Taniq: Rubber Factory of the future – ABSTRACT

1. Starting with an intro on global development and developments in the rubber industry. Followed by a more specific focus on the possibilities for (mandrel-built) non-tire rubber products.

2. Where after an explanation is given of how digital manufacturing is possible with software and automation technology.

3. Lastly, show the differences with the current processes and the changes required, supported by case study results (e.g. expansion joint and large diameter hoses).

Automation of custom rubber products

A drive for higher productivity in the early 90s has since led to mass automation of production throughout the rubber industry. With the help of retrofitting and new automation systems, mainly standardized and mostly repetitive processes have been automated for various products throughout the industry.

Unlike these automated production processes, mandrel built reinforced rubber products (except tires) have seen limited automation. The mandrel built products form a niche of the overall rubber industry. This niche market is pull-oriented and characterised by specialists, manufacturing products specifically upon customer specifications in small orders (sometimes only a single product). As a result, a large variety of products need to be manufactured on a single production line.

Typical products are large diameter rubber hoses, high-end expansion joints, bended hoses, pipe plugs, and others alike. The manufacturers mostly rely on production methods, systems and product designs that have improved over decades, yet mostly remained the same. All products share the same production concept of manual application of rubber, reinforcement material and curing tape by a trained operator on a rotating inner mandrel.

Over the past 25 years, many manufacturers have started to outsource the labour-intensive production to low-wage countries to reduce labour costs. However, high-end products requiring certification are still made in, or have returned to, western countries because of e.g. the conservative attitude of the customer-industries, quality concerns, and high-impact of potential product failures. As a result, labour costs have become a major part of the overall production costs.

Agile production of specialty products through digital design and manufacturing

Automation can provide an answer. In the past, new control technology led to retrofitting of the productions lathes, introducing basic automation to this niche market. However, retrofitting or redevelopment of the current processes has not provided an answer to all the problems at hand. Especially the large number of product variations seem to have, so far, left little automation solutions suitable. On the other hand, development of radically new automation solutions requires extensive expertise and significant financial investments, and then still offers no guarantee for success.

Taking inspiration from digital design and manufacturing techniques and the continuous advances in robotics can provide an answer to the demand of a flexible automation system for various mandrel built rubber products. Could this be the factory of the future?

Image 1 Automation system overview (3rd generation TANIQ Virgo robotics 2015)

Digital manufacturing is based on a direct connection between the digital design environment (e.g. software) and automated production equipment (e.g. CNC, 3D printer or laser cutter). The systems automate and optimise multiple aspects of the production process. The first key aspect is an optimised design environment to give the user direct access to the required design parameters in a logic and user-friendly workflow. The second is a direct link from the software to the equipment to ensure the product exactly represents the design. Lastly, the equipment and production processes are automated and optimised for efficiency and productivity.

Conventional production relies on manual processes based on extensive training, experience and expertise. Each individual variation of the products is hand-designed. Where after a trained employee manufactures the product manually based on the drawings and specifications. The conventional products rely on manually applied rubberized reinforcement sheets. At the ends of the product the sheets are slit and in some way connected to a coupling or other connection mechanism. For straight products this process could be reasonable fast, but especially for products with a double curvature (e.g. bellow) it is particularly difficult and time consuming to place the sheets.

By replacing the reinforcement sheet by single cords/yarn/fibres (possibly rubberized), it is possible to apply the reinforcement material in a continuous manner – so from end to end without the need to slit the cords. This enables a high speed continuous process, suitable for automation.

Image 2 The left image shows a conventional reinforcement structure of fabric rubber sheet. The right image shows an optimised structure with an individual fibre. The product shown is an automotive turbo-hose.

The idea of individual-cord winding systems for rubber composite structures is not new. Since the 50s, development of such technology for rubber products, such as tires, has resulted in various patents. Up until today, this technology has not been successfully applied because it could not be adapted to the large product variations within the mandrel-built product niche market. Using a robotic arm in combination with a digital design environment, can overcome the shortcomings of automation by retrofitting and the individual-cord winding systems.

Unlike the other systems, the automation equipment needs to be able to automatically apply all different material layers (and not only the cords). More importantly, the automation system needs to provide the required agility and flexibility to handle the variations in size, material and design between different products. State-of-the-art process control equipment that can cope with the demands is necessary, which can be found in an industrial robot arm.

Industrial robot arms have six degrees of freedom which enable manipulation of the material for accurate placement on the rotating mandrel. To apply different types of materials the robot can be fitted with different end-effectors dedicated for a specific job. For instance, placement of the fibres is achieved with a guiding tool at the end of the robot arm. The robot can switch the tools automatically, and thereby also automate rubber and tape application (which are applied manually in the conventional process). As a result, materials are continuously wound over the product, following the contours of the mandrel back and forth at high speed and automating the manual production processes.

Image 3 Automatic application of tape of a Pipe Plug (1st Generation of TANIQ Virgo robotics)

A distinct difference with conventional production is product design based on calculation of the reinforcement structure using algorithms. As part of digital manufacturing, special software has been developed that incorporates and automates the reinforcement structure calculation, as well as rubber and tape layer design. Robotic arms normally require reprogramming for each change made to the production process, limiting flexibility. However, a robot controller-program output function is incorporated in the software, enabling manufacturers to automatically generate a production file for the robotic system based on the product design. The production file dictates the robot and makes reprogramming obsolete. As a result, setting up the robot is very fast, providing the required flexibility for various products. Therefore, a major obstacle in the niche market has been resolved. In addition, designing the product in software makes it possible to perform Finite Element analysis/modelling for different load cases with the exact geometry of the design. This means that the designed product, analysed product and manufactured product are identical. Altogether the specially developed robotic system and software make automation of mandrel build reinforced rubber products possible.

Image 4 Expansion joint automation: Design Software, FEA, 3rd generation robotics.

Case studies

TANIQ is a R&D specialist developing automation technology and product optimisation. Using software and robotic setups based on the principles described above, multiple automation solutions for products have been delivered and studied. With the automation systems, production speed, application accuracy and consistency are no longer limited by human capabilities. As a result, increased productivity and reduction of labour costs can be realised. On the other hand, application of a robotic automation system requires a distinct move away from the conventional construction of the products, the production method and change of all material application processes.

Case studies, confirmed by manufacturers already in production, show significant differences between conventional manual labour processes and products compared to automation using robotic setups. Robotic setups are not always financially and/or operationally feasible. Manufacturers already in production, however, show consistent realisation of the advantages presented and interesting return on investment periods.

Image 5 Production time reduction per product. Case studies were performed for internal research. Product specifications originate from evaluation of frequent product specifications on market. Note: all sizes designed using software; all sizes evaluated with production simulation; selection of sizes manufactured for research.

Conclusion

Since the 50s, manufacturers have tried to develop systems to design high-end products based on individual reinforcement cords, accurately applied in an automated fashion. Despite the qualitative advantages, they have not been able to create a flexible design and automation solution required to adapt to the large variations of products. However, recent developments in digital design and manufacturing offer new opportunities. Design software integrated with robotic manufacturing, provides the flexibility required and desired increased productivity.

If the factory of the future will be filled with robotic setups is yet unknown. The technology, is available and the case studies show major benefits are realistic. If the advantages outweigh the concerns, and the scale is tipped in favour of robotic automation, another part of the rubber industry may see robotic automation in the near future.