Pure Passion –

Quo vadis, technical rubber goods?

Since the discovery of technical rubber goods, many industries and products have been influenced by them. HF Mixing Together takes a closer look.

Rubber may not exactly be ‘the stuff that dreams are made of’. However, since its discovery, this material has inspired mankind and made very important contributions to industrial and technical progress. As early as 1600 BC, inhabitants of Central America and the Amazon were making use of the water-repelling properties of caoutchouc. They named it simply after the method of production – the ‘tears of the tree’ (composed of the Indian cao for tree and ochu for tears) and used it to make hoses, containers, torches and even articles of clothing. Of course, they did not know about the process of vulcanisation, but they were already able to convert the plastic latex into an elastic, rubber-like material through the addition of tree and vegetable saps.

A breakthrough came in 1839 when Charles Goodyear invented the vulcanisation process, this is the process of transforming the plastic caoutchouc into elastic rubber, that is still used today. This marked the birth of rubber: a material with permanent elastic properties, relatively high tensile strength and elongation, and resistance to ageing and the effects of weathering. Natural rubber is still produced on a grand scale today. The five biggest producing countries are Thailand, Indonesia, Malaysia, India and the People’s Republic of China. Sixty per cent of the world’s requirements, however, are covered today by petrochemically manufactured synthetic rubbers.

Reliable partner of the technical rubber goods industry

For 150 years now, the HF MIXING GROUP (HFMG) has been supporting the rubber processing industry with machinery for producing an extremely wide variety of compounds. Significant innovations such as the Banbury® mixer, intermeshing rotor systems with fixed and variable axis spacing (VIC™) and tandem technology were devel­oped by the companies of the HFMG. A large share of industrial rubber production is used to manufacture tyres. It comes as no surprise, then, that the tyre manufacturers also represent a major customer segment of the HFMG. The group develops and produces machinery for automotive applications in the passenger car, heavy goods vehicle, off-road and bus segments along with machinery for tyre retreading.

Another very large customer segment is the technical rubber industry. The HFMG develops efficient, advanced solutions for this area – an activity which is both exciting and challenging. The customer companies of the TRG industry span an extremely broad range: they include major contract compounders who develop and produce practically all rubber and TPE blends. They serve a large number of sectors ranging from the automotive industry to the pharmaceutical industry. These compounds are used to produce seal profiles, conveyor belts, hoses, compo­nents for household appliances, footwear, and much more.

Most large compounders offer a broad product range for a variety of customer processes. This ranges from compact to foam rubber blends, black and coloured mixtures, pellets and strips of various widths, and some mixtures even have to be strained or calendered. They also have experience with a large number of polymer types, such as EPDM, SBR, NBR, HNBR, ACM, FKM, AEM, IIR, CR, CSM, CM, VMQ, ECO and NR/IR.

Along with large compounders, however, the technical rubber goods industry also includes highly specialised niche suppliers – who are likewise customers of the HF MIXING GROUP. They manufacture products such as special seals, cables, brake linings or products used in medical technology applications. As a rule, these rubber mixtures are designed to satisfy particularly demanding requirements regarding resistance to temperature or media, wear resistance, etc.

Flexibility – the be-all and end-all in the mixing room

Regardless of the size and business activity of its customers, HFMG has always worked closely together with each business in order to understand and satisfy their requirements. Wanting to have a better understanding of its customers, the editorial staff of HF Mixing Together asked the managers of four different firms from the TRG industry to tell us which market trends are currently driving their business operations, what requirements they require at this time and in the future, and how they see the market developing. Based on the feedback from those surveyed, it soon became apparent that – as far as the mixing room is concerned – the most important criterion is flexibility.

Carsten Rüter, President Technology at Hexpol Compounding, a leading group of companies in the development and manufacture of high-quality rubber compounds, TPE blends, and mixtures for roller coatings and special applications. Mr Rüter strongly emphasised: ‘Requirements such as small lot sizes, complex recipes, variable mixing cycles, and new materials are all relevant. The most important one, however, is the flexibility that a modern mixing room must provide in terms of raw material handling, flexible process control, and ultimately the machinery. The key to a successful mixing room concept is high machine availability, which is guaranteed by a robust and low-maintenance installation with a long service life.’

Adding to this, Klaus Bressel, who is currently head of engineering for KRAIBURG GmbH, reinforces that flexibility is the criterion: ‘For us as a specialised firm that also supplies small quantities, the greatest possible flexibility and efficiency of the TRG mixing room are decisive factors. The machinery must cover the broadest possible spectrum of batch sizes, supply quantities and forms while ensuring extremely high quality. This is the only way we can guarantee short delivery times and consistently meet our scheduling commitments with our customers.’

Automakers fuelling new growth

Whenever the topic of conversation turns to potential growth areas, the expression ‘automotive industry’ invariably comes up. Klaus Fassler, Operations Manager for the ContiTech AG affiliate PHOENIX Compounding Technol­ogy GmbH, explains it this way: ‘Technical rubber goods manufacturers follow the innovations emerging from the growth requirements and technology demands of the automotive industry. The former reap time-delayed benefits from the latter’s developments. The properties required of the products used, change at an extremely rapid pace. In particular, the demand for weight reduction necessitates and a reduction in the density of the compounds. Fibre composites, silicones and thermoplastic compounds also have a promising future.’

Paul Hallas, Operations Director at SPC UK and SPC Jevsa, in Spain, also emphasises the importance of this branch of industry: ‘In Great Britain, we are currently experiencing growth in the automotive industry, above all relative to new products for special applications in the high-end market of the automotive industry.’

E-mobility is still on the back burner

The opinions of the market players also converge with regard to whether e-mobility will have any effect on the TRG manufacturers, and if so, what those effects will be: ‘Sure, e-mobility will cause changes in our industry, but we’re talking about a timeframe of from 15 to 20 years. I think we’ll be driving with internal combustion engines for a long time to come,’ says Klaus Bressel von KRAIBURG with confidence. And Carsten Rüter adds: ‘E-mobility will no doubt affect TRG products, but for now it is still the last link in the ‘internal combustion engine – hybrid – battery’ product development chain. Once e-mobility achieves full coverage, the need for products such as fuel lines and hydraulic hoses will be eliminated, whilst lightweight construction will become increasingly important. Highly filled – and therefore heavy – elastomer components will then come under scrutiny and have to be replaced by components made of new materials. Where this is all heading is not quite clear at the moment, but it is a focus of attention at Hexpol Compounding. The TRG industry first needs to support the hybrid solutions of the drive concepts, and in that context the higher temperature stability of elastomer components is clearly of keen interest.’

Highly filled compounds are a reaction to price pressures

Whilst the other interview partners see no trend toward highly filled compounds in their segment, Carsten Rüter of Hexpol and Klaus Fassler of PHOENIX do indeed see one, but take a critical view. Rüter, for example, emphasises: ‘The development toward highly filled compounds is primarily the result of price pressure on the market. The resulting higher density is counterproductive for elastomer products from a cost perspective, however, and yields only a limited cost reduction for the processor. Accordingly, a balanced relationship of specific density and mixing costs plays the decisive factor in the final product costs.’ For the same reasons, Klaus Fassler believes that the possibilities for highly filled compounds are limited. He generally sees clear development away from the ‘mid-field’ and toward simple and inexpensive compounds on the one hand and highly complex, expensive compounds on the other.’

Equipment in the mixing room

The mixing rooms of the firms we asked use classical mixing machinery for the most part: conveyor and weighing technology for all raw materials, continuous and discontinuous mixing aggregates, rolling mills, strainers and pelletising systems, automatic batch-off and strip packaging machines, refrigeration systems, modern laboratories and process monitoring systems. Opinions on the use of double-screw extruders vary. On the one hand the rolling mill is undoubtedly considered as the standard discharge aggregate, now and in the future, because it can cool the mixture down rapidly and efficiently and is the most versatile relative to the customers’ strip width demands. On this point, all of the interview partners agree. However, for certain compounds to be produced in large volumes, the double-screw extruder is viewed in a very positive light and might replace the rolling mill, because it automates the mixtures and can therefore be operated unmanned. In the view of all who were asked, straining volume will continue to increase as a result of increasingly demanding quality requirements and is already well-established today at most suppliers. There does not appear to be any trend towards continuous mixing systems due to the fact that flexibility is considered the top priority.

Proximity to the customer is also expected of the machinery supplier

Regardless of their size, proximity to the customer is extremely important for all suppliers. The firms we asked all have international operations. In recent decades, they have followed their customers above all to Asia. Proximity to the customer is not only useful, but rather – with regard to the products and their properties and qualities – altogether essential in this industry. Paul Hallas of SPC insists: ‘We are a global company with a strong presence in Europe and Asia. Our manufacturing facilities are lo­cated near our customers, in a seven-to-ten-day delivery window, in order to ensure that the excellent quality of our products is not impaired.’

TRG suppliers also expect such proximity to the customer of the machinery manufacturers. Carsten Rüter explains: ‘For us it is important that a competent machinery manufacturer can provide worldwide service, but also that we have a central contact for strategic questions such as procurement of new equipment or basic modernisation projects for mixing operations.’ And Klaus Bressel adds: ‘Close collaboration with the machinery manufacturers is important to us, so that our specific requirements can be implemented. For us, factors such as short retooling times, easy cleaning, different batch sizes, and a high machine availability are important.’

And Paul Hallas would like a tailor-made life cycle programme for each and every machine, which can reliably predict its wear with reasonable accuracy. ‘I would like to know that I will be needing a new mixer body in five years, so that I am aware of any financial investment that may need to be made in the future on our part.’

Two megatrends: automation and energy efficiency

Automation has already been of interest to TRG suppliers for a long time now. Machine and automation are subject to an ever greater degree of networking. ‘For extreme flexibility in terms of raw materials and compound variety, this is also necessary,’ explains Carsten Rüter of Hexpol. ‘Condition Monitoring and process monitoring are an absolute must!’ PHOENIX has been working for more than 20 years on the networking of machine and control system, as Klaus Fassler reports. ‘We have a comprehensive control room system which handles everything from order management to material requirements by shift, and from process and quality monitoring and machine control right through to warehouse administration. It is all displayed for the employees and process engineers. At PHOENIX, the paperless factory is a reality. Moreover, we have an integrated TPM system.’

Also at KRAIBURG and SPC, the degree of automation of machines has become an increasingly integral part of the business, as Klaus Bressel and Paul Hallas report. ‘This trend continues. For technologies that we do not cover, it is important for us that the machinery manufacturer takes over that service,’ says Bressel. ‘One example of this is remote access to the control system and automation. As a rule, our spare parts catalogues enable faster availability of spare parts, which is in our interest, of course.’ And Paul Hallas adds: ‘The networking of machines and control systems is of crucial importance. All of our quality controls are fully automated, in order to minimise the risks associated with human error. Our high-quality products are completely traceable thanks to precise and constant processes. High-quality calibration is of central importance here.’

The second major topic that TRG suppliers are currently working on, and will continue to work on, is energy efficiency. Carsten Rüter reports: ‘Energy efficiency is a top priority for us globally, and complete energy studies of our mixing rooms are in the works. From mixer and rolling mill drives to support installations to mixing room lighting, everything is being subjected to testing. Clear objectives for the reduction of CO2 emissions have been established at Hexpol AB at the group level. Corresponding support from the various machinery and component suppliers would be desirable.’ The subject is also very important for KRAIBURG, as Klaus Bressel reports: ‘For two years now, we have had our own energy management system according to ISO 50001. From the manufacturers, we expect machinery with efficient drive technology and generally low consumption.’

PHOENIX Compounding established an energy team eight years ago. The team works on energy monitoring, low-consumption drive concepts, cogeneration, the use of heat exchangers, and other topics. This resulted in savings of more than one million euros just over the past five years! Klaus Fassler calls on machinery manufacturers: ‘They have to ensure that the new machines have energy-efficient drives. It would be a good thing if the customer could also purchase an energy monitoring system directly with the machine.’ Paul Hallas also welcomes the opportunity to work together with SPC’s machinery suppliers on new ways to improve energy efficiency. ‘I would be especially interested in innovations to recover energy, not only with regard to individual machines, but for the complete mixing room.’

Hexpol Compounding, KRAIBURG, PHOENIX and SPC can – on behalf of all suppliers from the technical rubber goods industry – be certain that the HFMG has taken note of their requests and will address their demands with excellent solutions – just as they have done for the past 150 years.