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Vendor Accent
RFID in manufacturing: automatic data capture
 RFID
has applications in industries other than retail. Full-fledged applications
have already been deployed in manufacturing, says Bhasker Joshi.
A lot of hype has been generated by the RFID tagging mandates
from major retailers in the past year. Several initiatives have been taken across
the world to achieve widespread adoption through technology standardisation
and driving down device costs. The efforts have been centred on the requirements
of the retail and consumer goods industries. This has led most people to incorrectly
believe that RFID is meant only for these industries. Though retailing and consumer
goods industries are still far away from large-scale deployments, there are
several full-fledged applications working in other industries. These applications
have been around for some time and generally they have been successful in areas
where traditional auto-ID technologies like bar codes have been found to be
inadequate.
RFID is a non-line-of-sight identification technology which can be made to work
in a non-intervention mode for faster data capture over longer distances. Unlike
other auto-ID technologies, RFID tags can carry data which can be updated on
the field. These unique capabilities open a whole range of possibilities for
applications built around the need and availability of authentic data in real
time.
The need for RFID
Almost all business processes involve instances of data capture
for transactions or for making tactical decisions, or both. In most of these
cases data capture is manual and often only transactional data is recorded and
retained while non-transactional (parametric) data is discarded after meeting
immediate requirements. In both these situations automatic data capture has
the potential to help improve process productivity by reducing waste and non-value-adding
activities. Automatic identification and data capture technologies can help
realise significant gains by way of cost reduction and cycle time improvements
on manufacturing shop floors. However, in many such scenarios the hassle of
manual intervention or the need for process changes becomes a barrier to deployment.
Such cases could be addressed with RFID by leveraging its intrinsic advantages
over otherauto-ID technologies.
There are several scenarios on the manufacturing shop floor,
where the availability of accurate data could lead to a manifold improvement
in productivity. Till recently, the existing auto-ID technologies could not
meet the challenges posed by the manufacturing environment to make for viable
solutions. For example, in a made-to- order manufacturing scenario, the sequence
of operations for two similar products or sub-assemblies may be radically different
even though these may have an identical appearance. As in the case of a computer
manufacturer like Dell, two units that look identical can have different configurations
and processing requirements. Line operators cannot be expected to memorise all
the subtleties of such variants and the corresponding sub-process steps. Thereafter,
being able to recall and perform these steps correctly is a tall order. To achieve
the highest productivity, different sub-process steps must be communicated in
the context of the product currently at the workstation. Also, this information
must be updated in real-time on the arrival of a different type at the same
workstation. In the RFID-enabled scenario, the kit will be automatically identified
with the tag, and the data will then be used to actuate a mechanism which displays
or highlights the relevant process steps. This kind of an application has been
deployed by Harley-Davidson in their assembly operations.
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On the assembly line
In an automobile paint shop or fabrication line, the identification of a particular
product (model, colour, order, lot number, etc) is vital to deliver the desired
result by initiating the appropriate settings of the equipment (painting robots,
PLC, etc). Traditionally, these production lines have worked with centralised
control, strict lot discipline and some equipment-level redundancies. These
are optimised to meet the demand on a best-effort basis since frequent changes
to the process settings involve line stoppages and manual interventions, both
of which are costly. Increasing redundancies increase flexibility, but is not
desirable as it drives up the capital and running costs.
When a company is producing multiple models and variants with different colour
combinations and has to deal with fluctuating demand, managing the fabrication
and painting operations becomes a challenge because it needs frequent changeovers.
RFID can be used to create a scenario wherein the body is automatically identified
at each workstation, and the corresponding process settings are relayed to the
respective controllers. This does away with the need for human intervention,
lowers running costs, and eliminates the possibility of errors. It also shortens
the lead-time of switchover and improves the productive time.
Several automobile companies including Toyota, Volkswagen
and Ford are already benefitting from similar applications in fabrication and
painting processes. Closer home, Tata Motors, Maruti and Mahindra are in the
process of deploying RFID at their paint shops.
Preventing errors
In a mixed flow assembly line, the possibility of mistakes is fairly high. Picking
and assembling wrong components could make the end product non-saleable, necessitating
rework. Frequent rework drives up costs and throws productivity targets and
schedules off track. Traditional poka-yokes cannot be used in all such cases
as there may not be any variations in the outer dimensions or shape.
For example, in an assembly line, cars of the same make and model may come with
multiple options in tyres and brake assemblies. A line operator can mistakenly
assemble an incorrect wheel or tyre unless he is careful enough to verify the
component with the model before assembling. But manual verification takes time
and slows down the assembly line; it also increases the likelihood of mistakes
especially if the operator is inexperienced or careless. If the number of variants
is large, the possibility of errors is higher, so an error proofing application
is used. In this, the operator has to validate the component before assembling.
This validation involves checking the component’s item code against the
bill of material of the main assembly; it is facilitated by bar codes or RFID.
However, bar code scanning requires manual intervention; it is therefore highly
likely that the error proofing will be bypassed whenever there is a need to
improve the throughput to meet a sudden spike in demand.
With RFID, the validation will be carried out in real-time without any manual
intervention. Each of the components at the error proofing station and the main
assembly is tagged with an RFID. Pick validation is carried out by reading the
assembly tag first and then checking the component ID against it. In case validation
fails, an alarm is generated so that the operator can take corrective action.
For smaller components where tagging is not feasible, the different types of
components are kept in a pigeonhole rack. This rack has light bulbs at each
of the pigeonholes which light up depending upon the configuration of the parts
to be picked. The light bulbs are actuated by the error proofing system with
the help of the data read from the RFID tag on the main assembly.
Parts replenishment: the electronic kanban
Kanbans have long been used in lean manufacturing operations following the just-in-time
replenishment model. These work on the principle of demand driving the supply
through a re-order card or any other method of triggering the pull based on
actual use of material. Kanbans are attached to the actual product or the containers
at the point of use, and have information about the parts (name, part number,
quantity, source, destination, etc). The suppliers or stores replenish the components
in pre-decided quantities after obtaining the data from the cards. In an electronic
Kanban system, the cards will be replaced with RFID tags. The order data is
made available to the suppliers or stores as soon as a particular lot is used
up at the assembly line. RFID-based electronic Kanbans are being used at Ford
Motors and General Electric (power systems division) for replenishment of parts
for their factories from their suppliers.
RFID can help create a lean, agile and flexible manufacturing set-up geared
to cater to the ever-changing demand of the markets of the future. However,
it is certainly not the killer application or a panacea that will revolutionise
manufacturing by solving all problems. Almost all RFID solutions will work with
the existing enterprise applications, manufacturing execution systems, or level
one electronic control systems. In the absence of these systems RFID can work
very little on its own. Wherever there are intrinsic benefits to be derived
from RFID, it has the potential to become the prime mover of a revolution in
manufacturing. The key is to get the overall objectives clear, identify the
right use-cases, and work towards realising the big picture. As most of the
applications require multi-domain expertise, selection of the right implementation
partner with the most appropriate experience and expertise is critical for success.
The author is with the RFID Solutions Team of Tata Consultancy
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