Plastic Injection Moulding

The plastic moulding dilemma

Fanuc intelligent multi-axis robots are addressing the offshore challenge for plastic injection moulders by adding value to component handling. On the surface, anyone taking a comparative snapshot of the use of robotics in plastics moulding between 1990 and 2004 could be forgiven for thinking not a lot has changed. Sadly up until recently very little in the way mouldings are handled has changed. What is transforming the industry dramatically is that much of the work undertaken in the UK during the 90's has either moved 'offshore' or is certainly under threat of going that way.

The 'off-shoring' dilemma does not just relate to handling mouldings but increasingly in all areas of manufacturing moving up the technology food chain. It is important to be able to compete with the offshore threat and in order to do this, more strategically thinking businesses are employing technology to improve quality, reduce cost and to add value for their customers.

Robots are nothing new to the moulding sector and their benefits are well understood and documented. The linear versus multi-axis articulated arm robot debate continues but now the stakes are higher. The relatively straight forward linear co-ordinate robots, or pickers dependent on the degree of control offered, are generally limited to point to point handling tasks and simple palletising routines - beyond this automation of post moulding operations can be limited without costly additional tooling.

In contrast multi-axis robots offer the opportunity to extend the scope to loading inserts, handling the moulding on ejection, de-sprueing, inspection, assembly of components, palletising and communicating statistical data to management. The possibilities are limited only by cost justification - ROI (return on investment). There are two other important considerations often overlooked when weighing up robots versus coordinate systems, first a robot can be moved round a factory to take up other duties, they are versatile. Second if finance is required the banks are much happier to provide funds for a robot and far less enthusiastic about a bespoke arrangement.

ROI is the fundamental measure for justification but, in today's challenging economic climate, maintenance of high value customers is also a core factor. The automotive and bio-pharmaceutical sectors are two high volume markets that demand both exacting quality standards with 'cost down' expectations. Furthermore, in these markets it is the development of supplier partnerships that lead to increased confidence and the adding of value to mouldings by post operations. Achieving this confidence is a result of control of the process and well-defined quality procedures. The control of the process is of course paramount and where the greatest improvements have been made in multi-axis robotics over the past decade. Increased intelligence of the FANUC controller and generic packages for vision, multi-robot control, force sensing and supervisory control has in real terms kept robot system costs static - in some cases relatively lower than ever before.

Programming the robot arm to perform post moulding operations is very straight forward and has the benefit of being able to have it carry out other duties while waiting for the mould cycle to complete its task. Cycle times average out at 60 seconds which provides plenty of time for post moulding operations typically these can be desprueing, printing, dropping de-gated sprues into granulators and pressing inserts into the mouldings. If required an automatic cropping station can be positioned within a number of moulding cells and so a very straight-forward tool is fully utilised to become a cost effective addition to the process. A robots range of additional tasks is considerable, for example putting mouldings into an assembly machine and then packing the assembled item into a tray; or because of their speed and accuracy, they cannot be matched by an operator for consistency of operations such as palletising.

As systems partners Micromech Robotics and Fanuc can specify, build and install the right equipment for you that is simple to programme and operate. Perhaps you are not already using a robot, then this might be the time to break the mould and change your production methods.