It is bad engineering and worse management practice to look only at benefits and to ignore limitations. Handling systems, at times, have consequences that may be distinctly negative. These too, should be evaluated before the changes are adopted. Some such possible disadvantages are
1) Additional capital investment:
It must be verified that the cost of the handling system is more attractively invested in the system under consideration than in any other part of the business. It should be assured that the gains expected are not based upon a more mechanized system v/s present practice, but rather the proposed new system v/s the best version of present practice.
2) Loss of flexibility
Proposed system must be flexible enough to be economically and quickly adapted to the likely range of changes in the product or production techniques. If not, change over cost and time loss must be included in the evaluation, or it must be shown that the investment will be satisfactorily recovered before the proposed handling system will require modification.
3) Vulnerability to downtime;
Since a handling system is a composite of mechanical and electrical machinery and controls, it must be recognized that it may break down at any times. What happens than how long will it take to get back to service and what will be done when repairs are being made. If this is serious-, the handling system must be re-design to provide for better reliability, for alternate handling techniques in event of breakdown or for in-process- storage that can feed subsequent operations while be system is being repaired. All of these can result in additional costs that must be charged against the handling system.
4) Maintenance
If it is planned to install additional handling mechanization, almost surely it will be necessary to take on more maintenance. This may mean the addition of new maintenance skills, or a provision for obtaining them when needed. It may be that extra pieces of handling equipment should be provided for use during downtime or breakdowns. It may be necessary to plan for periodic overhauls by skilled technicians. It may be necessary to carry a large supply of repairs parts, or a new or enlarged maintenance facility and staff may be required.
5) Auxiliary equipment costs
Frequently a new handling system carries with it requirements that involve hidden or unrecognized costs for auxiliary equipment or service, e.g. adopting a fork lift truck means more than taking on the mobile equipment, its power supply, and its maintenance. The point of identifying this drawback is neither to discourage nor disparage the adaptation of modern handling methods, but to emphasize that a careful balance of the total benefits and limitations is required before wise decisions can be reached.