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Abrasive Machining, Sawing, and Finishing

 

Grinders are going multifunction

    
       

Mike Hitchener, technology manager/vitrified CBN product manager. Saint-Gobain (Worcester, MA) sees these trends in the grinding industry.

"Customers are pushing to improve their capital investment payback through faster cycle times. This is sometimes done at the expense of increased tooling costs both on new and existing grinders. Therefore, capital equipment cost and payback time is becoming critical.

"Multifunction machines are becoming more common. There is a big move to incorporate grinding on turning centers, and turning or burnishing on grinders. Grinding is often introduced to improve dimensional accuracy or finish after turning. One typical area is in machine choices for the new transmission programs currently being tooled up. 

"Some sectors of the market are becoming mature for superabrasives, such as cam and crank grinding, while other sectors are just waking up to this material's potential. This includes through-feed centerless grinding with vitrified CBN, where falling grain prices are reducing the sticker shock of large wheels.

"There is an upsurge in acceptance of oil coolant. This allows novel processing methods such as high-speed peel or contour grinding, common in Europe, to be introduced into the USA as a challenge to hard turning."

At the show, Saint-Gobain will show these major developments in the vitrified products area: 

  • The T2 bond technology which continues to make major performance improvements in an increasing number of applications.           
  • Dressing technology (rotary diamond dressers and motorized dresser spindles) to match the performance requirements of the wheels

In conventional wheel developments

  • Norton XPG.90 grinding wheels last up to 10 times longer than previous wheels on fluting, pointing, and punch grinding applications           
  • XJP.90 wheels for HSS grinding are said to outperform all conventional abrasives on new and used grinders. The wheels work on new and old equipment, and they can be trued and dressed with either single-point diamond tools or rotary dressers

In evaluating customer demands for grinding equipment, David Barber of United Grinding Technologies (Miamisburg, OH) notes, "Flexible grinding platforms that address both production and short-run needs are becoming more and more in demand. This requires innovations to both software and hardware on today's grinding machines. This could be a machine with an easy to adjust loader, like Studer's new Autoloader. This loader, designed for the needs of small shops that want flexible automation, allows quick adjustment when the operator makes parts of differing lengths.

"Another example is adding toolchangers to grinding machines. This allows an operator to fixture a part on a grinder, then walk away."

At IMTS 2004, United Grinding's will feature the new Mägerle toolchanging technology, which increases the variety of applications to a great extent by increasing the number of operations that can be accomplished without operator interference. "By limiting operator involvement and eliminating the need to move a part from machine to machine the new toolchanger enhances process control and results in consistent performance and quality parts," explains Barber. "If the initial process parameters are correct, we can pretty much eliminate scrap as an issue. With this toolchanger, the operator can load all the tools required to finish a part -- multiple abrasive types, conventional wheels, aluminum oxide, CBN, and, of course, drills, mills, and taps. The idea is to have the perfect abrasive or tool in the changer for a particular part. You can rough with one type of abrasive and finish with another. Perhaps you have a feature that requires a very well-defined wheel diameter, and perhaps plated CBN would be best. However, you may have other features on the same part where the stock is heavy and requires more conventional abrasives. With this design it's possible to intermix tools and abrasives around the specific requirements of a given part and run that part complete, start to finish, in a single setup."

Typical applications include turbine vanes and blades, gear shifting shafts, rocker arms, small turbine and compressor blades, machining both sides of fir tree and root shank faces, shroud and Z-notch profiles -- both sides and slots if required. The new toolchanging system will be demonstrated on a Mägerle MMS (Mägerle Modular System) machine.       

"There are several trends that we have noticed since the last IMTS exposition," notes Dan Pheil, president, Landis Grinding Systems (Waynesboro, PA). "Part tolerances and processability requirements have become increasingly tighter in response to the demand for improved quality with lower cost. A manufacturer of fuel-system components, for example, now centerless grinds plungers at very high production rates to tolerances of 1 µm on diameter and 0.6 µm on taper at 1.33 Ppk. We have received many requests to grind very tough materials such as Inconel bolts for aerospace and specialty alloy steel bars for various precision applications. Many part designs have become more complex, such as families of crankshafts with multiple throws or camshafts with multiple features that must be accommodated in finish grinding. And many manufacturers have been seeking to replace multioperation, dedicated processes with more efficient grinding processes using fewer machines that combine operations.

"Landis Grinding Systems will be showing examples of the latest generation of flexible CNC production grinders that enable us to respond to these trends. These cylindrical grinders incorporate superabrasive wheels operating at very high speed and feature reliable, wear-free linear motor drives and the latest generation of PC-based open-architecture controls. Some of these new grinders can also minimize the number of machines in a process and reduce capital expenditure for our customers by combining multiple grinding operations in a single machine. For example, a typical five-machine crankshaft grinding process can now be reduced to only two machines by grinding crankshaft concentric diameters, including thrustwalls and eccentric crankpins, with an LT2 Twin Wheelhead grinder, one of the machines. We will feature at IMTS." Landis has also developed a machine for grinding crankshaft thrustwalls, flange face, pilot diameters, and reluctor ring all in one machine.

The company will also introduce the Landis Cincinnati Viking SuperSeries II centerless grinder, which incorporates a new spindle for improved reliability and open-architecture 6400 CNC control. The Viking grinder has a combination of advanced technology and features that makes it useful for high-production applications and for grinding a diverse range of materials and components to precise tolerances using either conventional or superabrasive wheels.

Part finishing requirements are encouraging the development of a variety of techniques.

"Industry, in general, is seeing a lot more outsourcing, more automation, more multifunction machines, more micromachining, and much more influence by the Chinese market," explains Donald Risko, Managing Director, Extrude Hone (Irwin, PA).

"As to company products, we have two units that use rapid prototyping technology for rapid tooling. One makes finished and semifinished parts. The other makes sand casting part models.

"We offer three deburring systems. Our thermal removal units are seeing wider acceptance in niche markets. The abrasive flow systems are able to clear smaller passages, and our electrochemical units are designed for radiusing passage size, and surface finishing as well as deburring.

"Our booth will also feature a precision washing system that combines high-pressure water, ultrasonics, and tumbling.

"Industry is beginning to recognize that maintaining clean coolant in the sumps is an integral part of any shop optimization program or a lean manufacturing initiative," explains Dick Strauss, president, Keller Products Inc., (Lexington, MA). "In the past, shops typically addressed tramp oil problems for environmental reasons, to eliminate odor and smoke and reduce the incidence of operator dermatitis. While the environmental issues are still important, the trend now is to set the overall improvement in shop efficiency as the main objective of a comprehensive coolant maintenance program. A comprehensive coolant maintenance program achieves this objective quite economically by reducing lost time for machine adjustments, extending the life of cutting tools, improving parts finish, and greatly reducing downtime and labor for coolant pumpout by multiplying the life of the coolant.

"Our model #315 separator has a good combination of flow rate, oil separation capacity, and price, and is our most frequently specified separator.

"It's the key component in coolant maintenance programs in many shops. The portable unit removes both tramp oil and floating chips from coolant in up to 10 machine tool sumps as large as 400 gal (1514 L). The cart-mounted separator, with a coolant recirculation rate of 180 gph (681 L/hr), can clean a sump in a few hours and then may be moved to another sump and set up for operation in minutes. It has a permanent oil separation elements plus a high-capacity bag filter to remove solids as fine as 5 µm."

Toshiba Machine Co. America (Elk Grove Village, IL) offers wet-blasting machines. Terry Matsuki, General Manager, new business development explained that their wet-blasting machine operates like an abrasive blasting machine, but with the added benefit of water. The process uses slurry which is water and abrasive combined with air at 50-60 psi (0.35 - 0.42 MPa) to remove burrs and scales and produce satin-matte finishes. This combination of water and abrasive prevents heat generation, decreases non-productive time and provides a significantly smoother finish. Furthermore, designed as a closed system, the wet-blasting machine recirculates water for environmentally friendly operation.

To deburr they typically use aluminum oxide grit and glass beads. For matte finish, glass beads are used. When needed, a rust inhibitor can be added to the fluid.

Typical parts cleaned include clutches, clutch housings, transmission parts, fuel injection components, nozzles, gears, and power steering sleeves.

The automated units can take loads up to 25 lb (11 kg) per part. Parts can be tumbled in a barrel or mounted on a fixed rack, depending on the product.

Abrasive is recycled in a cyclone system (high-speed spin) that separates the abrasive, chips, and residue from the liquid.             

Typical applications include turbine vanes and blades, gear shifting shafts, rocker arms, small turbine and compressor blades, machining both sides of fir tree and root shank faces, shroud and Z-notch profiles -- both sides and slots if required. The new toolchanging system will be demonstrated on a Mägerle MMS (Mägerle Modular System) machine.       

 

Product Previews

                           

General-Purpose Saw

Model 500-SNC saw features NC controls and a swiveling saw head for cuts to 45°. Unit has a 3-hp (2-kw) drive motor and 1.25" (32-mm)-wide blade. It can cut stock as large as 14 x 19" (356 x 483 mm) and diameters to 14" (356 mm). Controls can be set to stock size, length, band speed, and feed rate.

DoAll
Ph: 847-803-7353


Tool Grinder

Called the Helitronic Vision CNC tool grinder, this machine grinds carbide or HSS tools ranging from 3 to 320 mm in diam. Its five CNC axes--two rotary and three linear-use direct drives. Linear motors offer positioning accuracy and move at speeds to 50 m/min with high acceleration. Helitronic Tool Studio software offers programming flexibility and the ability to set up while the machine grinds. An optional pallet loader mounted to the side of the machine can hold several hundred tools.

Walter Grinders Inc.
Ph: 540-898-3700


Column-Type Precision Grinders

Ultra Precision Grinding (UPG) series of column-type grinding machines uses a noncontact type of variable-pressure hydrostatic slide way system that minimizes oil-film thickness variations. This system achieves consistent straightness of 0.000016" (0.4 µm) over 32" (813 mm) for the cross axis (Y axis) and less than 0.00002" (0.05 µm) over 40" (1016 mm) for the longitudinal axis (X axis). Minimum resolution is 0.4 µin. (0.1 mm) in both axes. Grind capacity ranges to 32 X 160" (813 X 4064 mm).

Okamoto Corp.
Ph: 847-520-7700


Bore Grinder

Model B+ grinder is designed to replace the Bryant Model B. It's designed for bore-grinding miniature ball bearing inner and outer rings, lifter rollers, and many other small-bore part requirements. Its X and Z travel range is 3 X 3" (76 X 76 mm). Accuracy is 0.0002" (5 µm) with 0.000004" (0.1 µm) resolution. The machine accepts Model B tooling, including wheelheads and work fixtures. It features hydrostatic slides, linear motors, quick change between the radius dresser and straight dresser, and a Fanuc 18i TB CNC.

Bryant Grinder
Ph: 802-885-5161


Grinding Machines

Line of three-axis CNC precision grinding machines is offered in three different models, depending upon the amount of cross-travel desired. Standard is 6" (152-mm) travel, and optional is 7 1/2" (190 mm) and 9" (230 mm). The three-axis system consists of a patented grinding unit and workholding accessories mounted to a grinder base, three-axis CNC controls, operator station with Pentium IV computer, and Windows-based Pick-N-Place Talking Software. Grinding unit provides 0.000030" (0.00076 mm) standard repeatability, and optional 0.000005 - 0.000010" (0.000127 - 0.000254-mm) repeatability on the Special Edition model.

Tru Tech Systems Inc.
Ph: 877-TRU-TECH


Peel Grinding

Three modular grinding machine families employ the company's Quickpoint peel-grinding process. Systems employ a CBN or diamond abrasive wheel a couple of millimeters wide. Cutting speeds to 140 m/sec can be achieved. Quickpoint 1000 series offers a center height of 100 mm and grinding length of 150 mm for parts to 5 kg. Quickpoint 3000 series has a center height of 150 mm, grinding lengths to 500 mm, and handles workpieces to 15 kg. Quickpoint 5000 has a center height of 170 mm, grinding length of 1200 mm, and handles parts to 130 kg.

Erwin Junker Machinery Co.
Ph: 937-433-0774


Burr/Cutting Tool Grinder

Model 8200 combination burr/cutting-tool grinder is an eight-axis turnkey production grinding system with a fully automated pick-and-place loader. It's equipped with the company's new Version 6 tool-grinding software, and runs on the Windows XP operating system. Proprietary Geometral software allows the operator to customize and modify tool geometry, and view designed tools in 3-D on a color flat-panel monitor. Features include automatic wheel compensation, and capacity for 10,000 part programs/wheel packs.

New Unison Corp.
Ph: 248-544-9500


Vertical Honing Systems

Models SV-200 and SV-1000 feature a tool-stroking system that produces a true vertical stroke, resulting in higher accuracy in bore size and finish. It permits the machine to dwell in any part of the bore. With this design you obtain a consistent crosshatch pattern throughout the bore's length. The SV-200--intended for medium to high-volume honing of 19 - 200-mm bores--has a three-axis handwheel control for fast setups, and a 5.5-kW spindle motor. The SV-1000 is designed for medium to high-volume production in bores 65-mm diam and below.

Sunnen Products Co.
Ph: 800-325-3670


Small-Bore Production

Studer S120 production grinder is designed for small diameter parts and components with an external diameter of 50 mm or less. Center height is 125 mm with a swing diameter of 130 mm. Unit has its own integrated feed system. Two spindles have independent programmable drives. X drive with 300-mm travel has a top speed of 15 m/sec. Linear resolution is 0.0001 mm. Z axis travel is 180 mm at 30 m/min and 0.0001 mm resolution.

United Grinding Technologies
Ph: 937-859-1975


EB Polishing Machine

The electron beam machine (EBM) PF32A uses an electron beam to apply a mirror finish on a machined workpiece. To use the machine, the operator places the workpiece or mold into the machine's work zone, where a 2.5" (63.5-mm) electron beam passes over the part, yielding a mirror finish. This process can reportedly eliminate the need for hand polishing.

Sodick
Ph: 847-310-9000


Flexible Hone

Each globule is independently suspended for superfinishing. It is self aligning and automatically compensates for wear. Tool removes surface peaks developing a plateau of over 60%. It produces an oil-holding cross hatch to a given Ra.

Brush Research Mfg. Co.
Ph: 323-261-2193


Surface Finishing

Tool allows fabricators to more quickly finish stainless steel to #4, without start/stop marks, avoiding buffs and compounds, by combining standard 6 X 9" (152 X 230-mm) nonwoven pads. The new stainless mandrel accessory and the company's flexible shaft tools maintain high torque at speeds as low as 1000 - 1900 RPM, for low surface temperatures.

Suhner Industrial Products Corp.
Ph: 800-323-6886


Flathoning Machines

Dual-wheel design of the model DLM 705 permits grinding both sides of workpieces simultaneously. The same or greater precision is reportedly achieved with fixed abrasives compared to conventional loose abrasive lapping or grinding. In most applications, the need for premachining or secondary grinding is said to be eliminated. Workpieces are held in carriers, allowing continuous loading/unloading. Open-bridge-style "05" series adapts to an automated or conveyorized handling system from both sides of the machine.

Stahli USA
Ph: 847-526-3527


Bandsaw Blade

Available in various widths, the Easy-Cut bandsaw blade provides a single blade that can cut materials ranging from nonferrous (plastics, copper, and aluminum) to stainless and tool steel. This blade reportedly lasts as much as four times longer than a conventional blade when cutting many different materials, without any sacrifice in quality.

Bahco North America Inc.


Centerless Grinder



Viking SuperSeries II centerless grinder incorporates the company's 6400 CNC. Its interface is intuitive for operators accustomed to manual grinders, and the RS-274 G-Code programming accommodates experienced programmers and more complicated jobs. The machine's design permits a 15-min spindle-to-spindle change, and it can grind parts from 0.05 to 2.4" (1.3 - 61-mm) diam. Surface speeds range from 8500 to 12,000 fpm (2590 - 3658 m/min) for conventional abrasives and up to 16,000 fpm (4877 m/min) for superabrasives. A 16" (406-mm) diam grinding wheel is standard, with an optional 18" (457-mm) wheel available.

Landis Grinding Systems
Ph: 717-762-2161


Microgrinding Center

The CAM SXE CNC microgrinding center functions as an OD grinder and a centerless grinder. It can import shapes directly from a CAD system and grind multiple shapes on the same guidewire. CAD data are fed directly to servomotors that automatically control the grinding of wires with diameters as fine as 0.0005" (0.013 mm), and tolerance as close as 0.0001" (0.03 mm). Length tolerance is within 0.002" (0.051 mm) and surface finish is reportedly better than 9 Ra. Parts can be of unlimited length and from 0.125 to 0.0005" (3.2 - 0.013-mm) diam.

Glebar Company Inc.
Ph: 800-235-5122


Roller Feed Saw

A fully automatic cold saw that provides uninterrupted cutting on tubing or solids, the CPO 315 RFA comes equipped with either a supply table or a full bundle-loading attachment. Either system allows the saw to automatically load, trim, cut, and sort lengths to 120" (3.05 m), and hold ±0.004" (0.10 mm) in length on material to 3 1/2" (89-mm) diam. Optional equipment permits programming multiple lengths, and feeding directly into a deburring machine. Saws come in ferrous and nonferrous models.

Scotchman Industries Inc.
Ph: 800-843-8844


Taper and ID Grinding

A universal machine capable of numerous grinding operations, the GU5R grinder features a CNC-controlled swivel table for fast, accurate taper grinding. The wheelhead supports three grinding wheels and rotates between straight, angle, and ID grinding automatically and without changing the part setup. The automatic swivel table rotates from 0 to 10º via NC motor, improving accuracy because the operator need only control one wheelhead axis for precision tapers. A cartridge-style spindle accommodates up to six different wheel arrangements and allows use of straight and angle grinding wheels up to 20" (510 mm) diam even when both OD wheels are on the same side of the wheelhead. Other features include a single, fixed dressing point for all wheels and touch-screen panel with preprogrammed grinding cycles that minimize programming time.

Toyoda Machinery USA
Ph: 847-253-0340


Abrasive Nylon Disk Brush

The Burr-Rx line of abrasive nylon disk brushes for in-machine deburring now includes 3 and 5" (76 and 127-mm) diameters as well as the 4, 6 and 9" (102, 152, and 229-mm) diameters. This type of brush is more aggressive than conventional abrasive nylon brushes, allowing a faster feed rate. The high-aggression filaments enable the removal of larger burrs than standard abrasive nylon brushes. These disk brushes don't alter part dimensions, and are well-suited for use on CNC machining centers or custom-designed machines.

Weiler Corp.
Ph: 888-600-5857

 

 

This article was first published in the August 2004 edition of Manufacturing Engineering magazine. 


Published Date : 8/1/2004

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