Toolmakers publish chip load recommendations along with cutting speed recommendations and express them in thousandths of an inch (millimeter for metric units). For milling and drilling operations, chip load is expressed in thousandths of an inch per flute. Flutes, teeth and cutting edges all describe the same thing and there must be at least one, but, in theory, there is no limit to the number a tool can have.

SAFE 1023 - Safety Basics – Lock-out Tag Out Lock-out Tag Out introduces students to the hazards related to energized systems and procedures to ensure worker safety. Related legislation and risk management is discussed and the student is exposed to the various types of lock-out devices. The course material is to be infused throughout the curriculum and may be delivered in the classroom, shop or other opportunity as designed and developed by the instructor.

Cutting speed calculations might well be the most important ones. They are easy to use and, with a little explanation, easy to understand. The cutting speed of a tool is expressed in surface feet per minute (sfm) or surface meters per minute (m/min.). Similar to mph for a car, sfm is the linear distance a cutting tool travels per minute. To get a better sense of scale, 300 sfm, for example, converts to 3.4 mph.

Here is where things get interesting, because by changing the values in the formula, the relationships of the different variables become evident. Try applying a 2" tool instead of the 1" tool. What happens? The rpm and feed rate decrease by half.

PRMA 1001 - Drills, Drill Presses and Grinders This course introduces machine shop drilling and grinding machines including sensitive, upright and radial arm, and drill presses, as well as the safe practice for the use of these machines and their attachments. Course materials include adjusting, repairing and maintaining these machines and their accessories, various drilling tools and drill sharpening. The course introduces the selection, handling and safe use of cutting fluids.

PRMA 2004 - Introduction to Computer Numerically Controlled Machining This course provides a basic introduction to modern machining methods used with Computer Numerically Controlled (CNC) machine tools. Course material covers the operating principles and basic procedures, terminology and coordinate systems. Projects reinforce shop safety and add the safety considerations specific to CNC machine tools.

Lathes are different, of course, because the workpiece rotates instead of the cutter. Because the formula for cutting speed is dependent on diameter, as the diameter of the workpiece decreases, rpm must increase to maintain a constant surface speed. After each circular cut on the lathe, the workpiece OD decreases or the ID increases, and it is necessary for the rpm of the part to increase to maintain the desired cutting speed. As a result, CNC manufacturers developed the constant surface footage feature for lathe controls. This feature allows the programmer to input the desired cutting speed in sfm or m/min. and the control calculates the proper rpm for the changing diameter.

Machining operation in which metal or other material is removed by applying power to a rotating cutter. In vertical milling, the cutting tool is mounted vertically on the spindle. In horizontal milling, the cutting tool is mounted horizontally, either directly on the spindle or on an arbor. Horizontal milling is further broken down into conventional milling, where the cutter rotates opposite the direction of feed, or “up” into the workpiece; and climb milling, where the cutter rotates in the direction of feed, or “down” into the workpiece. Milling operations include plane or surface milling, endmilling, facemilling, angle milling, form milling and profiling.

Develop skills to interpret engineered drawings and use precise measurements and hand tools to create custom parts and perform repairs with conventional hand-controlled methods.

PRMA 1003 - Turning Operations I This course introduces learners to metal cutting lathes and their operations. Course material covers lathe operation, set-ups, maintenance and machine construction. The course offers learners the opportunity to practice safe methods of operation of the lathe in the shop.

About the Author: Christopher Tate is senior advanced manufacturing engineering for Milwaukee Electric Tool Corp., Brookfield, Wis. He is based at the company’s manufacturing plant in Jackson, Miss. He has 19 years of experience in the metalworking industry and holds a Master of Science and Bachelor of Science from Mississippi State University. E-mail: chris23tate@gmail.com.

PRMA 1007 - Mathematics II Learners are introduced to mathematical problems commonly encountered by machinists. Topics include formula applications, plane geometry, and trigonometry, with the emphasis on the solution of problems relating to a wide range of shop applications.

SAFE 1021 - Safety Basics – Hazard Identification The learners are introduced to the types of hazards encountered in workplaces and the approach that should be followed when recommending and implementing appropriate controls. Two key elements of Hazard Identification are addressed: Hazard Assessment and Inspection. The Nova Scotia Occupational Health and Safety Act is discussed. The course material is to be infused throughout the curriculum and may be delivered in the classroom, shop or other opportunity as designed and developed by the instructor.

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PRMA 1100 - Work Experience The work experience component provides the learner with an opportunity to apply new skills and concepts appropriate for entry-level positions within the machining and manufacturing industry. Learners will assess their own performance and be evaluated by an industry partner. Learners will identify personal outcomes they wish to attain during the work experience and will keep a journal.

What is machining in Engineering

Workpiece is held in a chuck, mounted on a face plate or secured between centers and rotated while a cutting tool, normally a single-point tool, is fed into it along its periphery or across its end or face. Takes the form of straight turning (cutting along the periphery of the workpiece); taper turning (creating a taper); step turning (turning different-size diameters on the same work); chamfering (beveling an edge or shoulder); facing (cutting on an end); turning threads (usually external but can be internal); roughing (high-volume metal removal); and finishing (final light cuts). Performed on lathes, turning centers, chucking machines, automatic screw machines and similar machines.

Understanding these relationships and applying some creative thought can provide significant gains in efficiency. I will discuss how to take advantage of these relationships in my next column. CTE

Machining process

Value that refers to how far the workpiece or cutter advances linearly in 1 minute, defined as: ipm = ipt 5 number of effective teeth 5 rpm. Also known as the table feed or machine feed.

Microprocessor-based controller dedicated to a machine tool that permits the creation or modification of parts. Programmed numerical control activates the machine’s servos and spindle drives and controls the various machining operations. See DNC, direct numerical control; NC, numerical control.

Because the tool diameter is measured in inches, the “feet” in sfm must be converted to inches, and because there are 12 inches in a foot, multiply sfm by 12. In addition, the circumference of the tool is found by multiplying the tool diameter by π, or 3.14 to simplify. The result is: rpm = (sfm × 12) ÷ (diameter × π) = (sfm ÷ diameter) × (12 ÷ π) = (sfm ÷ diameter) × 3.82.

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Turning machine capable of sawing, milling, grinding, gear-cutting, drilling, reaming, boring, threading, facing, chamfering, grooving, knurling, spinning, parting, necking, taper-cutting, and cam- and eccentric-cutting, as well as step- and straight-turning. Comes in a variety of forms, ranging from manual to semiautomatic to fully automatic, with major types being engine lathes, turning and contouring lathes, turret lathes and numerical-control lathes. The engine lathe consists of a headstock and spindle, tailstock, bed, carriage (complete with apron) and cross slides. Features include gear- (speed) and feed-selector levers, toolpost, compound rest, lead screw and reversing lead screw, threading dial and rapid-traverse lever. Special lathe types include through-the-spindle, camshaft and crankshaft, brake drum and rotor, spinning and gun-barrel machines. Toolroom and bench lathes are used for precision work; the former for tool-and-die work and similar tasks, the latter for small workpieces (instruments, watches), normally without a power feed. Models are typically designated according to their “swing,” or the largest-diameter workpiece that can be rotated; bed length, or the distance between centers; and horsepower generated. See turning machine.

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Machinists produce precise parts based on technical engineered drawings. You learn how to do this by operating conventional hand-controlled methods, including:

So what is this telling us? Let’s say a 1"-dia. tool must run at 100 sfm. Based on the equation, that tool must turn at 382 rpm to achieve 100 sfm: 100 ÷ 1 × 3.82 = 382.

Toolmakers recommend cutting speeds for different types of workpiece materials. When a toolmaker suggests 100 sfm, it is indicating the outside surface of the rotating tool should travel at a rate of speed equal to 100 linear feet per minute. If the tool has a circumference (diameter × π) of 12", it would need to rotate at 100 rpm to achieve 100 sfm.

Cutting speeds are published in sfm because the ideal cutting speed for a particular family of tools will, in theory, be the same no matter the size of the tool. The engineer, programmer or machinist is expected to calculate the rpm needed to produce the proper cutting speed for each selected tool.

Chip load recommendations for turning operations are most often given in thousandths of an inch per revolution, or feed per rev. This is the distance the tool advances each time the part com-pletes one rotation.

Machining examples

PRMA 2000 - Engineering Drawings II This course is designed to provide learners with the technical skills to interpret detailed engineering drawings. Learners are instructed in the application of tolerances, fits, threads and sectional views for the production of machined parts.

SAFE 1000 - Introduction to WHMIS (Workplace Hazardous Materials Information Systems) This course offers learners basic overview of WHMIS principles and establishes a solid foundation to support workplace-specific training on the safe storage and handling of controlled/hazardous products. Upon successful completion of the course, students receive basic WHMIS certification.

Machining process steps

PRMA 1004 - Milling Operations I This course introduces learners to basic milling operations. Course material includes milling machine operation, set up, maintenance and machine construction. Learners have the opportunity to apply safe methods of operation of the milling machine and practice milling operations in the shop.

While this program focuses on hand-controlled methods, you also learn the fundamentals of computer numerical control (CNC). With CNC, a computerized machine is programmed to do detailed work and automation.

These are some of the courses offered in this program. It is not a complete list and courses are subject to change in advance of the academic year.

PRMA 1006 - Mathematics I This course will reinforce basic mathematical concepts and operations used in machining. The topic areas include whole numbers, fractions, ratio and proportion, rectangles and triangles, regular polygons and circles, solids and metric measure.

In addition to annual tuition, there are program costs (books, tools, etc.) and student fees for College services, health and dental plans, your student association and parking.

Machining definition in manufacturing

Machining is a critical part of industrial production. Many businesses and sectors rely on machinists to maximize overall performance and output.

Another way to consider this concept is to think about the distance the 1" tool would travel were it to make 382 revolutions across the shop floor. In that scenario, it would travel 100'; do it in 60 seconds and it would be traveling 100 sfm.

CNC machining

Any manufacturing process in which metal is processed or machined such that the workpiece is given a new shape. Broadly defined, the term includes processes such as design and layout, heat-treating, material handling and inspection.

PRMA 2002 - Milling Operations II This course builds on the skills and knowledge gained in Milling Operations I. Theory and project work will cover will cover information pertaining to indexable carbide tooling and more advanced work holding methods and set-ups.

The following equation is used to calculate spindle speed: rpm = sfm ÷ diameter × 3.82, where diameter is the cutting tool diameter or the part diameter on a lathe in inches, and 3.82 is a constant that comes from an algebraic simplifica-tion of the more complex formula: rpm = (sfm × 12) ÷ (diameter × π).

Surface feet per minute, chip load, undeformed chip thickness and chip thinning are familiar shop terms. Over the last few weeks, however, several occurrences in our shop have made me realize there are a lot of metalworking professionals who don’t understand these terms and the calculations that go along with them. Whether you work at a small job shop or a large contract manufacturer, it is important to understand cutting tool calculations and how to use them to help drive significant efficiency gains.

Tangential velocity on the surface of the tool or workpiece at the cutting interface. The formula for cutting speed (sfm) is tool diameter 5 0.26 5 spindle speed (rpm). The formula for feed per tooth (fpt) is table feed (ipm)/number of flutes/spindle speed (rpm). The formula for spindle speed (rpm) is cutting speed (sfm) 5 3.82/tool diameter. The formula for table feed (ipm) is feed per tooth (ftp) 5 number of tool flutes 5 spindle speed (rpm).

Machining pronunciation

PRMA 2003 - Turning Operations II This course builds on the skills and knowledge gained in Turning Operations I. Theory and project work covers the use of the lathe and carbide tools in turning between centres and taper turning. Learners use common set-ups and procedures for lathe operation.

PRMA 1005 - Engineering Drawings I This course gives the learner an overview of engineered drawings and their use in the Machinist trade. Course material includes engineering lines and symbols, parts and types of drawings and their purpose. The course also introduces sketching. Learners develop the ability to interpret drawings for use in the accurate machining of parts.

Angle between the side-cutting edge and the projected side of the tool shank or holder, which leads the cutting tool into the workpiece.

Types of machining process pdf

WORK 1100 - Workplace Mentoring I This unit of instruction is designed to assist learners in managing their learning as an apprentice in the workplace. Learners will study their own experiences with learning new skills and identify their own learning preferences as an aid to developing learning strategies.

What rpm and feed rate should be programmed for a 4-flute, 1" endmill, running at a recommended cutting speed of 350 sfm and a recommended chip load of 0.005 inch per tooth (ipt)? Using the equation, rpm = sfm ÷ diameter × 3.82 = 350 ÷ 1.0 × 3.82 = 1,337, the feed rate = rpm × no. of flutes × chip load = 1,337 × 4 × 0.005 = 26.74 ipm.

Milling cutter held by its shank that cuts on its periphery and, if so configured, on its free end. Takes a variety of shapes (single- and double-end, roughing, ballnose and cup-end) and sizes (stub, medium, long and extra-long). Also comes with differing numbers of flutes.

INDR 1010 - Industry Readiness A crucial component of trade practice is the ability to share information. Explaining work, applying trade skills and meeting industry standards involves communicating effectively. This course introduces these skills with a trade focus and will help prepare students to contribute to employment and in the classroom. Course work may tie directly to projects and assignments happening elsewhere in the program and in its shops.

PRMA 1000 - Safety, Tools and Basic Measurement Safety is the first consideration in machine shop operations. This course will introduces learners to general shop safety, safe rigging practices, WHMIS and Occupational Health and Safety. Course activities enable learners to identify common machine shop hazards, perform safe rigging for the machine shop, and understand their rights in safety matters. This course will also cover safe use of the common hand tools and devices used in machine shop work. Learners will be taught how to select the proper tools and demonstrate the correct use and maintenance of those tools. Course material introduces the theory and use of common machine shop semi-precision and precision measuring tools, both metric and imperial. Care, maintenance, adjustment and calibration of these measuring tools are addressed.

SAFE 1001 - Introduction to NS OH&S Act This course offers students an introduction to the Occupational Health & Safety (OH&S) Act of Nova Scotia, which is required by any person employed in a Nova Scotia workplace. This is a generic, introductory course that provides basic knowledge of the Act for students and is considered to be the basis from which more specific training can be given.

Feed rate for milling is usually expressed in inches per minute (ipm) and calculated using: ipm = rpm × no. of flutes × chip load.

While the tool or part is spinning, the machine must know how fast to travel while the cutter is engaged in the workpiece. Feed rate is the term that describes the traverse rate while cutting.

Notice the vertical lines, called tool marks, on the outside of the part being turned. As the feed rate increases, the distance between the lines also increases. The chip thickness is roughly equal to the feed.

Grooves and spaces in the body of a tool that permit chip removal from, and cutting-fluid application to, the point of cut.

Value that refers to how far the workpiece or cutter advances linearly in 1 minute, defined as: ipm = ipt 5 number of effective teeth 5 rpm. Also known as the table feed or machine feed.

INDR 1020 - Working Effectively in the Trades Almost all trades professionals will need to work well with others. Students in this course will learn to be effective team members and adapt and analyze how they share information with others. A selection of activities relevant to the particular trade will be used to practice collecting, analyzing and using trade information. Course work may tie directly to projects and assignments happening elsewhere in the program and in its shops.

PRMA 2001 - Introduction to Precision Measurement This course builds upon Introduction to Measuring Tools I and covers of all forms of measuring devices and methods, both metric and imperial, used in machine shop work. Using all types of measuring tools with confidence and reliability is one of the machinist's primary skill sets. Course material covers the theory and use of machine shop precision measuring tools. Learners practice proper care, maintenance, adjustment, calibration and use of these measuring tools.

Imagine the cutting tool as a rolling ring or cylinder. The distance traveled in one revolution times rpm is its surface speed. If the circle above had a diameter of 3.82", the circumference would be 12". As a result, every revolution would produce a linear distance of 1', and a spindle speed of 100 rpm would be a cutting speed of 100 sfm.

What is chip load? When milling, it is the amount of material that the cutting edge removes each time it rotates. When turning, it is the distance the part moves in one revolution while engaged with the tool. It is sometimes referred to as chip thickness, which is sort of true. Chip thickness can change when other parameters like radial DOC or the tool’s lead angle change.