Sandblasting and shot peening machines with pressure and vacuum systems: which one to choose and why

When one decides to use sandblasting or shot peening systems to process a component or workpiece, one is often faced with the great dilemma of pressure or Venturi systems, also known as “vacuum” systems.  These two processes have big differences both in terms of the machinery and systems used and the results. This is why it is a good idea to obtain adequate information before making a decision on the most suitable type of sandblasting machine in order to invest in the process that is best suited to our sector and the workpiece to be processed. Let us therefore clarify these two types of processes once and for all.

Industrial sandblasting machines with vacuum systems – Venturi effect:

By means of the physical Venturi principle, Norblast sandblasting machines are able to treat workpieces with so-called “vacuum” systems. Thanks to these machines, grit placed inside an accumulation tank is drawn towards the blasting nozzle by the Venturi effect produced in the gun and projected, with a precision blast, onto the workpiece to be processed. Two different pipes converge at the blasting gun, located inside the work chamber; the compressed air pipe, which creates a pressure difference and thus exploits the Venturi effect to blast the abrasive material at very high speed, and the grit pipe.

As can be seen in the picture, the gun is equipped with two distinct channels: the channel highlighted in grey conveys the compressed air, accelerates it, and contributes to obtaining the vacuum that draws the grit contained in the cyclone, while the blue channel, directly connected to the grit store, conveys it to the nozzle where it accelerates directly towards the object to be processed.

To optimise the blasting process, Norblast, in collaboration with the University of Pisa, conducted an in-depth analysis of the vacuum gun design to increase the amount of grit blasted for the same amount of energy expended.

All this with a view to sensitively increasing processing speed to reduce cycle times and make the process as immediate and efficient as possible.

Industrial sandblasting machines with pressure systems:

Norblast pressure sandblasting machines, on the other hand, work by pushing material – angular or spherical – from the pressure tank that is fired directly onto the workpiece. Thanks to a specific valve system, it is possible to balance both the grit flow rate and the compressed air pressure, thus achieving a machining process focused on the actual need; this makes machining even more precise and faster than with vacuum systems.

But how to decide whether to use sandblasters with vacuum systems or sandblasters with pressure systems? 

Despite the fact that both of these machines serve, in essence, the same task – the size of the workpieces to be processed and the different processes to prepare them for further processing – they differ greatly in terms of performance and final output. In fact, pressure systems are able to handle larger volumes, in less time and with more precision, due to the greater number of variables available to control. However, it must be considered that, precisely because of their high precision, they are more complex to handle, require more plant components and have higher operating costs due to a need for more maintenance and higher energy consumption. However, it must be considered that the higher production capacity often justifies the greater burden. On the other hand, the vacuum system is cheaper, simpler to implement, not as fast and supports a less extensive processing range.

Which industrial sandblasting machine to choose?

Both types have their own advantages. So to understand which type of sandblasting machine is right for you, it is necessary to define the type of machining and precision required. At Norblast, we recommend the use of vacuum system machines, whenever the treatment required makes it productively advantageous. This is because they are more immediate in terms of ease of use, maintenance and consumption, both with regard to quantity of grit and compressed air. Instead, we recommend opting for pressure systems in case of large surfaces to be processed, reasons intrinsic to the workpiece to be machined, cramped areas to be reached, particularly dirty/crusted/oxidised components to be processed, including shot peening treatment. It is understood that both pressurised and Venturi systems are compatible whenever specific quality standards are required, where safety parameters must be met, such as in the medical and biomedical, aeronautical and automotive sectors, where precision and machining of components demand excellent output quality.

Summary Table: Characteristics of Vacuum and Pressure Systems

  • Suitable for aesthetic finishing of visible surfaces
  • Light oxidation removal from environmental aggression/heat treatments
  • Achieving controlled roughness on materials without surface hardening heat treatment
  • Cleaning small moulds
  • Surface activation of small surfaces for coating adhesion/painting
  • Suitable for aesthetic finishing of large surfaces
  • Strong oxidation removal from environmental aggression/heat treatments
  • Achieving controlled roughness on heat-treated materials
  • Achieving controlled roughness with very high Ra/Rz values
  • Cleaning large moulds
  • Surface activation of large surfaces for coating adhesion/painting
  • Surface activation – composites
  • Cleaning of cast iron blast internal channels
  • Deburring internal channels after machining
  • Deformed internal grooves enlargement after TT
  • Stripping/removal of ceramic coatings; PVD, etc.
  • Cleaning of submersible pumps
  • Shot peening

Are you thinking of incorporating a sandblasting machine into your production chain but do not know which model to choose?

Call us and ask for a consultation, our experts will be able to show you the best solution according to your type of work and your needs!