HOW TO IMPROVE YOUR SANDBLASTING EFFICIENCY

Abrasive media, the operating cost of sandblasting equipment, the labour cost, and the associated overheads – all cost. While abrasive blasting is very effective for a wide range of applications, it is also imperative that it should also be efficient. When it comes to dry abrasive blasting, the efficiency of your blasting setup is often measured by how much area you can cover in a given time, and the amount of abrasive you use to do it. This article will cover the wide variety of ways you can increase efficiency in sandblasting work and describes the key operating parameters to find the optimum window for blasting. Following focuses on techniques and tips on how to utilize those tools, variables, and conditions to improve sandblasting efficiency.

1. Blast at the highest pressure suitable for the desired surface profile

It all starts with the mixture of air and abrasive. when these two elements come together, the high-pressure air provides the abrasive with kinetic energy. And the more energy your abrasive has, the more impact it will have on the surface you’re blasting. That means you can complete your job in less time and with less abrasive. So, how can you give your abrasive that extra kick of kinetic energy? It’s all about the mass and speed of the grit. The size and weight of your abrasive determine its mass, while the inlet pressure at the blast nozzle creates its speed. And here’s the kicker – the higher the pressure at the nozzle, the faster your abrasive will travel.

However, the pressure you blast at will determine both the speed and depth of the profile you’ll achieve. So, you need to select a pressure that’s appropriate for your specific application.

To maximize your blast efficiency, you must also avoid dynamic pressure losses. These losses occur mainly in the abrasive blast machine and across the length of the blast hose. Friction is the primary cause of dynamic pressure loss in the blast machine. Therefore, it’s crucial to design a blast machine with larger diameter pipework and as few restrictions as possible to reduce dynamic pressure losses. Finally, the condition and length of your blast hose also affect the amount of pressure loss. A newer, more rigid, or higher quality blast hose holds its shape better, ensuring a straighter, smoother path for the air and abrasive flow. The longer the blast hose, the more pressure you lose across the distance. By addressing each of these variables, you can significantly improve the efficiency of your blasting process and achieve impressive results.

It is also worth considering operator comfort and fatigue. After all, a happy operator is a productive operator. So, you can always opt for a lighter-weight line to make the process more comfortable.

2: Strike the Right Balance of Air and Abrasive media

The importance of getting the right mix of air and abrasive cannot be overstated One of the most common mistakes that sandblasters make is putting too much media into the air stream. We get it, you want to blast as much as possible, but more media does not always mean more productivity. It can slow down your air velocity and reduce the impact force of your media, ultimately hindering your overall blasting power. This not only makes your blasting less effective but also means you’ll end up using more abrasive than necessary, leading to additional clean-up and increased project costs.

Too little abrasive in the air stream means that you’ll end up spending more time blasting the same area, which is a total waste of time and resources.

That’s why finding the right balance is essential. With the correct setting of your abrasive media valve, you can maintain nozzle pressure and abrasive speed while still having enough abrasive to blast the surface efficiently.

There is no universally ideal setting as different manufacturers have different designs of abrasive valves and the media flow also depends on the air pressure and the type of media used. To properly adjust the media entering your air stream, start with a zero flow and have an operator trigger the sandblast pot. Slowly open the media valve until the air stream is ever so slightly discolored from the blast media. You should even hear a satisfying whistle when you close the valve. As you gradually open the media valve, listen for the crackling sound and adjust accordingly or use the visual test – whichever is easiest for you. By finding the perfect media-to-air balance, you can increase your blasting efficiency and achieve superior results.

3.Check the Airline Size and Nozzle size

To achieve maximum productivity, you need to ensure that you’re feeding your sandblast pot with an intake airline that is at least 4 times larger than the sandblast nozzle you’ve selected. Failure to do so could result in a significant reduction in CFM and pressure, making your blasting pot less efficient and causing it to malfunction.

Don’t let a small supply line limit your sandblasting efficiency. With a larger intake airline, you’ll be able to achieve higher CFM and pressure, resulting in a more effective blasting process.

4. Check your Blast Hose for constriction

Normally, abrasive media particles will create turbulence in the airflow in the blast hose but what can and should be controlled, is the unnecessary turbulence effects created by changes to the shape and angle of the blast hose. For every bend, constriction, and/or loss of rigidity in the blast hose a pressure differential is created. It is worth remembering that pressure differential causes a loss of energy and eventual reduction in pressure at the nozzle. A simple and low-cost tip to avoid unnecessary loss of pressure is to check if your old blast hose has lost its rigidity and if it has been incorrectly laid out with tight bends and is running over sharp edges.

5. Angle of Attack

When sandblasting, the angle at which the abrasive media is propelled onto the surface is determined by the position of the nozzle held by the operator. The angle of attack is the angle at which the nozzle is pointed to the work piece. Most field abrasive blast cleaning is performed with the nozzle held between 60º to 120º to the surface. Nozzles held perpendicular (90º) to the surface provide more direct energy that can help fracture tightly adherent coatings However, if you blast directly perpendicular to the surface of the substrate, the media from the blast nozzle will collide with the particles ricocheting from the surface and will reduce the impact. To limit blast media colliding and maximize productivity, instead of pointing the nozzle perpendicular to the surface, you should consider sandblasting at a slight angle to the blast surface. Experienced abrasive blast operators use a combination to achieve high productivity.

6. Standoff Distance

The standoff distance is the distance that the nozzle is held in relation to the item being blasted. This distance is important in abrasive blasting efficiency. Blast operators should optimize the distance to achieve the desired blast pattern and cleaning rate. This distance could range from 18cm to 60cm. Generally, nozzles are held closer to the substrate to clean tightly adherent mill scale or coatings that require a smaller blast pattern to achieve the specified surface cleanliness. When surfaces being cleaned exhibit loosely adherent coatings or flaking mill scale and rust, a larger blast pattern produced at larger standoff distances allows faster cleaning.

7. Stay Time

Stay time is the amount of time required to achieve the desired surface cleanliness before the nozzle can be moved to the next area on the substrate. It refers to the amount of time required to achieve the desired level of cleanliness before the nozzle can be moved to the next area. The stay time is heavily influenced by the size of the blast pattern. For smaller patterns, the nozzle is held close to the surface, resulting in a shorter dwell time. Conversely, larger blast patterns necessitate a longer stay time. Nonetheless, the operator’s expertise and matching the exact cleanliness requirements specified can help minimize stay time, ultimately leading to increased productivity.