How to Mill Delrin
The process of machining Delrin in a milling machine is the same as it would be for any other type of material. Delrin is a DuPont product that is harder than conventional plastics and bridges the gap between plastics and metals. It has some of the characteristics of metal including stiffness, strength and fatigue resistance. It machines like aluminum and the set up is often the most crucial step when machining this type of material.
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Instructions
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Set up the milling machine in the same way you would any type of material. Delrin is soft, but can be held in a standard vise. Clean off the work table and set the vise down toward the right side of the table. Slide the T-bolts into their slots and hand tighten them so that the vise is somewhat immovable.
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Place a dial indicator on the end of the spindle and move the work table or spindle so that the spindle is right above the vise. Rotate the dial indicator so that its tip is touching the front jaw of the vise. Move the spindle or work table half an inch in the negative direction on the y-axis. This will apply pressure to the indicator.
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Rotate the bezel of the indicator so that the needle is pointed at zero. Move the spindle or work table back and forth on the x-axis and tap the vise with a mallet or small hammer until the reading is zero along the whole 6 inches. Tighten the vise and recheck it to make sure that the vise did not move while being tightened.
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Place the Delrin in the vise. Pull up on the material to make sure that it is tight in the vise. Find the center by using a center finder, which is a spinning measuring device find the center on the x- and y-axis in a matter of minutes. Start the spindle with the center finder in the spindle and move toward one edge of the raw material and wait for the bottom part to pop off of the shaft. Lift the center finder up out of the way, reset the micrometer and move the spindle inwards half the diameter of its shaft. Reset again to zero and move in half the total distance of the Delrin piece for center. Repeat for each axis.
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Cut the Delrin using fast speeds and feeds. Delrin is one of the softest materials you can cut on a milling machine, so you do not have to be conservative with either. Use a finishing end mill and any drill bits necessary to finish the part. Set the feed and speed on the maximum setting to get the part done quickly. Use air blasts to remove the built up of Delrin scrap material that may get in the way of cutting.
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References
- Photo Credit Chad Baker/Digital Vision/Getty Images
