TL;DR — Direct answer: A watch and jewellery factory needs clean, dry, oil-free air at 6 to 8 bar for precision CNC machining of cases and movements, polishing, plating bath agitation, laser engraving and water-resistance testing, with a pressure dew point of 3 degrees C and filtration to 0.01 micron so no oil or moisture reaches a movement, a plating bath or a polished surface. Size on the coincident peak of machining and polishing, commonly 1.5 to 4 cubic metres per minute for a small to mid-size workshop, roughly an 11 to 30 kW screw compressor. QiAir, a Chinese screw compressor manufacturer and supplier, builds quiet fixed and variable speed machines sized for precision watch and jewellery workshops.

Watch and jewellery manufacturing is work at the scale of millimetres, and compressed air is the invisible hand behind it. CNC machines mill watch cases, bezels and movement plates to tolerances measured in microns, polishing wheels bring cases and bracelets to a mirror finish, plating baths lay down gold and rhodium, laser engravers mark dials and case backs, and finished watches are pressure-tested for water resistance before they leave the factory. A puff of oil on a movement plate can seize a hairspring, moisture in a plating line spots a finish, and a pressure dip during a water-resistance test gives a false pass. The air system has to match the precision of the product. QiAir is a Chinese manufacturer and supplier of screw air compressors, and its machines for watch and jewellery workshops are specified around cleanliness, dryness and quiet running first and flow second.

QiAir screw air compressor unit
QiAir screw air compressor unit

The mistake buyers make most often is treating a watch workshop like a general machine shop and buying a noisy, oversized compressor with basic filtration. Polishing dust is fine and abrasive, plating needs air that is genuinely oil-free, and the workshop is small, so a loud machine next to the bench is a daily problem for the people doing the finest work. This guide maps where the air goes in a watch and jewellery factory, explains how to size for machining and polishing peaks, sets the clean-air and dust standard, and shows what to put on a sizing sheet for a China supplier.

Where Air Is Used: Machining, Polishing, Plating and Testing

Precision machining is the steadiest user. CNC lathes and mills cut watch cases, crowns, bezels and movement components, using air for tool changes, workholding, chip blowing and spindle cooling, and the demand is steady while the machines run. Chip blowing is the hidden consumer: a nozzle left open at full flow can use as much air as a small machine tool, so fit flow-regulated nozzles and shut-off valves at every bench, and train operators to close them between jobs. A machining shop with six to twelve CNC machines typically draws its air in a smooth, predictable pattern, which makes it easy to size, provided the chip-blowing waste is counted honestly.

Polishing, plating and testing take the rest of the air and set the quality standard. Polishing wheels use air for spindle drive and dust extraction dampers, plating lines use it for bath agitation and rinsing, laser engravers use it for lens and workpiece cleaning, and water-resistance testers use dry air at a controlled pressure to check seals. Polishing dust is fine, abrasive and, in a jewellery shop, valuable: gold and platinum dust should be captured by the extraction system, not blown around the room. A plant that maps every user, including the small air tools used for cleaning, usually finds 15 to 20 percent more demand than the original estimate.

  • Machining: CNC tool changes, workholding, chip blowing and spindle cooling for cases and movements.
  • Polishing and plating: spindle drive, bath agitation and rinsing that need dry, oil-free air.
  • Engraving and testing: laser lens cleaning and water-resistance testing at controlled pressure.

Sizing for a Small Precision Workshop

List every machine with its flow at peak and at steady running, because the two differ even in a small shop. A watch and jewellery workshop with six to twelve CNC machines, four to eight polishing stations and a plating line typically peaks at 1.5 to 4 cubic metres per minute at 6 to 8 bar, which is roughly an 11 to 30 kW screw compressor, and the peak usually lands when machining and polishing run together in the middle of the shift. A variable speed drive is worth having even at this size: it follows the workshop pattern instead of loading and unloading a fixed-speed machine all day, and it holds pressure within the narrow band that machining and testing prefer.

Keep the pressure drop to the farthest polishing station under 0.3 bar at peak flow, and fit a receiver of 300 to 500 litres to absorb tool-change and polishing spikes. In a small workshop the compressor often sits close to the benches, so check the sound level: a machine rated under 70 dB(A) can sit in a corner of the workshop, while a louder one needs its own room or an acoustic enclosure. Log pressure at the farthest bench during a full working day for a week, because that log is the honest record of whether the compressor is big enough, and it settles arguments faster than any catalogue figure.

  • Size on the coincident peak of machining and polishing, and count chip-blowing air honestly.
  • Use a variable speed drive even in a small workshop, and keep far-end pressure drop under 0.3 bar.
  • Check sound level before buying: under 70 dB(A) can sit in the workshop, louder needs its own room.

Clean Air, Polishing Dust and Plating Quality

Oil and moisture are the two contaminants that damage watch and jewellery work, and both are invisible until the product fails. Oil on a movement plate can seize a hairspring or stain a dial, moisture in a plating line spots a gold finish, and damp air in a water-resistance tester gives a false reading. The standard that prevents this is a treatment chain, not a single filter: a pre-filter, a refrigerated dryer to a 3 degree C pressure dew point, a coalescing filter to 0.01 micron, and an activated-carbon filter for oil vapour, with a final point-of-use filter at the plating line and the testing bench. For movement assembly and plating, an oil-free screw compressor removes the oil risk at source rather than filtering it out.

Polishing dust needs its own discipline. Fit extraction at every polishing station, keep the compressor intake away from the polishing area so the machine does not breathe abrasive dust, and check the intake filter weekly in the first months. In a jewellery shop, the extraction system should recover precious-metal dust, so keep it maintained and emptied on schedule. Drain condensate with automatic zero-loss drains, slope lines to drain legs, and test the air at the plating line and the testing bench quarterly for oil, moisture and particles.

  • Fit pre-filter, refrigerated dryer, 0.01 micron coalescing filter and carbon filter, with a final filter at the plating line.
  • Consider an oil-free screw compressor for movement assembly and plating, where air contacts the product directly.
  • Extract polishing dust at source, keep the compressor intake away from polishing, and recover precious-metal dust.

Buying from China: Sizing Sheet for a Watch and Jewellery Workshop Compressor

QiAir is a Chinese manufacturer and supplier of screw air compressors, and a watch and jewellery order should start with a sizing sheet that names the precision users. Send the supplier the number of CNC machines, polishing stations and plating lines, the coincident peak at 6 to 8 bar, the air-quality standard the plating and testing stations require, the sound-level limit for the workshop, and the distance to the farthest bench. Ask for a quotation that states the dryer type, filtration grades and sound level explicitly, and ask whether an oil-free machine or a filtered oil-injected machine fits the plating specification better, with the cost and maintenance difference spelled out.

Agree the acceptance test before shipment: a full-load run at rated pressure, a dew point reading at the dryer outlet, an oil-aerosol check at the final filter outlet, and a sound-level reading at one metre. On arrival, install on a level plinth with clear cooler airflow, connect drains before the first run, and survey pressure at the farthest polishing station during the first full working week. Keep a log of pressure, dew point and filter changes, and review it monthly, because a slow rise in dew point is the earliest sign that a dryer needs attention before finishes start failing inspection.

  • Send the supplier machine and station counts, coincident peak, required air-quality standard and sound-level limit.
  • Ask for dryer type, filtration grades and sound level in writing, and compare oil-free against filtered oil-injected on total cost.
  • Accept on a full-load test plus dew point, oil-aerosol and sound checks, then survey pressure at the farthest bench in week one.

Frequently asked questions

What pressure does a watch and jewellery factory need?

A watch and jewellery factory needs clean, dry air at 6 to 8 bar for CNC machining, polishing, plating bath agitation, laser engraving and water-resistance testing. Keep far-end pressure drop under 0.3 bar, because a pressure dip during a water-resistance test can give a false pass, and size on the coincident peak of machining and polishing.

Why must watch and jewellery air be oil-free?

Oil on a movement plate can seize a hairspring or stain a dial, and moisture in a plating line spots a gold finish. A pre-filter, refrigerated dryer to a 3 degree C pressure dew point, 0.01 micron coalescing filter and carbon filter in series protect plating and testing, and an oil-free screw compressor removes the oil risk at source.

What size screw compressor does a watch and jewellery workshop need?

A workshop with six to twelve CNC machines, four to eight polishing stations and a plating line typically needs 1.5 to 4 cubic metres per minute at 6 to 8 bar, roughly an 11 to 30 kW screw compressor with a variable speed drive. Add a 300 to 500 litre receiver, check the sound level before buying, and verify pressure at the farthest bench under full load.

Related reading

QiAir is a Chinese manufacturer and supplier of screw air compressors. If you are sourcing a screw compressor from China — for a factory, a food plant, a construction site or a new production line — contact QiAir for a sized quotation, documented performance data and export support.