Feature: Just-in-time approach to final mixing & blending

 VMI reports on a project, also involving Rhein Chemie and Bekina, that offers a promising new approach to rubber compounding

London – During the last DKT exhibition, in 2012, ERJ reported on an innovative approach taken to final mixing & blending for rubber compounds, developed by VMI, with support from Rhein Chemie and Belgian compounder Bekina.

The concept, called iCOM, involves use of an integrated production line, comprising a gear-pump and extruder for highly controlled mixing & blending, a mill for greater control of throughout, and a batch-off system to cool and pack the final compounds.

The production line is semi-automated, with pre-dispersion packages of chemical active ingredients automatically added and controlled according to a programmable system.

When first installed, the technology was both innovative and productive, but three year later the VMI-Rhein Chemie concept of just-in-time mixing & blending has been developed further.

As an overview, the technology is designed to address the concerns experienced by all rubber compound manufacturers:

High energy use: because a process based on the use of internal mixers makes it necessary to go through a number of heat-up and cool-down cycles to move from stage one – plasticisation of the masterbatch – to production of final batches.

Complex logistics: due to the need to move time-limited final batches to the point of use before they start to vulcanise and thus become useless.

Reduced quality options: as the drive to achieve economies of scale through central production makes it harder to develop custom-made or innovative new compounds, or to ensure absolute consistency, for which continuous blending as well as continuous mixing is required.

The experience gained through working with Bekina has shown that it is possible to overcome all these deeply-rooted problems and achieve higher levels of productivity and quality through the just-in-time approach.

In simple terms, this involves returning to a two-stage production strategy, in which highly stable masterbatches can be produced  – if required through centralised mass-production – but in which final batches are prepared to highly specific recipes only as and when needed, and as close to the point of ultimate use as possible.

 Refined system

 The just-in-time concept has now been refined to the point where it can be taken to market as an integrated production line that delivers enhanced levels of productivity. For example, at Bekina one operator can produce 2 tonnes of compound per hour, compared with four operators producing 900 kilos per hour in the past.

Input from up to six different masterbatches, meanwhile, enables a high level of blending to take place and ensures much greater consistency in the final output.

Scrap levels can now also be virtually eliminated as a result of the more predictable performance characteristics of the final compound, produced by the controlled blending and mixing within the process.

Use of Rhein Chemie’s “Rhenogran” chemical additives, controlled by VMI’s computerised dosing systems, also allows different recipes to be precisely produced at high levels of efficiency.

Automated testing, using Rhein Chemie’s “Rhenowave” system, in which zinc oxide markers are inserted into the compound, offers a further efficiency. The markers can be read by ultrasonic transducers, which eliminates even the need to carry out periodic testing of the final compound.

The refined and integrated just-in-time system, therefore, has the potential to bring radical changes to the technical rubber market, in terms of operational efficiency and product quality alike.

To date, the hands-on experience has shown that even comparatively small manufacturers can gain financial and competitive advantage by using the iCOM approach, though it is necessary to take a new commercial approach to maximise potential.

The just-in-time philosophy recognises that masterbatches are essentially commodity items, which can be acquired from high-efficiency, low-cost centralised plants. That’s because the true product differentiators and added value actually comes from the final batches.

In final batch production, manufacturers can ensure that product quality and consistency are improved by blending multiple masterbatches and then through developing precisely targeted and innovative compounds, using the automated Rhein Chemie/VMI chemical additive dosing systems.

The iCOM technology is integrated and semi-automated and, in commercial terms, allows smaller plants, making smaller individual batches, to compete on price with larger, centralised final batch producers, while beating them on quality. Just-in-time final batch production eliminates most of the costs associated with transport and simplifies the producer – client relationship.

The future

 In future, there will be growing pressure on manufacturers to develop new compounds more quickly: to meet specific end-user needs and to take smaller batches of more product variants into the market, month by month, year by year.

When the demand is for large amounts of the same substance at the lowest price, central production on a huge scale is clearly the answer. In the new age of product variants, differentiated characteristics and faster response times, the rules of the game have to change.

Later in 2015, Rhein Chemie will be using the iCOM just-in-time concept as the basis for major new investments in both the US and Brazil: we will be watching progress of these projects closely and reporting on them as they develop. This really could be the shape of things to come for the rubber industry.

Last word, though, to Peter Uytterhaegen, Bekina’s operations & product innovation director, who comments: “When we needed to invest in a new line to meet growing demand, we quickly realised that traditional methods would not deliver to our needs.

“We wanted a new approach and joint working with VMI led to a solution that is now giving us exceptional productivity, [enhanced quality] … and no scrap at all. This has been transformational for us.”