Since I have waisted considerable time searching answers online and have not get any good answer, I turn to you for help.
We have a cnc oscillating knife machine with 1.6x3m table that we just bought. Machine has vacuum table with honeycomb layout and 12 vacuum zones. We put MDF on that table and cut on that. We have 1 Becker VTLF 2.250 connected to this machine that has following parameters:
Power 5.5 kw
Maximum airflow 244 M3/h
Max vacuum -200 mbar

On this table we cut rubber, gasket material, felt, porous rubber etc. The problem we have is that we can get a good hold down when we cover the material with film, but as soon as some cuts are made and there is considerable air leaking hold down is gone and operator has to cover material again.
We also have an older machine with working area 1.25x2.5m that has aluminium vacuum table with small holes in it and side channel vacuum pump connected to it with following parameters:
Power 9kw
Maximum airflow 1050 m3/h
Max vacuum -210mbar

On this table the hold down is better. Operator tells me it was even better when the machine was new.
So obviously what we did is tested old vacuum pump on our new machine. But the result was not good. Hold down was even worse than with new pump. Few things to mention here:
1. We had to use 50mm connection to old vacuum pump, it has 100mm inlet originally and is connected with 100mm hose to old machine
2. I measured both pumps with pressure gauge. On becker pump I got 0.08Mpa, but on old pump I only get 0,048Mpa. If I understand correctly they should be same

So my assumption is that our old pump is depreciated and that why we get poor results.
I would like to buy a new side channel pump for our new machine to get better vacuum that compensates leaking. Or is there some other thing Im missing here and why a side channel pump would not work for this setup?