OT - measuring grease flow

[RMA]

On the line I'm working on at the moment there's a worm drive in the product that needs to be greased. Every now and again the jet blocks and no grease gets fed to the worm. At the moment the only check that is made is by line foreman checking once an hour to see that the units coming from the station are greased before they go into the station where the lid gets screwed on. This means that in the worst case, up to 50 or 60 servo units may come off the line without being greased. If some of these have worm drives at the slacker end of the tolerance scale, there's a good (or should that be bad?) chance that some may slip through the End-of-Line final checks. If that happens, some poor character is likely to be extremely unhappy when his expensive luxury car's 7-speed automatic gearbox packs in after only a few thousand miles!

The customer says they have been unable to find a supplier of something to check that the grease is being correctly dosed, but I can't believe there isn't anything available on the market.

They are dosing approx. 0.7 grams of grease which represents a string of grease about 10 cm long out of the supply hose, which is about 3 - 4 mm diameter. Does anybody know a supplier of metering equipment capable of measuring this flow? The accuracy isn't really too important, a system which delivered, say, 10 pulses during normal operation would probably be ideal. The way the jet blocks tends to be so that there is no flow at all, so it would be easy to set an appropriate cut-off point in the PLC program - say 7 - 8 pulses, if 10 was normal.

Thanks in advance for any info,

Roy

 

[10BaseT.]

Measure pressure in the line to check for the gain in pressure caused by the blocked jet ? What is the motive force for the grease ? compressed air ?

don't worry about those boxes Roy - the electronics pack up before the mechanics ......

 

[RMA]

What is the motive force for the grease ? compressed air ?

It's apparently some sort of pump, but since it's enclosed in the grease container, nobody's quite sure what sort of pump. That idea of measuring the pressure sounds like it may be a possible solution though. It should also be relatively easy to implement.

Have to go check that out - thanks for the idea!

 

[OZEE]

I'm not sure, but a mass-flow meter may work, too. It'll be much more expensive than pressure, so I'd sure try that first.

 

[Mickey]

Not sure if the below systems will work for grease, but might be worth a phone call.

http://www.devcocorp.com/american/lubriquip.htm

 

[Ken Moore]

Not inexpensive, but you could use a vision system to "see" that grease is present.

 

[Thomas]

lube metering

You might look at something like this from Lubriquip/Trabon. You can add pulse switches etc.

 

[Paul T]

I agree with Ken. If the process is that importent, and if it is also failure-prone, add an inspection step after to verify. Cost of camera, lighting, tooling- maybe $12k? Plus your time programming and integrating into the line; 1-2 man months?

You might also look at a sensor called "Dualis" by IFM Effector. I don't know if it would work in this application, but at under $1000 it's worth checking into.

 

[MikeW]

A flowmeter that you can set up to measure a totalized flow from the time a given unit enters the cell and not let it progress until it reaches the correct dosing may be the answer. For a small flow, maybe a positive displacement flowmeter such as http://www.maxmachinery.com/flowmete.htm might be the ticket. Cost ~$3000 but the first non-irate customer will more than justify the cost.

 

[RMA]

Thanks for all the suggestions guys.

@Ken and Paul, there is actually a camera directly behind this station, which checks a few other things. We tried using it, but the grease is white, the worm silver (stainless steel) and the blob of grease varies wildly in shape - no chance.

We'll probably be going the route Mike suggests with a helical positive displacement system. We've found one here which measures down to 0.01 l/min, with 16900 impulses/l, which should do the job nicely.

Thanks again for all the suggestions

Roy