast and reset for the next cycle. Continuous workholding mode runs different ejector spec than high-speed pick.
4. 04
   Is there electrical service at the end-effector, or is this air-only?

   Ejector-based vacuum is the answer when there's no electrical at the end-effector — the venturi runs on shop air, no power, no pump. If there's electrical and the cycle is continuous vacuum, evaluate a centralized electric pump against the ejector air-cost over the install life.
5. 05
   How will the PLC know the part is actually held before the arm moves?

   Vacuum sensor on the line. SMC ZSE switched output to a PLC discrete input is the standard pattern. Skip this step and the robot will eventually drop parts it never actually picked up — the cost of that incident dwarfs the $100 sensor cut every time.
6. 06
   What's the hold time — instant grab and release, or sustained holding?

   Instant grab → cycle the vacuum on demand, ejector runs only during pick. Sustained holding (workholding, mill down-force) → ejector runs continuously and air cost compounds; evaluate centralized vacuum-pump alternative on continuous-duty jobs.
7. 07
   Is the part going through hot, cold, washdown, or chemically aggressive process?

   Process environment dictates cup material. Hot forming → silicone or fluorosilicone; food contact → FDA-grade silicone; oily machine shop → FKM; cold storage → silicone (NBR stiffens cold). Match the elastomer to the worst-case condition the cup will see in the cycle.
8. 08
   How many cups per station, and how many stations on the line?

   Multi-cup picks share the same vacuum source but each cup gets its own check valve so a missed pick on one cup doesn't dump vacuum on the others. Cup count drives ejector flow sizing and replacement-cup stocking levels. Multi-station lines need a working spare bank, not a single replacement.
9. 09
   What's the holding force the part actually requires — weight × safety factor × dynamic loads?

   Total holding force = part weight × 4 (typical safety factor) + any acceleration / deceleration load the robot imposes on the pick. Customers consistently undersize cup area by counting static weight only. Fast-acceleration picks need more cup area than slow-move picks of the same part.