Chain oil drips on the component

The incident being referred is from the automobile industry. The body is painted and then taken into the oven for curing the paint.

The transportation from the paint shop to the curing oven is through conveyor chains, from which the components are suspended. The components moving on these chains enter the curing oven. Needless to say, the chains need to be lubricated. If sufficient and timely lubrication is carried out, the performance of conveyor improves and the chain life gets extended. On the other hand, if there is improper lubrication then the movement becomes erratic, friction increases, power consumption increases etc.

The incident dates back to when I was working with the manufacturer of chain lubricants, among other things. We received a complaint from one of the reputed manufacturers that their chain lubricant was thin, did not have enough adhesiveness and hence was dripping on to the component below. This led to the presence of oil on the painted component when it was entering the oven and after curing they could observe streaks on the painted surface which, obviously, was unacceptable.

On visiting the customer, we noticed that every 5th component was having oil streak which means that oil was dripping on approximately every fifth component.

The possible reasons were quickly listed on a fishbone diagram – the classic man, material, machine & method template.

• Man: The system adopted at customer’s end was a centralized lubrication system which reduces human intervention and thus, causes of failure.
• Man: It was verified that the correct product was transferred from our packaging to a reservoir of the centralized lubrication system.
• Machine: the nozzles were verified to be ok.
• Machine: the spray from the nozzle was correctly directed at chain parts.
• Machine: there were no leakages from the piping/ tubing of a centralized lubrication system.
• Material: The batch sheets at our end confirmed that the product was produced as per recommended SOP and was meeting all the specified parameters.
• Material: The product was within its shelf life i.e., not an expired product.
• Material: The customer was using the correct product. The seal was verified ruling out pilferage. And a sample from their end was tested in our lab to confirm that product was not contaminated and its parameters were matching the batch parameters.
• Method: correct spray rate was being used.

Last two points made us re-think and slowly it dawned on us.

Earlier the customer was using a mineral oil-based product and our product was synthetic. It made sense that the spray rate would have to be modified to suit our synthetic product.

Though the viscosity of our product was the same as that of oil earlier used by them but the lubricity was different since it was made from a synthetic base. We had to take some trial and error adjustment to the spray rate. And ultimately, at about 75% of the earlier rate, we reached a stage where there was no dripping.

The problem was solved and the customer got an additional advantage - on account of reduced spray rate, they saved on lubrication cost.