Suction or pressure blasting: which one suits the job

A pressure system delivers abrasive at roughly twice the speed of a suction system, and cleans three to four times faster. The reason is mechanical: in suction, part of the air energy is spent drawing the abrasive, while in pressure all the energy goes into accelerating the particle. That higher velocity produces a deeper anchor profile and removes thick coatings and adhered contaminants that a suction system cannot lift.

This is the most concrete limit. Heavy abrasives — coarser steel shot and grit — cannot be drawn by the air stream of a suction system.

On CYM Materiales equipment, the abrasives recommended for suction are:

- Glass beads: up to Super Coarse
- Aluminum oxide: up to mesh 36
- Carbon steel: shot S170 or grit G80
- Stainless steel: shot S10/S20 or grit G10/G20

Above those sizes, a pressure system is the only alternative.

With a comparable nozzle size, a suction system consumes less air than a pressure system, which makes it viable in workshops with limited compressor capacity. The initial investment is also significantly lower: fewer components and no pressurised vessel. A pressure system demands more air and more equipment, but the cost per part processed drops once volume justifies it.

Both systems allow uninterrupted operation, although they get there by different routes. Suction is continuous by nature: it takes abrasive from the bottom of the cabinet with no vessel to pressurise. Pressure resolves it through the vessel configuration.

In manual work the single-chamber vessel is the standard: it depressurises to refill, but that pause fits the operator's rhythm, who stops during the shift anyway. On automatic equipment that must sustain the process without interruption, double-chamber vessels are used: the upper chamber fills at atmospheric pressure while the lower one keeps blasting, so the transfer does not break the cycle.

The suction blast pattern is wider than the pressure pattern at the same air flow, which helps cover surface on low-demand work.

Suction: low or intermittent production, touch-up and general cleaning, delicate parts, light abrasives, limited budget, low-capacity compressor, continuous-cycle automatic processes.

Pressure: intensive or multi-shift production, removal of thick coatings and adhered rust, anchor profile required by standard, coarse metallic abrasives, shot peening with specified Almen intensity.

This choice is not exclusive to cabinets: it appears the same way in blast pots, blast rooms and portable equipment. In blast rooms pressure prevails because of part size and job demands, but suction has its place in automatic cleaning or light shot peening installations.