{"id":13629,"date":"2018-06-07T14:50:10","date_gmt":"2018-06-07T18:50:10","guid":{"rendered":"https:\/\/dyzedesign.com\/?p=13629"},"modified":"2018-06-08T09:27:21","modified_gmt":"2018-06-08T13:27:21","slug":"nozzle-abrasion-mechanisms-behind-nozzle-wear","status":"publish","type":"post","link":"https:\/\/dyzedesign.com\/fr\/2018\/06\/nozzle-abrasion-mechanisms-behind-nozzle-wear\/","title":{"rendered":"3D Printer Nozzle Abrasion: Discover and understand the mechanisms behind your nozzle wear"},"content":{"rendered":"

Abrasive materials<\/h2>\n
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It\u2019s getting more and more common to see fiber reinforced polymer as 3D printer material. The most common filler is carbon fiber. Fiberglass is coming second with increasing use in 3D printing. It\u2019s been common in injection molding long before 3D printing.<\/p>\n

The goal of these added fibers is to enhance the mechanical properties. In general, you\u2019ll see increased tensile strength and increased bending modulus. These mixtures of polymer and fibers are sometimes called \u201cFilled Plastics\u201d and \u201cComposites\u201d.<\/p>\n

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\"Strength<\/a><\/p>\n

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Composites are made from two different materials or more. For 3D printing, the matrix is always a thermoplastic. The reinforcement can be one of the following:<\/p>\n

 <\/p>\n\n\n\n\n\n\n\n\n
Reinforcement<\/th>\nType<\/th>\nGoal<\/th>\n<\/tr>\n<\/thead>\n
Carbon Fiber<\/td>\nCeramic<\/td>\nStrength and rigidity<\/td>\n<\/tr>\n
Fiberglass<\/td>\nCeramic<\/td>\nStrength and rigidity<\/td>\n<\/tr>\n
Kevlar Fiber<\/td>\nPolymer<\/td>\nStrength and rigidity<\/td>\n<\/tr>\n
Metal powder<\/td>\nMetal<\/td>\nAesthetic<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

 <\/p>\n

As shown here<\/a><\/strong>, the tensile strength, flexural strength, and flexural modulus are increased.<\/p>\n

 <\/p>\n\n\n\n\n\n\n\n
Material<\/th>\nTensile strength (MPa)<\/th>\nFlexural strength (MPa)<\/th>\nFlexural modulus (GPa)<\/th>\n<\/tr>\n<\/thead>\n
Nylon 6\/6<\/td>\n81<\/td>\n103<\/td>\n2.83<\/td>\n<\/tr>\n
Nylon 6\/6 + 40% Glass fiber<\/td>\n213 (262%)<\/td>\n289 (280%)<\/td>\n11 (390%)<\/td>\n<\/tr>\n
Nylon 6\/6 + 40% Carbon fiber<\/td>\n276 (339%)<\/td>\n414 (400%)<\/td>\n23 (829%)<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

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Take these values with a grain of salt as 3D printing material use very short fibers. Also, fiber content is closer to 20% in most cases.<\/p>\n

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Wear mechanism<\/h2>\n
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As you push your filament through your hotend, pressure is building. For instance, our powerful extruder<\/a> generates pressure of 25 MPa. As the plastic exits out of the nozzle, many hard fibers are sliding and rolling against the inner wall. This causes Abrasive wear, also referred as  »cutting wear »,  »slurry erosion » and  »scratching wear ». Outside of 3D printing, debris, dirt or sand are often the cause in a moving mechanism.<\/p>\n

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\"\"<\/a><\/p>\n

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In short, abrasive wear happens when a hard material slides on another material. The fibers are short and looks like needles. It\u2019s easy to imagine them scratching as they pass through the nozzle. In this application, hardness is one of the key factor in wear resistance. Abrasion can occur even if the abrasive is softer than the nozzle material.<\/p>\n

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Measuring wear<\/h2>\n
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Wear can be measured using other techniques than extruding large amounts of plastic. In fact, it is true that only a few hundreds grams can make a significant difference on a brass nozzle hole size. On the other hand, the extrusion test could take many kilograms before observing a difference with high-performance materials.<\/p>\n

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Measuring techniques and tools<\/h3>\n

There are many standards for measuring wear. They all work on different principles and will result in different conclusion. It is very important to understand our application and base our measuring method on a valid equivalent measuring standard. Otherwise, the results would differ from design to application.<\/p>\n

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Comparable and valid measuring technique<\/h4>\n

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The key in our application is the presence of hard and sliding particles, that can either be in the form of a slurry or simply sand. The test ASTM G65 and ASTM G105 is an excellent example; To explain, a rubber wheel is constantly fed with sand and scratch the specimen surface. To clarify, you can compare the rubber wheel as the polymer in the fiber reinforced filament, and the sand particles as the fibers.<\/p>\n

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Other measuring techniques<\/h4>\n

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There are many other techniques for measuring wear:<\/p>\n