Rants and Raves regarding carbide inserts, cbn inserts, ceramic inserts, cermet inserts, and inserts in general. Occassionaly will take about nothing, and sometimes other cutting tools. Most of all a resource for information on cutting tools.
1. Use a tool that has higher thermal-conductivity Low thermal-conductivity of stainless steels accelerates tool wear resulting from a decline in hardness of the cutting edge of an insert, this is due to heat piling up. It is better to use a tool that has higher thermal conductivity and with enough coolant.
2. Sharper cutting edge-line It is necessary to utilize larger rake-angles and wider chip-breaker lands to reduce cutting-load pressue and prevent build-up on the edge. This will help provide better chip control to an operator.
3. Optimal cutting condition Inappropriate machining conditions like extremely low or high speeds or low feeds can cause poor tool life due to work hardening of work pieces.
4. Choose an appropriate tools Tools for stainless steel should have good toughness attributes, enough strength on their edge line (cutting edge) & a higher film adhesion.
Korloy offers three grades turning stainless steel:
Lose a screw, lock pin, or clamp for your boring bar or toolholder? Wondering what the heck a lock pin or clamp is? Use the following guide to help you sort out what you may need in replacement parts for boring bar or tool holders. Find a definition of each component below the picture.
Here is a diagram (click on image to enlarge) of a Multi-Lock Tool Holder courtesy of Dorian Tool:
INSERT Either conventional type or chipbreaker type may be used.
LOCK PIN A solid locking pin for permanent locating of the insert.
SHIM SCREW Reusable shim screw locks carbide shim into toolholder.
CARBIDE SHIM Forms a firm seat for insert. Fastened to the shank, but easily replaceable. Protects against damage to toolholder.
CLAMP Maximum retention clamp is made of high alloy steel, heat treated. Broad clamp nose provides positive clamping action. Clamp is positioned to allow for maximum insert retention, with or without chipbreaker.
CLAMP SCREW Rugged Clamp Screw provides maximum clamping strength.
CHIPBREAKER Solid carbide, for use when chip control is needed. Available in a range of standard chipbreaker widths.
Most toolholders and boring bars accept generic shim seats, screws, clamps, and pins. This includes tools from Valenite, Sandvik, Kennametal, and Iscar. Check your manufacturers catalog to be sure of the replacement items part number.
PCD Tipped Brazed Boring Tool. For Bore sizes smaller than 8 mm in diameter. PCD is brazed directly to a tungsten carbide shank providing a rigid boring tool capable of remarkable surface finishies and providing a high productive alternative to internal grinding.
For Bore sizes smaller than 8 mm in diameter, it is not possible to use PCD tipped cutting tool inserts. In order to put a PCD tip into the carbide insert, material must be removed. This makes the insert weak and prone to breakage when it is clamped into the boring bar. At the same time, clamping of small inserts into small boring bars becomes progressively more difficult as the bore size reduces.Top clamps trap swarf and, in order to fit inside the bore, become too small to exert enough clamping pressure. Screw locked inserts, while leaving space for swarf, require sufficient material under the insert for the thread of the clamping screw. These problems are overcome by using brazed tools. The PCD tip is brazed directly to a tungsten carbide shank providing a rigid boring tool capable of remarkable surface finishes and providing a highly productive alternative to internal grinding.
VALENITE INTRODUCES NEW TURNING GRADES FOR FINISHING, SEMI-ROUGHING STAINLESS STEELS
Valenite LLC has introduced two new tooling grades—expanding its targeted and application-specific lineup that allows users to better match machining operations and workpiece materials with tooling inserts for optimum production efficiencies, quality and economies. The new cutting technologies are the ValProTM VP8515 and VP8525 MT-CVD series of inserts. Both are being developed to augment the existing VP8535 grade and provide a complete range of turning capabilities for 304 and 316 stainless steels, Inconel and heat resistant alloys. The VP8515 is for finishing operations and the VP8525 is used for general duty semi-roughing/finishing. The existing VP8535 is for heavy metal removal tasks and roughing operations.
The VP8515 grade is set for high cutting speed (>200 m/min) at typical finishing
cut depths and has broad applicability with F5, M4, M6, M8, PM2, PM5 geometries. This grade is ideal for continuous turning of austenitic and duplex stainless steels at higher speeds providing reliable and predictable performance, with extended insert service life. Inserts using VP8515 grade have a thin yellow TiN outer coating for easy visual wear identification, an Al2O3 layer for thermal protection, a fine MT-CVD TiCN coating that helps to prevent flaking and reduces flank wear. Also incorporated in the tooling is a gradient area for added surface toughness, and a hard substrate offering greater resistance to wear and plastic deformation.
The TiCN/Al2O3/TiN coating is formulated specifically for turning of stainless steels and to resist sticking, notch wear and edge build-up, for enhanced hardness when hot.
The VP8525’s performance characteristics deliver high cutting speeds (>150 m/min) with mid- to large cutting depths...inserts have M4, M6, M8, R9, PM4, PM5 geometries to cover a myriad of cutting parameters. This grade is a basic choice for general duty M-class turning—continuous or intermittent cutting of austenitic and duplex stainless steels. These tools reduce the risk of plastic deformation and, like the VP8515, provide reliable performance and extended tool life. The VP8525 grade has similar coating technologies, layering and substrate construction as the finishing grade, including the TiCN/Al2O3/TiN coating for the efficient turning of stainless steels.
To produce hubs, rods, bushes, pulleys and shafts, CNC turning is utilized where the lathe generates materials after inserting the single cutter point in to the material turning. The procedure of cutting is executed through a cutting tool which is applied either parallel or at right angle to the axis, of work piece. The tool may also be fitted at an angle relative to the work piece axis for the machining angles and tapers. The work piece may be of any cross section, but the machine surface should be straight and tapered.
There are various shapes available in CNC like pointed, simple, radius with profile added with threaded surface, curve and fillet. CNC machining is more economical than the CNC milling for producing the actual form through CNC turning. The material used for CNC turning possesses various qualities like material of work piece should be firm and can be of solid plastics. For the short running procedure of the mill, arrangements or alternative machine should be kept. CNC turning reduces the cost by minimizing the design elements.
CNC turning procedure is done through applying pressure on the work piece or the weaker material to form the flexible shapes of the material. Sometimes through CNC, the cut surface is formed by applying the helical feed as it results in rotation. The cutting procedure through which the work piece is eliminated from a material block by the help of the rotation of the tool is known as CNC milling. The work piece can rotate in perpendicular or circular way to produce different shapes and sizes. The cutting tool generally rotates in the CNC milling at an axis in a perpendicular form on the podium to generate various structures.
Variety of shapes that can be formed through CNC milling is 3D or 2D and some compound structured material. CNC milling for short procedure is also very economical. It is utilized to make different parts of engine, multifaceted mechanisms, enclosures and mold and custom tooling.
Thus, is a very effective procedure to make various machine parts of various shapes which is very significant for running the machine.
Get carbide inserts or cutting tools for your cnc machines at www.pgstools.com. PGS sells cutting tools and carbide inserts from Korloy, Taegutec, Valenite, Iscar and generic carbide inserts online at discount prices.
The term tool bit generally refers to a non-rotary cutting tool used in metal lathes, shapers, and planers. Such cutters are also often referred to by the set-phrase name of single-point cutting tool. The cutting edge is ground to suit a particular machining operation and may be resharpened or reshaped as needed. The ground tool bit is held rigidly by a tool holder while it is cutting.
Back Rake is to help control the direction of the chip, which naturally curves into the work due to the difference in length from the outer and inner parts of the cut. It also helps counteract the pressure against the tool from the work by pulling the tool into the work.
Side Rake along with back rake controls the chip flow and partly counteracts the resistance of the work to the movement of the cutter and can be optimized to suit the particular material being cut. Brass for example requires a back and side rake of 0 degrees while aluminum uses a back rake of 35 degrees and a side rake of 15 degrees.
Nose Radius makes the finish of the cut smoother as it can overlap the previous cut and eliminate the peaks and valleys that a pointed tool produces. Having a radius also strengthens the tip, a sharp point being quite fragile.
All the other angles are for clearance in order that no part of the tool besides the actual cutting edge can touch the work. The front clearance angle is usually 8 degrees while the side clearance angle is 10-15 degrees and partly depends on the rate of feed expected.
Minimum angles which do the job required are advisable because the tool gets weaker as the edge gets keener due to the lessening support behind the edge and the reduced ability to absorb heat generated by cutting.
The Rake angles on the top of the tool need not be precise in order to cut but to cut efficiently there will be an optimum angle for back and side rake.
Cermet inserts can't quite replace the coated carbide inserts in heavy roughing operations with interrupted cuts, but in semifinishing and finishing cermet inserts outperform carbide. They permit a higher surface speed while maintaining an acceptable surface finish with good tolerance holding property and increased tool life. Because the cermet surface is slick it presents less friction to the chip flowing over the cutting edge which decreases the possibility of build-up when machining high alloy steels and cold-formed, low-carbon steels. Cermet inserts are available from several suppliers with a wide selection of pressed-in chipbreaker configurations or ground-in chipbreakers.
The cermet inserts work at surface speeds from 100 to 1000 sfpm. On multi-spindle-automatics, positive inserts made of cermets avoid build-up encountered when running carbide inserts with low surface speeds. Also cratering is reduced due to the low heat transfer properties of the cermet material.
The recommended cutting speed for turning unalloyed steel with approximately 200 HB is 250 to 800 sfpm with 0.002" to 0.015" fpr and depth of cut of 0.004" to 0.150". Alloy steels up to hardness of 300 HB will have satisfactory tool life when machined between 200 and 600 sfpm with the depth of cut and feedrate mentioned above.
Face milling with cermet inserts can be achieved with the same cutting speeds as turning with chip loads per insert from 0.002" to 0.12". Milling is performed dry, while turning can be dry or with coolants.
Up to the present, cermets are widely used in Japan with good results in reducing machining costs. They deserve a greater consideration for material removal in the United States.
Whether you’re making brake discs and flywheels in grey cast iron, or crank shafts and wheel hubs in nodular cast iron, there is always a successful solution.
Over the years there have been a number of CBN grades made available for machining cast iron with CBN. Most notably are DR-80 and DR-85. These grades are made for the following applications:
For rough and semi-finish turning, milling, grooving and boring of hardened ferrous and certain softer ferrous materials:-
Martensitic cast irons - Ni-hard - High chrome Chilled and heat treated cast irons
Fully hardened cold-work tool steels
Bearing steels
High speed steels (continuous cutting only)
Martensitic stainless steels
Cobalt and nickel based hard facing alloys
Fully pearlitic grey cast iron
DR-80 & DR-85 are high CBN content materials, diffusion bonded at the manufacturing stage to a tungsten carbide substrate. DR-80 is (80% CBN) has a greater particle size than DR-85, (85% CBN). DR-80 is better for hardened steel, but DR-85 has better wear characteristics when machining cast iron with CBN, particularly when the stucture contains Ferrite. For more information on machining with CBN Inserts please visit David Richards Engineering UK or David Richards Engineering US
Extend Tool Life In High Production Hard Turn Applications
Increase Thermal and Mechanical Shock Resistance to Handle the Most Demanding Contouring and Interrupted Cuts
Hard turning requires switching from carbide to CBN inserts.It’s easier and more economical than one would expect.The major adjustment is working with much higher surface speeds.
Earlier posts that deal with CBN Insert questions:
Hard milling with ceramic inserts can help a mold shop to reduce manufacturing costs in several ways. First, a mold shop can replace several operations with one operation. Instead of machining, hardening and remachining, the use of ceramic inserts enables a shop to harden the steel first and then machine the part in the hardened form. This reduces manufacturing time and improves job tracking by reducing the number of times that you must set up and move a component through various manufacturing phases. Furthermore, roughing a hardened part with ceramic inserts also can eliminate expensive and time-consuming EDM operations, as well as the need to make one or more electrodes.
Second, ceramic inserts are capable of machining hardened steel at much higher speeds than conventional carbide cutting tools. Combine the higher operating speed with the proper feedrate and a healthy step-over and the shop can achieve some impressive metal removal rates. Another key factor in increased production rates when hard milling is the cutter density. Every additional tooth in a cutter increases the cross feedrate. Higher speed and more feed add up to lower cycle times and money saved.
Third, many times the surface finish achieved by rough milling with ceramics leaves less work for a finish milling operation, and reduces finishing and polishing time. Milling at relatively light feedrates in hardened steel with carbide usually leaves a good finish, but many times with ceramic inserts the rough finish is even better than the required finish. In some cases, additional milling, grinding and polishing can be eliminated, saving several hours of manufacturing.
Boring out cylinders to accept oversized pistons or sleeves has long been a common practice in the engine rebuilding business. Boring allows worn blocks to be salvaged, and stock cylinder bores to be enlarged for more displacement. More recently, boring is also being used to install special cylinder liners with hard surface treatments in high performance racing engines. The hard liners almost eliminate ring and bore wear so the engine can run race after race with no increase in bore clearances blowby.
Like most other machine tools in today's shops, the equipment used to bore engines is also evolving to keep pace with changes in engine technology and the aftermarket. Small shops want equipment that is versatile and can do more than just bore holes. For this end of the market, combination boring/milling machines have become popular. At the other end of the spectrum, production engine remanufacturers (PERs) want equipment that works harder, works faster and requires less operator input. For this type of user, automated high speed boring equipment provides the needed boost in productivity and quality.
Tooling has also been improving. The latest generation of coated carbide inserts provides longer life and better cutting action. For high speed boring, polycrystaline diamond (PCD inserts) provides the longevity needed for this type of operation. The speed at which the boring bar turns has a significant impact on tooling life. High speeds just kill the bits unless you use a PCD or cubic boron nitride (CBN inserts) type of insert. The high speed boring machines that go up to 1,500 rpm need these type of inserts.
Korloy MGT Face Grooving Inserts or MGT tools, have double ended cutting edges, provide economic tooling cost. More so than conventional single ended type tools.
Insert grades available for the machining of carbon steel, alloy steel, stainless steel, and cast iron.
To cope with the increased needs for face grooving and boring of various material, the newly designed chip breakers are able to acquire good chip control.
Korloy Face Grooving Inserts provide various holder line-ups to expand your option, while adding more features and benefits.
Sumicrystal UP Cutting Tool Blanks 2 pictures above
What is this stuff? Synthetic Monocrystalline Diamonds: Perfectly flat, defect free synthetic diamonds- Monodie-100 and Monodie-111 from DeBeers, U.K. and Sumicrystals from Sumitomo Electric Industries, Limited., Japan-are used for specific customer requirements.
What is a PD Dresser Blank? The Sumicrystal PD dresser blanks are single crystal diamonds processed into the shape of a long, thin prism. They provide automated and high precision dressing through reliable performance and long tool life.
Ok, now what about the UP Cutting Tool Blanks? The Sumicrystal UP cutting tool blanks are just that...cutting tool blanks. They were developed by Sumitomo Electric to provide high performance and reliability for high precision cutting tools. They work well in ultra-precision machining processes, for machining products such as memory discs and polygon mirrors.
Now that I know, where can I get it? Interesting that you should ask. The pictures above are tools that are available. If you are s, interested in purchasing these tools, please contact us a sales@pgstools.com.
An important criterion for the economical application of cutting tools is their life in relation to the metal removal rates, especially with two materials such as ceramic and CBN. The latter is much more expensive. Thus, comparison of tool wear becomes most important.
The two materials show marked performance differences in both size and surface finish in roughing, interrupted, and finishing cuts. In comparison to grinding, however, both materials will achieve much higher metal removal rates.
CBN will out-perform ceramic in interrupted cuts. With depth-of-cut of 0.060 inch to 0.120 inch and a speed of 350 sfpm with 0.010 to 0.020 inch feed per revolution, ceramic often will fail when entering the interruption. With CBN, a tool life up to 20 minutes can be achieved with a half-inch round insert, under the above conditions. Flank wear in interrupted cuts is more irregular than in continuous cuts and can shorten tool life. Solid CBN inserts have greater flank wear resistance and are superior to ceramics for roughing, especially where the turning has interrupted cuts.
For finishing cuts where small depths of cut and low feed rates are required to achieve superior surface finishes, CBN inserts cannot equal the tool life of ceramic inserts. Under these conditions, the ceramic insert has less than half the flank wear of CBN after 30 minutes cutting time.
Considering that CBN is ten times more costly than ceramic for the same size and geometry insert, CBN economically can be justified only for machining heat treated steel in those situations where ceramic fails completely or breaks down before finishing the workpiece.
Ok, so in the title it says that on from time to time there would be an occasional rant about nothing. I haven't faithfully held my end of the bargain on that one. Therefore folks, here you go, a rant about nothing.
Over the weekend at our church, I had the pleasure of playing my acoustic guitar with some very talented musicians, in front of a few thousand people. I tell you what, in my life, this was up there with being one of the more difficult thing I've ever had to do. My attempts at public speaking, while enjoyable would be number one, but after time that becomes less nerve inducing. But doing something that has always been a hobby, in front of a large group of people was enough to put the sweat glands into overload. On more than one occasion it seemed like they had turned up the heat, then I realized, oh, its just me.
I am grateful that I was given the opportunity to share the talent that I have been blessed with. I was feeling pretty good about my guitar playing skills, until I came across the following video, shown below. I know now that I still have a long way to go. Hope you enjoyed the rant, now enjoy a truly talented musician.
A knurling device is used in combination with a lathe to stamp the ends of metal tubes and other shafts. The stamped ruts might also act as hand grips for the user or superior grip for rubber and the plastic covers. The knurling tool itself comprises of various rotary cutters that are held against the metal shaft as it turns on the metal lathe at a moderately slow speed (500 rpm on average). Turning is a technique by which cylindrical pieces of metal lathe or wood are spun in place by a variable-speed electric motor. As the piece spins, a variety of cutting tools could be placed against it to take away fabric or cut shapes. A knurling tool falls among an engraver and an embosser.
There are usually three shapes created by most knurling tools - straight lines, slanting lines and a diamond pattern. Knurling tools do come in different range of sizes and amazing designs, depending on the basis of the piece. The diamond pattern is mainly familiar with hand grips as it generates the most grips among a user's hand and the shaft. Diagonal and straight knurls are usually used to give additional traction to an outside handle or other connective piece. In order to generate a knurl pattern, the metal lathe should hold the metal piece entirely straight - a condition machinist call 'true'. As the lathe begins to roll, a particular holder for the knurling tool is attached to the perform table.
The knurling tool itself is fixed into the lathe and cautiously directed to the turning piece with a tiny crank. Since knurling is extremely a rough process, the machinist must use a liberal supply of machine oil on the rotating shaft. A knurling tool hardly ever makes a complete imprint the first time it is pressed against the shaft. Machinists usually make several passes with the knurling tool, allowing the individual cutters to make small bites into the metal. A knurling tool is best compatible for softer metals such as aluminum or normal grade steel. Hard metals such as titanium would most probable ruin the tool before any embossing could take place.
About the Author: John Russel is a Copywriter of Lathe chucks. He written many articles in various topics. For more information visit: Chuck manual contact him at aworkholding@gmail.com
In every machining system, one simply can't ignore the important role that cutting tools play. Oftentimes, the quality of a finished product would rely on the quality of the cutting tools. The quality and the performance of cutting tools would also directly affect a machining system's overall productivity. It is because of their importance that manufacturers would take into consideration several criteria before eventually buying a piece of cutting tool for their machining system. Included in these criteria are the tools ability to last long under rigorous operating conditions and their capability to perform at very high speeds. Also important is the tool's resistance to wear and tear, including resistance to breakage, edge and flank wear, cratering or top wear, chipping, built-up edge (BUE), deformation, and thermal cracking.
1. Kinds Of Tools
As the demand for better cutting tools increase, cutting tool suppliers also continuously develop products that can pass manufacturers' demands. Through the years, a lot of materials for the manufacture of cutting tools have been experimented upon; some have passed the standards while others were simply dropped. Today, there are only two types of cutting tools heavily favored in the machining industry: high speed steel (HSS) cutting tools and carbide cutting tools; and it seems that carbide cutting tools have slightly overtaken the other in popularity. So, what advantages do carbide cutting tools have over their HSS counterparts? Considering their lead in popularity, it is clear that the benefits of carbide cutting tools outnumber that of HSS cutting tools. And we'll understand these benefits better if we know what carbide really is.
In chemistry, carbides refer to any group of compounds made up of carbon and one other element that can be a metal, boron, or silicon. There are actually many compounds belonging to this group, among the more popular of which includes:
In the 20th century, carbides have been used for a lot of industrial applications. Carbides used in industrial applications are often called cemented carbide products and are classified in three major grades:
- Wear grades
Used primarily in dies, machine and tool guides
- Impact grades
Higher shock resistance carbide products used for dies, particularly for stamping and forming
- Cutting tool grades
Carbide tools used for cutting
4. Carbide Cutting Tools
Cutting tool grades of carbides are further subdivided into two groups: cast-iron carbides and steel-grade carbides. As their name implies, cast-iron carbides are specifically made for cutting cast-iron materials. These carbides are more resistant to abrasive wear, protecting the carbide cutting tool from edge wear due to the high abrasiveness of cast-iron. Steel-grade carbides, on the other hand, are specially made to resist cratering and heat deformation that may be caused by the long chips of steel on higher cutting speeds. Whichever grade of carbide is used in a carbide cutting tool, the main carbide material used in its manufacture is tungsten carbide (WC) with a cobalt binder. Tungsten carbide is well known for its hardness and resistance to abrasive wear. Cobalt, on the other hand, is used to further toughen the tool's surface.
5. Other Variants
Aside from tungsten carbide and cobalt, other alloying materials are added in the manufacture of carbide cutting tools. Among them is titanium carbide and tantalum carbide. Titanium carbide helps the carbide cutting tool to resist cratering while tantalum carbide can reduce heat deformations in the tool. Also commonly used in the cutting industry today are coated carbide cutting tools. Aside from the basic carbide materials, titanium carbide, titanium nitride, ceramic coating, diamond coating or titanium carbonitride are used as coating materials. The different coating materials aid the carbide cutting tool differently, although they are generally used to further toughen the cutting tool.
6. Benefits of Carbide Cutting Tools
- Toughness
- Exceptional resistance to abrasion
- Superior wear resistance
- Resistance to cratering
- Resistance to thermal deformations
- High modulus of elasticity
- Chemical inertness
- Torsional strength twice that of HSS
- Compressive strength
Plastics and reinforced plastics can be machined with PCD Inserts and PCD tooling.
The general perception is that plastic materials are easy to machine. However, soft plastics are not always so stable, and the machining process, which always generates heat, can affect dimensional and material properties like surface texture and colour, if the correct cutting tool is not applied.
PCD tools are particulary effective on abrasive plastics where plastics are reinforced with carbon fibres (CF) or glass fibres (GF).
DR-100 has a high CBN content, 99%, and is supplied as solid I.S.O format indexable inserts for top clamp tool holders. PCBN cutting tools machine hardened steels with apparent ease because, using relatively high surface speeds, heat is generated at the point of cutting so the PCBN tool cuts locally softened material.
Although most of the heat essential for efficient cutting exits with the chip, any increase in the temperature of the component will make accurate measuring difficult. Coolant can be used to reduce this effect.
Coolant can be used to drive away any swarf which might interfere with the cutting edge, particularly in boring operations. Coolant can help reduce vibration, especially where rigidity is limited.
Where interrupted cutting with CBN inserts occurs, coolant should not be used as this will thermally shock the CBN tool as it comes out of the cut, resulting in premature failure. Although interrupted cutting with coolant will never improve tool life, it is possible to use coolant machining hardened steel with DR-450 CBN inserts and coolant can be used when machining cast iron with CBN, that is not hardened, under all conditions.
Computer Numerical Control (CNC) Milling is a common type of automated machining process. These machines are specially used for drilling, facing, and turning functions. Their classification is based on the number of axes they have. These axes are labeled as x and y for the two horizontal directions while z is for vertical movement. CNC milling is a cutting process that is used to remove metal or plastic from a block of stock material by the rotating action of the tool. The tool is moved in three (or more) directions to get the desired cut of the material.
CNC Milling machines have been programmed with the help of a set of commands called G-codes. These codes are special CNC functions in alphanumeric format.
The cutting tool is usually rotated along the axis, which is perpendicular to the table where the material to be cut is placed. There are different cutter shapes (called milling bits) such as round (ball end), square, and angled.
Advantages of CNC Milling
A large variety of 2D and 3D shapes are possible. Complex shapes from rod, block, or sheet material can be created and is cost effective for short runs.
Specifications for CNC Milling
• Rigid materials such as metals and hard plastics are used.
• Alternative machines for 2D sheet shapes that include Laser Cut, Turret Punch and fixed punch are used.
• CNC Milling requires software program tooling or work holding jigs.
• To contain costs avoid large variations in work piece height and avoid thin walls.
The CNC Machining centers are computer controlled vertical mills which can move the spindle along the Z-axis. When the machine is used in combination with conical tools or a ball nose cutter it improves the milling precision without affecting the speed thus providing an economical substitute to flat surface job that requires hand engraving.
During the milling process pressure is applied to the material therefore it is better to avoid weak shapes, long thin shapes, or ones with thin walls. CNC milling offers a cut surface that has a visible pattern due to the rotation and movement of the cutter.
eMachineShop offers you information about a vast number of products and machines and CNC Milling machine is one of them. A unique online CMC provider allows you to design and even order custom CNC machined parts. Visit the site www.eMachineShop.com to get details about these and other services. While you’re there, don’t forget to download the company’s free 3D CAD software which makes designing CNC milled parts a snap!
About the Author: George is a well known author who writes on the topics related with CNC Milling , waterjet cutting and Free CAD Software for the site www.emachineshop.com.
Welcome to a new section of carbideinserts.blogspot.com. Our focus with these blog posts will be to provide application examples with insert type, speeds and feeds, to hopefully give you a baseline and to help you with your own machining applications. We will add these machining tips on a regular basis, so check back often!
PCD inserts are not recommended for the machining of Iron, Cobalt, or Nickel alloys. In the presence of these metals and the heat and pressure created by cutting, diamond is encouraged to revert to the metastable carbon form: graphite. It is possible to use PCD inserts to machine some stainless steels and other highly alloyed materials, which have the iron, cobalt or nickel tied up in a non-reactive state. Even so, these materials should be machined at low cutting speeds and feeds with coolant to reduce any heat generated.
This blog entry focus is on machining the following:
Cemented carbide with a Co content of less than 17%:
1. First choice for machining is CBN 2. Should use a round cbn insert 3. The insert should have a chamfered cutting edge 4. Machining with coolant is recommended 5. Chamfer the workpiece at entry and exit point.
Should you require further assistance in choosing an insert or pricing. Please contact the experts at David Richards Engineering.
CBN cutting tools machine hardened steels with apparent ease because, using relatively high surface speeds, heat is generated at the point of cutting so the PCBN tool cuts locally softened material. The heat is carried away by the swarf, which becomes brittle and harmless, and the PCBN tool, which has a high co-efficient of thermal conductivity. If a light cut is required, however, a tool with a high CBN content conducts too much heat away from the shear zone and the conditions for efficient machining cannot be achieved.
DR-50 & DR-50N have a low CBN content and the individual CBN particles are isolated within a ceramic matrix. This gives the materials a lower thermal conductivity and greater wear resistance in finish cutting operations.
Low CBN tools can therefore keep sufficient heat at the cutting point to enable the optimum cutting conditions to be achieved when a light cut is taken. In most cases, even when very light cuts are required, low CBN tools employ negative rake geometry to provide a strong edge. Due to the nature of cutting, however, cutting forces are still very small. Low CBN can be used to provide a productive and cost effective alternative to grinding.Tolerances achieved are comparable but machining time can be dramatically reduced.
DR-50 has a low CBN content and is designed for finishing and semi-finishing applications where grinding with conventional abrasives proves time consuming or difficult. DR-450 is tougher and performs well over severe interruptions.
At first it might seem that machining fiber-filled composites with hard cutting tools would be a recipe for disaster. Developers of cutting methods and tools for composites face all kinds of problems. A composite's fiber layers can delaminate from the machined surface; the fibers or other hard reinforcements are abrasive and reduce tool life considerably; and the combination of hard and soft materials that make up a composite complicates the best choice of tool and machining parameters.
What do I use then?
Diamond will interact with carbon in ferrous materials, so its use is largely restricted to nonferrous workpieces. Today, the automotive industry is the major user of diamond tools in machining components made of aluminum-silicon alloys--in particular the 300 series of aluminum alloys. Major applications for silicon-containing aluminum materials are in pistons, engine heads, blocks and manifolds, wheels, and transmission parts. Other significant applications for diamond tools are in machining graphite, carbon-carbon (C-C) composites, metal-matrix composites (MMC), and fiber reinforced plastics (FRPs).
Of uniform structure and composition, Cermet is composed of solid titanium carbide (TiC) and titanium nitride (TiN) with a super-alloy metal binder. Cermet has a low friction coefficient which eliminates built up edge and improves surface finish. Its high resistance to thermal deformation and its low conductivity make higher cutting speeds possible and result in lower flank wear and edge cratering. Its high degree of hardness and toughness, with resistance to oxidation, extend tool life.
Superalloys are hard; some grades of titanium are machined at 330 Brinell hardness. With conventional alloys, cutting zone temperatures greater than 2,000[degrees]F soften molecular bonds and create a flow zone for chips. In contrast, the heat resistance that makes HRSAs so desirable keeps them hard throughout the machining cycle.
HRSAs also tend to work-harden as they are cut, notching cutting inserts to premature failure. The difficulty cutting HRSAs is compounded where unpeeled stock is covered with abrasive, knife-edged scale that wears cutting edges down even more quickly.
Given their machining difficulty, superalloys are cut slowly. For example, Inconel 718 is milled for brake keys with Sandvik GC2040 grade carbide inserts at 200 sfm. Turning speed for the same alloy with Sandvik 7020 CBN inserts in an outside turning/facing application is 260 sfm. By comparison, uncoated carbide inserts typically cut tool steels at 400 to 800 sfm. Feeds for HRSAs are generally comparable to those used when machining tool steels.
The choice of cutting inserts to machine HRSAs depends on the material and the workpiece. Carbide inserts with positive rake geometries will cut thin-walled HRSA stock effectively. However, thick-walled parts may require ceramic inserts with negative cutting edge geometry to create a more productive plowing action. While dry machining is preferred in most difficult materials to maintain uniform edge temperatures, titanium requires coolant even at very low speeds.
Hard part grooving can be a difficult process without the correct tools. CBN cutting tools for grooving can ease that process. During heat treatment, many features of machined components suffer distortion. If the position or dimensions of a groove are critical to the performance of a hardened component, David Richards can offer a simple solution to this problem - ‘Hard Grooving’. Based on the Top Notch system, David Richards supply grooving tools in a wide range of sizes from 0.5 mm width upwards. David Richards supply tools for circlip and ‘O’ring grooves with controlled corners or full radii, either full form for plunging or undersize for profiling.
Using such surface speeds typical for turning, grooves are machined at low feed rates (0.01 / 0.05 mm/rev). The low feed rate ensures that the swarf is very weak and brittle, decreasing the likelihood of it breaking the tool. Where there are no interruptions to the cutting path, coolant should be used to aid evacuation of the swarf and ensure that the component remains at a stable temperature for ease of measuring. If the cutting path is interrupted, an air blast will serve the same purpose without the risk of thermally shocking the PCBN tool.
If practical, it is better to finish a groove that has been pre-formed at the soft stage. This ensures uniform hardness around the groove and maintains the structural integrity of the component. However, if it is acceptable, satisfactory results are achieved grooving through a hardened layer into the core material. Successful applications include grooving case hardened (58 / 63 HRc) splined shafts and gear teeth, internal circlip grooving hardened EN31 (58 / 60 HRc) bearing components, and producing profiles in the face of D2 tools steel tools using Full radii face grooving tools. All operations that would be time consuming and difficult to grind.
Whilst the Top Notch system offers an ideal base for most grooving tools, other systems have been employed with excellent results.
It naturally follows that, since David Richards can produce tools for ‘Hard Grooving’ full and partial form cbn threading tools, both external and internal, are available for ‘Hard Threading’. Where the pitch of the thread is large, or the diameter of the component is small, it must be remembered that the feed rate required, at the required surface speed for ‘Hard Turning’ will be relatively fast. But, producing a 90 mm diameter internal stub Acme thread 150 mm deep, with a 6 mm pitch in 58 HRc Ni-Hard iron, at 120 m/min from blank bore, though somewhat exciting, proved a major cost saver.
Finding it difficult to machine soft steels with cbn inserts? I would suppose that soft steel is relative, so generally speaking, cbn inserts will machine steels from 45-65 HRc. For soft steels (the ones on the lower end of the 45-65 HRc), the lower you are on the hardness scale, the faster you will want to machine the material.
CBN needs heat to cut at its fullest potential. A quick lesson: CBN generates heat in the shear zone, thus locally anealling the material, cutting it as if it were soft.
If you are having trouble with turning using CBN inserts or PCD inserts, please call to discuss your application with David Richards Engineering or email to sales@drengus.com
After completing a part in the lathe it is frequently necessary to separate the part from the excess material used for chucking. This operation is best accomplished with the use of a cut-off tool or "parting tool" as it is sometimes called. The Cut-off Tool and Holder consists of a very slender high speed tool steel cutting blade mounted in a special tool holder. The thinness of the blade (.040") enables it to feed into the part quite easily and at the same time minimizes the amount of waste material. The turning speed for parting should be approximately one half the normal turning speed for any given material. One word of caution; never use a parting tool on a part mounted between centers. The part may bind on the cutter and result in a scrapped part or a broken cutting tool.
Parting off material (free machining) over a 1.00" (25mm) diameter will always present problems on a machine of this size.
Always try to lay work out so the cut-off tool is used as close to the spindle as possible. Set blade height by sliding the blade in its slot in the tool holder. It should be set so the tip is aligned with the centerline of the part being cut. An unusual diameter may require a shim to be placed under the front or rear of the holder to accomplish this.
NOTE: ALWAYS USE CUTTING OIL WHEN USING THE CUT-OFF TOOL. The cut will be made much smoother, easier and cooler.
Speed should be slower than normal turning speed and feed rate should be a little heavy so the chip will not break up in the slot. If speed and feed are correct, there will not be any chatter, and the chip will come out as if it were being unrolled. Coolant (cutting oil) plays a major roll in this occurring properly.
If the tool chatters, first check to see if the work is being held properly. Then decrease speed (RPM) or increase feed rate or both. Once the blade has chattered, it leaves a serrated finish which causes more chatter. Sometimes a serrated finish can be eliminated by turning the spindle off, adding a liberal amount of cutting oil, bringing the blade up so there is a slight pressure on it without the spindle turning, and then turning by hand or as slowly as possible with the speed control.
All Irons... use silicon nitride in all applications...turning, boring, milling & facing. Use for roughing, semi-roughing, semi-finishing & finishing applications. Generally speaking, silicon nitrides can be used in all iron applications.
All Irons... use the black (CC-20) and/or white (CC-10) ceramic on semi-finishing & finishing applications. They are less costly and harder than silicon nitride (more abrasion resistant & longer lasting).
Steels below Rc58 in hardness... use the black (CC-20) and/or white (CC-10) ceramic in almost every semi-finishing & finishing applications. They can even cut with mild interruptions. If your customer isn't using CC-10 & CC-20 on almost every finishing application, he's losing money.
Steels above Rc58 in hardness... use the black (CC-30) for finishing applications, especially to replace grinding. You can also use silicon nitride for roughing.
Aerospace Metals... Inconel, Hasteloy, Waspeloy, Renee, Etc. For roughing or finishing use CC-5477 Silicon Nitride specifically designed for these materials.
We have found that this insert performs quite well for turning wood. There are two choices available for chipbreakers. In the first picture is the "TA" and the "HA" is in the second picture. Each one serves a different purpose, so read carefully. Both inserts are from Korloy. These inserts are available in packs of 2. For pricing on carbide inserts for turning wood: www.pgstools.com
The Problem: Inconsistent tool life and insert would chip after two parts
Solution:
I am sure that some may have already figured this out based on the radius size of the insert compared to the feed rate, but for those not in the know, here is the fix:
