MFG240 Name___________________ March 19, 2014 100 points Must be typed except ca
ID: 2995011 • Letter: M
Question
MFG240 Name___________________
March 19, 2014
100 points
Must be typed except calculations. They can be written
1) (3 points) Why is machining so difficult to analyze
For the following show all work. If there is something not included, make an assumption and WRITE it down. 5 points each unless otherwise specified
2) (10 points) I have an unknown material in which I have been asked to turn for an experiment. The people contracting me want to know the shear strength of the material. I measure the cutting force at 400 lbs and the thrust force at 285 lbs. The tool I am using has a rake angle of 8
Explanation / Answer
Knowing that the goal of any manufacturing project is to reduce costs and make you more competitive, our team of mechanical and manufacturing engineers will work in partnership with your company to recommend the best possible solution for the greatest return on investment. Realizing that some of our best ideas come from our customers, our approach to engineering solutions is to take our combined talent, and your manufacturing knowledge, to design equipment that will exceed your performance expectations for years to come. Technology Resources? We support what we build! From onsite testing, installation, startup assistance, training and field service, no one is more committed to your success than we are. Our track record speaks for itself. It is easy to see why our customers are repeat customers. We guarantee the highest quality materials, manufacturing methods, and OEM components available. Our equipment warranty on all of our standard and custom equipment demonstrates that we stand behind the equipment we build. In terms of annual dollars spent, machining is the most important of the manufacturing processes. Machining can be defined as the process of removing material from a workpiece in the form of chips. The term metal cutting is used when the material is metallic. Most machining has very low set-up cost compared to forming, molding, and casting processes. However, machining is much more expensive for high volumes. Machining is necessary where tight tolerances on dimensions and finishes are required.
4) Reduced friction in cutting reduces heat in the chip and tool, and this will prolong tool life. The reduced friction also decreases the wear rate and prolongs tool life.
5) operating conditions, cutting tool material and geometry,
6) Anyone who is even casually involved with a machining process knows that cutting tools generate large amounts of heat. Heat is generated in three ways; by the deformation of the metal in the shear zone ahead of the cutting edge, at the point of separation when the metal is physically pulled apart and by the friction of the chip as it rubs along the surface of the tool as it is pushed out of the way. In fact, much of the horsepower drawn at the spindle motor winds up as heat which is concentrated in a very small area at the cutting edge of the tool, and in the chip itself.
7) flank wear in which the portion of the tool in contact with the finished part erodes. Can be described using the Tool Life Expectancy equation. crater wear in which contact with chips erodes the rake face. This is somewhat normal for tool wear, and does not seriously degrade the use of a tool until it becomes serious enough to cause a cutting edge failure. Can be caused by spindle speed that is too low or a feed rate that is too high. In orthogonal cutting this typically occurs where the tool temperature is highest. Crater wear occurs approximately at a height equaling the cutting depth of the material. Crater wear depth ~ t0 t0= cutting depth built-up edge in which material being machined builds up on the cutting edge. Some materials (notably aluminum and copper) have a tendency to anneal themselves to the cutting edge of a tool. It occurs most frequently on softer metals, with a lower melting point. It can be prevented by increasing cutting speeds and using lubricant. When drilling it can be noticed as alternating dark and shiny rings. glazing occurs on grinding wheels, and occurs when the exposed abrasive becomes dulled. It is noticeable as a sheen while the wheel is in motion. edge wear, in drills, refers to wear to the outer edge of a drill bit around the cutting face caused by excessive cutting speed. It extends down the drill flutes, and requires a large volume of material to be removed from the drill bit before it can be corrected.
8) a) Cutting tool should be more harder than the material to be cut otherwise it can break uring the process
b) Cutting tool should be tough well ,there is much difference between the word hard and tough. Hardness implies resistance to scratch wheres toughness measure ability to withstand shock.
c) The toll should be able to withstand the heat generated in the metal cutting process . Also the tool must have a specific geometry designed so that the cutting edge can contact the workpiece without the rest of the tool dragging on the surface of the piece part surface . The angle of the cutting face is also important must be able to withstand the heat generated in the metal cutting process. The angle of the cutting face is also important as is the flute width , tool margin and tool material
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