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DC618 2012-11-02

Reman or Retrofit

Reman or Retrofit

Phrases on Component

Reliable operation of automation equipment nearing the end of its operational life is a very high risk strategy. Reducing productivity and increasing production costs are classic symptoms of this mode of operation for the end-user. What are the answers? Paul Hickman of Bosch Rexroth offers a solution.

There are three distinct phases in the product life cycle of automation equipment, early-life phase, useful-life phase and wear-out phase. Each phase has unique qualities requiring different support strategies. However, for equipment operating in the “wear-out” phase it is possible to “push” the device back into useful-life phase – thus extending the overall length of operational benefits to the end-user.

In the useful-life phase the unit, be it a drive, motor, control equipment or HMI screen for example, is in standard production and spares are freely available. During this phase operators can expect a fairly low but constant failure rate and a high level of machine availability.

The useful-life phase is characterised by lower production costs, due to reduced machine failures. When supported with planned maintenance schedules, no unexpected costs are incurred. Spares usage can be accurately calculated, maintained and budgeted for. Manufacturers need only carry the spares they need, which in turn reduces lower inventory costs.

Typically, the wear-out phase for a product begins circa 8-10 years after launch. Drives and motors, for example, will go into the service-phase 10 years after launch while HMIs will go into service within five years.

In the wear-out phase, we begin to see the characteristics of increasing failure rate, which in turn leads to increasing downtime and production costs. Spares usage is likely to increase as will costs. Repair of equipment becomes increasingly risky and less cost-effective (see figure 1).

The increased risk comes from the repair of individual components within a unit in order to return it to operation. Other components within the unit will have similar operational hours to the failed component. Therefore, a high probability exists that another component will subsequently fail. Continuing to repair a unit during its wear-out phase will result in “multiple repeat” failures of that unit. This is a well-known effect of ageing systems and simply results in higher operational costs.

During the wear-out phase, end-users are faced with the possibility of significant capital investment to return production machines to their previous levels of availability. One major end-user for example was recently facing a capital cost of circa £20 million for the replacement of more than 1,500 drives, motors, HMI controls and power supply equipment in one plant.

Faced with this sort of capital investment many end-users of automation equipment are turning to an alternative solution for ageing equipment nearing the end of its serviceable life, namely remanufacture.

Remanufacture can effectively extend the useful life of a product. Critically, this option involves the easy exchange of the unit with machine wiring and software systems unaffected. For the user, this means lower risk with no system disturbance.

What’s more “REMAN” can offer fast exchange time with the process being carried out by the end-user during planned shutdown which means no loss of production. Large scale unit exchange can be planned and staggered to meet customer schedules. For example, a bank of 4-5 drives can be exchanged in an hour.

Reman’ involves the stripdown and cleaning of units, with wearable parts being replaced with original Rexroth specified components. Units are updated to the latest levels to achieve optimum performance and reliability characteristic. Once this process is completed, a functional operation test is carried out in accordance with company quality procedures. An extended warranty of two years is offered on all remanufactured parts which can be increased to five years if required, subject to conditions.

For the end user the benefits can include no re-engineering costs, due to like-for-like product replacement and no re-training of operators to use or maintain new equipment. What’s more, end users should benefit from reduced manufacturing costs and improved equipment uptime with no increase in spares, which should put a ceiling on capital expenditure.

A further option is called Reman’ +5 which offers end-users a further five years through the unit’s service life. This option not only extends the product lifetime, but also guarantees component parts.

However, an optimum point exists where reman’ is possible (see figure 2). Beyond this point, typically when replacement spares products are no longer available, retrofit is the only answer.

The key issue for end-users however is clearly cost. Whilst investing in new product may offer a cheaper option from a unit cost view, it is important to take into account associated costs. New products will often mean a re-engineered solution, new wiring, production downtime, replacement of all spares and retraining, with the added risks associated with the debugging of new software.

Reman’ on the other hand takes out a unit and replaces with a like-for-like unit with all cabling and software being the same, ultimately offering a quicker more effective solution.


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Melanie  Bright
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