According to Sumitomo (SHI) Demag faster return on investment, sterile conditions and safer production processes are thanks to the automation of precision moulding operations
Added benefits: Where high precision is required, integrating robots into moulding cells is beneficial
Robotic automation in the injection moulding (IM) process is no longer the preserve of pharmaceutical manufacturers with cleanroom environments. The latest statistics released by the European plastics machinery organisation EUROMAP, shows that the number of IM machines sold equipped with robots rose from just 18% in 2010 to almost a third (32%) in 2015.
“There has been a significant upwards trend,” observes Nigel Flowers, managing director at IM machinery supplier Sumitomo (SHI) Demag UK. “I think part of this has been driven by demand for more flexible solutions, and the use of 6-axis industrial robots, especially in precision IM, is certainly more commonplace today.”
Trend setter: Nigel Flowers, Sumitomo (SHI) Demag UK, says there has been a significant upwards trend in the use of robots
He adds: “In terms of robotic configurations, there is certainly plenty of choice. If all the robot is doing is moving a part from the moulding machine, a 3-axis robot should be sufficient. However, a 5 or 6-axis robot can perform more complex manipulation tasks. Precision components, such as electronic parts or hearing aids, are typically getting smaller and smaller. When you are handling or trying to remove parts from a mould that measure just millimetres, a dexterous robot is very important.”
In 2009, the Sepro Group, in partnership with Sumitomo (SHI) Demag, developed a special range of robots adapted to the company’s popular Systec and IntElect systems. Both systems are widely used in electronics and medical moulding.
Noting the benefits of integrating robotics into precision injection moulding systems, Glen Eves, general manager at Sepro UK, says: “In precision moulding applications, robots are looked at for their range of operation, accuracy, repeatability and cleanliness. Sometimes the customer needs to transfer parts, insert load, apply labels or remove complex parts in non-linear movements.”
Despite growth both in the number of IM machines fitted with robots and of broader acceptance of their value, questions remain for many in the plastics industry. Flowers and Eves address some of those lingering doubts.
How do I know the return on investment (ROI) adds up?
The fact that larger numbers of smaller businesses are finding the capital cost of robot-equipped IM machinery more affordable is helping to make ROI calculations easier. Of course, these calculations will be different for every business, but should take into account benefits such as quality improvements, repeatability and extended working hours.
“Being able to operate around the clock inevitably increases productivity and consequently profitability,” says Flowers. “Also, there is greater awareness among users that with industrial robots today, you’re not just specifying for a single application,” he points out. “Whether it is three months or three years, or whatever the product lifecycle turns out to be, a robot can be reprogrammed to support a different product. We are seeing larger numbers of customers switch from Cartesian robots to industrial 6-axis systems, which is in part due to the price gap closing but can also be attributed to technical applications involving complex take out movements and assembly operations. Additional evidence suggests that customers are also future-proofing their investments.”
Eves concurs: “Customers are increasing the specification of their robots at the time of order, rather than paying for costly retrofits. Typical requests run from additional stroke lengths to cover a larger working envelope for downstream automation, adding in second and even third rotations for product orientation and additional valves for extra gripping circuits. Upgrading to a robot controller also facilitates complex path tracking movements, enabling the management of downstream automation from a handset and control of all the robotic equipment from a single screen.”
Robotics is a ‘black-box’ technology that we will have no control over?
Robotic IM technology has moved on significantly, particularly in relation to adjusting settings and switching between programmes. “You no longer need to call in an absolute expert to carry out reprogramming,” states Flowers. “Control systems have evolved. Although the individual responsible for setting up and operating the machine will still require some form of training, the entire skill set is now within a customer’s own capabilities.”
However, at a national level, there remains a pressing need to ensure that the next generation of IM technicians and engineers are equipped with the necessary skills to fill these in-house roles.
At the design stage it too is easier for customers to be directly involved in scoping out the different options with regard to layout and robot specification using sophisticated computer graphics.
Flowers elaborates: “In order to minimise the number of compromises later down the line, we ideally bring the customer and all other partners together at the earliest stage of each project. The earlier decisions about robotics are taken, the better the solution.”
For a small company, is robotic automation appropriate?
Although the strongest associations for sophisticated robotics are with large and already highly automated operations, such as automotive plants, robotic development is just as rife among smaller-scale manufacturers.
“Even precision moulders with just three or four IM machines are seeing the benefits of being able to extend their working hours,” says Flowers. “If they want to move to longer shifts, they may be looking at the simplest solutions, such as Cartesian robots.”
As those companies grow, plan for the longer-term and put more emphasis on in-built flexibility, there is always the option of moving to a 6-axis alternative.
Do I really need a vision system?
There is a widespread misunderstanding that robots are inseparable from vision systems, and that vision adds another major layer of cost and complexity to the IM operation. For precision applications, vision provides quality assurance and is especially beneficial specialist sectors such as automotive components and medical devices where product dimensions and overall specifications have to be precise.
“Realistically, integrating vision into the IM process will only suit specific applications,” notes Flowers. “Aside from inspection quality control and guaranteed repeatability, in precision moulding it can be beneficial for determining the orientation of products, accurately guiding the robotic arm to trim away flash, or for assembly and packing.”
What are the commercial benefits in precision moulding?
“Applying robotics to precision moulding tends to be about minimising damage to parts and reducing quality costs and defects,” says Flowers. “The materials used will often be more expensive than in other sectors, so you set out to reduce waste as much as you can.”
Eves adds: “The use of poly-articulated robots has seen a growth in this area as they have many of the attributes required for these precision applications. But recent years have seen the bringing together of the technologies of Cartesian robots with poly-articulated units.”
Benefits include shorter interruption times in the moulding cycle and faster overall cycle times. There are also safety and accuracy benefits.
Robots can also be used to strip sprues and waste from around the mould and placing them in a granulator for recycling, notes Flowers.
It is also important for customers to realise that the theoretical benefits of a system can be maximised and tailored to suit specific needs at the installation stage.
FLowers emphasises: “Commercial advantage is not just about installing this IM machine or that robot. At Sumitomo (SHI) Demag we are focused on optimising customer investments, and continue to develop our application engineering team in order to ensure that ROI is maximised in specific environments, including precision moulding.”
Will a robot truly boost my already flexible plastics workforce?
‘Flexibility’ is an attractive idea, yet for many manufacturers in the precision moulding arena, consistent performance and consistent quality are the most important criteria. Both can be provided for by robotics.
At the same time, the UK cost of labour continues to rise. “One operator can look after, say, 10 machines equipped with industrial automation,” notes Flowers. “You can achieve more consistent output while reducing manufacturing costs. Rather than being a jobs taker, there’s strong evidence that adoption of robots across all manufacturing sectors is driving the need for more advanced engineering skills.”
There’s little doubt that in terms of flexibility and dexterity, integrating robotics and automation into IM precision set-ups can increase manufacturing competitiveness.
“Plastic processors today are rarely considering the injection moulding machine in isolation,” observes Flowers. “There is a definite shift towards integrated production cells, with a need for robotics and peripheral equipment to work seamlessly together.”
Until recently, much of the resistance has been tied to cost, expertise and lack of understanding on how a precision moulder could produce an attractive return on their investment. However, for moulders producing premium quality parts, robots stabilise the manufacturing process, boosting efficiency and output. Combined with lower capital costs, this makes the business case for investment in robotics stronger than ever.