AboutWillie Cutit Expertise Types of Tools to use on machining applications.
Experience My expertise is in cutting tools. Present job is Senior Applications Engineer with a major Indexable tooling line which supports turning, milling, boring and drilling.
Education/Credentials Tool and Die trade, over 25 years in the industry
Expert: Willie Cutit Date: 10/6/2007 Subject: About cutting tools
Question Good day to you...I have a project about topics in cutting tools..I've been researching in the internet but i can't find any website about machines or cutting tools...that's why i need the help of an expert...like you...
Here are the questions:
1.Explain the different operations involving the depth of cut, rake angle, wedge angle, shear plane, and clearance angle applying machine or hand cutting tools.
2.Describe the effect of cutting when adjusting the rake angle to the cutting tool of a shaping machine.
3.Estate the recommended rake angles and cutting speed for common engineering materials obtainable from published tables.
4.Describe the essential requirements when setting up tools, estating normal dimensional tolerance.
5.Describe the use of straight knife edge tools and oblique cutting tools.
6.Describe the following:
a. side rake angle
b. side clearance angle
c. approach angle
d. trail angle
e. direction of feed
f. side cutting edge
g. front clearance angle
h. back rake angle
7.Explain the difference between grinding and sharpening tools.
8.Describe the uses of the following cutting tools:
a. straight knife edge
b. straight roughing
c. facing knife-edge
d. facing roughing tool
e. straight parting tool
f. round nose tool
g. finishing tool
h. cranked tool
i. boring tool
9.Compare the use of a tool holder with that of a solid tool.
10.Describe the function of the cutting tool.
11.Compare the use of water soluble oil with that of lubricants.
12.Sketch the items listed on nos. 6 and nos. 8(not necessary to be answered...co'z its not a question...hehehe)
Answer Good day to you...I have a project about topics in cutting tools..I've been researching in the internet but i can't find any website about machines or cutting tools...that's why i need the help of an expert...like you...
Here are the questions:
1.Explain the different operations involving the depth of cut, rake angle, wedge angle, shear plane, and clearance angle applying machine or hand cutting tools.
Depth of cut in Turning operations is radial to the diameter going to center line. Axial for Milling. There are several rake angles to address, all addressing cutting forces for a given material. Side rake is relative to cutting edge. With positive cutting tools the rake is in the tool, for negative tools, the rake is relative to the position of the tool to the center line. Since there no clearance in negative inserts, clearance is provided by normally having a 5 to 7 deg negative rake and side rake for clearance to avoid rubbing. Shear plane is recognizing the shearing of metal at a given plane. the plane is relative to your cutting edge. A negative plane offers less shear, more pushing of the material, more horsepower and a stronger edge engaged in the cut zone. A positive plane reduces cutting forces offers freer cutting, less horsepower and a weaker cutting edge. Clearance is the angle below or behind the cutting edge.
2.Describe the effect of cutting when adjusting the rake angle to the cutting tool of a shaping machine.
Shaping machine eh, that's going back some years. Negative rake tools will offer a stronger edge and the cutting forces will address the full thickness of the cutting substrate. It will push material verses shearing the material. Positive rake angles comes in a various degrees and normally are dependent on the material you are cutting. Softer gummy materials would welcome a greater positive rake than say, hard materials, Having a suitable nose radius is also important in shaping relative to your feed rate and Depth of cut.
3.State the recommended rake angles and cutting speed for common engineering materials obtainable from published tables.
Generally speaking, Surface footage is relative to the cutting composite and hardness and tensile of the material you are cutting. Also the type of machine you are doing the job on comes into play. 25 years ago one would say that using carbide on a given material like CRS would be 3 times faster than HSS. Today cutting composites like carbide are engineered substrates with engineered chip breakers and enhanced coatings.
That being said:
Steels (RC up to 30)
HSS: 80-120SFM Positive rake 5 to 11Deg.
Carbide: 250-1200Sfm positive and negative rake. Speeds are dependant of DOC, Feed, machine, and hardness of cutting composite.
Cast Irons: Bhn 135-180
HSS : 70-110
Carbide: 250-850 SFM Cast iron is a short chip material, Negative rake angles will offer a stronger approach into work piece.
Aluminums
Hss: 180-300 High rake angles are recommended
Carbide: 900-5000 SFM Rake angles from 10 to 25 degrees. Silicon content will dictate SFM for this material. 8% and under will offer higher SFM. Over 9% and the need to moderate SFM is advised.
13% and over PCD diamond substrate will offer best results in production applications.
4.Describe the essential requirements when setting up tools, stating normal dimensional tolerance.
Always have your tools on center to the work piece relative to turning boring and single point threading applications. Have your tools close to the turret or compound for rigid setups. Most indexable tools are qualified for length with in .003". Tools come in many different shapes, all with engineered purposes. The common Indexable solution in turning applications is a 80 Degree diamond insert. This allows for on tools to turn and face. The more acute the angle, better the clearance for profiling or necking. Also a weaker cutting tool. For milling, use closest overhang condition for a given application. Normal rule of thumb is 2 X diameter for gage length. Lead angles on milling offers easier entry and exiting into a work piece. it will also thin the chip which offers the ability for increased feed rates.
5.Describe the use of straight knife edge tools and oblique cutting tools. This sounds like more of a wood working application verses a metal removal application.
6.Describe the following:
a. side rake angle : angle below the cutting edge entering the work piece
b. side clearance angle for brazed cutting tools or indexable tools, angle supporting side rake angle. ( larger angle than side rake angle
c. approach angle Can be positive, (cutting edge addresses work piece before nose radius, radial forces are increased) 0 deg approach, (depth of cut and cutting angle the same, least radial forces), Reverse lead angle,(nose radius enters the work piece first. for turning and facing
d. trail angle, Angle behind nose radius of the cutting tool. Certain materials like titanium have high tensile and can spring back while cutting. Higher trail angles will address issues like this, Also offers ability to profile.
e. direction of feed: controls longitutal forces against the cutting edge. Normally recognized as feed per rev in turning, boring. Feed per tooth, feed per rev, inches per minute of millimeters per minute in milling.
f. side cutting edge: The edge you are shearing the material with
g. front clearance angle: Angle behind front rake angle
h. back rake angle: coming from the front of the tool to the back of the cutting composite. Positive back rake angles offers less tangential forces and freer cutting. Negative back rake angles offers high tangential forces, forces are going directly into cutting composite.
7.Explain the difference between grinding and sharpening tools. I'm going to throw a dart on the wall with this one as the question hasn't been thrown in the mix that often. I will say that grinding tools is the process of creating a tool to a given print or feature with a given tolerance. Sharpening tools might fall in line with reconditioning of tools.
8.Describe the uses of the following cutting tools:
Some of these terms might be relating to wood tools which is not my expertise.
a. straight knife edge
b. straight roughing
c. facing knife-edge
d. facing roughing tool : Cutting edge is facing the work piece to center.
e. straight parting tool : for cutting off the work piece, a blade which will have a neutral face or left or right hand face
f. round nose tool: Guessing for wood operations for multi directional operations. Also for blending
g. finishing tool: for light depths of cuts,
h. cranked tool ???
i. boring tool ID boring operations
9.Compare the use of a tool holder with that of a solid tool. I will relate this relative to an indexable tool verses a brazed on carbide tool or HSS tool. Indexable tools offers the ability to address a host of materials, nose radiuses Depths of cuts by changing the insert. It saves time and money. Brazed on or solid HSS tools addresses special operations where indexables tools don't offer a standard solution due to clearances, widths, or cutting forces. Grinding a solid tool is a dying art, one that all machinists should master and understand. Being able to make a tool to address a feature like nose radius, or machining thin wall work pieces or soft materials will given the machinist a better understanding of cutting forces.
10.Describe the function of the cutting tool. The ability to shear material from a given work piece recognizing the hardness, tensile and cutting forces of a given operation.
11.Compare the use of water soluble oil with that of lubricants.
Water soluble oils offers the combination of cooling, the work piece, flushing of chips and lubricity to the cutting edge. There is an emulsifier chemical mixture to have oil mix with water. There are soluble oils which have the highest lubricity characteristics (25 to 70% boundary oils), Semi synthetics which are a combination of chemical and boundary lubrication (5 to 25% boundary oils) and Synthetics, ( straight chemical lubricity) Straight oils are addressed in operations where machine lubrications and cutting tools lubrication is needed. Screw machines are a good example for straight oil lube.
