I get this 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 the milling process. Plus, 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 & Its Effect on the Milling Process
One of the main functions of flood coolant, aside from the obvious cooling and lubricating of the cut itself, is to wash away the resulting chips from the cutting process – 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 isn’t 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 away the majority of the heat 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 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, 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 and in most 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’s 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’s milling at a depth that’s several multiples of its diameter, and in a 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, you need to select a cutting tool with a properly designed chip channel that sufficiently ejects the chip from such a pocket.
Chip Management & Disposal
Most machines with flood coolant either come standard with or have the option of a chip conveyor. 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, the chips are brought up a few feet and dumped into a bin or barrel. For a machine operator that’s 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, the majority of DATRON milling 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 therefore are much easier to manage.
If you look carefully at any DATRON, you’ll find there’s a significant amount of space below the machining table. This area serves as the chip tray and is designed to be a large space chips can accumulate in without interfering with the machine operation or milling process. The chip tray is removable in every DATRON, so when it’s time to dispose of the chips, they can be shoveled, dumped, or vacuumed out. The chip bin is large enough to accommodate the chips from several days of continuous milling and still accessible enough to dispose of its contents without difficulty. Much care was taken to design the inside of the machine cabin with little to no accumulation points, so the chips fall down naturally into the chip tray. Machine operators who have managed both flood coolant and evaporative-mist coolant machines comment that cleaning up dry chips is no more 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. The MQL system isn’t the only aspect the manufacturer looked at to create an efficient high-speed mill, read about the DATRON design here.