So you have a machine shop and you need a synthetic graphite component? If you’re thinking of machining graphite yourself, our advice would be to give Semco a shot at doing it for you. Machining graphite doesn’t necessarily require a graphite mill, or decades of experience working with synthetic graphite, but these things don’t hurt. We have built Semco on highly specialized knowledge about machining graphite, and we will share some of that knowledge with you here. If you still want to do the graphite machining yourself, you’ll be better equipped to do so. You may also become aware of the demands synthetic graphite can make on your machines and decide to let the pros with the graphite mill handle the job for you. That’s why we’re here after all, to help our customers with all their graphite machining needs.
Tips on Working With Synthetic Graphite
First of all, we understand why you want a graphite component. We are great champions of synthetic graphite. Its unique qualities make it useful in various industries. We think you’ve chosen a great material. But the qualities that make synthetic graphite so versatile can be the same qualities that make it difficult to machine.
Liquid Coolant and Synthetic Graphite
Let’s start with coolants, which you probably use in your milling or turning machines. If you do the graphite machining yourself, the coolant will have to be removed from your machine first. Once the liquid coolant is removed, dust happens. Lots of it. And it is basically impossible to clean a machine filled with graphite dust. And that’s just the tip of the iceberg of things that can go wrong when you machine graphite without properly setting up your milling machines to be graphite mills.
But why, you may ask, should synthetic graphite be machined dry, without the use of liquid coolants? Because the use of coolants when working with graphite will produce an abrasive slurry when the coolant combines with the graphite bits and powder. As we said above, it is often the unique qualities of synthetic graphite that make it a troublesome material to machine. For instance, graphite is porous, allowing the material to, among other things, be easily impregnated with other materials to customize its performance in different conditions. The porosity of the material, though, also means that the coolant fluid will permeate the synthetic graphite. Essentially, the graphite will act as a sponge, as capillary action draws the coolant into the open pores. This contamination will cause problems when the graphite is used in an application that requires the inert nature of the graphite material.
A Graphite Mill Likes Dry Material
And here’s a related tip should you do the graphite machining in house: the starting raw graphite material should be dry before machining. If your raw material stock has been stored outside or been exposed to water, it should be baked to dry out any excessive moisture. The water and dust will make an abrasive slurry, which will dramatically reduce your tool life. The damage that wet graphite can do to machines can most clearly be observed when cutting wet graphite on a band-saw. The dust does not exit the material during cutting, but instead packs up in the kerf. Essentially, the cutting tool re-cuts the same graphite chips over and over again, degrading the tool unnecessarily.
Ventilation is Key to Safely Machining Graphite
Still thinking of machining the graphite in-house? This next aspect of machining graphite is very important. You must have an adequate ventilation system to contain and vent the graphite dust and chips produced during the machining operations. Graphite dust is sneaky. Because of its electrical conductivity (another of its useful features in other contexts), the dust will find its way into every crack or opening in a machine enclosure. Static electricity will draw the dust to circuit boards and create short circuits when the build up bridges contacts. Machining graphite on a CNC machine that has not been specifically modified to handle the graphite dust can lead to expensive damage and can potentially void a warranty. You could be left holding not only the damaged machine but also the bill to fix it.
Use Only Very Sharp Tools
Here’s another important word to the wise when doing in-house graphite machining: use only very sharp tooling to prevent particle pull-out or edge chipping. Once a cutting tool has lost its sharp edge, it will fracture the graphite material or cause a blowout of an edge when exiting a cut. This happens because the dull tool pushes rather than cuts the material. Graphite has great compressive strength, but will fracture if the force is directed out of the material rather than into it. Tooling made from micro-grain carbide designed for cast iron works well in graphite. Vapor deposition diamond coated end mills also work well, but can be very expensive.
Work From the Outside In When Machining Graphite
Lastly, it is a good practice when milling graphite to ''climb mill,'' or work from the outside into the material. For instance, when milling pockets, avoid leaving islands when the end mill cuts from the pocket perimeter into the center of a pocket. The island material will break out when the final island is removed, resulting in a pockmarked cavity. It is a better practice to drill a center hole and mill the pocket from inside to the outer edge.
We Can Do This For You
These are just a few basic tips if you decide to machine synthetic graphite. And these tips only scratch the surface of the specialized knowledge about machining graphite that our machinists have accumulated in their decades of combined experience. As a custom graphite machining facility as well as a supplier of graphite material blanks, Semco has accumulated the knowledge and established the appropriate processes to correctly and effectively machine graphite.
We would love to make things simpler for you and machine your next graphite project. Contact us for a quote.