cooling parts

Does anyone here know a good method to cool parts for press fit assembly.I used CO2 before;but our shop doesn't use CO2 extinguishers any more.Thanks for reading.

Dry Ice works well and so does R134A refrigerant.As a mechanic for many years I"ve used both.

check for availability of dry ice {co2} in your area, also check with dairy delivery trucks, i say this because the refrigerated truck that delivered to local grocery hauled milk at normal cooler temps but ice cream ect. was kept in coolers with dry ice on top, when the grocery placed frozen products in freezer the dry ice was dumped on the loading dock.

liqui nitrogen, available at most welding supplies. Take a cooler and get what you need.

The spray compressed"air" in a can works.
Locktite sells a spray can chiller for bearings and sleeves too.

The best way to freeze bushings is liquid nitrogen. I've used it on bushings that were 12 plus inches in diameter and nearly as long with no problems. Just drop the part in til the liquid stops bubbling and your ready to go. The problem with it is to get large amounts you have to have a dewar (a big thermos) to safely carry it. Something like a plastic cooler will not work as the nitrogen is so cold it will cause the plastic to get brittle and the possibility of it shattering exists.

The easiest thing to use for small items is dry ice. It is readily available in block and pellet form and can be transported in a standard cooler. One word of caution when transporting, do not do so in an enclosed vehicle. As the dry ice sublimates it turns into carbon dioxide which will displace the oxygen and kill you.

With either you have to wear proper protective gear. The nitrogen can not be handled, only poured, and you need to make some way to put the part into and take it out of the liquid. The dry ice can easily be packed around the item by hand, as long as you are wearing heavy (welding type at least) gloves. The same goes for handling the parts after they are frozen, you have to have heavy golves to protect your hands.

If you have access to neither, you'd be amazed how good just setting the part in the freezer overnight works.

Have successfuly used CRC contact cleaner, in the green spray can for bearings, and races, pullys and gears, for many years, as a industrial crane mechanic.