۱۴۰۰-۹-۵، ۰۶:۰۸ صبح
Super abrasives are tools used in precision grinding. Superabrasive materials attach to a wheel to make Superabrasive grinding wheels. The reason some abrasives are Superabrasives is due to their extraordinary hardness, unparalleled performance, and longevity.
WHAT ARE SUPERABRASIVES?
Abrasives that belong to the Superabrasive family includes,Industrial diamonds: an industrial diamond is a non-gem quality small diamond that is for abrasives, cutting, and drilling tools.
Cubic boron nitride (CBN): Usually called CBN it is the second hardest cutting tool material after a diamond.
Polycrystalline: Is an abrasive material that has a multiple collection of crystal grain structures with individual orientations
CVD Diamond: These are synthetic diamonds made by a process known as chemical vapor deposition.CVD diamonds grow from a hydrocarbon gas mixture. They are extremely hard, have a high thermal conductivity that is five times that of copper. They also have broadband optical transparency, are chemically inert, and only reach graphitization at very high temperatures.
Nanodiamonds: These tiny diamonds are the product of a controlled explosion. Sometimes called a detonation nanodiamond (DND) or an ultradispersed diamond, as this is how they form.
INDUSTRIES THAT USE SUPERABRASIVES
A great number of industries use Superabrasive grinding wheels and the coated abrasives subsection of the abrasives industry continues to grow. Industries that are prime buyers of Superabrasive grinding wheels are:
ADVANTAGES OF SUPERABRASIVES
The advantages of Superabrasive grinding wheels are more than extraordinary hardness, unparalleled performance, and longevity. These three features of Superabrasives are the core of many advantages manufacturers gain by an aggregation of services that normal abrasives simply cannot deliver.
Less expensive tooling and fixturing costs
More wheels on the spindle, smaller wheels, multiple operations
Less floor space needed for manufacturing
Virtual elimination of wheel wear
Automated CNC machines, less labor intensive operations requiring less training
Consistent surface speed from part to part
Better overall throughput with fewer machines needed
Improved Material Removal Rates, Lower Per Part Abrasive Costs and higher speeds
With Superabrasives, production increased by automated CNC equipment, industries have found one way to compensate for the lack of availability of skilled labor. With fewer machines needed, so is fewer workers. With Superabrasives CNC, automation is more concerned with defining a manufacturing process using machine capabilities and mechanization. There is less concern on operator technique. A properly defined process, combined with automatic loaders make for equipment that is almost running itself.
Future growth of the abrasives industries will primarily be in Superabrasives. Currently, research and development of Superabrasives are taking place in the following areas:
Custom designed “hard to grind”? materials in an increasing number of industries
Creep or deep feed grinding
High-speed, high-performance grinding of hardened steel
Form grinding, sometimes with electroplating, in high precision, high-removal, and high-surface quality applications
CNC-control of line grinding machines
In a nanotwinned crystalline structure, neighboring atoms share a boundary, the way neighboring apartments do. And like some apartments, the twins mirror each other. Typically, to make a substance harder, scientists decrease the size of the grains, which makes it harder for anything to puncture it — small grains equals less space between them for any point to enter. But the process hit a wall: in anything smaller than about 10 nm, inherent defects or distortions are nearly as big as the grains themselves, and thus weakens the structure.
But the nanotwinning also makes substances harder to puncture, and in the case of boron nitride, maintained that characteristic strength at sizes averaging about 4 nm, explains Tian. And as a bonus, the cubic boron nitride was stable at high temperatures as well.
"In our nanotwinned cBN, the excellent thermal stability and chemical inertness are maintained with hardness competitive to or even more than diamond, making it the most desirable tool material for industry," says Tian.
He anticipates that, with further research, the product will be comparable in price to the softer, commercial forms of cubic boron nitride that are currently available. Probable uses include machining, grinding, drilling and cutting tools, as well as scientific instrumentation.
Articles About cutting tools
1 Material Properties and Performance Considerations for High-Speed Steel Gear-Cutting Tools
Users of gear-cutting tools probably do not often consciously consider the raw material from which those hobs, broaches or shavers are made. However, a rudimentary awareness of the various grades and their properties may allow tool users to improve the performance or life of their tools, or to address tool failures. The high-speed steel from which the tool is made certainly is not the only factor affecting tool performance, but as the raw material, the steel may be the first place to start.
2 Cutting Tools Now
The cutting tool is basic to gear manufacturing. Whether it's a hob, broach, shaper cutter or EDM wire, not much gets done without it. And the mission of the tool remains the same as always; removing material as quickly, accurately and cost-effectively as possible. Progress in the field tends to be evolutionary, coming gradually over time, but recently, a confluence of emerging technologies and new customer demands has caused significant changes in the machines, the materials and the coatings that make cutting tools.
3 Cutting Tools Roundup
The cutting tool industry has undergone some serious changes in the last couple of years in both technology and the way the industry does business. The emerging technology today, as well as for the foreseeable future, is dry cutting, especially in high volume production settings. Wet cutting continues to be as popular as ever with lubrication advances making it more economical and environmentally friendly. There has also developed a process called "near dry cutting." this process offers many of the benefits of fluids while eliminating many of hte associated problems.
4 Big Gears Better and Faster
Indexable carbide insert cutting tools for gears are nothing new. But big gears have recently become a very big business. The result is that there's been a renewed interest in carbide insert cutting tools.
5 High Speed Steel: Different Grades for Different Requirements
Hobs, broaches, shaper cutters, shaver cutters, milling cutters, and bevel cutters used in the manufacture of gears are commonly made of high speed steel. These specialized gear cutting tools often require properties, such as toughness or manufacturability, that are difficult to achieve with carbide, despite the developments in carbide cutting tools for end mills, milling cutters, and tool inserts.
When considering the use of CBN (cubic boron nitride) grains in an aerospace part grinding process, the first questions that come to mind may be associated with the grinding conditions and machine capabilities. It’s commonly assumed that CBN grinding wheels need very specific operating conditions that only a re-tooled or new machine can achieve. It’s also typical to think that those conditions are completely different from the ones used by conventional grinding wheels. However, depending on the bond system, some of the conditions may resemble those suitable for conventional wheels.
The first thing to determine when considering a CBN wheel is whether it will bring any advantage to the current process. A cost analysis should be completed to make this determination. In other words, how many parts can be ground using the CBN wheel and what is the cost? This information can be used to make a cost/piece analysis, which can be used for comparison to the current wheel (usually a conventional wheel) to determine if there is value in incorporating the CBN wheel. After cost justifying the use of a CBN wheel, it is helpful to look at the different bond options in order to optimize the grinding process.
The most common bond systems for CBN wheels are resin, vitrified and electroplated matrixes. Depending on the grinding conditions, each system has its own unique requirements which will allow the wheel to achieve optimal performance.
Features: Resin is a bond that gives up easily and it is the most forgiving bond among all. One downside of this bond is that resin does not do well if the grinding conditions generate too much heat. Since the CBN grain is held in place by a mechanical method, a resin bond tends to release the CBN grain before it dulls, so the wheel will keep its cutting ability, but may never use the CBN grain completely.
Dressing Conditions: The wheel can be dressed outside or inside the machine. It is usually done by using another grinding wheel such as silicon carbide, which trues the CBN wheel slowly. A white stick made of Alox could be used to open the structure again after truing the wheel.
Grinding Conditions: Resin bonded wheels can be run wet or dry. The wheel speeds range from 30 to 40 m/s when using coolant, and from 10 to 15 m/s when running in dry conditions without the use of coolant. However, running a dry process can have a negative effect on wheel life.
Cost: The cost of the wheel is based not only on the CBN concentration and wheel size, but also on the thickness of the abrasives layer (usable layer). In many cases it is possible to reuse the core of the wheel, but that can depend on the size of the wheel and if the core material is reusable, such as steel. In some cases the actual technology or manufacturing process doesn’t allow for reuse.
The History Of Diamond Jewelry
We all know that diamonds have been here longer than we have, but when exactly were they first discovered? More importantly, when were they first used for jewelry? By taking a quick look at the history of diamonds we will be able to learn a bit more about how diamond jewelry came to be.
India – Where it All Began
Diamonds are located all around the world, but for our intents and purposes, our story begins in India. This is because the first diamond is believed to have originated from this particular country. At the time, they were valued not for their beauty or durability but for they’re ability to refract light. This made them ideal for talismans and decorations. As the times changed, diamonds were sought out for different purposes. During the Dark Ages people believed that diamonds had medicinal value. The diamond later evolved from a medicinal object into an item of value during the Middle Ages.