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Mill Cutters

Mill Cutters. http://www.jjjtrain.com. CHSE Lance Tatro 2010. Vocabulary Terms and Words.

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Mill Cutters

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  1. Mill Cutters http://www.jjjtrain.com CHSE Lance Tatro 2010

  2. Vocabulary Terms and Words Feed Rate: The unit distance divided by a time scale that a tool travels while machining. Usually the unit distance is "inches" and the time scale is "minutes". The resultant rate is then expressed as "inches per minute" (or i/m or IPM) High Speed Steel: Refers to steel that can cut at a higher speed than other tool steels. Cobalt: Atough lustrous silver-white magnetic metallic element that is related to and occurs with iron and nickel and is used especially in alloys. Carbide: In the machine shop this usually refers to cutting tools made of cemented tungsten carbide and cobalt. Flute: Refers to the undercut of the cutting edges of multi-edged end mills, reamers, drills, and other cutting tools. http://www.jjjtrain.com CHSE Lance Tatro 2010

  3. Objectives By the end of this lesson, you should beable to: • Compare and contrast different cutting and finishing tools for the mill. • Identify the different materials used to make mill cutters. • Understand lubricating fluids and which fluid is best for a given cutting situation. CHSE Lance Tatro 2010

  4. Cutter Materials and Styles • HSS • Cobalt • Carbide • Coated • Single-end • Double-end High Speed Steel • Inexpensive and exists in many sizes but has a limited cutting capacity. • Excellent for aluminum , mild steel, and other soft metals. Cons • It will not cut very hard steels. CHSE Lance Tatro 2010

  5. Cutter Materials Cont… Cobalt Cutters • Improved hardness over the HSS end mill. • Will stay sharper longer. Cons • More brittle. Solid Carbide Cutters • Increased hardness. • Allows the machining of many types of materials. • More costly than Cobalt Cutters and HSS cutters. CHSE Lance Tatro 2010

  6. Cutter Materials Cont… Coated Cutters • Has a solid carbide or HSS body with a coated cutting edge. • Last longer and allows the machine to run at a greater cutting speed. *Titanium Nitrite coating is most popular coating. Double End Mills • They cost less to purchase as compared to two single-end end mills. Cons • Limited in size • Will not fit in some collets when size is increased. CHSE Lance Tatro 2010

  7. End Mills Multi-flute: Center Cut and better finish. End Mills • Cutters that have an end-cutting capability. • Machine on the end as well as the sides. • There are two types of helixes used on end mills: right end and left end. Note • You must be thinking about chip removal to decide which one you want to use. • A convention is usually that the cutter is right ended if it rotates counterclockwise when viewed from the cutting end. Double-flute: Center Cut and faster cutting. Multi-flute: Will not plunge, so you need to start off the material http://www.jjjtrain.com/vms/cutting_tools_mill/cutting_tools_mill_02.html CHSE Lance Tatro 2010

  8. Speed This term is used quite often to denote the calculation of spindle speed in RPM  Calculating Proper Speed: RPM = (CS x 4 ) / D RPM = Revolutions Per Minute CS = CS is the Cutting speed of the particular material D = Diameter of the cutter CHSE Lance Tatro 2010

  9. Feed Rate • The motion of moving the work piece and the cutting tool together so as to remove material. • Feed = RPM x Chip load per tooth x Number of teeth on cutter • Chip loads can be found using The Machinery's Handbook or the manufacturers specifications. CHSE Lance Tatro 2010

  10. Standard Speeds and Feeds CHSE Lance Tatro 2010 http://www.niagaracutter.com/techinfo/millhandbook/speedfeed/chart1.gif

  11. Special Cutters • Fast-Spiral End Mills • Used when machining relatively soft materials that will get hot easily. • Allows for fast removal of the chip and reduces heat transfer to the work piece. Roughing Cutter • Their flutes are truncated to break chips thus reducing horsepower requirement. http://www.jjjtrain.com CHSE Lance Tatro 2010

  12. Special Cutters Cont… Key Slot Cutters • Used to machine key-slots in shafts. Dove Tail End Mills • Used to machine dove tail shapes in the work piece. http://www.jjjtrain.com CHSE Lance Tatro 2010

  13. Special Cutters Cont… Ball Nose End Mills • Used when the work piece requires a 90 degree concave fillet or when machining a three dimensional surface Corner Rounding • Used to make a 90 degree convex radius on a work piece edge. • Useful for esthetic removal of a sharp corner. http://www.jjjtrain.com CHSE Lance Tatro 2010

  14. Special Cutters Cont… The T-slot Cutter • Designed to cut slots similar to the slots in the top of a machine table Concave Cutters • Can cut a full 180 degree arc on a work piece if the work piece is the same width as the cutter. A Convex End Mill • Cuts a perfect 180 degree U shaped groove. CHSE Lance Tatro 2010 http://www.jjjtrain.com

  15. Cutting Fluids Visit • http://www.jjjtrain.com/vms/cutting_tools_mill/cutting_tools_mill_04.html Guided Practice Read the webpage and answer the following questions: • What is best used when cutting cast iron? • What is the disadvantage of using synthetic fluid when cutting polypropylene plastic? • What are emulsions? • What are some of the problems with using water as a cutting/cooling fluid? You have 15 minute to research these question CHSE Lance Tatro 2010

  16. Answers to the questions…. When machining cast iron with carbide end mills, it is often recommended to use compressed air rather than cutting fluid to enhance tool life. When machining polypropylene plastic, using a synthetic cutting fluid the plastic will absorb the cutting fluid making it grow in size temporarily. Emulsions (mostly water) - also called soluble oil, emulsifiers keep it mixable, 3 to 10% concentration Good lubrication & heat transfer but not as good as chemical fluids. More inexpensive than chemical fluids. Using water as a cutting fluid has two problems. • Water will rust the machine and possibly the work piece. • Plain water does not spread evenly. Chemical waters spread out over the part more uniformly and can therefore remove heat much more efficiently. CHSE Lance Tatro 2010

  17. Homework… • Use the provided worksheets to help you determine what you have learned. • Look at each of the pictures and provide the type of cutter that it is, what it is used for, and any negatives that might be associated with that cutter. • You will be graded on your accuracy and appropriateness of the information you provide. CHSE Lance Tatro 2010

  18. Teacher Information Sheet • Description: • Students will learn about mill cutters and lubricating fluids for machine finishing using the mill. • Standards: • California: Manufacturing and Product Development Industry Sector • Foundational: 2.2 Writing (1.4); 5.0 Problem Solving (5.3) • Pathway:C2.1, C3.2, C4.2, C6.1, C6.2 • Teacher Performance Expectations: TPE 1, TPE2, TPE 3, TPE 5, TPE7, TPE 9, • TPE10, TPE 12 • SDAIE Strategies: Modeling, Bridging, Contextualization • Objectives: • By the end of the lesson, students should be able to: • Compare and contrast different cutting and finishing tools for the mill. • Identify the different materials used to make mill cutters. • Understand feed rates and necessary speeds for proper cutting. • Understand lubricating fluids and which fluid is best for a given cutting situation. Resources: The Virtual Machine Shop (http://www.jjjtrain.com) Selection of Speeds and Feeds and Cutting Tool Materials (http://www.niagaracutter.com/techinfo/millhandbook/speedfeed/chart1.gif) CHSE Lance Tatro 2010

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