Micromachining isn’t new. People have been machining in miniature in some form or another for years. What is new is the degree to which it is now necessary in manufacturing. Academics only refer to micromachining as work in one-millionth of a meter. The rest of us aren’t so literal.
Micromachining is not only a highly-specialized niche in machining, but it is a niche that has its own language. Sure micro machinists still talk about feeds and speeds, but here are a few terms to add to your shop lingo if you want to talk like a microdrilling pro.
Micro Drill Adapters
Micro drill adapters modify your equipment for micro drilling. They are perfect if you do occasional micro drilling and have equipment with spindle speeds in the 2000 to 4000 rpm range. You may find micro drilling runs better with lower spindle speeds, especially if you are drilling plastic. Otherwise the plastic may melt.
Microdrilling uses a process referred to as a “peck cycle”. Picture the way a chicken pecks at seed and you know where the process gets its name. The microdrill is repeatedly inserted and removed from the work. This is vital to keep chips clear. If you linger at the bottom of the cycle, your material will be hardened by the work. If the drill is completely removed at the top of the peck cycle, a slight taper may result. This is avoided by beginning the down cycle before the drill leaves the hole.
Wait, is it air or is it fluid? The answer is “Yes”. Air fluid is the mixture of cutting fluid and air that is used as a lubricant to help remove chips during the peck cycle. If straight fluid were used as a lubricant, it would pool, become stagnant, and instead of removing chips it would actually foul the drill. Here’s a great picture of the bad stuff that happens when you use fluid only for microdrilling.
When you hear “spades” do you think of the card game, the suit of cards, or a garden tool? If so, you aren’t microdrilling much. When a micro machinist refers to “spades” they are referring to the unique shape of a microdrill. As mentioned earlier, chip removal is a real problem with micromachining. One way to counteract this is by use of a drill that does not have a pointed or chiseled end. The end of the microdrill consists of a cutting edge that is created by two intersecting planes. The cutting edge removes material primarily by extrusion. The cutting energy along the edge is relatively large compared to the drill’s cutting edge. But watch out! As the rotating cutting edge first contacts your work, anything on the surface can cause the drill to walk. No matter what type of machinist you are, you know walking is a bad thing.
Sierra American Speaks Your Language
Whether you machine in full size or microsize, Sierra American Multi Systems speaks your language. Depend on Sierra American for your machining needs. Everything we sell is proudly made in the USA and backed by a full manufacturer’s warranty. From micro drill adapters to custom arbors, we’ve got you covered. If your supplier doesn’t offer Sierra American, ask for it by name. You will be assured of quality tools and supplies from a company that speaks your language.
graphic art courtesy Stuart Miles@freedigitalphotos.net