))) TI's Electronic Tags revolutionise Rubber Manufacturing for Trelleborg Industrial AVS, Leicester

))) DALLAS, TX (October 13, 2000)

As a major UK manufacturer of rubber compounds, Trelleborg Industrial AVS faced a major logistics challenge. The company needed a reliable identification, tracking and control system to ensure that any combination of up to 100 pre-mix additives are correctly weighed and ready for use at precisely the right time and at the right place in the process. Any missing components or re-scheduling of production can result in costly delays, wasted batches or, worst of all, a batch actually curing during production. Most of all, it needed a system that could operate reliably in the extremely difficult and rugged environment of an industrial rubber manufacturing plant.

Previously, the company relied on a traditional manual production scheduling system for operation but this lacked the accuracy and flexibility required for efficient automated production.

To streamline its manufacturing process, Trelleborg (formerly Metalastik) looked at various solutions including bar-coding and electronic tagging. Bar-coding each bin was rejected as it had practical limitations in terms of reading and alignment and its durability/reliability in an industrial carbon black environment was a major issue. The final solution was an electronic tagging system based on Texas Instrument's RFID (Radio Frequency Identification technology), which has allowed the company to improve its production control and efficiency while providing greater flexibility to change production schedules to meet customer demands.

The RFID system was designed by John P Waterhouse Co. Ltd, the systems integrator who teamed up with Texas Instruments, through their approved distributors RFID Components, to trial TI's RF tagging technology for non-contact bin identification. Trials were initially conducted on a range of standard RF Tag configurations, the eventual tag selected being a read/write disk tag that not only allows data to be read from the tag but also allows new data to be written to the tag whenever required.

According to Stuart Sutherland of John P Waterhouse Co, "the RFID system has revolutionised logistics management for Trelleborg and proved highly successful in eliminating production problems while giving the flexibility to change production schedules without disrupting the production process."

Rubber Compound manufacture is an intensive mixing process and a new batch cannot be started until all constituent raw materials including off-line prepared constituents such as Small Chemical additions are correctly proportioned and available. At Trelleborg, there are about one hundred different chemicals that can be added to the process and these are stored in four vertical carousels. The chemicals are selected and manually pre-weighed according to a small powders off-line production schedule and delivered by container to the mixer operator when required. Trelleborg's production runs are usually variable and often short and this, combined with the large number of additives, results in a difficult to manage process. Production schedules can be adversely affected by raw material shortages or changing priorities resulting in frequent revisions to the schedule posing a significant logistics challenge.

The pre-mix ingredients are stockpiled on the factory floor. If the main production schedule needs changing, all the small chemicals ingredients must be re-scheduled. This is where the logistics becomes a real challenge and it is easy to see the potential for human error and inefficiency.

The tagging solution. John P Waterhouse Co's innovative solution involved a fundamental change to the existing production methodology whereby the off-line small chemical preparation became the main scheduler for the entire process.

The key was to identify each small chemicals container during preparation and during its transfer to the mixing line. Trials were conducted using non-contact bin identification using a range of standard RF Tag types and the eventual choice was a TIRIS disk type tag with full read/write capabilities combined with standard TIRIS Reader/Programmers. Following successful trials, implementation of a fully integrated RF Tag Identification system was undertaken at Trelleborg's compounding plant in Leicester.

How it works

Each of 100 Small Chemical containers is fitted with an RFID tag that is unobtrusive, yet robust and can be reliably interrogated / programmed by a fixed Reader/Programmer unit, even when surrounded by other steel components. One Reader / Programmer unit is located at the Small Chemicals Weighing Station and another at a point near the end of the container transfer conveyor.

Operation begins at the Small Chemicals Weighing Station. The Operator is prompted, via a display screen, to place an empty Additives container onto a platform scale. The RF Tag is interrogated to ensure that the container is not considered by the system to be still in use. If the RF Tag is valid, all erroneous data is erased allowing it to be re-used.

The Operator is prompted, material by material through the complete Small Chemicals Weighing Operation, until all the ingredients are assembled. In the event that a small chemicals batch cannot be completed, for example, because of a shortage of raw materials, the relevant batch can be suspended and parked as a semi-finished component. At this point the container's RF Tag is programmed with the appropriate part-complete data. At a later date, this batch can be physically retrieved and its container simply placed on the platform scale. The container's RF Tag is now automatically interrogated and the operator prompted to complete the unfinished additives from where the process was suspended.

When a batch has been completed, the RF Tag is programmed with appropriate data for that batch and this uniquely identifies the container and all its constituent chemicals.

The completed container is then manually placed onto a transfer roller conveyor, which transports it to the Mixing Station at the end of the conveyor. At the same time, a second Reader/Programmer unit interrogates and extracts data from the Container's RF Tag. This data is interpreted by the Mixer Control System, also designed and implemented by John P Waterhouse Co, and displayed to the Mixer Operator who is given the opportunity to Accept or Reject the particular batch.

If accepted, the container is released and the control system prepares all automatic Weighing and Mixing sequences according to a specific recipe linked to the data on the RF Tag. Because there is space for three containers at the end of the conveyor, up to three batches can be active at any one time (one weighing, one in transfer and one mixing). This means that not only are all the additives ready for the next batch but batches can be interchanged quite simply by physically removing or even inserting new, giving the improved control and greater flexibility required by Trelleborg Industrial AVS.

The use of electronic tagging has virtually eliminated the possibility of batches with wrong or incomplete additives reaching the final mixing stage and the system's robustness allows it to cope with even the most arduous conditions including a carbon black environment which would have defeated any barcode system.