Vacuum Pump for Pick and Place: How to Select One for SMT and Electronics Handling
HCEM Engineering TeamShare
To select a vacuum pump for pick and place, start at the nozzle and work back to the pump. Work out the vacuum each nozzle needs to hold its heaviest part during the fastest move. Work out the flow the machine needs when nozzles are open, leaking and cycling. Then choose an oil-free pump whose flow at that working vacuum, not its headline flow, covers the demand with margin, and check that its voltage, noise, heat and duty rating fit inside the machine.
This guide works through each step for SMT pick-and-place machines and other electronics handling: chip placement, tray and wafer handling, test fixtures. The worked examples use round numbers you can replace with your own, and the model data come from our oil-free piston vacuum pump datasheets.
What does a pick-and-place vacuum pump have to do?
It keeps the vacuum manifold that feeds the nozzles at a stable working level while the machine picks, moves and releases parts. The pump is only one part of the circuit. Nozzles, nozzle filters, valves, tubing, the manifold and any reservoir all sit between the pump and the part, and each one loses a little vacuum or adds volume to evacuate.
Three questions decide the pump, and it helps to keep them apart:
- How much vacuum does the nozzle need to hold the part through acceleration and travel?
- How much flow does the machine draw at that vacuum, with open nozzles, leaks and repeated picks?
- How fast must the vacuum recover after a pick, a release or a missed part?
The first two size the pump. The third depends as much on the circuit (short, small-volume lines between valve and nozzle, a reservoir near the head) as on the pump. If the basics of vacuum units are new, our guide on how vacuum pumps work explains gauge and absolute pressure first.
What vacuum level does a pick-and-place nozzle need?
Enough for the pressure difference across the nozzle opening to hold the part with a safety margin. The holding force is:
F = Δp × A
where F is the holding force in newtons, Δp is the pressure difference between the atmosphere and the nozzle in pascals (−60 kPa gauge means Δp = 60,000 Pa), and A is the area of the nozzle opening that the part seals, in square metres. Use the opening's inner diameter, not the outer diameter of the tip.
Worked example. A nozzle with a 1.0 mm opening picks a 0.5 g component, and the head accelerates it upwards at 20 m/s² (about 2 g).
- Opening area: A = π × (0.5 mm)² = 0.785 mm² = 7.85 × 10⁻⁷ m².
- Load during the upward move: m × (g + a) = 0.0005 kg × (9.81 + 20) m/s² = 0.0149 N. At rest the part weighs only 0.0049 N, so the acceleration triples the load.
- With a safety factor of 2: 2 × 0.0149 = 0.030 N needed.
- Vacuum needed: Δp = F ÷ A = 0.030 ÷ 7.85 × 10⁻⁷ ≈ 38,000 Pa, so at least −38 kPa at the nozzle.
- Check at −60 kPa: F = 60,000 × 7.85 × 10⁻⁷ = 0.047 N, which is 3.2 times the dynamic load.
So a working point of −60 kPa at the nozzle holds this part with comfortable margin, and −40 kPa would be the bare minimum. The pump itself must pull deeper than the nozzle target, because filters, valves and tubing lose some vacuum on the way.
Two effects need extra margin:
- Sideways moves. When the head accelerates sideways, only friction between the nozzle tip and the part stops it sliding. Friction is a fraction of the holding force, so the sideways move is often the tighter limit. Machines deal with it through larger nozzles for heavy parts and lower head acceleration in the placement program; test with your real parts at full speed.
- Imperfect seals. Rough or curved tops, worn nozzle tips and parts sitting at an angle in the tape pocket all let air in, so the vacuum at the opening is weaker than in the manifold.
The table shows how strongly the opening size matters at the same −60 kPa:
| Nozzle opening | Area | Holding force at −60 kPa | Heaviest part at safety factor 2 and 20 m/s² upward |
|---|---|---|---|
| 0.4 mm | 0.126 mm² | 7.5 mN (0.8 gf) | 0.13 g |
| 0.7 mm | 0.385 mm² | 23 mN (2.4 gf) | 0.39 g |
| 1.0 mm | 0.785 mm² | 47 mN (4.8 gf) | 0.79 g |
| 1.5 mm | 1.77 mm² | 106 mN (10.8 gf) | 1.78 g |
| 2.0 mm | 3.14 mm² | 189 mN (19.2 gf) | 3.16 g |
Doubling the opening gives four times the force. That is why heavier parts get larger nozzles rather than deeper vacuum: the pump can never deliver more than the atmosphere's 101 kPa of pressure difference, and the last few kPa cost a lot of flow.
How much flow does a pick-and-place machine need?
Flow comes from three places, and the first one usually dominates:
- Open nozzles. A nozzle with no part on it (before contact, after a missed pick, or after release) is an open hole to the atmosphere. Once the vacuum behind it is deeper than about −48 kPa, the air through the opening reaches the speed of sound and the flow stops rising, so an open nozzle draws an almost fixed flow however deep the pump pulls.
- Leakage at closed nozzles. A nozzle holding a part still leaks through the imperfect seal, and fittings, valves and rotary joints in the head leak too. Measure it on your machine rather than guessing.
- Evacuating the line on every pick. Each time a nozzle valve opens, the volume between the valve and the tip has to be pumped down again, and the release puff refills it.
| Nozzle opening | Open-nozzle flow, theoretical maximum (free air) |
|---|---|
| 0.4 mm | 1.5 L/min |
| 0.7 mm | 4.6 L/min |
| 1.0 mm | 9.4 L/min |
| 1.5 mm | 21 L/min |
| 2.0 mm | 37 L/min |
These figures are for a sharp-edged opening at sea level with the vacuum behind it deeper than −48 kPa. Real nozzles flow less because the narrow bore and the nozzle shaft restrict the air, but the table shows the scale: one open 1.5 mm nozzle can draw more air than all the leaks in a well-built head. That is why placement heads switch the vacuum off at a nozzle that has no part, and why a vacuum that dips every time one nozzle misses is a sign of an undersized supply.
Worked sizing example. A head has eight nozzles with 1.0 mm openings, each picking once a second, working at −60 kPa.
| Demand | Assumption | Free-air flow |
|---|---|---|
| Open nozzle | One nozzle open at a time, at the theoretical maximum | 9.4 L/min |
| Closed-nozzle leakage | Seven nozzles at 0.5 L/min each (replace with your measurement) | 3.5 L/min |
| Line evacuation | 2.5 mL between valve and tip, pumped from 0 to −60 kPa (about 1.5 mL of free air), 8 picks a second | 0.7 L/min |
| Total | 13.6 L/min | |
| With a 1.5 × margin | For filter loading, wear and tolerance | about 20 L/min at −60 kPa |
Now compare that with the pump in the same units. A datasheet's headline figure is free-air flow at 0 kPa, and the flow at −60 kPa is much lower: each stroke still sweeps the same volume, but at 41 kPa absolute that volume holds only 40% of the air it holds at atmospheric pressure. In a simple model of a piston pump with an ultimate vacuum of about −92 kPa, the free-air flow left at −60 kPa is roughly a third of the rating. That puts the example at a pump rated somewhere above 60 L/min. Use that only to make a shortlist: the measured flow curve of the exact model at your working vacuum decides. Our guide to CFM and L/min explains free air and why vacuum flow falls with depth, and the CFM to L/min converter handles the units.
Recovery time is a separate check. The pump keeps the manifold at vacuum; how fast an individual nozzle reaches it depends on the volume and restriction between the valve and the tip. A small reservoir close to the head buffers short peaks (see our vacuum reservoir sizing guide), and the time to pump down a larger volume is covered in vacuum pump evacuation time.
Central vacuum system or one pump per machine?
Both work. The choice depends on how many machines you run and who builds them.
| One pump per machine | Central vacuum system | |
|---|---|---|
| Who sizes it | The machine builder, for that machine's own demand | The plant, for the sum of all connected machines |
| Vacuum stability | Only this machine's nozzles affect it | Leaks or open nozzles on one machine can pull the vacuum down for all |
| Piping losses | Short lines, small losses | Long header pipes; size them so the drop at the furthest machine stays small |
| If a pump fails | One machine stops | Every machine stops, unless pumps run in parallel with spare capacity |
| Noise and heat | Inside or beside the machine | Moved to a plant room |
| Typical HCEM fit | Compact DC or AC pumps | Larger AC pumps, often several in parallel with a reservoir |
Many placement machines make their vacuum with venturi ejectors running on the plant's compressed air. An ejector has no moving parts and responds fast, but it consumes compressed air for as long as it makes vacuum, and making vacuum from compressed air usually takes more energy than an electric vacuum pump making it directly. Machine builders who move to an electric pump also remove the machine's dependence on the plant air pressure.
Why should a vacuum pump for SMT be oil-free?
Because oil must not reach the boards. An oil-sealed pump gives off oil mist at its exhaust and can carry oil back up the inlet line when it stops. In an electronics line that oil can settle on pads, parts, nozzles and optical sensors, where it causes solderability and coating problems and makes the vision system's job harder. An oil-free piston pump seals its piston with a dry, self-lubricating ring, so there is no lubricating oil in the air path at all, and there is no oil to change inside a machine your customer will run for years.
Oil-free does not mean the exhaust is clean. It carries whatever the nozzles drew in (flux fumes, dust) and fine wear particles from the piston ring. Pipe the exhaust out of the machine, or at least away from the board path, the feeders and the cameras. If the machine also uses compressed air to blow parts off the nozzle, that air touches the part directly, and its quality is specified separately under ISO 8573-1 air purity classes.
How do you filter flux, solder and dust out of the vacuum line?
In two stages, because the nozzles and the pump need protecting from different things:
- Nozzle or head filters stop solder balls, tape and paper fibres and part debris at the source, before they reach the valves.
- A pump inlet filter protects the pump's valves and piston rings. Flux vapour drawn in near the reflow or rework area can condense in cooler lines and leave a sticky film on valve plates, which slowly cuts flow and vacuum.
Put the inlet filter where it is easy to change, watch the vacuum drop across it, and replace elements on running hours rather than by the calendar. A blocked filter looks exactly like a weak pump. Our inlet filtration guide covers element choice and pressure drop.
How do you handle pump noise and heat inside the machine?
Treat both as design inputs, not afterthoughts:
- Heat. Almost all the electrical power a pump draws ends up as heat, in the pump body and in the exhaust air. A pump drawing 180 W inside a closed cabinet adds close to 180 W of heat to it. Leave space around the cooling fins, keep the pump away from drives and power supplies, and route the exhaust outside. See our thermal management guide.
- Noise and vibration. A piston pump pulses, and a thin sheet-metal panel can amplify it. Mount the pump on isolators, keep hoses from touching panels, and measure noise with the covers closed. Datasheet noise is a bench figure; how to write it into a specification is in specifying vacuum pump noise and vibration.
24 V DC or AC: which vacuum pump suits a machine builder?
For a pump inside the machine, 24 V DC is often the simpler choice, because the machine already has a 24 V DC supply for its controls. For a central pump in a plant room, AC mains is usually simpler.
| 24 V DC (also 12 V and 48 V) | AC mains (220 V/50 Hz or 110 V/60 Hz) | |
|---|---|---|
| Supply | Shares the machine's DC supply; size it for the pump's running and starting current | Mains wiring and protection inside the machine |
| Flow in different markets | The same at the same voltage, wherever the machine ships | Differs between 50 Hz and 60 Hz versions: the HC100A, for example, is rated 45 L/min at 220 V/50 Hz and 50 L/min at 110 V/60 Hz |
| Current | High: a 150 W pump draws about 6.3 A at 24 V, or half that at 48 V | Low |
| Control | Switched directly from the machine's DC outputs through a relay | Needs a contactor or solid-state relay |
With DC, check the voltage at the pump terminals while it runs: a long, thin cable from the supply drops voltage and the pump delivers less flow. More detail is in AC vs DC oil-free pumps for OEM equipment and our electrical integration guide.
What duty cycle should you specify?
A placement machine in production draws vacuum all the time it runs, so its pump usually runs for the whole shift. Specify it as continuous duty at your working vacuum and at the highest temperature inside the machine, and confirm the rating with the pump maker for that exact condition. If the demand is intermittent (a test fixture, a tray handler that picks every few seconds), a reservoir and a vacuum switch can let the pump stop between cycles, but then the number of starts per hour matters too. How to work out on-time and load is explained in duty cycle calculation, and the start-stop limits in vacuum pump duty cycle and start-stop frequency.
Which HCEM vacuum pumps suit pick-and-place machines?
These oil-free piston vacuum pumps cover per-machine and central duty. Figures are from our datasheets; models with a second figure also come in a high-vacuum version that reaches deeper but moves less air.
| Model | Supply | Free-air flow | Ultimate vacuum | Power | Noise | Weight | Typical use |
|---|---|---|---|---|---|---|---|
| HC30 | Ask for supply options | 12 L/min (0.43 cfm) | −92 kPa | ≤50 W | ≤50 dB(A) | 0.55 kg | Single-nozzle tools, small test fixtures |
| HC100D | 12/24/48 V DC | 50 L/min (1.77 cfm), or 25 L/min | −90 kPa, or −98 kPa | ≤150 W | ≤56 dB(A) | 2.45 kg | Small heads, tray and fixture handling |
| HC280D | 12/24/48 V DC | 90 L/min (3.18 cfm), or 45 L/min | −92 kPa, or −98 kPa | ≤180 W | ≤58 dB(A) | 4.9 kg | Multi-nozzle heads, as in the sizing example |
| HC580D | 12/24/48 V DC | 120 L/min (4.24 cfm), or 60 L/min | −92 kPa, or −98 kPa | ≤260 W | ≤62 dB(A) | 7.3 kg | Larger machines or several heads on one DC pump |
| HC100A | 220 V/50 Hz or 110 V/60 Hz | 45 or 50 L/min, or 22.5 or 25 L/min | −90 kPa, or −98 kPa | ≤110 W or ≤150 W | ≤50 or ≤51 dB(A) | 3.4 kg | Bench equipment and fixtures on mains |
| HC580A | 220 V/50 Hz or 110 V/60 Hz | 120 L/min (4.24 cfm), or 60 L/min | −92 kPa, or −98 kPa | ≤340 W | ≤60 or ≤61 dB(A) | 10.1 kg | Mains-powered machines, small central systems |
| HC1500A | 220 V/50 Hz or 110 V/60 Hz | 210 or 250 L/min, or 110 or 130 L/min | −92 kPa, or −98 kPa | ≤700 W or ≤750 W | ≤69 or ≤71 dB(A) | 17.5 kg | Central systems, in parallel for redundancy |
For AC models, the first figure is the 220 V/50 Hz version and the second the 110 V/60 Hz version. All flows are free-air flow at 0 kPa; ask us for the curve of the model you shortlist at your working vacuum before you fix the design. For a pick-and-place head the standard version is usually the right one: −60 kPa is well within its range, and at 0 kPa it moves twice the air of the high-vacuum version.
How do you check the vacuum system once it is built?
Measure at the nozzle, not only at the pump. Block all nozzles and check the vacuum the system reaches; then run at full speed with your lightest, heaviest and roughest parts, and watch the vacuum at the head when a nozzle misses. Measure the leak rate with the pump isolated. Our guides on how to test a vacuum pump and vacuum system leak rate testing give the methods, and ultimate pressure vs working vacuum explains why the two readings differ.
Common questions
What vacuum level does a pick-and-place machine use?
It depends on the nozzle and the part, so calculate it with F = Δp × A and a safety factor rather than copying a number. In the worked example above, −40 kPa at the nozzle was the bare minimum and −60 kPa gave more than three times the load. The pump must reach deeper than the nozzle target to cover losses in the circuit, but going much deeper adds little force and costs a lot of flow.
Why does the vacuum drop when one nozzle misses a part?
An open nozzle draws far more air than a closed one. If the pump or manifold has little spare flow, one open nozzle pulls the vacuum down for every nozzle on the same supply. The fixes are a valve that shuts the vacuum off at an empty nozzle, a reservoir near the head, or a pump with more flow at the working vacuum.
Can I use the same pump for robot grippers and suction cups?
Yes, the same method applies: holding force from F = Δp × A, flow from leaks and open cups. Cups are larger and often grip porous or rough surfaces, so the flow is higher. See our guides on vacuum pumps for robot grippers and cobot end effectors. Other electronics processes, such as conformal coating and encapsulation, need deeper vacuum and a different selection.
What should I send to get a pump recommendation?
The nozzle sizes and count, the heaviest part and the head's acceleration, the working vacuum at the nozzle, measured leakage if you have it, pick rate, supply voltage, the space and temperature inside the machine, and the duty cycle. Our vacuum pump specification checklist lists the rest.
Browse our oil-free vacuum pumps, or send us your flow, working vacuum, supply voltage and duty cycle, and our engineers will suggest a model, including OEM versions with the ports, cables and mounting your machine needs.