Robotics is one of the most sought-after technologies across the globe. The demand for industrial robotic automation systems is rising exponentially. In the early 1970s, the evolution started for CNC machining process, like milling, grinding, turning, etc. This was also the time of evolution of industrial robots for handling and welding applications. There are also some limitations in CNC technology, such as, flexibility, scalability, complexity of motion & cost factors that are overcome in robotics. From 2000 onwards, these two technologies were combined and robotic machining was introduced in the early 2000s.
Robotic machining is a very wide spectrum. It includes: robotic milling and sculpting, robotic trimming and cutting, robotic grinding and deflashing of castings and forgings, robotic finishing and polishing and robotic deburring. These systems consist of an industrial robot and controller, spindles and tool changers, tool rack, fixtures and programming software. Robotic machining is a major leap from Industry 2.0 to Industry 4.0 and towards next generation manufacturing. This transformation towards smart manufacturing practices will have a deep impact on productivity, enhanced and consistent quality, health and safety, flexibility/multitasking, reduction in cycle time and neat & clean shop floor.
Approaches in robotic machining
Robotics have some key technologies that include application/process development, tooling and fixtures, controls and programming software. There are two approaches in robotic machining – the first one is robot moving tools. In this approach, one or multiple tools are mounted on a robot wrist and workpiece is clamped in the fixture. This approach is suitable for large parts with a wide variety. The second approach is robot moving parts; one or multiple tools are fixed in a cell and workpiece is moved by a robot and gripper. This approach is suitable for small parts made in dedicated production lines.
Automated robots delivering quality
Robotic machining is the use of industrial robots to automate and standardise repeatable manufacturing processes/tasks. Automation of this process brings several key benefits to the manufacturers of castings, like, increase in productivity, upgradation in quality and healthy & safe working atmosphere. The technology behind robotic fettling and how it may be successfully deployed across the iron casting industry serves as a guide of dos and don’ts for good executions. Iron castings of manufactured parts, as everyone is aware, have the most complex shapes. And this is where automated robots come to the rescue by delivering quality with accuracy down to the last, thou (a thousandth of an inch).
Robotic fettling systems
Robotic grinding/fettling gives tremendous improvements in the consistency and completeness of fettling. Manual operations are subject to numerous variations through the days, weeks and months of the year, where more than one operator never works in the same style. Multiple operators work on one component leading to handling damages. Cutting tools manually operated invariably causing scratch marks, dents dig into unwanted areas, which are a major cause for rejection of castings. The tool selection in robotic grinding is very critical because the process reliability, cycle time and running cost of the system are majorly based on the type of tools used. In certain cases, it is observed that selecting the most advantageous tool can reduce cycle time and cost running by as much as 90 per cent. The most commonly used tools in robotic fettling include diamond-plated wheels for cutting and grinding.
Robotic fettling have various costs associated with it, whichhave to be considered while calculating cost per piece over the long run, such as, the maintenance costs (annual maintenance, spares etc), energy costs, consumables costs (use of customised tools for robotic application can save significantly), retooling, reprogramming costs and labour costs (including future rise in the same). Significant improvement in quality is considered while calculating the investment returns of a robotic fettling system. A drastic reduction in rejection rate and removal of rework/checking stations also brings space savings. Correct selection of application and wise implementation can ensure a Return on Investment of robotic fettling systems within one to two years.
Robotic sculpting operation is nothing but creating sculptures using heavy duty industrial robots instead of human hands. It automates the sculpting process and maintains the aspect ratio and proportions (scalability) of the sculpture. It eliminates the chances of errors and drastically reduces the pattern making process in large sculptures. Small sculptures can be created directly in one go from the raw block of material. The prototype/sample is scanned and designed, after which the robot is programmed using specialised software and then is sculpted using the robot. Robotic sculpting includes operations, like rough milling, finish milling and engraving. It is the most advanced technology with which one can sculpt on wood, thermocol, foam, graphite stone, granite, marble, brass and copper.
Importance of tool selection in robotic machining
While working in robotic machining technology, tool selection is extremely important and critical. One must study the mentioned parameters while selecting the proper tool, such as, process, flash level, material, material removal, estimated cycle time, running cost and reliability.