I get the question all the time when someone is trying to wrap their head around how milling works without flood coolant – what about that chips? It’s a fair question, and an important one given how much havoc chip accumulation can be in a milling process, as well as how much work it can take to clean chips up or out of a machine tool. In this blog post, we’ll spell out exactly what happens with the swarf that’s created in a milling process where the coolant is sprayed in a fine mist and evaporates just as the cut is completed.
Chip Accumulation & It’s Effect on the Milling Process
One of the main functions of flood coolant, aside from the obvious cooling and lubricating the cut itself, is to wash the resulting chips away from the cutting process – and thereby preventing them from being re-cut or clogging up the cutting tool. Knowing this, many traditional machinists are concerned that with an evaporative coolant applied as a fine mist they’ll encounter significant interference in the milling process with the chips they’ve just created. Fortunately, this is not at all the case in the vast majority of milling situations.
The evaporative coolant used in DATRON equipment is applied using an atomizing system called a MicroJet. This system feeds pressurized air together with the coolant to the MicroJet nozzle, which atomizes and sprays the evaporative coolant directly at the cut. Since the cooling fluid evaporates upon contact with the cutting process (and wicks the majority of the heat away in the process) the resulting chips are perfectly dry as they clear the endmill flutes and are ejected away from the cutting tool.
Since the chips are dry by the time they land, clearing them away requires much less effort than it does when the chips are soaked in flood coolant. The chips do not stick to the inside of the machine cabin, to the fixture, to each other, or to anything really. As a result, should the machine head come to an area where chips have accumulated, the same high-pressure air/coolant blast that cools the cut will also blow the chips away before the cutting tool even comes in contact with the workpiece. For this reason, in the majority of cases, the chips do not pose any sort of risk to the milling process.
Of course, there are exceptions to every rule. Even with evaporative coolant and a high-pressure air blast, it is possible for chips to have a hard time getting out of the way. In my experience this can happen when you have a very small diameter tool, that is milling at a depth that is several multiples of its diameter, in pocket that isn’t a whole lot bigger than the tool itself. Since you don’t have flood coolant to carry these chips out of the pocket, care must be taken to select a cutting tool with a properly designed chip channel to sufficiently eject the chip from such a pocket.
Chip Management & Disposal
Most machines with flood coolant either come standard with or have optional chip conveyors. Chip conveyors are systems that live at the bottom of a machine tool and actively move chips out of the machine cabin, either via an auger or a conveyor belt. From there they are brought up a few feet so that they can be dumped in a bin or barrel. For the machine operator used to this process, it can be a bit puzzling to look at a DATRON machine and see no chip conveyor of any sort.
While it should be noted that the flagship M10 Pro does have an optional chip conveyor, it is true that the majority of DATRON machines in the field do not. The reason for this comes back to the fact that the chips are dry by the time they leave the endmill flute, and are therefore much easier to manage.
If you look carefully at any DATRON you’ll find that there is a significant amount of area below the machining table but above the bottom of the machine. This area serves as the chip-tray and is designed to be a large space that chips can accumulate in without interfering with the machine operation or milling process. This chip-tray is removable in every DATRON so that when it comes time to dispose of the chips they can be shoveled, dumped, or vacuumed out. This area is large enough to accommodate the result of several days of continuous milling, yet still be accessible enough to dispose of its contents without difficulty. Much care is taken to design the inside of the machine cabin with little to no accumulation points so that the chips fall naturally down to the chip tray. Machine operators who have managed both flood coolant and evaporative-mist coolant machines commonly comment that cleaning up dry chips is no more easy or difficult than cleaning up wet chips, it’s just different.
The use of mist coolant is gaining in popularity, particularly in the realm of high RPM cutting where it’s more effective than traditional flood coolant. The fact that DATRON machining systems have evaporative coolant is unique and means that – at least with your DATRON machine – you can enjoy the chips without the dip.