Traditionally, robots have not played a prominent role in the implementation of lean strategies. However, due to robots’ repeatability, speed, accuracy and flexibility, the role of robots in lean implementations is constantly increasing. Automation equipment, which includes robots, is rapidly becoming a core component to lean manufacturing and the reduction of manufacturing costs.
Robotics have made it possible for manufacturers to vastly increase the scale of factory automation over the past three decades. With over 115,000 sold each year, industrial robots have become a mainstay of all sizes and types of manufacturing facilities. This increase in robotic automation has resulted in higher production rates, improved quality with decreased requirements for human intervention, while elevating the nature of work by removing people from dull, dirty & dangerous tasks. Adding robotic automation, however, does not automatically make a manufacturing environment lean.
Robots are not innately lean since they could be used to automate a faster creation of waste, but they are often integrated within the manufacturing process to support and enhance a lean manufacturing system’s success criteria such as:
Repeatability - Robots drive product quality or consistency and reduces waste.
Speed - Robots can help increase production and reduce wait time.
Accuracy - Robots help to reduce scrap.
Flexibility - Robots reduce training and changeover time – with a target of Single Minute Exchange of Die (SMED), and often achieving One-Touch Exchange of Die, (OTED) goals.
Lean systems and robots
One thing that often gets overlooked is that automation systems (with or without robots) can actually speed up the creation of waste and reduce profitability, if not designed into the system properly. No automation system or robotic solution is by nature lean by themselves.
Designing the manufacturing system to be lean is one of the largest challenges faced by engineers today. A few of the factors which must be taken into account, while designing a lean manufacturing system with robots are allowable scrap rate, conveyor and other transportation requirements, cycle time requirements by station or operation, equipment reliability and downtime statistics, flexibility required in the process, human machine interface requirements, life cycle of manufactured product to ensure acceptable ROI, line automation requirements (% Automation vs Manual), line production rate requirement, product handling requirements, maintenance requirements, repair time of equipment, space availability for robotic operations, number of product variants, safety standards and ergonomics guidelines.
Traditional production lines are designed to be an effective collaboration between man and machine. While the machines (including robots) can be programmed for optimal performance, people cannot. Effective ‘lean’ robot cells must take this into account. An mefficiently designed automated robotic station must take into account the ‘human variable’ and not limit the stations ahead in the line by rigidly ensuring consistent system performance.
Most importantly, the decision to use robots must be justified by an ROI (return on investment) analysis. Small and large manufacturers have proven today’s robots can significantly improve the ROI in a manufacturing environment, especially when implementing robots in support of a lean initiative – but again, planning is critical. The robots must be properly incorporated into the overall lean manufacturing environment to get the desired results.
Robots in lean systems
There are several instances where robots can strengthen a lean manufacturing environment to significantly help drive a positive ROI and support lean manufacturing goals. The following section cites one such example of robots in lean systems, which involves material handling and machine tending applications.
Prior to robots, material handling and machine tending were purely manual tasks. Operators would transport material from one fixture or machine to the next, wait on the equipment to finish its task, and then relocate the processed part(s) to another tool or process fixture. Several operators were usually required. Today, these labour-intensive tasks are often accomplished using robots, especially in operations requiring high speed and accuracy.
Many applications, such as baked goods coming out of an oven on a conveyor, are picked and set into their packaging. Then, the individually packaged products are automatically placed into cases, ready to be palletised. The palletising robot can then place cases accurately on the pallet. Each of these robotic applications may be configured specifically for the customer the product is being shipped to. For example, Walmart may have a different packaging and palletising requirement than Costco or Kroger. Each order can be picked, packaged and palletised automatically to meet the customer’s unique requirements.
How do robots make the system lean?
There is no wait time for operators. A material handling robot can be set up to multi-task, performing additional processing operations between operations.
Robots have negligible downtime. Robots deliver a limited production loss compared to manual operations, which tend to be error prone and inconsistent in terms of production rate, shifts, work breaks, etc.
Robots are less expensive to operate, compared to human labour – especially when overtime is required. Robots’ return on investment can be quickly realised when there is high demand for the manufactured product.
Robots are capable of highly accurate, highly repeatable tasks, which results in lowered scrap parts once the robot tasks are optimised.
Robots do not get fatigued and are not subject to heat, dust, humidity and other challenging work environments.
Robots and cycle time (speed and accuracy)
Many food packaging applications are solved by an operator (or team of operators) manually picking and packaging the products. This adds costs, can be physically demanding, and may create the potential for product contamination. Often fixed automation is used, but this can severely reduce the flexibility of the application. When product marketing develops a new product or a customer demands a new package size or type, the fixed automation is often too inflexible to cost effectively deal with the change. Robots have become a powerful tool in the automation of pick and place applications, such as pancakes, sausages, muffins and many other packaged or pre-packaged foods.
In major manufacturing assembly plants, there are often hundreds of robots performing material handling, machine tending, welding, finishing, painting and other assembly operations. Wasted robot motion can cause cycle time issues, creating bottlenecks and loss of production. Poor path planning can cause product quality issues that can lead to scrap parts. The cost of lost production is a major drain on overall corporate profitability. Ensuring that the cycle time for robotic workcells is optimised is very important to the lean manufacturing plan.
Workplace safety and robots
Most manufacturing operations have a degree of human injury risk. One of the primary reasons to automate a process using robots is to improve workplace safety. High-risk tasks like unloading parts from a fast-moving press or working with molten metal are definitely not tasks suited for human operators. In these cases, robots are invaluable in lowering the risk of injury or death.
An unsafe workplace leads to feardriven human inefficiency, lowered production rates, higher insurance and workmen’s compensation costs, and high employee turnover. Conversely, a safe workplace boosts morale, increases employee retention and lowers costs, which ultimately improves the bottom line. And again, robots can significantly elevate the nature of work by removing people from dull, dirty & dangerous tasks.
Robots can make the work environment safer by performing functions that are unsafe for humans, but robots themselves can be unsafe. For example, if a robot cell is not guarded properly, operators may take longer to service the station because of fear of injury. Whenever robotics are used, the environment must be carefully analysed and proper protocols instituted to keep the workcell safe. If the employees don’t feel safe, the robotics implementation will not be as lean as designed.
Many applications require the strengths of both people and robots, but until recently, this could be very dangerous. Now specialised software can allow robots and operators to collaborate much more closely without compromising on safety. This combines the flexibility of human interaction with the precision and handling capacity of robots to make applications lean, accurate and very safe to operators.
Robots, if used correctly, can enhance a lean manufacturing environment. Robots offer speed and accuracy that can’t be achieved with human labour. Robots can also reduce operating costs, reduce scrap – and are flexible for future changes. Few other manufacturing solutions can reduce waste as well as robots when designed into the system properly.
Robotics’ capabilities have only increased with time, while costs have continued to fall. Major robot manufacturers are constantly upgrading their robots with increased payload capacity, greater accuracy, increased reach and range of motion, improved speed and acceleration, faster communication with external equipment, better safety features, and lower operational costs.
If you have not explored incorporating robotics into your manufacturing environment lately, it is probably time to take another look. With a lower cost, more capabilities and a Advt
large number of successful manufacturing implementations, robots can increase your return, improve quality, reduce costs and help you eliminate waste.☐ Courtesy: ABB Robotics