Designing an Air Float Conveyor: Calculating Pressure and Flow for Moving Objects

[mohammed11ahmed]

You start by defining in detail exactly what you are conveying:

1) What are you conveying?
2) How heavy are they?
3) What are the dimensions of the surface of the objects in contact with the table?
4) How flat is the surface in contact with the table?
5) How rough is that surface?
6) Is the object porous?
7) Does the table need to move the objects, or merely float them?
8) What are the table dimensions of your prototype, and the finished table?

Use that information to calculate:
10) Calculate the average pressure to float the objects.
11) Calculate the minimum flow rate under the objects.
12) Calculate the plenum pressure.
13) Calculate the air flow through the uncovered holes (or use air table check valves).
14) Calculate total air flow.

Answering questions 1 through 8 above will give you the information to answer 10 and 11. I suggest that you give detailed answers to questions 1 through 8, then we can help you from there.

[Mentor Note: Thread created by moving some posts from a previous thread into this new one by the OP.]

if I have
1)10X10 cm box
2) weight 300g
3) The dimensions of the surface sheet that will be in contact is 60x25 cm
4) should be flat with holes for the air
5) that surface either can be an Acrylic or Stainless Steel sheet
6) no porous
7) it needs to move them along the table
8) 60X30 table

also for the sheet which will be the top surface that the air goes through to lift the object and make it move. I want to make the holes made in angle so when the air goes through it will help not just lift the object but also make it move along the bath. like inclined air jet how we choose the angle and how to calculate the forces acting on it.

 

[mohammed11ahmed]

 

[mohammed11ahmed]

I want to apply this concept but how do I decide the angles to drill these holes and and how to calculate and what formula to use

 

[jrmichler]

Start with perpendicular holes.

1) Assume that the table is exactly the same size as the box. What pressure and how much flow is needed to float the box? If both the box and table are perfectly flat and nonporous, the flow would be quite low. In the real world, nothing is perfectly flat, so there will be a minimum flow. You can estimate that flow by assuming a worst case flatness, then calculating the flow through the gaps at sufficient pressure to float the box. It is better to run a test and measure the pressure and flow.

2) There is a pressure drop through the holes. The pressure under the table is higher than the pressure to float the boxes. How much higher is a function of the hole size.

3) When you have a hole size and pressure under the table, then you can calculate the flow through the holes that are open (not covered by the box). You will need to investigate the effect of hole size - smaller holes at higher pressure versus larger holes at lower pressure.

4) The total flow will be the sum of the flow that floats the box plus the flow through the open holes. You can use large holes (several mm diameter) with a blower or small holes (about 1 mm or less) with compressed air. I have seen air conveyors with both methods, you need to find the best solution for your specific situation.

5) NOW you can use angled holes. Angled holes will move the boxes. I once saw literature from a company that was selling air conveyors that would move the product uphill, so it can be done. If you choose the large hole design, you can explore using louvered sheet similar to the image below. The louver shape will be different, and the sheet metal needs to upside down from that shown:

If you choose drilled holes, try drilling at a 45 degree angle, then experiment from there.

6) If you get enough experience with air float conveyors, you should be able to calculate air flow, air pressure, hole size, hole angle, and hole spacing. Those calculations will start with experimental data, then use standard fluid flow calculations to extrapolate that data to your specific requirements.

7) This is a situation where you absolutely, positively need to do experiments. Then compare the experimental results to your calculations. Then do more experiments based on what you learn. Expect to do the calculate >> experiment >> calculate >> experiment cycle several times before you fully understand how to design this type of conveyor.

8) This sounds like a fun project, so enjoy.