Tracking saw timber through the supply chain
Sawtimber harvesting operations produce a set of products which may vary in value, market and end product produced. There are also several different parties involved in getting the timber from the stump to the processing site. This means that timber needs to be quantified and monitored throughout the supply chain. Several methods currently exist for carrying this out, but recently, there have been significant international advancements on this issue which could potentially be of benefit in South African applications, one of which is radio-frequency identification (RFID) tagging.
|The RFID tag staple gun is mounted on a pivot arm on the harvesting head. When it comes time to tag, the stapler comes down and fires a tag into the log.|
|The canister for the harvester applicator.||Hand-held 'axe' RFID tag applicator.|
|RFID tags embedded in log ends. No compression or scuffing damage is possible.||Painting and tallying by Bosbok Ontginning in a York sawlog compartment in Mpumalanga.|
Methods used to track sawtimber through the supply chain
According to a report drawn up for the World Bank/Worldwide Fund for Nature Alliance (Dykstra et al., 2002), the types of labelling technologies available for tracing timber through a supply chain include the following:
- Conventional paint and chisel labels
- Branding hammers
- Barcode labels
- Magnetic stripe cards (the black strip on the back of most bank and access cards)
- Smart cards (micro-chips such as the gold chips on modern bank cards)
- RFID labels
- Microtaggant tracer paint
- Chemical tracer paint
- Chemical and genetic fingerprinting.
Currently, forestry operations in South Africa typically use chalk, paint, tags and/or barcodes to track timber through the supply chain. A common South African sawtimber operation using cut-to-length technology would involve the following steps to ensure timber can be accounted for and quantified:
- Once the tree has been felled and crosscut by the harvester, an employee measures the length of the log and writes the length measurement on the end of the log with chalk.
- A second employee follows and staples a blank, weatherproof tag onto the same end of the log.
- A third employee follows and measures the log diameter, then records the diameter measurement on the tag, as well as transcribing the length measurement (chalked onto the log by the first employee) onto the tag.
- Once tagged, measured and recorded, the logs get forwarded to roadside.
- Two employees work together at the stacked timber on roadside. One person tallies and records the information on the tags into a data sheet. Another person paints at least one end of each log a unique colour (this is to deal with theft and improve traceability).
- The logs are loaded onto a timber truck. Once the truck is fully loaded, the logs on the truck must be tallied. This is done by two people; one on the truck checking the sizes of the logs according to the tags (and marking each log that has been tallied with a piece of chalk), and another on the ground recording the sizes on a sheet. The truck stands dead still, fully loaded while this takes place.
The system outlined above requires seven people working within a harvesting operation to ensure that timber can be traced through the supply chain. A typical operation could produce around 500 m3 of tagged and tracked timber through the supply chain per day. Some of the disadvantages of this approach include:
- The safety concerns of people and machinery working in close proximity of one another.
- The safety concerns of a person climbing around a timber truck to read log dimensions out to the person recording.
- The likelihood for human error throughout all the links of the timber tracking chain, and the associated incorrect invoicing and payment which results from this.
- Tags getting coated with mud or being pulled off or damaged during the extraction and loading operations.
- The impact that this system of tracking timber has on the eventual delivered cost of timber to the mill.
What is RFID tagging?
Radio-frequency identification (RFID) has been around since World War II, but due to technology advancements, has come into the spotlight in recent years. RFID basically does what a barcode does, but with a few differences. Instead of the barcode stuck to an object, RFID uses a tag (a microchip with an antenna) either stuck to or embedded in the object and instead of a barcode scanner, it has an RFID reader (interrogator) (Gjerdrum, 2009).
So what are the benefits? The RFID reader does not have to make contact with or even be in line of sight of the RFID tag (unlike a barcode scanner which has to scan directly on the barcode). Like the name indicates, RFID uses radio-frequency waves to convey data/information from a tag to the reader.
RFID scanners can scan multiple tags at once, whereas barcodes can only scan one barcode at a time. This means one can drive an entire truck of individually tagged sawlogs through a scanner and immediately every log will be registered.
How is the RFID Tag applied?
RFID tags traditionally have been stapled or nailed onto log ends by people within the harvesting operation. The Technical University of Munich, however, developed a prototype RFID-enabled harvesting head in collaboration with Ponsse (Wessel, 2006). The harvesting head has an industrial staple gun mounted onto it which staples RFID tags into the logs it crosscuts during the processing and crosscutting operations.
The head is also mounted with an RFID interrogator which takes the first reading of the log's data.
The forwarder in this system is also mounted with an RFID interrogator, which reads the entire load. Secondary transport timber trucks, similarly, also have these interrogators mounted on them. The final reading occurs at the processing plant, performed by an interrogator attached to a conveyor belt handling log intakes.
In a test of about 500 tags in a forest near Munich using this system, none were damaged during the process of felling timber and stacking logs, though approximately 5% were lost somewhere between the forest and the processing plant. The project team calculated that the application would cost €4.50 ($6.00) per cubic metre of harvested wood, assuming a transponder price of 50 eurocents per tag, plus the costs of associated hardware and software.
The tags applied through the harvester head were made of plastic. Advancements in manually applied biodegradable tags have been made as well, meaning that tags can be sent through processing systems without any complications, even in a sector where the entire log is processed, such as pulp and paper.
Generally, forestry RFID tags are designed to penetrate fresh timber. The tag should be inserted soon after the log is cut, and as close to the centre of the log as possible. This allows the tag to be protected from mechanical stress on the outside of the log through the processes of the supply chain.
Advantages of RFID tagging
- Some RFID tags are made almost entirely of biodegradable material, meaning they can be processed without any complications.
- The potential for integration of an RFID labelling device on the harvester head means fewer operations are required within the supply chain.
- There is a huge potential for increased mill sorting automation using RFID, for example, using RFID tags to sort logs into appropriate processing lines.
- Far more data can potentially be stored in an RFID label than using conventional systems (e.g. GPS co-ordinates of the tree at the stump site).
- Due to increased automation, there is less room for human error.
- There is an improved level of safety in harvesting operations due to less people tagging logs on the ground.
- Depending on the type of RFID tag being used, new information can be added to the tag within the supply chain process, making it more relevant as it is tracked through the system.
- Technology becomes more affordable and reliable with time.
- Value chain savings, such as less standing time for trucks, because timber no longer has to be manually tallied.
- Many harvesters already have the ability to measure log sizes built into them. This means in the case of mounting an RFID tagger to a harvester head, one would be making better use of technology and information from the harvester which is already available.
- RFID tag damage during extraction, loading and transport is not likely since the tag is embedded in the centre of the log's diameter.
Disadvantages of RFID tagging
- Costs associated with RFID tags and corresponding scanning systems may make them currently unaffordable.
- The potential of missing identification data in an RFID tag would have implications on the system.
- Data could potentially become corrupted in the scanning systems (as with other technological systems).
- Potential inaccuracies by the person or harvester head calibrating the log sizes would be carried through the supply chain, as with the manual system.
- Lost RFID tags within the system would have implications (especially if contractors are paid on RFID-calculated timber volumes and operators are incentivised by these volumes as well).
- The general trend of diminishing average tree size in South Africa means one would need more and more tags to trace the same amount of timber into the future (thus increasing the delivered cost per unit timber further).
The use of RFID tags has potential application in other forestry systems apart from sawtimber such as poles, mining timber, pulpwood, etc. Due to the cost per tag and scanner systems, it is best suited to higher value, larger piece size timber products. As technology advances and RFID tagging becomes more common (such as luggage tracing in airports), it is expected the costs will decrease and reliability will increase, making it a more viable option.
Dykstra, D., Kuru, G., Taylor, R., Nussbaum, R., Magrath, W., Story, J. 2002. Technologies for wood tracking: Verifying and monitoring the chain of custody and legal compliance in the timber industry. World Bank/WWF Alliance for Forest Conservation and Sustainable Use Report.
Gjerdrum, P. 2009. RFID tags applied for tracing timber in the forest products chain. Proceedings of the 5th meeting of the Nordic-Baltic Network in Wood Material Science and Engineering (WSE), pp. 209-114.
Indisputable Key Website. [Online]. 2012. Available at: http://www.indisputablekey.com/. [2012, May 06].
Wessel, R. 2006. University in Munich Develops RFID-Enabled Log Harvesting. [Online]. 2006. Available at: http://www.rfidjournal.com/article/view/2861. [2012, May 05].
Published in June 2012