Many fabricators are discovering the benefits of robotic welding in areas they never before suspected. In fact, more and more job shops, small businesses and large manufacturers are finding enormous productivity gains moving to welding automation in previously ignored applications.
While robotics was once considered a means exclusively for mass production, companies such as Crown Equipment Corp. have dispelled that myth and continue to find substantial gains welding as few as one unit for a variety of separate parts using automation.
Crown manufactures electric lift trucks worldwide as high as 45 feet to assist in a variety of material handling and manufacturing applications. The company’s trucks are used to transport materials and goods in warehouses, distribution centers and manufacturing facilities.
In a unique production model, the company produces nearly 85% of all its truck parts within the company. Each part is often made in small quantities — as few as one to twenty at a time, to meet real-time demand on the assembly line.
For years, however, the Greencastle, Ind. location had manually welded more than 1,500 miscellaneous parts in nine welding stations using MIG processes, along with the welding of the frame of four different models of lift trucks. Five years ago the company began reevaluating that strategy.
Crown chooses Lincoln Electric
A Crown manufacturing engineering team began looking into automation. The first step was to ask for an automation survey of Crown, its parts and its processes by a team composed of Crown personnel and experts from the welding and robotic industry. As a result, Crown invited Fanuc Robotics, The Lincoln Electric Company and several other automation and welding companies to review their operations.
The invited companies performed a two-day review of Crown’s complete welding operations and procedures, both manual and robotic. They discovered hundreds of parts could in fact be welded better, faster and more consistently with robots, despite the small unit quantities. Moreover, the data showed Crown that the investment would pay for itself in a matter of months.
Lincoln Electric tested its assessment in its Cleveland headquarter laboratories and presented Crown with the final results. Crown engineers took those findings to its senior management team and purchased the first of three Fanuc Robotics robots and Lincoln Electric welding cells, all powered by Lincoln Electric Power Wave 455M power sources with Super Arc L-56 MIG wire.
The welding and material handling process
But the changes didn’t stop there. Crown engineers, using a universal mounting and fixture plate system, started building dozens of robotic welding fixtures for the new welding cells. They were all built on common fixture plates that matched up with the locating pins on the frames and tables in the robotic weld cells for easy installation and removal. This allowed every welding fixture the ability to be quickly changed in and out as needed or moved from one robotic weld cell to the other.
They found that the average fixture change-out time was about five minutes, using the new universal plates and pinpoints. Crown put the new system to work on parts identified by the survey for immediate cost savings, such as motor mounts, cross braces, brake pedals, carriages, latch plates, light brackets and battery retainers.
Overcoming the material handling issues involving all of the parts and fixtures entering and leaving the cells was a key to success of this automation project. Crown utilized its own material handling expertise to tackle this problem. The solution was the design and installation of a system of 20-foot-high industrial racking and fixture storage shelving. Fixtures and parts to be welded on the robotic weld cells are stored on the new racks, often weighing several hundred pounds each.
As needed, the fixtures and parts are retrieved from the shelves with a Crown TSP lift truck and placed in a short-term staging area for installation and use as soon as a robotic cell becomes available. Crown designed the TSP 6000 Series Turret Stockpicker to maximize cube utilization navigating very-narrow aisles. The TSP 6000 is equipped with features setting new standards in operator comfort and confidence. Productivity is enhanced through blending. Crown’s exclusive multi-task controls allow the TSP 6000 operator to blend multiple load handling tasks simultaneously. In addition, Crown incorporated ergonomic features such as its MoveControlTM seat that swivels to four different positions, a revolutionary platform design, multi-task controls and adjustable, cushioned armrests.
The TSP 6000 Series is a man up lift truck. The features allow operators to pick, transport and move items as necessary. Its three-point design offers tight turning radiuses and powerful AC lift and traction motors provides industry-leading travel speeds — 25% faster than typical trucks — with smooth and precise acceleration. The main lift speeds are more than 40% faster than industry standards.
The TSP works well in applications utilizing very-narrow aisles. The method Crown put in place in Greencastle reduces downtime and minimizes the amount of time for an operator to locate a fixture and parts. Once a fixture is changed, the same people who arrange and coordinate the fixtures in and out of the welding area return the previously used ones to their assigned storage area on the shelves using the TSP lift truck. Another benefit of this material handling solution was the physical floor space savings realized by utilizing the high density storage racking.