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Advantages of Flexible Assembly Automation Systems


Posted in Automation by emdtadmin on November 1, 2009

Careful planning and design of an automated production system will optimise return on investment throughout the entire lifecycle of a product. This article explains how.


Diversity in one system

Automated assembly of medical products is today the standard way of producing goods. The requirements of a highly regulated market in terms of product safety and the need to reduce costs mean that there is almost no alternative to automated production of parts, at least for mass/high volumes.

There has been no significant change in technical and user requirement specifications for assembly systems in recent years. What has changed is the variety of products and parts that must be produced with the same assembly system. In many cases, these various products differ greatly with regard to components and lot sizes. Another remarkable change concerns the wide selection of possible automated assembly systems that are available. Once, purchasing companies always wanted cam driven systems, which are not flexible, for their assembly tasks. Today, they ask for systems with high flexibility because they have learned that in certain circumstances spending more on purchasing a flexible system can be worth it.

Darragh Staunton at Automation Tooling Systems Munich, asserts, “Flexible automation can be a powerful instrument to improve profitability and to reduce risk. Although flexible systems may cause some higher costs for purchase and installation, the option to adapt a system to current requirements can be economically and technically convincing.”

As pointed out in a previous article,1 the better a project is planned, the more effectively the automation company can build a flexible high tech production system. One of the important questions an assembly system manufacturer has to ask during the planning phase is: How much flexibility is necessary to achieve a good ratio between the required flexibility, which may cost more than standard technology with no or less flexibility, and the calculated return on investment over the lifetime of the system and certainly of the produced product?

Try to plan for the unexpected

Figure 1: A flexible system can follow productivity requirements as necessary.
(click to enlarge)

The typical development of lot sizes during a product’s lifetime is that the required quantity of parts is smaller at the beginning, rising to the maximum for a period and then decreasing when the product comes to the end of its lifecycle. The task is to support this development curve by selecting the right production technology (Figure 1). If successful, earnings during the entire product lifecycle can be optimised significantly while risk is mitigated. The following describes how this can be achieved.

In this scenario, an installed production system was planned well and now produces medical parts that are assembled from a number of single parts into one complex medical product. During the planning phase, client and system manufacturer considered carefully how much flexibility is necessary and where in the production line this flexibility is reasonably to be installed. As mentioned, lot sizes are low in the beginning and grow steadily as the product gains market acceptance as a good product. As the number of required parts reaches the expected high quantity, the assembly system reaches the limit of its production capacity. A decision must then be made on how this can be addressed. The “normal” way would be to purchase a second system, but the flexible way would be to modify the existing one to obtain higher productivity from it. This can be achieved in various ways.

The drive system. In most cases the level of flexibility is based on the transport system that is used to move the parts through the single machining stations. If work piece carriers are rigidly coupled with the drive system, it is highly unlikely that any flexibility will be possible by way of adding optional components or production steps to enhance productivity.

Figure 2: A linear motor based modular conveyor system that provides a high level of flexibility. Carriers can be programmed singularly and each can operate independently in terms of in positioning, acceleration, speed and direction.

However, if the drive system is flexible, if it allows additional stops or additional movements back and forth, and if there is some space available in the production line, additional machining stations can be added, which will solve, in most cases, the need to increase productivity with practicable changes in the assembly system.

Step-by-step approach. Trying to plan for the unexpected requires the assembly system manufacturer to be able to supply adequate technology so that the system can be open to various changes. The assembly system can be extended to increase productivity in several steps, which allows current specifications to be met and a reduction in initial investment, which mitigates risk. This will also cover a situation when the quantity of parts needed to be produced is lower than expected. A production system built in this way can remain in operation indefinitely and the lower investment costs help to keep projects in the profit zone, even if the product sales do not reach expectations. Typical ways to extend an automation system include increasing the number of parts in the work piece carrier, cloning machining stations and increasing work speed.

Supplementary stations. A flexible system can also be expanded for the production of other types of product/line extensions not expected during the planning phase (Figure 2). This may affect the layout of a system in a significant way. Thorough planning during an early project phase will allow supplementary stations to be added to adapt the entire systems to additional tasks.

Reusability. In addition, elaborate flexible production systems offer the advantage of reusability over other technical solutions, and this can affect single components of a production line as well as an entire system. A workstation that is added to increase productivity can be removed when it is no longer required and added to another system. At the end of a product lifecycle, with relatively minor retrofit measures, an assembly system may be used for completely different products.

Qualification. This leads directly to another advantage of a flexible system: significantly reduced effort and cost for qualification and validation to meet legal requirements.

Many automation system specialists have experience of introducing product diversity that delivers a positive influence on assembly automation. But it will remain the purchaser’s responsibility to decide if flexibility is necessary and reasonable, and if so, how much. This is the new challenge for the medical device industry.

 
Reference

1. A. Sedlak, “How to Effectively Partner With An Automation Company,” Medical Device Technology, 18, 7 (2007).

Alexander Sedlak is Manager Technical Marketing, ATS Automation Tooling Systems Munich GmbH & Co. KG, Heimstetten, Germany, tel. +49 89 4272 210, e-mail: europe@atsautomation.com, www.atsautomation.com



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