Positech Corporation of Fairfield, OH manufactures intricate machined parts for the automotive, motorcycle and aerospace industries.
One of their machinists, Dave Gray, had a frequent problem rough-milling pockets in type 410 stainless steel when using a two flute 3/8" carbide cutter on their Okuma vertical machining center. Coolant produced thermal shock, resulting in micro cracking of the carbide inserts. Without coolant, thermal cracking of the inserts was almost immediate. They were constantly changing inserts.
The company installed a Model 5215 Cold Gun System. The 20°F cold air kept the inserts cool and allowed all the heat to be carried away on the chips. Tool life increased by 50%.
How the Cold Gun Works
The Cold Gun incorporates a vortex tube to convert an ordinary supply of compressed air into two low pressure streams, one hot and one cold. The hot airstream is muffled and discharged through the hot air exhaust. The cold air is muffled and discharged through the flexible hose, which directs it to the point of use. The magnetic base provides easy mounting and portability.
Heat build up can ruin expensive tooling as well as the part being machined. In Positech's situation, it would have been easy to constantly ruin a $200 cutter. When asked how others solve this problem, Dave replied, "We've seen companies go so far as to defeat the safety interlocks so the machine runs with the doors open - just to blow a little compressed air at the part to cool it. For us, the Cold Gun keeps the tooling cool and allows us to immediately handle the part since the heat blows away with the chips."