Uniflow drum unloaders are known for melting and pumping hot melt materials faster than any competing machine. In fact, they are guaranteed to pump at least 40% faster!
But what do you do when you notice that your Uniflow pump rate is starting to decline? Can you get back to that sizzling pump rate you had in the beginning? Absolutely!
Pump Rate Troubleshooting Steps
There are several troubleshooting tips you can run through to determine why your pump rate may have started slowing down.
1. Test Pump
- Raise the platen partially out of the drum so the hose manifold is accessible.
- Remove one of the ¼” pipe plugs on the manifold and attach a 0-3000psi pressure gauge.
- Remove the heated hose and install a plug in its place. (Note: Some hose manifolds do not have plugs. In this case, you will need to drill and tap a hole in the hose plug to accommodate the pressure gauge.)
- Lower the heated platen back down until you get a good bleed from the bleed valve.
- Start the pump slowly and read the pressure gauge. It should be above 1000 psi. A new pump is capable of achieving 2,200 to 2,500. If the maximum reading is 500psi or less, the pump needs to be replaced.
- If the pump pressure is okay, check the heaters.
2. Check Heaters in Platen
The method for checking the heaters is dependent on which Uniflow model you are using.
Model 230 Machines
Open the main control box. Using an ammeter, check the current draw on all three banks of heaters. This can be done at the solid state relays located on the heat sink. They should read around 47 amps on a 34 KW plate.
There are (12) cartridge heaters in each of the three banks. If a heater has failed, the current draw will be proportionally less. Hence, if two banks are drawing 47 amps and one bank is drawing 43 amps, the third bank has a failed heater.
The machine will still function properly even if one or two heaters have failed in a bank. If more than two heaters have failed, they should be replaced.
Replacing heaters is not a trivial task. This is typically done by an IMMCO service technician.
If you would like to replace the heaters yourself, please contact us and ask for assistance in talking you through the process.
If the heaters are okay, check the cylinders.
Model 4230 Machines
There are only two heaters in a Model 4230 platen, so you only need to be sure that both heaters are working.
If the heaters are okay, check the cylinders.
3. Check Ram Cylinders
The steps for troubleshooting ram cylinders varies based on the model Uniflow hot melt drum unloader you are using.
Air Unit (Model 4230)
Put the ram in hold. Remove the hose from the fitting on the bottom of the cylinder.
Put the ram in ram down. If air is blowing out of the bottom of the cylinder, the cylinder needs a rebuild kit, or replace the air cylinders. Rebuild both cylinders at the same time.
Hydraulic Unit (Model 230H)
Put the ram in hold. Remove the hose from the fitting on the bottom of the cylinder and plug the hose that is removed. Have a container ready to catch the hydraulic oil that drains out from the cylinder.
Put the ram in ram down. If fluid is leaking from the bottom of the cylinder, the cylinder needs a rebuild kit, or replace the cylinders. Rebuild both cylinders at the same time.
4. Check for CHAR
Start by pushing a long screwdriver into one of the holes located below the bottom drum seal on the platen. If it is very difficult or impossible for the screwdriver to penetrate the hole, then it is full of char. NOTE: Platen must be HOT for this test.
Try to push a thin piece of metal up between the fins of the platen. It should reach a depth of two inches.
If there is significant char on the platen, it will not be able to heat your material properly. The only two remedies are to return the platen to IMMCO for cleaning or to replace the platen.
Remove the pump and inspect the pump cavity on the platen. Clean any charred material from the feed holes.
Improving Hot Melt Production Rates
If you’ve run through these troubleshooting tips with no luck, or you simply want a service technician to give you expert oversight, IMMCO is here to help.
Let one of our technician’s help you get your Uniflow hot melt drum unloader back up to speed in no time.
