Bespoke encoders handle the heat for Kodak

Kodak's photographic paper manufacturing plant at Harrow has achieved zero downtime using bespoke replacement high-temperature encoders.

Kodak's photographic paper manufacturing plant at Harrow has achieved zero downtime using bespoke replacement high-temperature encoders from Wyko.

The harsh working environment caused standard high-temperature shaft-mounted encoders to fail after only two months use with the potential to cause over GBP 6000 worth of downtime.

The new encoders are designed and built to match the application conditions using high temperature compatible components, aluminium construction and improved sealing.

Kodak manufactures photographic paper in continuous batches that can take several days to process; large rolls of base paper are fed through a kilometre long track that spans four storeys and ends in the final drying section, which has an ambient temperature between 60 and 70C.

Standard high-temperature incremental encoders were being used to provide positional feedback information from several 1.5m width rollers used for speed and web tension control.

The high ambient temperature meant that grease lubrication in the bearings was breaking down, leading to seizure.

The standard units were being replaced every two months in an operation that took around 1.5h.

If a natural break in production was not available, the downtime costs are GBP 70 a minute; hence the replacement Wyko items provide a potential GBP 6000 saving every two months.

Without effective feedback, consistent exposure of the paper and the smooth winding on and off of the paper rolls is at risk, hence if an encoder starts to fail, it has to replaced at the first opportunity.

If a seizure occurs during a process batch the result is even worse, as the entire process is carried out in the dark to avoid exposure of the chemicals and paper.

If light enters the process area during a batch process the whole batch can be lost causing thousands of pounds to be lost in production time and materials.

In order to avoid both frequent replacements and breakdowns, Wyko has supplied bespoke encoders that are rated to operate in a 1200C ambient temperature, using high-temperature sealed grease-lubricated bearings, aluminium component mounting discs to dissipate heat and machined Aluminium cases.

The encoders are equipped with the latest generation ASIC and employ an autocalibration feature to offset the effects of large variations in temperature.

All but the prototype encoder are still in operation after 12 months and carry a 3-year warranty.

The mounting design has also been changed from an awkward collet arrangement to a slot and grub screw fixing, making fitting far easier and possible in limited lighting conditions.

An added benefit of the bespoke design is that the new encoder has been designed to fit both of the two sizes of standard encoder employed on the Kodak machine using a simple 24mm sleeve.

The pin arrangement of the original units has also been matched so the new encoders can be fitted ready to plug and play.

Only one encoder type is now kept in stock and routine replacements take minutes rather than 1.5h.

Kodak is so pleased with the result of Wyko's encoder on this machine that they have employed similar solutions on other equipment such as mixers and seen similar savings in downtime and lost production.

Victor Harris of Wyko's Electronic Repairs Division comments: "The encoder market has suffered in a similar way to other industrial products that have become commodities, prices have been driven down and quality has suffered.

Standard encoders are often part of a package sold on cost and although they work adequately in mild operating conditions, any excess vibration, temperature or ingress of moisture can cause failure.

The need to find an alternative arose first from Wyko's industrial electronics repair business, our own requirements meant that we had to be able to supply a flexible and robust design of encoder that could be assembled to meet varying cost and environmental demands.

The product we are now able to offer has many options such as bespoke circuits with very high temperature mounts, sealing up to IP68 can be achieved and a variety of machined cases up to marine grade stainless steel.

Having achieved this, demand is extremely high for the product and Kodak is a good example of a finished unit in action".

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