New materials and technologies make abrasive machining simpler and more productive
Abrasive machining is a tried-and-true technology for meeting exacting tolerances and producing superior finishes. Manufacturers continue to develop new capabilities.
These advances were to be showcased at the now-cancelled IMTS 2020 show. A few of them can be seen here, in Manufacturing Engineering’s Show-in-Print coverage.
New features include remote monitoring, multi-axis machining, safety and damping, guideways, cross slides, custom solutions, and more to help end users meet today’s more challenging manufacturing environments, especially in growing industries such as medical.
Lasers are being used for the first time in a Vollmer of America product as the Carnegie, Pa.-based company recently released the VLaser 270, a laser-based sharpening machine. “With this laser, we have incorporated all our knowledge from precision engineering that we have been acquiring from our grinding and erosion machines for decades,” said Dr. Stefan Brand, CEO of parent company Vollmer Group.
According to Brand, the VLaser 270 “always keeps the tool in the center of the focal point based on the C-axis. This allows tool manufacturers to machine a cutting edge in a highly precise and stable manner with minimal movement.”
At the core of the VLaser270 is its fixed laser beam guidance with innovative machine kinematics. The way in which the five axes are arranged on top of each other means that the tool is always machined at the pivot point of the C axis with minimal axis movement, ensuring stable process control. At the same time, the kinematic chain enables high path accuracy, which has a positive impact on the machining accuracy and quality of the tools, Brand said.
The VLaser270 can be used in an unmanned, lights-out operation. It can sharpen the cutting edges of cutting tools that are tipped with PCD or other ultrahard materials. The technology can optimize different processes in tool manufacturing, including the machining of chip guide notches, as well as do chamfer machining and cutting edge preparation.
Rotary Surface Grinders
Custom-designed features on grinders are commonplace for DCM Tech, said Doug Henke, technical specialist for the family-owned grinder manufacturer based in Winona, Minn. Henke estimates that as much as 50 percent of machines are customized in some way. “At DCM, we handle everything in house and can customize machines and processes per customer request,” he said. The company is highlighting its newest rotary surface grinder, the IG 280 SD. The 282 SD, part of the company’s IG series of grinders that ranges from the manual IG 080 to the massive IG 480, is an upgraded version of DCM’s 280 model.
It is the first DCM-style rotary surface grinder to feature a precision servo driven cross-slide motor that allows the machine to grind tight tolerances along both the Z and X axis. Other upgrades include an autodress feature; regrind feature; and an IoT-like remote monitoring system. Another upgrade is a new sensor-based part detection system. “The automated sensor allows the operator to load the part, hit the go button, and the sensor detects the part and grinds it to a perfect height,” Henke said. “It is a huge advantage in avoiding a crash and takes human error out of the equation.”
Universal Grinding Machine
Grinding flexibility is also a guiding principle behind the GL-4i Switch universal grinding machine from JTEKT Toyoda Americas Corp., Arlington Heights, Illinois, that features a manually adjustable wheelhead for straight and angular applications. Shane Farrant, national product manager-grinders, said the wheelhead works in increments of 0o, 30o and 45o for flexible grinding, which increases cycle times and reduces the probability of burning on face grinds.
“The Switch is one of our most popular models in North America because of its price point and its versatility,” he said. “It is a fit for job shops that have frequent changeovers, and can be used by high-production facilities running lights-out.”
Gearing up for large part grinding applications, Toyoda’s GL4i Switch model ranges from 500-2,000 mm distance between center, up to 400 mm swing, and increased part capacity ranging to 300 kg. The model features a Toyoda stat bearing and flat plate technology to ensure high accuracy and position, and a reinforced cast-iron bed to improve coolant flow and reduce thermal displacement. The stat bearing uses a hybrid hydrostatic/hydrodynamic technology to eliminate metal-to-metal contact inside the bearing.
The Switch uses the company’s own conversational control, the Toyopuc Touch, that gives the operator intuitive and easy-to-learn data entry capabilities with visualization of equipment status for smart manufacturing, Farrant said.
Cutting Tool Grinder
Rollomatic’s GrindSmart 830XW is a tool grinding machine that integrates hydrostatic guideway technology and linear motors with six-axis machining to produce both large and small tools from 1 to 32 mm diameter and flute lengths of up to 200 mm. “The most significant feature of the 830 XW is that the guideways are hydrostatic,” said Eric Schwarzenbach, president, Rollomatic Inc., Mundelein, Illinois. “Normally, you have recirculating shoes that ride on rails, but with this we have no mechanical contact. Everything is riding on a highly pressurized film of oil.”
Hydrostatic guideways help damp vibration and can withstand heavy loads. “Adding to stability and vibration damping is a three-point base design and an enclosure that is physically disconnected from the machine base so it will not transmit vibration to the base,” he said. The model features a synchronous, direct-drive spindle that provides constant wheel rotation independent from the spindle tool. “If you are driving the spindle at 3,000 rpm, it will turn at exactly 3,000 rpm; it will never deviate from that,” said Schwarzenbach.
The six-axis capability of the GrindSmart 830XW opens up new options for innovations in tool design, particularly for high-precision tools, he said. The arrangement of the grinding spindle axis on the machine enables freedom of movement on both sides via a total rotation angle of 240°. This means that both right-hand and left-hand tools can be ground with the same wheel pack.
Adapting Abrasives to Hard-to-Grind Materials
Norton | Saint-Gobain Abrasives, Worcester, Mass. has added new abrasive products to meet requirements for demanding, precision applications. “With new, harder-to-grind materials, tighter finishing specifications, and more automated manufacturing processes, we need to adapt to meet the needs of our customers,” said Will Lang, technical business development manager. Norton Winter Paradigm diamond wheels can grind difficult-to-grind engineered alloys and composites, such as gamma titanium aluminide and ceramic-matrix composites. New to Norton | Saint-Gobain’s product offering is the Norton Winter Vitron7. When combined with the company’s CarbonForce, carbon-fiber core, the vitrified cubic boron nitride (cBN) wheels are exceptionally lightweight, resulting in improved grinding performance and maximum operator safety when mounting and during changeover. The wheels feature a high-precision vitrified bond, excellent retention of the grain to the bond, and a uniform force per cBN particle. Also new is the Fixed Abrasive Buff (FAB) that adds abrasive grains to the cloth of a buffing wheel, virtually eliminating the need for messy compounds.
Grinding Medical Products
United Grinding North America, Miamisburg, Ohio is highlighting Studer cylindrical machines; Ewag and Walter tool and measuring machines; Blohm and Magerle profile grinders; and flexLoad automation. Determining the machine best suited for an application can be a challenge. “A lot of parts that can be made on a Walter grinder that can also be made on a Blohm or a Magerle grinder,” said Phil Wiss, regional sales manager. “It depends on customer needs.”
Simon Mans, general manager, tool division, added “if the part or device is something like a bone pin or medical drill, something that looks like a tool, then the Walter product line might be best. If there is customized fixturing behind it, a progressive fixture, a multi-axis interpolation of that part, then a creep grinder or a Magerle Blohm-type process” is better.
Wiss said Magerle and Blohm grinders are used in medical projects, from orthopedic implants to cardiovascular implants. Common denominators are “difficult-to-machine materials from ceramic to carbon to cobalt chrome; cycle times for the processes we were replacing were long; and the processes being replaced were expensive and generated inconsistent quality with excessive scrap.”
Medical device manufacturers often don’t know that grinders are suitable for this work, said Simon Bramhall, general manager, automation solutions. “Medical companies using a vertical mill or a multi-axis machine” on difficult-to-machine materials “may be struggling with it,” he said. “Grinding lends itself to areas where they can get an 8-16" [203-406 mm] diameter grinding wheel into a cut.”