Cleaning Paint Jigs 1

[Manfreds2]

Anyone have any ideas on how to clean paint jigs used in automotive paint booths?

I'm open to all ideas. Current way includes 36,000psi water spray and it destoys the jigs.

Thanks!

 

[CoryPad]

Can you provide more information? Must the cleaning take place withing the booth? Any restrictions on vapors, liquids, solids (contamination, pollution, disposal, etc.)? How large are the jigs, how thick is the paint? What is the paint composition?

 

[racookpe1978]

How much buildup can you tolerate before the jigs have to be cleaned?

Are there places where a lot of buildup can be tolerated, and others where dimensions have to be closely held?

 

[Manfreds2]

These jigs are used to paint bumpers. Our standards require that the jig must be cleaned every 100 cycles which includes a primer, color, and top coat. This process needs to work for both water based and petroleum based paints.

The biggest reason for the cleaning is to reduce contamination in the paint booths when they re-enter with a new part. We've found that if the jigs are dirty (after 100 cycles) the contamination in the paint booths rises very quickly.

 

[racookpe1978]

Could you wrap the jig in the stretch plastic strips sold for wrapping packages - the strips I've seen are 12 to 48" wide and are similar to the commercial Saran Wrap.

When too dirty - unwrap the plastic and put a new layer on.

Very little time, no water and sewage disposal, and low cost. If the wrap doesn't cover everything, you at least only need to clean a much smaller area.

 

[CoryPad]

If you can clean the jigs offline, then there are several options:

abrasive blasting - sand, walnut shells, corn cobs, etc.

dry ice - solid phase CO₂ shrinks and fractures plastics, sublimation helps separate the fragments from the substrate

thermal decomposition - thermal energy destroys/combusts hydrocarbon components of paint

plasma decomposition - photon energy destroys hydrocarbon components of paint

Of course, there are the mundane options of solvents and mechanical abrasion (3M Bristle Brush is a very nice product).

 

[Manfreds2]

Plastic wrapping has been tried before and it has a hard time holding up through the drying ovens. The last time it was tried, the paint lines were shut down for almost 2 weeks to decontaminate the booths when the plastic degraded and broke apart!

I'm interested in the dry ice and plasma decomposition? A lot of the jigs are alumnimum and the high pressure water just blows them apart!

As always, I'm open to all ideas!

 

[Ron]

I would suggest having two sets of identical jigs. That way you can take your time with the cleaning, thus almost any process (solvent, dry ice, etc.) would be workable. Trade out a cleaned set for the dirty ones and clean away.

 

[Manfreds2]

Taking the jigs offline isn't a problem. The biggest problem is the cost of having someone spend 15 mins a jig to clean them with the high pressure water and the safety concerns with running the high pressure lance.

 

[ornerynorsk]

Have you checked out a fluidized bed system like what is used to clean injection molding screws? Not an option if you're trying to do it "on the cheap". Sandblasting would definitely be the most economical and time effective, in my opinion.

 

[ornerynorsk]

Wait a minute, I just re-read one of your posts. You said the biggest problem is for someone to spend 15 minutes to clean the jig. 15 Minutes !?!?! A production cycle of 100 bumpers will require 15 minutes of jig maint.??? Where's the problem? You're effectively adding 9 seconds per bumper.

The safety issues are legit, but the cycle time addition does not seem to even qualify as an issue. Wet sandblasting will lower your pressure requirement, but whatever process you're using will safety considerations of one type or another.

 

[CoryPad]

One equipment vendor for dry ice blasting:

http://www.enviro-blast.com/index.htm

One equipment vendor for plasma (mainly semiconductor fab):

http://www.novellus.com/default.aspx

The fluidized bed suggestion from ornerynorsk is a good one.

 

[vpl]

ornerynorsk - I think the OP is concerned that some jigs are being destroyed by the hydrolazing.

Maybe the answer is too take more than 15 minutes and use a lower pressure spray.

Patricia Lougheed

Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of the Eng-Tips Forums.

 

[Manfreds2]

The suggestions are great so far. I am currently investigating the dry ice blasting.

As for the added 9 seconds per bumper to clean jigs...that is a lot of time.

This is how I figure it:

(9 sec/bumper) x (2 bumpers/car) x 2,000,000 (cars/year) = (10,000 hrs cleaning jigs/year)

Figure in going hourly rate and it adds up very quickly.

As for sandblasting, we are realling looking at something that is not going to remove material from the aluminum itself. It is a delicate process to remove the paint quickly but without damaging the aluminum jigs.

They have to be aluminum for ergonimic reasons.

Adding a chemical process will add a whole other safety concern and evironmental impact.

 

[ornerynorsk]

That sheds some new light on your problem. You do have multiple jigs, correct? Given the volume of cleanings per year (40,000 cycles) a thermal fluidized bed process just might be the ticket. Very low labor requirement, the process is largely passive except for the load/unload. Depending on the bed media, I'm not sure how the aluminum substrate of the jig will hold up. This process is used in the injection molding industry to clean some of the nastiest crud you have ever seen off of machinery parts.

Could you share a little more on how the jig interfaces with the bumper being painted? Would steel be acceptable for the jig, or is weight a genuine concern?

 

[ajack1]

I do not claim to know the answer to your problem but would something like this not be an option?

http://www.ecologicalcoatings.com/antistick.html

Failing that could you not have a vacuum moulded protective cover that could be replaced every so often, I see you said you have tried this and the heating was a problem but I am thinking of the sort of thing that oven ready meals come in.

 

[Manfreds2]

I'll look up that fluidized bed process. Sounds like it could have some real potential!

Thanks to everyone!

 

[MiketheEngineer]

How much do the jigs cost -- maybe just replace them???

 

[TIMMAAYY]

Manfreds, if you need any information on dry ice blasting, let me know. I think it would work very well for your application. If you get on youtube and search for some of the terms, you will see quite a few demo videos. There are several manufacturers of machines to do this... all very similar in their basic design.

You can buy a machine, rent a machine, or just have someone come in to do e service for you. Expect to pay about $200 an hour... but they can do a lot of cleaning in an hour's time.

Check out this guy in Michigan/Indiana.

http://www.nu-age.com

They do a lot with weld cells and dry ice cleaning.

 

[unclesyd]

For the amount of cleaning you are proposing I would go with a Pyrolysis Furnace from Pollution Control. We have 9 of these furnaces in service cleaning polymer from our process equipment. There are no moving parts in the furnace and they use off the shelf parts for all controls and burners. Our small furnaces are rated at 900,000 BTU so they are very inexpensive to operate. The max temperature is 900F.
These furnaces easily meet all emission standards.

http://www.pcpconline.com/