Шесть принципов проведения эффективных испытаний обрабатываемости материалов

6 Design Tips for Machining Tests There is no standard test for machineability, so job shops must create their own. Following a few key principles should ensure they are useful and accurate. Share Phillips Corporation Featured Content View MorePhillips Corporation - Education Featured Content View MoreI recently wrote about a machinability study Nucor undertook for one of its non-leaded 1215 steels, based on a visit to the Tajmac USA facility where the testing took place and a white paper written by Dr. Julius Schoop, a University of Kentucky professor who worked with Tajmac’s staff to conduct the test. While I focused on the results in that article, during my initial visit to Tajmac the stakeholders discussed how they would set the testing parameters and why they made certain choices. Not long after, I saw John Miller’s article on the principles behind a successful test cut, which echoed several of the points behind the experiment design for Nucor. From these sources, I picked up on several points that could be useful for any tests a job shop might run. I’ve collected six of those below: The testers at Tajmac optimized testing parameters for NuCut1215, establishing it as a baseline. They did not know the chemical composition of the other four materials, and so treated the leaded and non-leaded materials equally. 1. Test blind where you can It’s easy to introduce unintentional bias into studies when the testers know exactly what they’re testing and how it is supposed to perform. Keeping the tools or materials being tested anonymous where possible forces testers to treat each tool or material the same, minimizing the chance of bias-induced error. 2. Work with realistic parts Testing for a single feature in isolation may not reveal a machine, material or tool’s real-world performance. Testing a realistic use case will get you better-quality data for the situations in which the machine, material or tool you’re testing will be employed. 3. Choose realistic parameters Realistically, shops want to make as many parts as possible, and this means using some aggressive cutting parameters. At the same time, you need to limit cutting speeds and feeds so they are sustainable and don’t wear out the tool too quickly or degrade performance. If you plan to run a tool or material on multiple machines, your test should be designed to address that, or at least use testing parameters that reflect the capabilities of both. 4. Set a baseline The testers were very clear about one thing: There is no universal machinability standard. No matter what, you will need to set your own baseline, and that will probably take some experimentation before starting the main portion of the study. 5. Expect extrapolations and plan accordingly For many processes with durable tooling, cutting tools may not wear out in the time you have allotted for the test. To extrapolate from the results, ensure you have run the test long enough to differentiate the tools being tested. 6. Determine educational testing intervals The more often you stop machining to measure a tool, the longer testing will take, the less realistic it will be and the more likely you are to introduce some variability in the tool’s positioning when indexing it back into the toolholder. Instead, determine a regular interval, whether based on parts machined or time, to check the wear on the cutting tool. Related Content Understanding Process Damping in Milling Operations Despite the advances in modeling machining operations over the past decades, process damping remains a topic of interest, including new tool designs that increase the effect. Read More4 Manufacturing Trends That Cannot Be Ignored The next five years will present their own unique set of challenges, and shops can alleviate them by embracing these technologies and trends. Read More4 Commonly Misapplied CNC Features Misapplication of these important CNC features will result in wasted time, wasted or duplicated effort and/or wasted material. Read MoreHow to Determine the Currently Active Work Offset Number Determining the currently active work offset number is practical when the program zero point is changing between workpieces in a production run. Read MoreRead Next How to Stabilize Machining With Tap Testing Use tap testing to generate stability maps and maximize productivity with chatter-free machining parameters. Read More3 Principles to Achieve Test Cuts Worth Trusting A test cut — justified by specific risk, designed on a clean canvas and used to confirm rather than analyze — can expose if uncommon machining traits fit your needs. Read MoreUnleaded Steel Leads the Way in Machinability Test Even in conditions better suited to leaded 12L14 steel, a domestically produced non-leaded 1215 steel showed stronger results in turning and drilling, with comparable results in grooving. Read More