”Automation” and “zero defect manufacturing” are buzz words that are increasingly gaining importance for manufacturers of elastomer products. In particular when it comes to using resources more effectively and improvements in cost savings. The basis of this strategy is the deployment of process integrated control systems using sensors. The motto here is: more performance and optimal unit costs or higher delivery assurance with less process risks. In general this means reduced costs and increased customer satisfaction. Especially in the case of high volume elastomer parts, automation offers excellent process design and at the same time, through the use of sensors for improved vulcanisation processes, a new level of quality. Vulcanisation can then truly become an industrial process with a production flow of zero defect parts.
The latest example of this development is the delivery of a new manufacturing unit to an important development partner of the automotive industry for precision moulded parts. These parts are subjected to tough demands in terms of temperature and medium resistance and also have to exhibit convincing elastic recovery for the life of the part. In the case of this special development on the basis of a MaplanMTF400/250editionS machine with two hydraulic drives featuring Cool-Drive technology with servo actuation, the customer required specification presented sales engineers Gerald Kemper and Paul-David Betea from Maplan with a series of challenges.
At the core of the production cell is the Maplan MTF400/250 editionS elastomer injection moulding machine. The machine’s components enable a high level of processing in terms of process design, energy efficiency and process reliability. To ensure fully automated manufacture of precision moulded parts with metal inserts, automated separation and feed of the metal parts was required. Overall, the solutions for automation were comprised of four main assemblies:
Feed unit for metal rings
Separation and postioning unit for metal rings
Pick and place unit
Sprue removal unit
The machine’s inspection module comprises of a laser sensor for sprue detection and cameras that check the moulded parts in a multi-cavity mould. For tooling and ergonomic reasons, a wider clamping unit at an optimised operating height was specified. Thus providing ample space for large multi-cavity moulds. The optimised operating height guarantees the operator improved access for inspection and maintenance as well as for changing moulds.
The precision moulded part is made out of rubber, as well one or more metal rings, which are placed in the mould by means of an automatically extendable hotplate shuttle. Paul-David Betea states: “since the whole cycle is fully automatic, there are practically no sources of error.” Productivity is maximised by means of multi-cavity moulds.
A laser sensor is mounted on the sprue removal unit at the front of the machine. This device moves into the clamping unit of the machine on every cycle to grasp the sprue and then remove it on the basis of the “pick and place” principle. As it moves out of the machine, the laser sensor scans the sprue plate to check whether for example a sprue has not been removed from the mould. The metal rings are fed from a vibration hopper. This hopper supplies rings sequentially. In addition, it also separates the single or multiple rings and places them in the correct position onto a separation section, so that the rings are laid out in a matrix ready for the next cycle.
The shuttle with the finished precision moulded parts is then moved to the rear of the machine. High resolution cameras are mounted between the rear shuttle and the machine for QA inspection purposes. The cameras check the positioning of all parts on the shuttle as it moves into the machine. When the shuttle plate moves into the machine again, the cameras check whether the moulded parts have beencorrectly ejected. The parts require sensitive handling – due to their shape, it is absolutely essential that they are ejected obliquely from above. The parts then fall onto a conveyor belt below which transports them to the finished parts container. Such concepts are a logical step towards zero defect manufacturing.
“The trend towards higher levels of automation in connection with sensor technology is steadily growing. Customer-specific requirements have considerably increased in the last three years”, comments Paul-David Betea. Due to the high degree of globalisation of elastomer processing, in particular in the automotive industry, this effect can be seen in every region of the world. As Paul-David Betea explains further: “with reference to automation and sensor components, we estimate there is an average extra cost of up to 50% compared to conventional capital expenditure for machines. Particularly in the case of moulds for high volumes or with many cavities, there is, however, a significantly higher level of quality and considerably faster amortisation.”
The integration of automationand sensor technology in new elastomer processing plant has a very long-term effect on profitability. This naturally also applies to the whole lifespan of a machine. Operating faults can be avoided or process deviations identified early on. By moving towards zero defect manufacturing, disturbance variables become more manageable. Whereas in the case of conventional machines quality has to be checked after the production process, i.e. offline, a fully automated machine can implement in-line QA controls, assuring quality during the ongoing production run. The reduced risk of faulty parts in part flow means a high degree of reliability and possible cost savings. A consistent flow of parts generates a “feel good factor” for all parties involved in the supply chain: parts producers, OEMs and users.