How Aerosol Production Works: A Step-by-Step Guide
Understanding the aerosol production process is the first step to selecting the right equipment. This guide walks through each stage of a standard aerosol filling line — whether semi-automatic or fully automatic — so you know exactly what happens from empty can to finished product.
The Core Process: 6 Essential Stages
Every aerosol production line, regardless of scale or automation level, follows the same fundamental sequence:
Stage 1: Can Preparation & Feeding
Empty aerosol cans enter the production line. In semi-automatic setups, an operator manually places each can on the filling station. In automatic lines, a can unscrambler orients and feeds cans onto a conveyor belt at the programmed speed.
Key consideration: Can diameter and height determine which unscrambler and conveyor guides you need. Standard aerosol cans are 35-66 mm in diameter and 80-330 mm in height. Ø20 mm crimp containers (used in cosmetics) require specialized handling.
Stage 2: Liquid Filling
The liquid concentrate — whether a water-based air freshener, solvent-based insecticide, or viscous paint — is dispensed into the can. Fill accuracy of ≤ ±1% is the industry standard for both quality control and cost management. Overfilling wastes expensive active ingredients; underfilling risks regulatory non-compliance.
Fill volume ranges:
| Application | Typical Fill Volume |
|---|---|
| Small-dose (cosmetics, pharmaceuticals) | 3-50 ml |
| Standard (deodorants, air fresheners) | 150-400 ml |
| Large (insecticides, industrial sprays) | 400-600 ml |
Viscosity matters: Water-thin concentrates fill easily. Viscous products (paint, foam, cream) require larger nozzle diameters and slower fill speeds to prevent splashing and ensure accurate volume. Some fillers use bottom-up filling for foaming products to reduce air entrapment.
See our semi-automatic fillers and automatic filling lines for equipment options.
Stage 3: Valve Placement & Insertion
After filling, a valve is placed into the can opening. This is the most operator-dependent stage in semi-automatic lines. In automatic lines, a valve inserter (FD9951) uses a rotary disc to select, orient, and insert aluminum valves automatically — synchronized with the conveyor speed.
Valve types:
- 1-inch (25.4 mm): Standard for most consumer aerosol products — air fresheners, insecticides, spray paints, car care products
- Ø20 mm: Common in cosmetics, personal care, and pharmaceutical aerosols. Requires a crimping machine rather than a standard sealer
- BOV (Bag-on-Valve): Used when propellant must not contact the product. Different filling process entirely — see our BOV production guide
Stage 4: Valve Sealing / Crimping
The valve must be permanently sealed to the can to create a leak-proof, pressure-tight closure. This is done by either:
- Crimping (Ø20 mm valves): The can neck is mechanically deformed around the valve
- Sealing/Capping (1-inch valves): A sealing jaw presses the valve cup onto the can opening with controlled force
The sealing jaw material matters: Cr12 steel with hardness ≥48 HRC (used in our FD9301 sealer) provides long service life even with aggressive solvent-based formulations. Softer jaw materials wear faster and produce inconsistent seals.
Stage 5: Propellant Gassing
Propellant is injected through the valve stem into the sealed can. This is the most safety-critical stage, especially with flammable propellants (LPG, DME). All equipment in the gassing area must be explosion-proof rated.
Propellant types and characteristics:
| Propellant | Type | Common Uses | Safety |
|---|---|---|---|
| LPG (Butane/Propane) | Liquefied gas | Air fresheners, insecticides, paints | Flammable — explosion-proof required |
| DME (Dimethyl Ether) | Liquefied gas | Water-based formulations, foams | Flammable — explosion-proof required |
| Compressed Gas (N₂, CO₂) | Permanent gas | BOV products, food-grade, medical | Non-flammable — standard equipment OK |
A booster pump (FD9405) transfers liquefied propellants from storage cylinders to the gas filler. For compressed gases, the cylinder regulator provides sufficient pressure.
Stage 6: Quality Control & Packaging
After gassing, every can must pass quality control before packaging:
- Hot Water Bath: Cans travel through a 55-65°C water bath for 3-5 minutes. This heat test reveals micro-leaks and validates pressure integrity. Mandatory for most export markets. See FD9955 water bath.
- Checkweighing: Each can is weighed to verify correct fill volume. Under/overweight cans are automatically rejected. See FD9954 checkweigher.
- Coding: Batch number, production date, and expiry are inkjet-printed on the can bottom. See FD9958 coder.
- Actuator & Cap Placement: Spray head and overcap are placed — manually in semi-auto lines, automatically via FD9956 and FD9957 in auto lines.
Semi-Automatic vs Automatic: Process Differences
| Stage | Semi-Automatic | Fully Automatic |
|---|---|---|
| Can Feeding | Manual placement | Unscrambler + conveyor |
| Filling | One can at a time, operator-controlled | Continuous, synchronized with conveyor |
| Valve | Manual insertion | Automatic insertion |
| Speed | 600-1,600 cans/hour | 1,600-3,600 cans/hour |
| Operators | 3-4 | 2-3 |
For a detailed comparison, see our Semi-Auto vs Full-Auto guide.