The primary impact of workholding on surface finish is vibration. Rigidity in all areas is key to a fine surface finish and any vibration of flex is going to be bad for your surface finish. See our article on the role of coolant for more. The chips won’t clear of their own accord, although the tendency for gravity to help the process along is one reason horizontal mills can be more productive than vertical mills (or lathes too for that matter). Either Flood Coolant or an air blast with mist if needed will do the job if properly set up. Keep the chips clear so they won’t scratch the workpiece or dull your cutter… Hurco calls this out as one of the first and most important things to attend to in order to improve your surface finish. Use your coolant or air blast to get the chips completely out of the way of the hole. With work hardening materials like stainless, you may as well scatter a handful of hardened steel chips to scratch up your work. Sounds like a geat tip to me! Clear the Chips!Ĭhips down in the work will scratch it up as your cutter slides them around in the hole. This will improve surface finish and reduce chatter. When you do the finish pass, reduce depth of cut a few thousandths so that only the side of the endmill is cutting. Saw a great tip from an aerospace machinist on one of Hoss’s CNCZone threads: The lighter pass will reduce cutting force and keep things smoother for a better finish. I do a lot of finish passes in the 0.015″ neighborhood. Usually something like 2-3x chip load will be right for the finish pass. The depth of cut has to be larger than the chip load, or you can get rubbing. Keep a low cut width (or cut depth if you’re talking the floor of a pocket or surfacing with a Face Mill) and do a separate finish pass. In general, the Tortoise-Hare slider provides a tradeoff between quality of finish and how fast it removes material when roughing.
Move the Tortoise and Hare slider all the way left when finishing…ĭon’t allow the chip load to go too low or you’ll be rubbing the tooling instead of taking clean cuts. That’s its special “Fine Finish” setting which puts the chip load as close to rubbing as you want to go for best possible finish. G-Wizard has its “Tortoise and Hare” slider to do this adjustment. Keep the rpms up where surface speed says they should be and back off the feedrate for a finer finish. Use a proper feeds and speeds calculator like G-Wizard–most finish work needs to take radial chip thinning, ballnose compensation, and a host of other sophisticated factors into account. It’s absolutely critical to have the right feeds and speeds for finishing work–no guessing! Which Surface Finish Measurement system will be used–RA, RZ, or some other? The link will take you to our page on Surface Finish Measurement which will help you understand the ins and outs of these systems as well as provide handy conversion between the different systems. If your concern for surface finish is based on the requirements placed on a particular part, understand how the Surface Finish will be measured. Understand How Surface Finish Will Be Measured This article is about the little tricks focused expressly on creating a better surface finish. Want to improve your milling finish? Trying to reduce post-machining finish work or just get better looking parts?
#Cover desk edge to keep from rubbing off finish free
Note: This is Lesson 7 of our Free Feeds & Speeds Master Class.
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