The case for a new Modern Machining course

Readers of Cutting Tool Engineering have likely made two observations about the modern machining industry.

First, the industry has experienced dramatic changes over the last 20 years. This point is proven by the bewildering variety of cutting tool geometries, substrates, coatings, toolholders, specialized machine tools, automation and software solutions available to modern manufacturers. Global competition, non-traditional materials and machine tools themselves have all driven the industry toward one fact: everything is designed to optimize the performance of the cutting tool in the cut. Specialized, high-performance tooling is now normative among high-volume manufacturers. In turn, the industry has found new ways to use this tooling, and this specialization has unlocked a silent surge of innovation across aerospace, automotive, medical, semiconductor and other industries.

Second, most undergraduate-level engineering education about machining processes hasn’t kept pace with technological advancements. The industry itself is starved for talent, and new graduates have very little context for making wise business decisions or pushing the technical boundaries of what machining can accomplish. Engineering students have usually made a few aluminum parts using low-quality tools, low-quality toolholders, and low-quality machines — with machining strategies that represent the state of the industry several decades old. Today’s world is starkly different. Material removal rates are higher, tolerances are tighter, surface quality is more controlled, and machined parts are smaller (or larger!) than most graduating engineers can imagine. Machine tools, software and automation are expected to accomplish what was impossible 20 years ago. The types of materials that can be profitably machined — and the rules and tools for machining those materials successfully — go far beyond any experience that a student might have had in a university lab.

This context is the motivation behind a new engineering course at Utah Tech University. The new course aims to create a wave of engineers who possess a fascination with the machining industry and a relevant foundation to navigate real-world decisions about modern machining processes.

Called “MECH 4990 – Modern Machining,” Utah Tech’s new course is a technical elective for junior and senior engineering students with an interest in manufacturing generally and machining processes specifically. The course is a mixture of technically deep lectures and challenging labs, but the approach is markedly different from that of most other universities. The entire course is based on one fundamental question: What do engineers need to know about modern machining processes?

Most undergraduate-level engineering education about machining is run as if it were a crash course for would-be machinists. Typically run by ex-machinists who certainly have valuable insight, these courses can train students to design or make one or two parts with moderate success. However, they lack elements needed to prepare engineers to make engineering decisions — decisions about creating parts repeatably, reliably and profitably. In these situations, details and decisions about cutting tools, toolholding, workholding, machining strategies, automation, software, and even machine kinematics have an enormous influence on the overall success and profitability of a process. In order to help engineers make wise decisions about modern machining processes, this course is distinguished by three core ideas.

Technical Depth
First, engineering students need more technical depth. It is unfortunate how many engineers and machinists graduate without any understanding of carbide substrate quality, what phenomena actually drive chatter, when to consider PCD tooling, or even an awareness of the differences between ISO material groups. Therefore, the technical depth of this course goes beyond what most engineers (and many trained machinists) may know.

The course begins with the physics and thermodynamics of chip formation, helping students understand fundamental phenomena that constrain machining processes: temperature and force. Students will see where heat is generated as the chip is formed, how cutting forces are affected by machining strategy or chip formation, or what work-hardening actually is. These fundamentals will be used to talk about how macro- and micro-geometry affects cutting tool performance. Students also will learn to identify geometries suitable for certain materials or cutting conditions. The course will include a significant discussion of sintered carbide substrate manufacture, morphology and coating — helping students understand the reasons for choosing particular substrates and coatings for particular applications. Alternative cutting tool materials like PCD, cermets and ceramics also will be covered.

Once the cutting process and tool construction is understood, the course will move on to a broader understanding of machining processes themselves. Lectures on machine kinematics and vibration will help students understand sources of dimensional error and poor surface quality. One lecture will introduce milling toolholder technologies — both tool and spindle side — comparing their relative benefits and limitations. Specific machining strategies like trochoidal or high-feed machining will be covered, and another lecture will discuss considerations for hole making and reaming.

Pulling all this information together, several lectures cover considerations for successfully machining each ISO material group, composites and ceramics. From there, students will discuss workholding, zero-point clamping, palletization and automation — learning how and why these solutions can affect cycle time and improve dimensional repeatability.

In each case, the goal is to tie technical topics to machining economics, helping students understand how small decisions can have a big impact on the productivity of a machine tool. Since the time spent cutting material is often (or should be!) the most significant limitation for a machining process, all aspects of the process — from the design of the machine tool to the cutting fluid to the software — exist to support what happens at the cutting edge. As tool designer Viktor Astakhov is known for saying, “productivity is literally determined on the tool cutting edge.” (Astakhov, Viktor P. High-Productivity Drilling Tools: Design and Geometry. CRC Press, 2nd ed. 19-20. )

Hands-on Learning
But this course is not merely theoretical. It is profoundly hands-on, which is the second core idea that distinguishes it from typical machining education. To be fair, hands-on experience with machining is not unique among engineering curricula. But in many cases those experiences are only minimally applicable to what engineers actually do. A student who has only ever machined individual aluminum parts with low-cost tools on a low-cost machine using a vise is simply unprepared to make decisions in a high-volume role.

This course aims to make hands-on experience more relevant. Students won’t simply hear a lecture about PCD cutting tools, they’ll be running tests in a real machine to measure how PCD cutting tools can reduce cycle time and improve surface finish. After a lecture about substrate quality and cutting tool geometry, students will test multiple endmills to their breaking point to compare how substrate quality and geometry affect material removal rate and surface finish. After a lecture about vibration and harmonics, students will measure the frequency response functions of an identical tool in different toolholders, generating stability lobe diagrams for each one. By intentionally using a tool in stable and unstable conditions, students will learn why pushing tools harder and faster can sometimes make a cut more stable.

The course will also include several projects specially designed to give students relevant experiences. They will machine a titanium or nickel impeller designed by students in another course. The choice of material is intentionally difficult, and the purpose is to put students in a situation where they need to think carefully about their tool selection and approach. Another project will require students to design a multi-operation part, and then design a process (selecting workholding, designing fixtures, etc.) to make 10 of those parts repeatably. They will write work instructions for a different student to machine their 10 parts while they record data like cycle time and spindle uptime.

One project in particular deserves special mention. After discussing the details of cutting tool geometry, students will use professional endmill design software to design their own endmill for a specific cutting scenario. Since this course will have 12 students annually, the plan is to find 12 companies that would be willing to grind one of these custom endmills every year. The students then will test these endmills in a competition to see who has designed the best endmill for a specific scenario. The project is bold and full of logistical challenges; but it promises to be an amazing experience for students who are already interested in the machining industry. Imagine interviewing at a cutting tool manufacturer and being able to talk about your experience designing and testing your own endmill.

The final project is perhaps the most real-world of all. Students will find a company doing machining, anywhere in the country, and work with them to identify a problem, pain point or question. Maybe a company wants to reduce cycle time, avoid burrs on a drilled hole, improve surface finish, machine without coolant, or reduce chatter on a specific feature. Students will discuss the issue, work with tooling manufacturers, run tests using Utah Tech’s tooling and machines, and then write a report that explains the financial and technical benefits of actionable solutions. Students may suggest that companies purchase a specific tool, a new toolholder or workholding solution. This project gives students a realistic connection with actual machining processes, and it provides an opportunity for tooling and workholding manufacturers who partner with Utah Tech to put their products in front of real companies in a very personal way.