EC-400 Door Slamming

[Pittsburgh Manufacturing]

We bought two brand new 2019 EC-400's over three years ago. The tool change door on one of them has been slamming open since the install. We have had 4 different HAAS Techs evaluate the issue and attempt to fix it. No fix has lasted more than 24 hours. It's only a matter of time until the track begins to damage and HAAS is just shrugging their shoulders. Has anyone found a solution to this?

 

[thesidetalker]

The air cylinder should have a cushion at end of travel. Have they replaced the cylinder? and it still slams?
How many tool changes do you have? One of mine is at 130k and its working fine still.

 

[Orange Vise]

Seen this on other horizontals as well.

Directional air cylinders usually have adjustable exhaust ports. When opening or closing the door, the cylinder gets pressurized on one side while exhausting the air out the opposite side. The adjustable exhaust port provides resistance to prevent the cylinder/door from moving too fast and slamming.

Try to locate the exhaust port and see if there's a little thumbscrew that can be used to adjust it. Closing it slightly will provide more cushion.

This is the preferred method over regulating incoming air pressure. Reducing incoming pressure too much can cause the door to get stuck if/when the rails get contaminated with dried coolant and chips.

Think of incoming pressure vs. exhaust as max force vs. max speed.

 

[Garwood]

Do they make air cylinders like hydraulics where the rod has a protrusion with a small milled taper that enters a bore in the blind end of the body? You can't possibly slam those cylinders. It's the ultimate KISS- get full speed travel and a perfectly smooth transition to a crawl in the last inch of travel. And nothing to wear out or break.

 

[guythatbrews]

Seen this on other horizontals as well.

Directional air cylinders usually have adjustable exhaust ports. When opening or closing the door, the cylinder gets pressurized on one side while exhausting the air out the opposite side. The adjustable exhaust port provides resistance to prevent the cylinder/door from moving too fast and slamming.

Try to locate the exhaust port and see if there's a little thumbscrew that can be used to adjust it. Closing it slightly will provide more cushion.

This is the preferred method over regulating incoming air pressure. Reducing incoming pressure too much can cause the door to get stuck if/when the rails get contaminated with dried coolant and chips.

Think of incoming pressure vs. exhaust as max force vs. max speed.

Surely this cylinder has this feature. If it doesn't, and you can get to the cylinder, just add one. They are cheap.

 

[guythatbrews]

Wish I coulda added one to the screen door when I was a kid. I can hear my dad now, "Get back here and close that thing right." Must have had to close that damb thing twice a thousand times.

 

[Peter S]

I don't know anything about the Hass door, so this might be no help at all...

I would first disconnect the air supply and then manually slide the door back and forth. This will check there is nothing binding. It will also tell if the cylinder end-of-stroke cushions are working.

If the load (door) becomes stiff at some point, an air cylinder will build up pressure to overcome the load, then move faster as the load is overcome. If the stiffness was just before the end of the stroke, slamming might occur.

Two of the suggestions made in previous posts need to be considered separately. Cushion and speed are separate issues.

Air cylinders usually have an adjustable cushion built-in to each end. It allows the piston to stop gently at the end of its stroke. The cushioning is adjusted by a needle valve (usually with an allen key or screw driver).

However, if the door is fully open (or shut) before the piston reaches its cushion zone, the door will slam. (The cushion is only available at the very end of the piston stroke). This would occur if the piston stroke was greater than the door stroke.

(I have seen separate mechanical shock absorbers used to provide cushion to a heavy load when cylinder cushion was not available, but I doubt it applies here).

The speed which the cylinder moves is a separate issue. A common method of speed control is to restrict the exhaust from the "other" side of the double-acting cylinder. This ensures the working side of the piston receives full air pressure, but the exhaust air from the other side of the piston is restricted, thus slowing the piston speed. The exhaust restriction is often an adjustable needle valve combined with an exhaust silencer. It may be found on the cylinder port or the solenoid control valve exhaust port.

So cylinder cushion and flow (speed) control are separate issues, but commonly both are needed.

This was the first YouTube that popped up when searching. Note that the adjusters fitted to the cylinder ports have no effect on the air entering the cylinder, just the exhaust air coming out. I prefer to fit them to the solenoid exhaust ports so they can be adjusted without getting near the cylinder while it is working (but some solenoid banks are probably too miniaturised to allow this).

 

[Ryan at Sparrow]

Hopefully you got it fixed by now, but our EC400 had the same issue two times. The culprit just being the giant nut that holds the cylinder became loose. Tightened her up and was good to go. Took a few months and then had to tighten it again. Probably could benefit from some loctite but oh well.