Processes Achieve Production Flexibility
Speed and accuracy are primary
By Robert B. Aronson
Manufacturers are refining well-known processes and looking for new ones to keep up with the ever-growing demands for high-speed production, precision, and quality. In the welding industry, key trends include:
- Environmental air quality issues are causing a review of welding-fume control. Recent OSHA and EPA regulation of welding-fume emissions are forcing a review of welding-fume control methods, including substitution, isolation, ventilation systems, and work practices.
- The aging of experienced welders and lack of new talent has have stimulated both a strong recruiting effort in the industry, simplification of welding processes, and greater automation.
- Because of lower prices for automatic equipment and lack of welders, more smaller companies are finding it economical to use robots to automate their welding processes.
- Automated orbital welding machines are seeing service—on pipe lines, for example. This may reduce the manpower needed.
- A move to "green" equipment has encouraged companies to redesign of equipment to use less energy.
According to Chris Bailey, general manager, Lincoln Electric Automation Div. (Cleveland). "The more active markets for welding equipment are in construction, pipeline work, and winddriven power generators. Several recent bridge failures may stimulate more bridge building and repair work in the near future."
Bailey notes that vision systems are a key part of accurate, automatic operations. "For example, a programmed, robotic welding head can scan a part. The program determines the required weld position, and the head is positioned to make the appropriate weld."
With an industry focus of "faster is better, and quality is king," robotic welding systems need to be designed as intelligent solutions with ease of use and flexibility being key attributes. In a partnership with Fanuc Robotics, the latest units from Lincoln are the ARC Mate 100iC arm and Lincoln Electric's Power Wave i400. The AutoDrive is the wire drive and the Power Wave is the power source. For example, the company's AutoDrive 4R90 needs no tools for the drive roll, wire drive, or pressure-arm adjustment. The unit has an integrated design and can be mounted on the upper arm of a Fanuc Robotics ARC Mate iC arm.
Fanuc's R-30iA Controller comes with iRVision hardware. By loading the vision software option and connecting a 2-D camera or 3-DL sensor, the user can add a vision process that provides reliable part location and orientation regardless of variations in part size and occlusions.
One way the welding industry is responding to its many challenges is through new welding technologies. Last year, ESAB (Florence, SC) introduced its hybrid laser welding system, and this year they are introducing a friction stir welding system for ferrous steels and other high-melting-temperature alloys. "The advantages these systems offer include automated operation, reducing the need for skilled workers; lower heat input, reducing distortion and improving weld quality; greater efficiency, and less environmental impact than traditional arc welding techniques," explains Jeff Hoffart, senior vice president and general manager, equipment, cutting and steel industry products, ESAB North America.
ESAB's friction stir welder operates without fumes, heat, noise, or welding arc, and causes no deformation of the workpiece, making it viable for many welding applications. The process uses no filler metal and, because the parent material does not melt and harden, there are no solidification defects in the weld. This process can be used in a number of mechanization styles, and is effective for out-of-position welding. ESAB's circumferential pipe welder uses friction stir welding to join almost any grade of steel pipe up to 1/2" (12.7-mm) thick in a single pass, in or out of position.
Mitsubishi Laser (Wood Dale, IL) is introducing the next generation of its LVPLUS series, which has several new performance-enhancing features.
The machine's new 40CF-R resonator technology, derived from Mitsubishi's CFX-series resonator, reduces rise-time/fall-time of the square-wave pulse. This provides a more consistent beam power during the cutting process, and delivers a more-consistent edge quality. The uniform low-current discharge provides low-power stability for improved micromachining and etching.
The LVPLUSII is said to produce a cutting-surface roughness equivalent to the typical machined finish, along with reduced taper and discoloring on the heat-affected zone.
The new Jet Pierce technology decreases part-processing time because material is pierced faster and more aggressively during small-hole processing. Improved height-sensor hardware gives the LVPLUSII twice the tracing ability of the original machine.
Mitsubishi's Diamond-Path technology maintains consistent beam quality by using a constant-beam-length system. It provides cutting stability at speeds up to 1150 ipm (29 m/min) across all processing areas.
"Mels Eye" optional Intelligent Process Monitoring System has auto focusing to ensure cut quality. Burn detection tracks each cut, and pierce detection increases productivity by eliminating the buffer in conventional oxygen piercing. Plasma detection minimizes scrap in high-production runs by tracking plasma and adjusting the machine's speed as necessary.
"Most of our laser-cutting work is with low volume, highly variable parts," explains Trumpf (Farmington, CT) company Vice President, Burke Doar. "That is because industry, in general, is trying to serve a wider variety of markets.
"The number one trend in laser cutting equipment is the demand for very efficient machines. And that means equipment that is versatile. The user's goal is a machine that cuts parts from a sheet of 0.25" (6-mm) thick steel, followed immediately by making a different part from 0.5" (13 mm) stainless, and right after that cut yet a third part from 0.75" (19-mm) aluminum.
Trumpf's new TruLaser 2030 has the automation components integrated into the machine. This design optimizes untended operations. Ideally, after the parts have been cut there should be a minimal skeleton, or the remnants of the cut plate. Another critical feature is making a clean, burr-free part. When this is practical, secondary operations are eliminated.
When the goal is burr-free punching. Trumpf uses a rolling tool to perform a finishing operation that eliminates the secondary operation of the deburring processes such as grinding.
After the perimeter of the parts have been punched but are still held in the sheet, the part edges are passed between two wheels. As one wheel applies pressure to the top of the part, the bottom wheel rolls the existing burrs back into the part's underside.
Top speeds for the process can be up to 1600 ipm (41 m/min). This process can work on straight lines, radii, and complex contours. In addition, material as thick as 0.120" (3.06 mm) can be deburred.
"Among the metal-bending product manufacturers, most newer developments are aimed at increasing automation," says Scotchman Industries (Philip, SD) company President, Jerry Kroetch. "We now offer an automatic feed system that increases productivity and minimizes labor. Formerly, the metal to be sheared was manually positioned. This system automatically moves your material to position and cycles the machine. The size and number of parts are programmed either at the machine or off line."
The feed system can help automate other Scotchman or similar machines, however it's standard on the company's new ShearMaster 610 Pro-duction Flat Bar Shear. This machine combines large capacity with high-production shear capabilities. Standard features include: electric stroke control setting to reduce the travel of the upper blade, hydraulic hold down, and electric back gage for automatic cycle. A 10-hp (7.5-kW) motor can give the shear a top speed of 12 strokes or 30 half strokes per minute.
Finn-Power International (Arlington Heights, IL), is a manufacturer of sheetmetal fabrication machines and automated systems, including servoelectric and hydraulic turret punch presses, punch/shear and punch/laser combination machines, lasers, press brakes, automated panel benders, and management systems.
The main bending products made by Finn-Power are press brakes and panel benders. Both are used to bend flat metal sheets. The press brake uses different bending dies that need to be changed to meet various specialized bending needs, and requires an operator to manipulate the part through the bending operations. The bender uses a primary set of standard tooling, and will automatically set the part up according to the part requirements. Parts are also automatically loaded in the bender, manipulated through the bending operations, and unloaded, eliminating the direct involvement of an operator.
"I've noted four trends in this industry." says Bending Product Manager Michael Stock. "The shortage and cost of qualified operators, lower volume orders, greater emphasis on worker safety, and demand for more energy-efficient machines.
The company attacks the manpower issue with three programs.
- Partially automate the press brake operation with robotic integration so one person can operate a number of machines.
- Totally automate the bending operation with the bender so the workpiece is fed into the machine, the bending process is actuated, and the finished piece is removed.
- Integration of the bending process into the previous flat-blank fabricating process.
The challenge of lower-volume production is to minimize setup time. Often, a company will change setup in a press brake 30 or more times a shift. Setup time reduction in a press brake can be accomplished with hydraulic clamping and quick-set tooling, a fully functional easy-to-use CNC, an accurate multiaxis machine, software for programming jobs offline, and a network connection. The bender is well-suited for low-volume production, because often the part setup is accomplished automatically in seconds before the first part is introduced.
KMT Waterjet Systems Inc., (Baxtor Springs, KS), a manufacturer of high-pressure pumps and components for waterjet systems, now offers an ultra-high-pressure (UHP) 90,000-psi (6200-bar) pump. The 60-hp (45-kW) pump has one intensifier which can mean reduced operating costs by cutting products in less time than conventional waterjet systems. The pump can also operate at 60,000 psi (4136 bar) when less waterjet force is needed.
This 90,000-psi pump reflects a trend in waterjet-cutting to more power, or higher water pressure, to cut more material/product faster. Increased cutting capacity can significantly decrease product lead times and increase shop cycle times. "We introduced 87,000 psi [6000 bar] to meet the demand of manufacturers who demand faster cutting with lower abrasive usage, and improved production capacity at lower operating costs," says Chris Maier, product manager, Flow International (Kent, WA). "The new technological advance provides angular compensation for trail-back phenomena and taper, and allows for faster waterjet cutting with improved accuracy that also eliminates inside-corner damage. Combined with 87,000-psi technology, there are significant production-efficiency improvements."
At IMTS 2008, Flow International will showcase 87,000-psi HyperPressure waterjet cutting, now available as part of Flow's WMC2 waterjet machining center and Integrated Flying Bridge (IFB) waterjet machines. Flow's WMC2 and IFB machines cut parts from almost any material up to 8" (203-mm) thick with no heat-affected zone. — Robert Aronson
This article was first published in the August 2008 edition of Manufacturing Engineering magazine.