Vacuum Zones on CNC Router

[Matt-Aburg]

I have taken on a job programming, setup and operate a brand new 5 x 10 CNC router. This machine has a Mach 3 controller. I had no problem getting it going, and ran programs successfully.

We do have a major problem. The vacuum is inadequate for that size table. It could also have a manufacturing defect, leak, or for some other reason yet unknown. The vacuum is pure 100 percent chinesium knockoff. If is 7.5 KW, 3 phase 220 V.

I have talked to my own manufacturer (where mine came from). They only sell USA made products when it comes to pumps. Becker is the preferred model. According to Becker's marketing, a 5 x 12 table should take 24 HP. This 7.5 KW according to my calculations is 10 HP.

Anyway, if anyone has a large table like this and can recommend the proper pump size or other suggestions to get this going. I have a golden goose now with that machine, and need to get her going ASAP !!!

 

[LenVW]

When sizing the vacuum pump you need to estimate the leaks along with the total volume of air being evacuate in CFM. Your vacuum pump manufacturer will use appropriate factors for air movement and piping losses.
Whether it is a Liquid Ring Vacuum pump or a Screw Type makes a big difference for vacuum generation.

At SIHI Vacuum Systems we used huge systems for refinery applications (1200hp).
With PE pipe forming, we typically had 30 to 40hp Liquid Ring vacuum pumps.

Air is a challenging fluid to control in an open system.

Try to limit the areas that act as free air inlets. You also want to have a relief valve so that you do not ‘choke’ the vacuum pump by creating a closed system, however, with an open table you will likely have to limit the air ports to match the pump inlets.
With the liquid ring system you need a little leaking for the service liquid to perform as it should.

Sizing a vacuum pump involves compiling your line losses, evacuation leaks and designing the system properly.

 

[Matt-Aburg]

When sizing the vacuum pump you need to estimate the leaks along with the total volume of air being evacuate in CFM. Your vacuum pump manufacturer will use appropriate factors for air movement and piping losses.
Whether it is a Liquid Ring Vacuum pump or a Screw Type makes a big difference for vacuum generation.

Today we we at it again. The owner is kind of bullheaded in that he won't listen to some suggestions such as..

-Face side 1, and put in holes around outside to clamp MDF into the clamp slots.
-turn over and manually C-bore to suit BHCS.
-fasten and vacuum on, then face side 2.

Also, we are going to seal around the outside edge.

The vacuum pump may still need doubling, and or the circuits re-configured. An example of this is AXYZ has zones in the back and front. You would be able to run front, then back.. Essentially loading and unloading while the machine is working on the other half. All things to be considered... I found out the pump cost 3K... so only running 1/2 table / pump would greatly increase pressure...

 

[Tom O]

Wow that really sucks!
I wonder where the bell jar was bought it would be perfect for degassing

 

[Shoprat]

We use 2 of those Becker’s on our table. That being said we use mdf as a spoil board and suck the melamine down to it right through the mdf . A single system of your size is only used with pod systems usually.

 

[Matt-Aburg]

We use 2 of those Becker’s on our table. That being said we use mdf as a spoil board and suck the melamine down to it right through the mdf . A single system of your size is only used with pod systems usually.

Is it possible to use Uniboard for the spoilboard, since it is so much coarser? more air though?

 

[Shoprat]

Not sure, I don’t think it’s accurate enough and it definitely won’t surface off as well.