Going "Lean" with Robots
When you take into account wages, overtime and benefits that human employees require, it's no wonder that robots are quickly becoming the go-to technology for manufacturers across multiple industries.
But not all manufacturing practices are created equal with regard to automation. One such example is lean manufacturing – a type of manufacturing that predates the advent of robotics, but still hasn't jumped on the automation bandwagon.
Lean manufacturing was coined by Toyota engineer John Krafcik (thus the common moniker, “Toyotism”) in 1988 and was originally defined as a manufacturing system focused on the reduction of overproduction, transportation, wait times, inventory, motion, over-processing and defects.
Until now, robots had not been considered for lean processes because just as they can produce many products more quickly than human operators, they can also produce scrap more quickly. However, if robots are programmed to minimize waste output consistency, speed, accuracy and flexibility could help to cut down on scrap and production time.
If manufacturers are to take advantage of robots' speed and efficiency while maintaining a lean manufacturing practice, they must establish a number of variables that limit scrap production. Some factors, such as allowable scrap rate, line automation requirements and production rate, play self-evident roles in regulating and minimizing waste output.
However, less obvious waste contributors such as waiting time are not to be forgotten. These factors include: maintenance requirements, equipment repair time, safety standards, equipment reliability and equipment downtime statistics.
While machines can overcome problems of efficiency with ease through effective programming, people cannot. Essentially, robots must allow for some variance in system performance in order to not limit the stations ahead of them in line. Even though human operators are already a part of many lean manufacturing plants, this is a major factor that manufacturers cannot overlook in “slimming down” their robots.
Repeatability and Speed
Historically, material handling and machine tending have been situated squarely in the domain of the operators in a manufacturing facility. This task generally required several workers: one to wait for a machine to finish its work before relocating the processed parts to another tool or fixture, while another would load new material in its place.
Robots are quickly becoming a popular replacement for operators here, as they help to improve speed and accuracy while taking the physical burden off factory employees.
A prime example of this can be seen in the food and beverage industry, where robots can easily pick up baked goods right out of the oven and arrange them in their packaging. Then the packages are placed into cases, and another robot places them on a pallet.
Because of the robots' flexibility, it's simple to customize packaging and pallet requirements for each customer depending on their unique needs.
In this particular use case, robots offer multitasking capabilities that allow them to handle additional operations in the downtime between two existing tasks. There are naturally consistent, overcoming downtime and productivity variation between workers and shift changes. Similarly, they are unaffected by adverse working conditions such as heat, dust and high humidity that could inhibit the performance of some workers.
Autonomy and Cooperation
Capitalizing on robots' inherent flexibility is a major step in ensuring ROI. As a result, factory layout is one of the first factors that manufacturers must address when planning for robot implementation. In effect, a factory is optimized for both lean processes and robots when it allows a single robot to process as many operations as possible.
While robots of the past have had a single tool on a single arm, many of today's robots come equipped with tool changers that diversify the possible tasks one machine is able to perform, making for a leaner environment.
In the die cast industry, for example, the same robot could be used for material handling, de-gating, deburring, and grinding. Or take for example the automotive industry, where robots commonly handle both materials and welding. To make this possible, external servo motor-driven axes provide auxiliary axes of motion to free up the machine to go where it is needed.
Conversely, two or more robots can coordinate their movements through a single controller to work on a single large part. For example, in the automotive industry, two robots can assemble the roof to the main auto body by having one robot hold the roof while another welds it to the frame.
On the whole, most of these applications in lean manufacturing are benefited by robots because of the reduction in production bottlenecks and time wasted. However, due to improved accuracy and consistent performance over human operators machines can help reduce waste output as well, demonstrating their value for lean manufacturing systems.