New advances in abrasive technology allow machining center operators to perform surface finishing and other machining operations simultaneously, thereby reducing cycle times, improving quality, and saving time and money on offline finishing. Abrasive finishing tools are easily integrated into a CNC machine’s rotary table or toolholder system.
While contract machine shops are increasingly choosing these tools, there are concerns about using abrasives in expensive CNC machining centers. This issue often stems from the common belief that “abrasives” (such as sandpaper) release large amounts of grit and debris that can clog cooling lines or damage exposed slideways or bearings. These concerns are largely unfounded.
“These machines are very expensive and very precise,” said Janos Haraczi, president of Delta Machine Company, LLC. The company is a machine shop that specializes in producing complex, tight-tolerance parts from titanium, nickel alloys, stainless steel, aluminum, plastic and other exotic alloys. “I won’t do anything that would compromise the accuracy or durability of the equipment.”
People often mistakenly believe that “abrasive” and “grinding material” are the same thing. However, a distinction must be made between abrasives and abrasive finishing tools used for aggressive material removal. Finishing tools produce virtually no abrasive particles during use, and the amount of abrasive particles produced is equivalent to the amount of metal chips, grinding dust, and tool wear generated during the machining process.
Even when very small amounts of fine particulate matter are generated, the filtration requirements for abrasive tools are similar to those for machining. Jeff Brooks of Filtra Systems says that any particulate matter can be easily removed with an inexpensive bag or cartridge filtration system. Filtra Systems is a company that specializes in industrial filtration systems, including coolant filtration for CNC machines.
Tim Urano, quality manager for Wolfram Manufacturing, said any additional filtration costs associated with using abrasive tools are so minimal that they “really aren’t worth considering, since the filtration system itself is supposed to remove particulate matter from the coolant generated during the machining process.”
For the past eight years, Wolfram Manufacturing has integrated Flex-Hone into all of its CNC machines for cross-hole deburring and surface finishing. Flex-Hone, from Brush Research Manufacturing (BRM) in Los Angeles, features tiny abrasive beads permanently attached to flexible filaments, making it a flexible, low-cost tool for complex surface preparation, deburring, and edge smoothing.
Removing burrs and sharp edges from cross-drilled holes and other hard-to-reach areas such as undercuts, slots, recesses or internal bores is essential. Incomplete burr removal can result in blockages or turbulence in critical fluid, lubricant and gas passages.
“For one part, we may use two or three different sizes of Flex-Hones depending on the number of port intersections and hole sizes,” explains Urano.
Flex-Hones has been added to the tooling turntable and is used daily, often several times an hour, on some of the shop’s most common parts.
“The amount of abrasive that comes off Flex-Hone is negligible compared to other particles that end up in the coolant,” explains Urano.
Even cutting tools like carbide drills and end mills generate chips that need to be filtered out of the coolant, says Eric Sun, founder of Orange Vise in Orange County, California.
“Some machine shops may say, ‘I don’t use abrasives in my process, so my machines are completely particle-free.’ But that’s not true. Even cutting tools wear out, and carbide can chip off and end up in the coolant,” Mr. Sun said.
Although Orange Vise is a contract manufacturer, the company primarily makes vices and quick-change parts for CNC machines, including aluminum, steel, and cast iron. The company operates four Mori Seiki NHX4000 high-speed horizontal machining centers and two vertical machining centers.
According to Mr. Sun, many vices are made of cast iron with a selectively hardened surface. To achieve the same result as a hardened surface, Orange Vise used a NamPower abrasive disc brush from Brush Research.
NamPower Abrasive Disc Brushes are made from flexible nylon abrasive fibers bonded to a fiber-reinforced thermoplastic backing and are a unique combination of ceramic and silicon carbide abrasives. The abrasive fibers act like flexible files, following the contours of the part, cleaning and filing edges and surfaces, ensuring maximum burr removal and a smooth surface finish. Other common applications include edge smoothing, parts cleaning and rust removal.
To perform surface finishing operations, each CNC machine tool’s tool loading system is equipped with abrasive nylon brushes. Although it also uses abrasive grain, Professor Sun said the NamPower brush is “a different type of abrasive” because it is essentially “self-sharpening.” Its linear structure keeps sharp new abrasive particles in constant contact with the work surface and gradually wears away, revealing new cutting particles.
“We have been using NamPower abrasive nylon brushes daily for six years now. In that time, we have never had any issues with particles or sand getting onto critical surfaces,” added Mr. Sun. “In our experience, even small amounts of sand do not cause any problems.”
Substances used for grinding, honing, lapping, superfinishing and polishing. Examples include garnet, carborundum, corundum, silicon carbide, cubic boron nitride and diamond in various particle sizes.
A substance that has metallic properties and is composed of two or more chemical elements, at least one of which is a metal.
A thread-like portion of material that forms on the edge of a workpiece during machining. It is usually sharp. It can be removed by hand files, grinding wheels or belts, wire wheels, abrasive brushes, water jetting, or other methods.
Tapered pins are used to support one or both ends of a workpiece during machining. The center is inserted into a drilled hole in the end of the workpiece. A center that rotates with the workpiece is called a “live center” and a center that does not rotate with the workpiece is called a “dead center.”
A microprocessor-based controller specifically designed for use with machine tools to create or modify parts. The programmed CNC system activates the machine’s servo system and spindle drive and controls various machining operations. See DNC (direct numerical control); CNC (computer numerical control).
A fluid that reduces the temperature rise at the tool/workpiece interface during machining. Usually in liquid form, such as soluble or chemical mixtures (semi-synthetic, synthetic), but may also be compressed air or other gases. Because water has the ability to absorb large amounts of heat, it is widely used as a carrier for coolants and various metalworking fluids. The ratio of water to metalworking fluid varies depending on the machining task. See cutting fluid; semi-synthetic cutting fluid; oil-soluble cutting fluid; synthetic cutting fluid.
The manual use of a tool with many small teeth to round off sharp corners and protrusions, and to remove burrs and nicks. Although filing is usually done by hand, it can be used as an intermediate step when processing small batches or unique parts using a power file or contour band saw with a special file attachment.
Machining operations in which material is removed from a workpiece by means of grinding wheels, stones, abrasive belts, abrasive pastes, abrasive discs, abrasives, slurries, etc. Machining takes many forms: surface grinding (creating flat and/or square surfaces); cylindrical grinding (of external cylinders and cones, fillets, recesses, etc.); centerless grinding; chamfering; thread and shape grinding; tool sharpening; random grinding; lapping and polishing (grinding with a very fine grit to create an ultra-smooth surface); honing; and disc grinding.
CNC machines that can perform drilling, reaming, tapping, milling, and boring. Usually equipped with an automatic tool changer. See automatic tool changer.
The dimensions of the workpiece may have minimum and maximum deviations from the established standards, while remaining acceptable.
The workpiece is clamped in a chuck, which is mounted on a faceplate or fixed between centers. As the workpiece rotates, a tool (usually a single-point tool) is fed along the periphery, end, or surface of the workpiece. Types of workpiece machining include: straight-line turning (cutting around the perimeter of the workpiece); taper turning (shaping a cone); step turning (turning parts of different diameters on the same workpiece); chamfering (beveling an edge or shoulder); facing (trimming at the end); threading (usually external, but may be internal); roughing (significant metal removal); and finishing (final light cuts). It can be performed on lathes, turning centers, chuck lathes, automatic lathes, and similar machines.
Post time: May-26-2025